June will bring us hot and humid weather. In turf this will mean brown patch disease starting to show up. The following is information on this disease from NC State University.
Brown patch is the most common and damaging disease of tall fescue in Delaware. The symptoms of brown patch are roughly circular patches that are brown, tan, or yellow in color, ranging from 6 inches to several feet in diameter. The affected leaves typically remain upright, and lesions are evident on the leaves which are tan in color, have a dark brown border, and are irregular in shape. When the leaves are wet or humidity is high, small amounts of gray cottony growth, called mycelium, may be seen growing amongst affected leaves in the turf canopy.
Brown patch is most severe during extended periods of hot, humid weather. The disease can begin to develop when night temperatures exceed 60°F, but is most severe when low and high temperatures are above 70°F and 90°F, respectively. Brown patch also requires at least 10 to 12 hours of continuous leaf wetness in order to develop. Poor soil drainage, lack of air movement, shade, cloudy weather, heavy dew, over-watering, and watering in late afternoon favor prolonged leaf wetness and increased disease severity. Brown patch is particularly severe in turf that has been fertilized with excessive nitrogen. Inadequate levels of phosphorus and potassium have also been shown to contribute to injury from this disease.
Varieties of tall fescue vary widely in their susceptibility to brown patch. Selection of a tall fescue variety with a high level of brown patch resistance is a critical first step in any management program. Current lists of varieties with good brown patch resistance that perform well in Delaware can be found at the National Turfgrass Evaluation Program (www.ntep.org).
High levels of available nitrogen favor the spread of brown patch. Nitrogen induces tall fescue to produce soft, lush leaf tissue that is easily infected by the brown patch pathogen. Excessive foliar growth also results in a dense canopy that holds moisture and humidity for extended periods of time.
In general, tall fescue should not be fertilized with nitrogen in late spring or summer so as to discourage brown patch development. Following this type of program will result in yellowing and thinning of tall fescue during the summer as nitrogen is depleted from the soil. Turf in this condition is very resistant to brown patch, but may not be acceptable from an aesthetic standpoint. If fungicides are used to protect tall fescue from brown patch, then application of small amounts of slow-release nitrogen (≤ 0.25 lb N/1000 ft2/month) during the summer can help improve the quality of tall fescue turf. This practice, however, will encourage the development of other diseases, such as gray leaf spot and Pythium blight. Tall fescue that is fertilized during the summer should be monitored frequently for these diseases so that they may be controlled before widespread damage occurs.
Avoiding prolonged periods of leaf wetness will drastically reduce the severity of brown patch. Leaf wetness can originate from either irrigation or dew. To minimize leaf wetness, do not irrigate the turf on a daily basis. Instead, water deep and infrequent, every 3 to 4 days to a depth of 6 to 8 inches. The timing of irrigation is also critical; it is best to irrigate early in the morning, just before sunrise. This removes large droplets of dew and guttation water from the leaves and speeds drying of the foliage after sunrise. Avoid watering after sunrise or in the late afternoon/evening, as this will increase the duration of leaf wetness. For intensely managed athletic fields, daily removal of morning dew can help to reduce leaf wetness duration and minimize brown patch development. This can be accomplished by mowing, dragging a hose or rope over the turf, or running the irrigation system for a short time.
Brown patch is particularly severe in soils that are wet and compacted. Providing adequate surface and subsurface drainage, and minimizing compaction through regular aerification, will help to minimize the development of this disease.
Fungicides are effective for brown patch control, and can be applied on a preventative or curative basis. Fungicides vary widely in residual control, or the number of days of brown patch control after application. Fungicides containing the active ingredients azoxystrobin (Heritage 50WG, 0.2 oz/1000 ft2), pyraclostrobin (Insignia, 0.7 oz/1000 ft2) or flutolanil (Prostar 70WP, 2.25 oz/1000 ft2; Systar 80WDG, 3 oz/1000 ft2) consistently provide 28 days of brown patch control, even under severe conditions. For homeowner applications, products containing the thiophanate-methyl are sold under various brand names at garden stores and provide good brown patch control, but these products must be re-applied every 14 days.
Curative fungicide applications for brown patch may not be effective during periods of hot weather because tall fescue does not grow well during these conditions and will recover from brown patch injury very slowly. For this reason, a preventive fungicide program should be considered on tall fescue when conditions are favorable for disease development.
Information from "Managing Diseases of Tall Fescue" Turfgrass Disease Information Note 6 (TURF-006) by Lane P. Tredway, Extension Turfgrass Pathologist, North Carolina State University. Go to the following website for the full fact sheet: http://www.ces.ncsu.edu/depts/pp/notes/Turfgrass/Turf006/Turf006.html#BROWN_PATCHtarget
Saturday, May 31, 2008
Landscape and Nursery - Ambrosia Beetles
The ambrosia beetle, Xylosanrus germanus, is showing up in a wider range of plant material. Be on the watch for this pest as it can be very damaging, especially in nurseries. The following is a report from the University of Maryland.
University of Maryland Extension personnel have found Ambrosia beetles in London plane, river birch, zelkova, dogwood, sugar maple, sweet bay magnolia, Styrax and now golden rain trees. We Be sure you examine the trees in your nursery for the characteristic pencil-like thread of wood and frass projecting from your trees.
Top picture ambrosia beetle, bottom picture, characteristic damage.
Control: The beetles of the first generation are in the larval stage at this time. You can apply Onyx or Astro now to try and control the second generation that will come out at the end of June. There will already be damage from the first generation of beetles.
Information from the May 30, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
University of Maryland Extension personnel have found Ambrosia beetles in London plane, river birch, zelkova, dogwood, sugar maple, sweet bay magnolia, Styrax and now golden rain trees. We Be sure you examine the trees in your nursery for the characteristic pencil-like thread of wood and frass projecting from your trees.
Top picture ambrosia beetle, bottom picture, characteristic damage.Control: The beetles of the first generation are in the larval stage at this time. You can apply Onyx or Astro now to try and control the second generation that will come out at the end of June. There will already be damage from the first generation of beetles.
Information from the May 30, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Friday, May 30, 2008
Landscape and Nursery - Scales to Watch For
The following is information on some scale pests you should watch for and apply control measures in the next few weeks.
Two species of Lecanium scales are problematic in our landscapes and the next few weeks offer good management opportunities. Fletcher scale (Parthenolecanium fletcheri) affects a wide variety of coniferous plants such as Taxus, arborvitae, junipers, and even Taxodium spp.. European fruit lecanium (Parthenolecanium corni) affects a broad range of broadleaved woody plants such as redbud, hawthorn, dogwood, and oak.
These soft scales appear like little brown lumps grouped along tree branches as adults. They feed in the phloem (on plant sap). Honeydew rain (clear sticky substance that is scale excrement) from the developing nymphs and adults of both species was noticeable in early May. A black fungus called sooty mold often grows on the honeydew.
Lecanium scales have one generation per year. Crawlers will start to appear in early June and will migrate to the undersides of leaves/needles and spend the summer months there then migrate back to the branches to spend the fall and winter. They will resume growth, mate, and lay eggs the following spring.
The settled crawler stage is the best time to control lecanium scales. Many insecticidal products are registered for this purpose but horticultural oils work quite well. Occasionally, a re-application is needed about 3 weeks after the initial application to ensure that all crawlers have emerged. Many naturally occurring parasites and predators often control lecanium scales,
but parasites have been less active recently on a regional level. Still, many predators such as lady beetles feed on them. Insecticides sprayed later provide only limited effectiveness against nymphs and soil systemic insecticide applications must be properly timed.
Information from Casey Sclar, IPM Coordinator, Longwood Gardens
Two species of Lecanium scales are problematic in our landscapes and the next few weeks offer good management opportunities. Fletcher scale (Parthenolecanium fletcheri) affects a wide variety of coniferous plants such as Taxus, arborvitae, junipers, and even Taxodium spp.. European fruit lecanium (Parthenolecanium corni) affects a broad range of broadleaved woody plants such as redbud, hawthorn, dogwood, and oak.
These soft scales appear like little brown lumps grouped along tree branches as adults. They feed in the phloem (on plant sap). Honeydew rain (clear sticky substance that is scale excrement) from the developing nymphs and adults of both species was noticeable in early May. A black fungus called sooty mold often grows on the honeydew.
Lecanium scales have one generation per year. Crawlers will start to appear in early June and will migrate to the undersides of leaves/needles and spend the summer months there then migrate back to the branches to spend the fall and winter. They will resume growth, mate, and lay eggs the following spring.
The settled crawler stage is the best time to control lecanium scales. Many insecticidal products are registered for this purpose but horticultural oils work quite well. Occasionally, a re-application is needed about 3 weeks after the initial application to ensure that all crawlers have emerged. Many naturally occurring parasites and predators often control lecanium scales,
but parasites have been less active recently on a regional level. Still, many predators such as lady beetles feed on them. Insecticides sprayed later provide only limited effectiveness against nymphs and soil systemic insecticide applications must be properly timed.
Information from Casey Sclar, IPM Coordinator, Longwood Gardens
Turf - Using Spent Mushroom Soil as an Ammendment
We ge a lot of questions on the use of mushroom soil on turf. The following are guidelines for selecting a mushroom soil from Penn State University.
Selecting a Spent Mushroom Soil (SMS) product - some guidelines to follow
Although many of the ingredients that go into SMS products are similar, not all products are alike. Quality of SMS can vary depending on the ingredients, how it is produced, and how it is treated after it comes out of the mushroom production houses. Because of potential quality differences among products, it is important to have some basis for determining suitability for use on turf. Ideally, the product you intend to use has been field tested and used successfully by other turf managers. Using a SMS product with a proven track record can take some of the guess work out of the selection process provided that it is consistent from batch to batch.
Whether you are using a field-tested SMS or one that has never been used on turf, be sure to obtain a sample of the product prior to use and examine it for undesirable objects and peculiar or offensive odors. If the producer does not have an analysis of chemical and physical properties, submit a representative sample to a laboratory that will conduct appropriate tests and provide recommendations that you can understand. Penn State's Agricultural Analytical Services Laboratory offers a compost testing service with several options for analysis of SMS products. Information on the compost testing program and other soil testing programs can be accessed at http://www.aasl.psu.edu/.
Some basic guidelines for evaluating the suitability of SMS products for use on turf follows.
General appearance: The appearance of fresh SMS is similar to peat, with a light brown color and a light, fibrous texture. Weathered SMS products should resemble dark topsoil and have a loose, crumbly structure. All SMS products to be used on turf should be free of large stones, plastic, and other objectionable objects.
Particle size: The size of SMS particles can vary depending on how it is produced. For use in surface applications on athletic fields, lawns, or golf course fairways, the SMS should pass through a 1/2 inch screen (or be of similar size). Composts with slightly larger particles can be used as soil amendments if thoroughly tilled into the soil prior to seeding or sodding.
Odor: A good quality SMS product should have an 'earthy' aroma. It should not emit peculiar or offensive odors such as those associated sulfur or rotten eggs. Also, it should not emit a strong ammonia odor. Peculiar odors may be an indication that the product is not mature (not fully composted). Immature SMS may have adverse effects on turf and should not be used.
Weed seeds: If the SMS product has been properly composted and stored, weed seed contamination will not be a problem. On rare occasions, SMS products are stored for long periods and neglected. In such cases, weed plants can begin to grow in the piles. If these weeds are not controlled immediately they can deposit seeds in the product.
Although a few weed seeds do not necessarily preclude the use of a SMS product as a soil amendment for turf, products containing large amounts of weed seeds are unacceptable. If possible, inspect the production site to make sure that weeds are not growing in and around the SMS piles.
Moisture content: The moisture content of a SMS product is important where uniform application and good mixing with soil is desired. Products with moisture contents between 30 and 50% are usually ideal for handling, surface applications, and soil incorporation. Wet products (greater than 60% moisture content) tend to form clumps and do not spread evenly when applied to turf surfaces. Tilling wet material into soil may result in poor mixing with soil and uneven turf establishment. Wet SMS is heavy and difficult to handle.
A quick field test that you can use to determine suitable water content of SMS is to squeeze the product in the palm of your hand and watch for water oozing from the product. If water drips from the SMS upon squeezing, then the product may be too wet, and further drying should improve product handling. If the SMS remains together when you release your grip and no water drips from the product, it probably has suitable water content for spreading and mixing with soil.
Organic matter and ash content: When using SMS as an organic matter supplement, keep in mind that not all of the product is organic matter. Spent mushroom substrate products typically contain between 40 and 60% organic matter on a dry weight basis. Organic matter content can be determined by a lab test. The most common procedure employed by laboratories, "loss on ignition", considers everything that is combustible as organic matter.
Some test labs report a value called 'ash content'. Ash is the mineral matter that remains after the SMS sample has been subjected to extremely high temperatures in a furnace. Assuming that everything burned-off in the furnace is organic matter, the percentage of ash in the sample can be subtracted from 100 to provide an estimate of percent organic matter. For example, an ash content of 40% indicates that there is an estimated 60% organic matter in the sample.
Carbon to nitrogen ratio: The amount of carbon (C) relative to the amount of nitrogen (N) in a SMS product is an important indicator of nitrogen availability. The carbon to nitrogen (C:N) ratio of a product should be 30:1 or below. If above 35:1, soil microorganisms can immobilize nitrogen, making it unavailable to the turf. Most SMS products have C:N ratios well below 30:1.
Nutrients: When compared with fertilizers, SMS products generally contain low amounts of plant nutrients. Whereas a small amount of quick-release nitrogen (ammonium) is present in SMS, most nitrogen is in the organic form and is slowly available to turf. Test results of SMS products typically indicate 1.5 to 3% total nitrogen on a dry weight basis. Other nutrients found in SMS include phosphorus (0.5 to 2.0 %, reported as P2O5), potassium (1.0 to 3.0%, reported as K2O), calcium (3 to 6%), and magnesium (0.4 to 1.0%).
Typically, significant amounts of SMS must be applied to supply all or most of the turf's nutrient requirements. In some cases, this can be achieved for short durations (8 to 10 weeks) with surface applications of ¼ to ½ inch of SMS, aerated into the soil surface. In many cases, a 1 or 2 inch layer of SMS tilled 4 to 6 inches into soil can supply all of the nutrients necessary for turf growth and development for an entire year and possibly longer.
pH: The pH of most SMS products is between 6.0 and 8.0, a range favorable for turf root growth. On rare occasion, a product may fall outside of this range. The pH of organic amendments may be detrimental to turf when very high (greater than 8.5) or very low (less than 5.5). Extremes in pH may result in reduced availability of some plant nutrients and/or aluminum toxicity problems. Fortunately, most soils are buffered against rapid and drastic changes in pH and even organic amendments with extremes in pH may not alter the overall soil pH a great deal. To be on the safe side, however, try using products with a pH between 6.0 and 8.0.
Soluble salts: Soluble salts may be higher in SMS products than in other types of organic amendments. Whereas, excess soluble salts can cause turf injury, research conducted at Penn State shows that good quality SMS products do not contain salt levels high enough to damage turf. If you have questions regarding the soluble salt content of a particular SMS product and how safe it is to use on turf, send the product to a soil test lab that performs soluble salts analyses on composts.
Penn State's Agricultural Analytical Services Lab and other laboratories measure soluble salt content in SMS by saturating the sample with water, extracting the solution from the sample, and determining salt content by measuring the electrical conductivity of the solution. The higher the electrical conductivity of the solution, the higher is the salt content of the SMS. Soluble salt content is most often reported in units of electrical conductivity (mmhos/cm or dS/m).
From "USING SPENT MUSHROOM SUBSTRATE (MUSHROOM SOIL) AS A SOIL AMENDMENT TO IMPROVE TURF" Department of Crop and Soil Sciences - Cooperative Extension, Penn State University http://turfgrassmanagement.psu.edu/spentmushroomsubstrate.cfm
Selecting a Spent Mushroom Soil (SMS) product - some guidelines to follow
Although many of the ingredients that go into SMS products are similar, not all products are alike. Quality of SMS can vary depending on the ingredients, how it is produced, and how it is treated after it comes out of the mushroom production houses. Because of potential quality differences among products, it is important to have some basis for determining suitability for use on turf. Ideally, the product you intend to use has been field tested and used successfully by other turf managers. Using a SMS product with a proven track record can take some of the guess work out of the selection process provided that it is consistent from batch to batch.
Whether you are using a field-tested SMS or one that has never been used on turf, be sure to obtain a sample of the product prior to use and examine it for undesirable objects and peculiar or offensive odors. If the producer does not have an analysis of chemical and physical properties, submit a representative sample to a laboratory that will conduct appropriate tests and provide recommendations that you can understand. Penn State's Agricultural Analytical Services Laboratory offers a compost testing service with several options for analysis of SMS products. Information on the compost testing program and other soil testing programs can be accessed at http://www.aasl.psu.edu/.
Some basic guidelines for evaluating the suitability of SMS products for use on turf follows.
General appearance: The appearance of fresh SMS is similar to peat, with a light brown color and a light, fibrous texture. Weathered SMS products should resemble dark topsoil and have a loose, crumbly structure. All SMS products to be used on turf should be free of large stones, plastic, and other objectionable objects.
Particle size: The size of SMS particles can vary depending on how it is produced. For use in surface applications on athletic fields, lawns, or golf course fairways, the SMS should pass through a 1/2 inch screen (or be of similar size). Composts with slightly larger particles can be used as soil amendments if thoroughly tilled into the soil prior to seeding or sodding.
Odor: A good quality SMS product should have an 'earthy' aroma. It should not emit peculiar or offensive odors such as those associated sulfur or rotten eggs. Also, it should not emit a strong ammonia odor. Peculiar odors may be an indication that the product is not mature (not fully composted). Immature SMS may have adverse effects on turf and should not be used.
Weed seeds: If the SMS product has been properly composted and stored, weed seed contamination will not be a problem. On rare occasions, SMS products are stored for long periods and neglected. In such cases, weed plants can begin to grow in the piles. If these weeds are not controlled immediately they can deposit seeds in the product.
Although a few weed seeds do not necessarily preclude the use of a SMS product as a soil amendment for turf, products containing large amounts of weed seeds are unacceptable. If possible, inspect the production site to make sure that weeds are not growing in and around the SMS piles.
Moisture content: The moisture content of a SMS product is important where uniform application and good mixing with soil is desired. Products with moisture contents between 30 and 50% are usually ideal for handling, surface applications, and soil incorporation. Wet products (greater than 60% moisture content) tend to form clumps and do not spread evenly when applied to turf surfaces. Tilling wet material into soil may result in poor mixing with soil and uneven turf establishment. Wet SMS is heavy and difficult to handle.
A quick field test that you can use to determine suitable water content of SMS is to squeeze the product in the palm of your hand and watch for water oozing from the product. If water drips from the SMS upon squeezing, then the product may be too wet, and further drying should improve product handling. If the SMS remains together when you release your grip and no water drips from the product, it probably has suitable water content for spreading and mixing with soil.
Organic matter and ash content: When using SMS as an organic matter supplement, keep in mind that not all of the product is organic matter. Spent mushroom substrate products typically contain between 40 and 60% organic matter on a dry weight basis. Organic matter content can be determined by a lab test. The most common procedure employed by laboratories, "loss on ignition", considers everything that is combustible as organic matter.
Some test labs report a value called 'ash content'. Ash is the mineral matter that remains after the SMS sample has been subjected to extremely high temperatures in a furnace. Assuming that everything burned-off in the furnace is organic matter, the percentage of ash in the sample can be subtracted from 100 to provide an estimate of percent organic matter. For example, an ash content of 40% indicates that there is an estimated 60% organic matter in the sample.
Carbon to nitrogen ratio: The amount of carbon (C) relative to the amount of nitrogen (N) in a SMS product is an important indicator of nitrogen availability. The carbon to nitrogen (C:N) ratio of a product should be 30:1 or below. If above 35:1, soil microorganisms can immobilize nitrogen, making it unavailable to the turf. Most SMS products have C:N ratios well below 30:1.
Nutrients: When compared with fertilizers, SMS products generally contain low amounts of plant nutrients. Whereas a small amount of quick-release nitrogen (ammonium) is present in SMS, most nitrogen is in the organic form and is slowly available to turf. Test results of SMS products typically indicate 1.5 to 3% total nitrogen on a dry weight basis. Other nutrients found in SMS include phosphorus (0.5 to 2.0 %, reported as P2O5), potassium (1.0 to 3.0%, reported as K2O), calcium (3 to 6%), and magnesium (0.4 to 1.0%).
Typically, significant amounts of SMS must be applied to supply all or most of the turf's nutrient requirements. In some cases, this can be achieved for short durations (8 to 10 weeks) with surface applications of ¼ to ½ inch of SMS, aerated into the soil surface. In many cases, a 1 or 2 inch layer of SMS tilled 4 to 6 inches into soil can supply all of the nutrients necessary for turf growth and development for an entire year and possibly longer.
pH: The pH of most SMS products is between 6.0 and 8.0, a range favorable for turf root growth. On rare occasion, a product may fall outside of this range. The pH of organic amendments may be detrimental to turf when very high (greater than 8.5) or very low (less than 5.5). Extremes in pH may result in reduced availability of some plant nutrients and/or aluminum toxicity problems. Fortunately, most soils are buffered against rapid and drastic changes in pH and even organic amendments with extremes in pH may not alter the overall soil pH a great deal. To be on the safe side, however, try using products with a pH between 6.0 and 8.0.
Soluble salts: Soluble salts may be higher in SMS products than in other types of organic amendments. Whereas, excess soluble salts can cause turf injury, research conducted at Penn State shows that good quality SMS products do not contain salt levels high enough to damage turf. If you have questions regarding the soluble salt content of a particular SMS product and how safe it is to use on turf, send the product to a soil test lab that performs soluble salts analyses on composts.
Penn State's Agricultural Analytical Services Lab and other laboratories measure soluble salt content in SMS by saturating the sample with water, extracting the solution from the sample, and determining salt content by measuring the electrical conductivity of the solution. The higher the electrical conductivity of the solution, the higher is the salt content of the SMS. Soluble salt content is most often reported in units of electrical conductivity (mmhos/cm or dS/m).
From "USING SPENT MUSHROOM SUBSTRATE (MUSHROOM SOIL) AS A SOIL AMENDMENT TO IMPROVE TURF" Department of Crop and Soil Sciences - Cooperative Extension, Penn State University http://turfgrassmanagement.psu.edu/spentmushroomsubstrate.cfm
Thursday, May 29, 2008
Turf - Apply Bermudagrass Control Measures Soon
Bermudagrass control in cool season turf can be a challenge. There are some herbicide tools available but you need to start early. First herbicide applications should go on now. The following are some recommendations.
Bermudagrass suppression has been achieved by applications of Acclaim extra (fexoxaprop-p-ethyl) applied at 0.46 fl. oz. per 1000 sq. ft. every 4-5 weeks (maximum of 6 applications) starting at bermudagrass first greenup in May. Acclaim extra mixed in combination with Prograss (ethofumisate) or Turflon Ester (triclopyr) has given better bermudagrass control (do not use Prograss on fine fescues) and fewer applications may be needed. Both Prograss and Turflon Ester both have some bermudagrass activity when used alone.
This program based on Acclaim Extra will be the best option for light to moderate infestations. For heavy infestations a complete renovation will be needed. Kill the bermudagrass with glyphosate applications (2 applications, 3 weeks apart) in mid summer and reseed around Labor Day.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Bermudagrass suppression has been achieved by applications of Acclaim extra (fexoxaprop-p-ethyl) applied at 0.46 fl. oz. per 1000 sq. ft. every 4-5 weeks (maximum of 6 applications) starting at bermudagrass first greenup in May. Acclaim extra mixed in combination with Prograss (ethofumisate) or Turflon Ester (triclopyr) has given better bermudagrass control (do not use Prograss on fine fescues) and fewer applications may be needed. Both Prograss and Turflon Ester both have some bermudagrass activity when used alone.
This program based on Acclaim Extra will be the best option for light to moderate infestations. For heavy infestations a complete renovation will be needed. Kill the bermudagrass with glyphosate applications (2 applications, 3 weeks apart) in mid summer and reseed around Labor Day.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Nursery, Landscape, and Turf - Moisture and Diseases
Moist conditions favor disease development in landscape plants. The following is an article on the subject.
In Mid-May, there were days with persistent rain, mist, fog, and humid, overcast weather in many parts of Delaware. Wet weather increases disease pressure for most foliar fungal and bacterial diseases of plants in the garden and landscape. Many fungal pathogens require free moisture on the host plant surface for germination of their spores. The longer it is that leaves remain continuously wet, the better chance it is that fungal spores on the host will succeed in infecting the host plant. At average temperatures of 60-65 F, the apple scab fungus needs 9 consecutive hours of wet leaves for successful infection, the grape black rot fungus needs 8-9 hours, the rose black spot fungus needs 7 hours, shade tree anthracnose fungi need 6-12 hours, and the cedar-apple rust fungus needs only 3-4 hours. Following infection promoted by wet weather, disease symptoms typically appear on the plant a week or two later.
The two other components of the plant disease triangle, the susceptible host and the virulent pathogen are needed for a disease outbreak. For example, diseases such as apple scab, oak anthracnose, cedar-apple rust, and rose black spot are already present on susceptible host plants in many landscapes. These infections occurred during wet periods this past month. Depending on where susceptible plants are located, recent disease-favorable wetness periods have lasted anywhere from 9 hours in one day to 45 consecutive hours over two or three days. Thus, for the rest of this spring and even into summer, expect these infections to produce symptoms and more spores to continue the cycle of disease every time a prolonged wet period occurs.
Adapted from COMPLETING THE PLANT DISEASE TRIANGLE - DISEASE-FAVORABLE ENVIRONMENT By John Hartman in the May 19 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
In Mid-May, there were days with persistent rain, mist, fog, and humid, overcast weather in many parts of Delaware. Wet weather increases disease pressure for most foliar fungal and bacterial diseases of plants in the garden and landscape. Many fungal pathogens require free moisture on the host plant surface for germination of their spores. The longer it is that leaves remain continuously wet, the better chance it is that fungal spores on the host will succeed in infecting the host plant. At average temperatures of 60-65 F, the apple scab fungus needs 9 consecutive hours of wet leaves for successful infection, the grape black rot fungus needs 8-9 hours, the rose black spot fungus needs 7 hours, shade tree anthracnose fungi need 6-12 hours, and the cedar-apple rust fungus needs only 3-4 hours. Following infection promoted by wet weather, disease symptoms typically appear on the plant a week or two later.
The two other components of the plant disease triangle, the susceptible host and the virulent pathogen are needed for a disease outbreak. For example, diseases such as apple scab, oak anthracnose, cedar-apple rust, and rose black spot are already present on susceptible host plants in many landscapes. These infections occurred during wet periods this past month. Depending on where susceptible plants are located, recent disease-favorable wetness periods have lasted anywhere from 9 hours in one day to 45 consecutive hours over two or three days. Thus, for the rest of this spring and even into summer, expect these infections to produce symptoms and more spores to continue the cycle of disease every time a prolonged wet period occurs.
Adapted from COMPLETING THE PLANT DISEASE TRIANGLE - DISEASE-FAVORABLE ENVIRONMENT By John Hartman in the May 19 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Wednesday, May 28, 2008
Nursery and Landscape - Learn More About Phytophthora
Phytophthora diseases are a common problem in Delaware nurseries and landscapes. You can learn more about diseases caused by these organisms now with an on-line course from Oregon State University. The following is information on this training.
Phytophthora, a fungus-like organism, is a persistent threat to nursery crop production and landscape plantings in Delaware. Learning more about this plant pathogen and the diseases it causes would benefit anyone involved in the nursery or landscape trade. In addition, nursery growers are aware of the need to be alert for new diseases such as "sudden oak death" (also known as ramorum shoot and leaf blight on nursery stock) caused by Phytophthora ramorum. Growers who examine their plants carefully are, in effect, "first detectors" of new and exotic diseases in the nursery industry. Nursery producers and landscapers now can participate in a free online Phytophthora training program from Oregon State University. The goal of helping to minimize these diseases in the nursery setting; however, landscapers should alsto benefit. The training is free and consists of three 1 to 1.5 hour modules. There is an optional online exam that does have a fee of $100. If you pass the test, participants will receive a Certificate of Mastery on Phytophthora from Oregon State University Extended Campus. For more information on this training, please visit the OSU Phytophthora Online Course. A link is given below.
http://oregonstate.edu/instruct/dce/phytophthora/
Phytophthora, a fungus-like organism, is a persistent threat to nursery crop production and landscape plantings in Delaware. Learning more about this plant pathogen and the diseases it causes would benefit anyone involved in the nursery or landscape trade. In addition, nursery growers are aware of the need to be alert for new diseases such as "sudden oak death" (also known as ramorum shoot and leaf blight on nursery stock) caused by Phytophthora ramorum. Growers who examine their plants carefully are, in effect, "first detectors" of new and exotic diseases in the nursery industry. Nursery producers and landscapers now can participate in a free online Phytophthora training program from Oregon State University. The goal of helping to minimize these diseases in the nursery setting; however, landscapers should alsto benefit. The training is free and consists of three 1 to 1.5 hour modules. There is an optional online exam that does have a fee of $100. If you pass the test, participants will receive a Certificate of Mastery on Phytophthora from Oregon State University Extended Campus. For more information on this training, please visit the OSU Phytophthora Online Course. A link is given below.
http://oregonstate.edu/instruct/dce/phytophthora/
Nursery and Landscape - Biological Fungicides
There are a number of biological fungicides on the market. The following is information on these products and their effectiveness.
Biological fungicides tend to have negligible toxicity to humans, and no history of carcinogenic or developmental effects on test animals. Data on the effectiveness of the biologicals in landscape use is often limited, but the labels are helpfully broad, encouraging product use for suppression of many different pathogens. Some of the pathogens named on the label may have been suppressed in laboratory plate tests rather than in field trials; time will tell whether they are also effectively treated for under the less controlled conditions in the outdoor environment. Rather than thinking of biofungicides as cures for diseases, think of them as biological tools for treating plants preventively, decreasing the odds that a pathogen will successfully attack to cause disease. Biological controls are thus used as health insurance, not in response to the appearance of disease symptoms. They are very compatible with overall integrated pest management (IPM) philosophy—but one should not wait for a disease threshold to be reached before deploying a biofungicide. In many instances, the best use of a biological may be occasional treatments in alternation with reduced-risk chemicals.
One of the best known of the biologicals for disease control is Rhapsody AS, which contains Bacillus subtilis strain QST 713, a bacterium. This protectant material is even approved by OMRI for use in organic production, as well as for use in a broad range of sites including landscapes and golf courses, plus sod and ornamental production. Using a surfactant to improve coverage is recommended, and the higher labeled rates may be needed under significant disease pressure. Rhapsody may be applied as a spray or as a drench. As a spray, its forté is powdery mildew, but a measurable benefit from Rhapsody has also been seen against some bacterial leaf spots, Cercospora leaf spot, Botrytis blight and downy mildew. Only copper treatments offer similar versatility, with effectiveness against bacteria as well as fungi. As a soil drench, the Rhapsody label offers suppression of Fusarium, Pythium, Phytophthora and Rhizoctonia.
Actinovate SP, a biofungicide labeled for production and landscape use, has Streptomyces lydicus WYEC 108, an actinomycete, as its active ingredient. Drenches and foliar sprays may be made in the landscape as new plants are being transplanted, or to established plants. Treatments are of benefit only when made preventively. Actinovate’s original use was for soilborne diseases—the label lists problems caused by Pythium, Rhizoctonia, Phytophthora, Verticillium and Fusarium. Some suppression of powdery mildew, downy mildew, Botrytis, Alternaria, and Sclerotinia is also claimed for foliar applications. Studies on ornamental crops have thus far shown powdery mildew and Botrytis to be measurably reduced by Actinovate treatment. The Actinovate AG label, which relates to agricultural uses, includes a mention of Monilinia control, which suggests that the Actinovate SP may help to keep ornamental cherries free from brown rot. This biocontrol is effective at temperatures above 45ºF. A non-ionic spreader-sticker such as Latron B1956 should be added for the best results. For landscape use, treatment can be at transplant or to established plants. Ornamental bulbs may also be dusted or soaked in a suspension of Actinovate SP prior to planting, or drenched subsequently. The material may also be used for pre-plant treatment of bare-root trees.
Information from "Exploring alternatives for disease control on trees and shrubs" by Margery Daughtrey, Cornell University Department of Plant Pathology and Plant-Microbe Biology in the May 23 edition of the Michigan State University Landscape Alert Newsletter.
Biological fungicides tend to have negligible toxicity to humans, and no history of carcinogenic or developmental effects on test animals. Data on the effectiveness of the biologicals in landscape use is often limited, but the labels are helpfully broad, encouraging product use for suppression of many different pathogens. Some of the pathogens named on the label may have been suppressed in laboratory plate tests rather than in field trials; time will tell whether they are also effectively treated for under the less controlled conditions in the outdoor environment. Rather than thinking of biofungicides as cures for diseases, think of them as biological tools for treating plants preventively, decreasing the odds that a pathogen will successfully attack to cause disease. Biological controls are thus used as health insurance, not in response to the appearance of disease symptoms. They are very compatible with overall integrated pest management (IPM) philosophy—but one should not wait for a disease threshold to be reached before deploying a biofungicide. In many instances, the best use of a biological may be occasional treatments in alternation with reduced-risk chemicals.
One of the best known of the biologicals for disease control is Rhapsody AS, which contains Bacillus subtilis strain QST 713, a bacterium. This protectant material is even approved by OMRI for use in organic production, as well as for use in a broad range of sites including landscapes and golf courses, plus sod and ornamental production. Using a surfactant to improve coverage is recommended, and the higher labeled rates may be needed under significant disease pressure. Rhapsody may be applied as a spray or as a drench. As a spray, its forté is powdery mildew, but a measurable benefit from Rhapsody has also been seen against some bacterial leaf spots, Cercospora leaf spot, Botrytis blight and downy mildew. Only copper treatments offer similar versatility, with effectiveness against bacteria as well as fungi. As a soil drench, the Rhapsody label offers suppression of Fusarium, Pythium, Phytophthora and Rhizoctonia.
Actinovate SP, a biofungicide labeled for production and landscape use, has Streptomyces lydicus WYEC 108, an actinomycete, as its active ingredient. Drenches and foliar sprays may be made in the landscape as new plants are being transplanted, or to established plants. Treatments are of benefit only when made preventively. Actinovate’s original use was for soilborne diseases—the label lists problems caused by Pythium, Rhizoctonia, Phytophthora, Verticillium and Fusarium. Some suppression of powdery mildew, downy mildew, Botrytis, Alternaria, and Sclerotinia is also claimed for foliar applications. Studies on ornamental crops have thus far shown powdery mildew and Botrytis to be measurably reduced by Actinovate treatment. The Actinovate AG label, which relates to agricultural uses, includes a mention of Monilinia control, which suggests that the Actinovate SP may help to keep ornamental cherries free from brown rot. This biocontrol is effective at temperatures above 45ºF. A non-ionic spreader-sticker such as Latron B1956 should be added for the best results. For landscape use, treatment can be at transplant or to established plants. Ornamental bulbs may also be dusted or soaked in a suspension of Actinovate SP prior to planting, or drenched subsequently. The material may also be used for pre-plant treatment of bare-root trees.
Information from "Exploring alternatives for disease control on trees and shrubs" by Margery Daughtrey, Cornell University Department of Plant Pathology and Plant-Microbe Biology in the May 23 edition of the Michigan State University Landscape Alert Newsletter.
Tuesday, May 27, 2008
Greenhouse and Nursery - Use of Florel on Garden Mums
As garden mums start to arrive at greenhouses, growers may consider using Florel to replace hand or mechanical pinching. The following information from Rick Yates, Griffin Greenhouse and Nursery Supplies Inc. provides some good details on using Florel.
Florel can be used to replace mechanical pinching when applied as a thorough foliar spray at 500 PPM (1.6 oz./gal.). Typically this is done one week before you would hand pinch. Even though your cell pack mums are pinched when you receive them, they will benefit from an application of Florel applied as soon as possible after they arrive. While this initial spray to pinched cuttings does not increase branching, it does reduce premature budding by getting the plants under the influence of Florel as early as possible. Repeated at two week intervals, Florel helps to keep plants vegetative as well as providing more breaks per plant when compared to hand pinching.
Florel also reduces internode elongation, reducing or eliminating the need for other growth regulators later in the season. Labor savings are significant and greatly appreciated! Using more than 1 pinch and 2 Florel treatments (counting the one applied when you received the pinched cuttings) is not usually desirable. So many branches are produced that stem strength is reduced and the plants may pull apart at flowering.
Most growers report great results from one application upon arrival, and one more 14 days later. You can also time your crop with Florel, since it delays flowering. Make your last Florel application before July 1st to avoid delaying the natural season flower date. CAUTION: Highly alkaline water may need to be treated in order for Florel to be effective. When Florel is added to your spray tank it must be able to drop the pH of that solution to between 4.0 and 5.0 to work properly. Distilled or acidified water may be needed in some cases. Use an acidifier to adjust the pH of the spray water to between 5.5 and 6.0 before adding the Florel to allow the final solution to be in the correct range.
Sample Program (normal season flowering)
Pinched cuttings arrive about June 10th and are sprayed upon arrival with Florel @ 500 ppm
Two days later (allows for 48 hr REI for Florel) cuttings are potted into 8 x 5 or 9 x 6 mum pans.
Reapply Florel @ 500 ppm two weeks after the first treatment (~ June 24th)
Information from the Fact Sheet: "Garden Mums from Cell Packs" by Rick Yates, Griffin Greenhouse and Nursery Supplies, Inc.
Florel can be used to replace mechanical pinching when applied as a thorough foliar spray at 500 PPM (1.6 oz./gal.). Typically this is done one week before you would hand pinch. Even though your cell pack mums are pinched when you receive them, they will benefit from an application of Florel applied as soon as possible after they arrive. While this initial spray to pinched cuttings does not increase branching, it does reduce premature budding by getting the plants under the influence of Florel as early as possible. Repeated at two week intervals, Florel helps to keep plants vegetative as well as providing more breaks per plant when compared to hand pinching.
Florel also reduces internode elongation, reducing or eliminating the need for other growth regulators later in the season. Labor savings are significant and greatly appreciated! Using more than 1 pinch and 2 Florel treatments (counting the one applied when you received the pinched cuttings) is not usually desirable. So many branches are produced that stem strength is reduced and the plants may pull apart at flowering.
Most growers report great results from one application upon arrival, and one more 14 days later. You can also time your crop with Florel, since it delays flowering. Make your last Florel application before July 1st to avoid delaying the natural season flower date. CAUTION: Highly alkaline water may need to be treated in order for Florel to be effective. When Florel is added to your spray tank it must be able to drop the pH of that solution to between 4.0 and 5.0 to work properly. Distilled or acidified water may be needed in some cases. Use an acidifier to adjust the pH of the spray water to between 5.5 and 6.0 before adding the Florel to allow the final solution to be in the correct range.
Sample Program (normal season flowering)
Pinched cuttings arrive about June 10th and are sprayed upon arrival with Florel @ 500 ppm
Two days later (allows for 48 hr REI for Florel) cuttings are potted into 8 x 5 or 9 x 6 mum pans.
Reapply Florel @ 500 ppm two weeks after the first treatment (~ June 24th)
Information from the Fact Sheet: "Garden Mums from Cell Packs" by Rick Yates, Griffin Greenhouse and Nursery Supplies, Inc.
Landscape and Nursery - Boxwood Spider Mite
The Boxwood Spider Mite, Eurytetranychus buxi, is a problem pest in Delaware. The following is information on this pest that is hatching now and its control.
Boxwood spider mites started hatching this week. They overwintered as eggs. The mites are small and clear to light yellow in color and you will need a hand lens to see them. As they mature they will be light yellow to yellowish-brown. They are on the undersides of the foliage. The feeding of the mites will cause stippling to the foliage and heavily infested leaves will turn yellow and drop.
Control: Japanese boxwood appears to be less susceptible, but we found boxwood mite on several cultivars of Japanese boxwoods growing in full sun in 2007. The common boxwood such as the English and European types tends to be very susceptible. Columnar forms of boxwood appear to be very susceptible. We have used the mite growth regulator Hexagon and obtained season long control if applied early in the season. Other materials that work well include Floramite, Akari, Avid, and horticultural oil (directed at the undersides of the foliage).
Reprinted from the May 23, 2008 edition of the TPM/IPM Weekly Report for Arborists,
Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Boxwood spider mites started hatching this week. They overwintered as eggs. The mites are small and clear to light yellow in color and you will need a hand lens to see them. As they mature they will be light yellow to yellowish-brown. They are on the undersides of the foliage. The feeding of the mites will cause stippling to the foliage and heavily infested leaves will turn yellow and drop.
Control: Japanese boxwood appears to be less susceptible, but we found boxwood mite on several cultivars of Japanese boxwoods growing in full sun in 2007. The common boxwood such as the English and European types tends to be very susceptible. Columnar forms of boxwood appear to be very susceptible. We have used the mite growth regulator Hexagon and obtained season long control if applied early in the season. Other materials that work well include Floramite, Akari, Avid, and horticultural oil (directed at the undersides of the foliage).
Reprinted from the May 23, 2008 edition of the TPM/IPM Weekly Report for Arborists,
Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Monday, May 26, 2008
Landscape - Some Beneficial Beetles
Everyone is aware that lady beetles are beneficial as they are a great aphid predator. However, there are other beneficial beetles in the landscape. The following is an article on the subject.
Ground beetles (family Carabidae) are important predators that can be found in most gardens and home grounds. They may be the most numerous predatory insect around the home. They vary in size from less than ¼" to over 1½" long. Adult ground beetles run quickly when disturbed, but they rarely fly.
The adults of most ground beetles are dark brown or black, shiny, and somewhat flattened, with slender legs for running. A few are iridescent blue or green. They are commonly found under leaves or debris, in cracks in the soil, or running along the ground (but not often in bright sunlight). Some species also climb into trees, shrubs, and crop plants looking for prey. They may wander indoors at ground-level entry areas.
Adult ground beetles are fierce predators that chew up their prey with large, sharp mouthparts. Common prey include caterpillars, grubs and adults of other beetles, fly maggots and pupae, earthworms, and other small soil dwellers. They can consume their body weight in food daily.
Firefly larvae feed primarily on snails and slugs. Like the more familiar adults, they are mainly nocturnal in habit. They prefer moist habitats, such as under boards, decaying vegetation and beneath bark. Closely related glowworms (larvae and the adult female are luminescent) occur in more wooded areas and feed primarily on millipedes and soft-bodied insects under decaying tree bark.
Soldier beetles resemble fireflies – their larvae are predacious (as are fireflies), but compared to fireflies, adults and larvae are more active during the day. Acommonly are seen on flowers, and larvae prefer the "old field" habitat. Click beetles are another familiar adult beetle. The larvae of some click beetle speciefeed on insects in dark, secluded environments.
The family Staphylinidae, or rove beetles, with about 2,900 species, is the largest family of North American beetles. Most species are small and seldom seen. Although common, the group as a whole is not well studied. Some species are predaceous as in adults and larval stages; the larvae of other species are parasitoids and others are scavengers.
Adult rove beetles are generally less than ¾ inch long. They are recognized by their slender, usually black or brown bodies and shortened front wings (elytra) that may look like pads on the abdomen. When disturbed rove beetle adults have the distinctive behavior of curling the tip of the abdomen upwards. Adults are usually strong fliers despite the shortened forewings (hindwings are normal sized). The mobile larvae of nonparasitic rove beetles may be distinctly segmented.
Most rove beetles are found in association with soil or decaying organic matter. They may be seen under debris or rocks, in compost piles or crawling on plants. They are frequently found in soils when in home gardens. Adults will visit flowers to feed on pollen.
Predaceous rove beetles, depending on the species, feed on eggs and larvae of mites, insect eggs or small soil insects. Some feed on the eggs and maggots of flies. A few species found in vegetation feed on many types of small insects and mites.
Information from Dewey Caron, Extension Entomologist, UD.
Ground beetles (family Carabidae) are important predators that can be found in most gardens and home grounds. They may be the most numerous predatory insect around the home. They vary in size from less than ¼" to over 1½" long. Adult ground beetles run quickly when disturbed, but they rarely fly.
The adults of most ground beetles are dark brown or black, shiny, and somewhat flattened, with slender legs for running. A few are iridescent blue or green. They are commonly found under leaves or debris, in cracks in the soil, or running along the ground (but not often in bright sunlight). Some species also climb into trees, shrubs, and crop plants looking for prey. They may wander indoors at ground-level entry areas.
Adult ground beetles are fierce predators that chew up their prey with large, sharp mouthparts. Common prey include caterpillars, grubs and adults of other beetles, fly maggots and pupae, earthworms, and other small soil dwellers. They can consume their body weight in food daily.
Firefly larvae feed primarily on snails and slugs. Like the more familiar adults, they are mainly nocturnal in habit. They prefer moist habitats, such as under boards, decaying vegetation and beneath bark. Closely related glowworms (larvae and the adult female are luminescent) occur in more wooded areas and feed primarily on millipedes and soft-bodied insects under decaying tree bark.
Soldier beetles resemble fireflies – their larvae are predacious (as are fireflies), but compared to fireflies, adults and larvae are more active during the day. Acommonly are seen on flowers, and larvae prefer the "old field" habitat. Click beetles are another familiar adult beetle. The larvae of some click beetle speciefeed on insects in dark, secluded environments.
The family Staphylinidae, or rove beetles, with about 2,900 species, is the largest family of North American beetles. Most species are small and seldom seen. Although common, the group as a whole is not well studied. Some species are predaceous as in adults and larval stages; the larvae of other species are parasitoids and others are scavengers.
Adult rove beetles are generally less than ¾ inch long. They are recognized by their slender, usually black or brown bodies and shortened front wings (elytra) that may look like pads on the abdomen. When disturbed rove beetle adults have the distinctive behavior of curling the tip of the abdomen upwards. Adults are usually strong fliers despite the shortened forewings (hindwings are normal sized). The mobile larvae of nonparasitic rove beetles may be distinctly segmented.
Most rove beetles are found in association with soil or decaying organic matter. They may be seen under debris or rocks, in compost piles or crawling on plants. They are frequently found in soils when in home gardens. Adults will visit flowers to feed on pollen.
Predaceous rove beetles, depending on the species, feed on eggs and larvae of mites, insect eggs or small soil insects. Some feed on the eggs and maggots of flies. A few species found in vegetation feed on many types of small insects and mites.
Information from Dewey Caron, Extension Entomologist, UD.
Landscape and Nursery - Phos-Acid Fungicides
We have seen a proliferation of phos-acid fungicides in recent years. These are reduced risk products that have been very effective on certain diseases. The following is an article on the subject.
Another category of “safer” systemic materials are the phosphorous acids or phosphonates. The first of these was Aliette, fosetyl-Al, which was introduced decades ago. Now a large number of products including Avalon, Flanker, Phostrol, Alude, Fungi-Phite T&O, and K-Phite have been labeled in New York with the same mode of action as Aliette. These vary in their acidity, and in whether there is aluminum included in the formulation, but they all have similar modes of action. The phos acid materials offer some key uses: downy mildew control on roses, Pythium and Phytophthora management, as well as some suppression against certain bacterial diseases. Aluminum toxicity has been problematic with application of Aliette on some plants, such as azaleas. Precautions given on some of the phos acid labels indicate that they should not be applied to heat-stressed or drought-stressed plants, or within 14-20 days of a copper application. These materials should not be applied if the foliage will not dry promptly. Some of the phos acid products are not safe to tank-mix with spreader-stickers, or with flowable chlorothalonil or mancozeb products, so be careful to read the label of the particular material you are using.The phos acid materials may be used on ornamental and bedding plants in landscape, nursery and greenhouse. The ability of these materials to limit Phytophthora disease is unquestioned—this is their strongest suit. Results on other kinds of diseases will be variable. The leaf spot on English ivy caused by Xanthomonas campestris pv. Hederae is one of the bacterial diseases for which phos acids are labeled. Fire blight suppression is also listed for some ornamentals.
Reprinted from "Exploring alternatives for disease control on trees and shrubs" by Margery Daughtrey, Cornell University Department of Plant Pathology and Plant-Microbe Biology, in the May 23, 2008 edition of the Michigan State University Landscape Alert newsletter.
Another category of “safer” systemic materials are the phosphorous acids or phosphonates. The first of these was Aliette, fosetyl-Al, which was introduced decades ago. Now a large number of products including Avalon, Flanker, Phostrol, Alude, Fungi-Phite T&O, and K-Phite have been labeled in New York with the same mode of action as Aliette. These vary in their acidity, and in whether there is aluminum included in the formulation, but they all have similar modes of action. The phos acid materials offer some key uses: downy mildew control on roses, Pythium and Phytophthora management, as well as some suppression against certain bacterial diseases. Aluminum toxicity has been problematic with application of Aliette on some plants, such as azaleas. Precautions given on some of the phos acid labels indicate that they should not be applied to heat-stressed or drought-stressed plants, or within 14-20 days of a copper application. These materials should not be applied if the foliage will not dry promptly. Some of the phos acid products are not safe to tank-mix with spreader-stickers, or with flowable chlorothalonil or mancozeb products, so be careful to read the label of the particular material you are using.The phos acid materials may be used on ornamental and bedding plants in landscape, nursery and greenhouse. The ability of these materials to limit Phytophthora disease is unquestioned—this is their strongest suit. Results on other kinds of diseases will be variable. The leaf spot on English ivy caused by Xanthomonas campestris pv. Hederae is one of the bacterial diseases for which phos acids are labeled. Fire blight suppression is also listed for some ornamentals.
Reprinted from "Exploring alternatives for disease control on trees and shrubs" by Margery Daughtrey, Cornell University Department of Plant Pathology and Plant-Microbe Biology, in the May 23, 2008 edition of the Michigan State University Landscape Alert newsletter.
Sunday, May 25, 2008
Landscape - Cool Weather Favors Aphids; Look for Aphid Predators
Aphids are very common in spring on a large variety of plants because the weather favors them over their enemies like lady bug beetles, lacewings, and hover flies (Syrphid flies). This is more prenounced in a cool spring like we have been having. The following are images and information on the natural controls of aphids.
Aphids are found predominately on the undersides of leaves. Aphid feeding often causes leaves to curl under making it difficult for predators to reach them. Aphid populations explode quickly because they are all females giving live birth to females, which will soon be giving live birth to females. Insecticides may not be necessary if there are enough predators present. Look for the adult lady bug beetles and their larvae (they look like alligators), lacewing larvae (with long scissorlike mouthparts extending out of their heads) and hover flies (tiny sluglike larvae).
Green lacewing larve feeding on aphid. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Syrphid (Hover) fly larvae, a predator of aphids. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Lady beetle larvae, a predator of aphids. Photo by Frank Peairs, Colorado State University, Bugwood.org
Aphids are found predominately on the undersides of leaves. Aphid feeding often causes leaves to curl under making it difficult for predators to reach them. Aphid populations explode quickly because they are all females giving live birth to females, which will soon be giving live birth to females. Insecticides may not be necessary if there are enough predators present. Look for the adult lady bug beetles and their larvae (they look like alligators), lacewing larvae (with long scissorlike mouthparts extending out of their heads) and hover flies (tiny sluglike larvae).
Green lacewing larve feeding on aphid. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Syrphid (Hover) fly larvae, a predator of aphids. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Lady beetle larvae, a predator of aphids. Photo by Frank Peairs, Colorado State University, Bugwood.org
Turf - Cool Temperatures and Herbicide Activity
We have had an unusually cool May. Broadleaf herbicide activity can be affected by these cold temperatures. The following is an article on the subject.
As most of us know, optimum weed control with broadleaf weed herbicide mixtures is obtained when weeds are actively growing. Conditions that promote active growth are good soil moisture and moderate daytime/nighttime air temperatures. In general broadleaf weed herbicide mixtures work best when applied when daytime air temperatures range between 75 to 85 degrees and nighttime temperatures range between 55 to 65 degrees. April and May have brought us a prolonged early spring weather pattern with many days below 70 degrees and nights below 50 degrees. Due to these cool weather conditions herbicide activity has been very slow to develop.
This has been observed even with herbicide mixtures formulated as esters, which work better in cooler weather conditions. In addition, up until May 12 we experienced dry soil conditions, which may also detract from optimum broadleaf weed herbicide activity if applications were made prior to May 12 on sites that were not receiving supplemental irrigation. Due to these conditions expect the possibility of a significant number of broadleaf weed herbicide failures for applications made prior to May 12 regardless of the product. This possibility may be even greater for tougher to control broadleaf weeds such as oxalis, veronica, ground ivy, and mouseear chickweed. Keep a close watch on sites that have received broadleaf weed herbicide applications under these conditions. If re-treatment is necessary, wait for more moderate air temperatures and visible signs of active regrowth of the weeds before a second herbicide application.
Information adapted from an article by Dr. Steve Hart, Turf and Ornamental Weed Specialist, Rutgers University.
As most of us know, optimum weed control with broadleaf weed herbicide mixtures is obtained when weeds are actively growing. Conditions that promote active growth are good soil moisture and moderate daytime/nighttime air temperatures. In general broadleaf weed herbicide mixtures work best when applied when daytime air temperatures range between 75 to 85 degrees and nighttime temperatures range between 55 to 65 degrees. April and May have brought us a prolonged early spring weather pattern with many days below 70 degrees and nights below 50 degrees. Due to these cool weather conditions herbicide activity has been very slow to develop.
This has been observed even with herbicide mixtures formulated as esters, which work better in cooler weather conditions. In addition, up until May 12 we experienced dry soil conditions, which may also detract from optimum broadleaf weed herbicide activity if applications were made prior to May 12 on sites that were not receiving supplemental irrigation. Due to these conditions expect the possibility of a significant number of broadleaf weed herbicide failures for applications made prior to May 12 regardless of the product. This possibility may be even greater for tougher to control broadleaf weeds such as oxalis, veronica, ground ivy, and mouseear chickweed. Keep a close watch on sites that have received broadleaf weed herbicide applications under these conditions. If re-treatment is necessary, wait for more moderate air temperatures and visible signs of active regrowth of the weeds before a second herbicide application.
Information adapted from an article by Dr. Steve Hart, Turf and Ornamental Weed Specialist, Rutgers University.
Saturday, May 24, 2008
Turf - Volatilization and Drift of 2,4-D and Dicamba
Many broadleaf control products in turf contain dicamba and/or 2,4-D. Sometimes, late spring and summer applications of these materials are used to control broadleaf weed escapes (those not controlled by spring treatments). Unfortunately, these material may volatilize and move from the site of application in hot weather. The following is an article on the subject.
Common sense is critical for spraying dicamba and 2,4-D. Both of these products are volatile and prone to move from the treated areas as vapors. Volatility can cause dicamba or 2,4-D to move up to a few miles. Spraying these postemergence broadleaf herbicides in large turf areas may require additional considerations because of the temperature. Furthermore, many of the home gardens and landscapes have been planted with vegetables, fruits, and annual plants and they are often very sensitive to these herbicides. It is not recommended to spray dicamba or 2,4-D when the temperature is expected to be 85 degrees or hotter; or spray late in the day when temperatures drop below 85. Many turf herbicide pre-mixes have dicamba and/or 2,4-D. Use lower drift formulations of these products when available. Amines and esters are the most common formulations of 2,4-D. The esters are the most active and can be used at the lower rates and for brush control. Since vapour drift is a potential problem with the ester formulations, only the amines should be used on lawns, or near gardens. Granular products are somewhat safer but still can volatilize under certain conditions.
Information from Mark VanGessel, Extension Weed Specialist, UD and other sources.
The following is a comment from a representative of PBI Gordon, a company that produces 2,4-D products with details on safety of the newer ester formulations.
The following is an over statement "esters are the most active. Since vapour drift is a potential problem with the ester formulations, only the amines should be used on lawns, or near gardens" and very missleading. It is painted with such a broad brush and is technically inaccurate. Different products due to their potential to volatilize will carry a label statement that states that it should not be applied if the temperatures are expected to go above a set temperature like 85F. The majority of products will only state not to broadcast apply when the temperatures are above 85F. The newer longer chained esters are much lower in their potential to volatilize. We now have ester based products that volatilize no differently than amine salt formulations.What I see is more particle drift than actual volatilization. The new ride on sprayers can leave a cloud of small spray particles especially when there is minimal air movement at the time of application and then a breeze occurs and moves the cloud of small particles that were never dispersed onto off target plants.
S. Gary Custis, CPAgManager: R&D and Technical SupportPBI Gordon Corporation
Common sense is critical for spraying dicamba and 2,4-D. Both of these products are volatile and prone to move from the treated areas as vapors. Volatility can cause dicamba or 2,4-D to move up to a few miles. Spraying these postemergence broadleaf herbicides in large turf areas may require additional considerations because of the temperature. Furthermore, many of the home gardens and landscapes have been planted with vegetables, fruits, and annual plants and they are often very sensitive to these herbicides. It is not recommended to spray dicamba or 2,4-D when the temperature is expected to be 85 degrees or hotter; or spray late in the day when temperatures drop below 85. Many turf herbicide pre-mixes have dicamba and/or 2,4-D. Use lower drift formulations of these products when available. Amines and esters are the most common formulations of 2,4-D. The esters are the most active and can be used at the lower rates and for brush control. Since vapour drift is a potential problem with the ester formulations, only the amines should be used on lawns, or near gardens. Granular products are somewhat safer but still can volatilize under certain conditions.
Information from Mark VanGessel, Extension Weed Specialist, UD and other sources.
The following is a comment from a representative of PBI Gordon, a company that produces 2,4-D products with details on safety of the newer ester formulations.
The following is an over statement "esters are the most active. Since vapour drift is a potential problem with the ester formulations, only the amines should be used on lawns, or near gardens" and very missleading. It is painted with such a broad brush and is technically inaccurate. Different products due to their potential to volatilize will carry a label statement that states that it should not be applied if the temperatures are expected to go above a set temperature like 85F. The majority of products will only state not to broadcast apply when the temperatures are above 85F. The newer longer chained esters are much lower in their potential to volatilize. We now have ester based products that volatilize no differently than amine salt formulations.What I see is more particle drift than actual volatilization. The new ride on sprayers can leave a cloud of small spray particles especially when there is minimal air movement at the time of application and then a breeze occurs and moves the cloud of small particles that were never dispersed onto off target plants.
S. Gary Custis, CPAgManager: R&D and Technical SupportPBI Gordon Corporation
Safety - Lightning
The thunderstorm season is fast approaching and workers and business owners in the green industries should take time to be familiar with lighting safety. The following are some general tips and web sites to visit.
If you can hear thunder, you are close enough to the storm to be struck by lightning. Lightning can strike as far away as 10 miles from the area where it is raining.
If you can see lightning flashes, count the seconds after a flash until you hear thunder. If that time is 30 seconds or less, the storm is within 6 miles and is dangerous. Seek shelter immediately.
The best shelters are buildings with closed windows and doors, and plumbing and electrical wiring, which provide grounding. Enclosed vehicles can also be used as shelter, but avoid convertibles. It is the metal shell of a vehicle that protects you--not the rubber tires. Roll up the windows and don't touch any metal.
Lightning can strike as far as 10 miles from the area where it is raining. That's about the distance you can hear thunder. Don't be fooled by sunshine or blue sky if a storm is approaching.
Avoid flag poles, utility poles, isolated trees, open fields, metal bleachers, metal fences, covered patios, and convertible cars. Lightning often strikes the tallest object. Metal does not attract lightning, but it is a conduit for any electrical charge. Be sure you are not higher than your surroundings or YOU could be the conduit.
If you feel the hairs standing up on the back of your neck, lightning may strike very near you in a matter of moments. Crouch down and hug your knees. If you can, balance yourself on the balls of your feet. The less contact you have with the ground the better.
Get out of and completely away from the water. Don't stand in puddles of water even if you are wearing rubber boots.
Avoid Unsafe Shelters: A shelter that does not contain plumbing or wiring throughout is not safe. Plumbing and wiring provide grounding; a small outdoor shelter may shield you from rain and wind, but it will not protect you from lightning.
Don't rely on the fact that taller objects may draw the lightning away from you. The electrical charge will likely spread out along the surface of the ground for a distance of more than 100 feet.
NO PLACE OUTSIDE IS SAFE NEAR A THUNDERSTORM!
Wait at least 30 minutes after the last clap of thunder before leaving shelter. Don't be fooled by sunshine or blue sky! Lightning is more likely to come from the back edge of a thundercloud than from the front edge.
Visit these sites for more information.
http://www.lightningsafety.noaa.gov/
http://www.lightningsafety.com/index.html
Information taken largely from an Oklahoma State University training site on lightning safety http://www.pp.okstate.edu/ehs/modules/lightning/Outdoors.htm
If you can hear thunder, you are close enough to the storm to be struck by lightning. Lightning can strike as far away as 10 miles from the area where it is raining.
If you can see lightning flashes, count the seconds after a flash until you hear thunder. If that time is 30 seconds or less, the storm is within 6 miles and is dangerous. Seek shelter immediately.
The best shelters are buildings with closed windows and doors, and plumbing and electrical wiring, which provide grounding. Enclosed vehicles can also be used as shelter, but avoid convertibles. It is the metal shell of a vehicle that protects you--not the rubber tires. Roll up the windows and don't touch any metal.
Lightning can strike as far as 10 miles from the area where it is raining. That's about the distance you can hear thunder. Don't be fooled by sunshine or blue sky if a storm is approaching.
Avoid flag poles, utility poles, isolated trees, open fields, metal bleachers, metal fences, covered patios, and convertible cars. Lightning often strikes the tallest object. Metal does not attract lightning, but it is a conduit for any electrical charge. Be sure you are not higher than your surroundings or YOU could be the conduit.
If you feel the hairs standing up on the back of your neck, lightning may strike very near you in a matter of moments. Crouch down and hug your knees. If you can, balance yourself on the balls of your feet. The less contact you have with the ground the better.
Get out of and completely away from the water. Don't stand in puddles of water even if you are wearing rubber boots.
Avoid Unsafe Shelters: A shelter that does not contain plumbing or wiring throughout is not safe. Plumbing and wiring provide grounding; a small outdoor shelter may shield you from rain and wind, but it will not protect you from lightning.
Don't rely on the fact that taller objects may draw the lightning away from you. The electrical charge will likely spread out along the surface of the ground for a distance of more than 100 feet.
NO PLACE OUTSIDE IS SAFE NEAR A THUNDERSTORM!
Wait at least 30 minutes after the last clap of thunder before leaving shelter. Don't be fooled by sunshine or blue sky! Lightning is more likely to come from the back edge of a thundercloud than from the front edge.
Visit these sites for more information.
http://www.lightningsafety.noaa.gov/
http://www.lightningsafety.com/index.html
Information taken largely from an Oklahoma State University training site on lightning safety http://www.pp.okstate.edu/ehs/modules/lightning/Outdoors.htm
Friday, May 23, 2008
Nursery and Landscape - Boxwood Psyllid
Damage from the Boxwood Psyllid may be evident now. The following is information about this pest.
Boxwood Psyllid. Photo by Nancy Gregory, Extension Plant Diagnostician, UD
Boxwood Psyllid Damage. Photo by Brian Kunkel, UD Ornamental IPM Extension Specialist.
The Boxwood Psyllid, Cacopsylla busi (Linnaeus) occurs wherever boxwoods are grown. It causes the cupping of leaves and may affect twig growth, but the damage caused is purely aesthetic and not as destructive as other boxwood pests.
Plants Attacked
Boxwood psyllid is a common pest of all boxwoods, but the American boxwood (Buxus sempervirens) is most susceptible.
Insect Identification
The small, orange eggs are laid between the bud scales with only the tip of the egg protruding past the edge of the scale. The nymphs are yellowish and covered in a white waxy exudate. The
Life History
Winter: Over-winters as a tiny, orange egg deposited in the bud scales.
Spring: The eggs hatch when the buds of the host plant open. The nymphs immediately begin to feed and develop a white flocculent material over their bodies. Winged adults appear by early June.
Summer: After mating, the female deposits her eggs between the bud scales of the host plant.
There is one generation each year in Delaware.
Damage Symptoms
The nymph stage damages the host plant by feeding on newly developing foliage, causing the leaves to become cupped. This cupping conceals the psyllid, and provides protection while feeding. Damage to the host plant is purely aesthetic.
Management Options
Insecticides should be directed towards the nymph in early May before leaf cupping occurs. Formulations of acetamiprid, azadirachtin (Ornazin 3% EC only), Beauveria bassiana, bifenthrin (Bifenthrin Pro Multi-Insecticide, Talstar F, Talstar Lawn & Tree Flowable, and TalstarOne Multi-Insecticide only), carbaryl, chlorpyrifos (Dursban 50W only), cyfluthrin and imidacloprid, deltamethrin (5SC only), horticultural oil (for immature psyllids), imidacloprid, insecticidal soap, and pyrethrins and piperonyl butoxide are labeled for psyllid management. Marathon 1% G and Marathon 60 WP are labeled for use only on plants grown in containers, flats, benches, or beds.
Management Hints: Treat when young psyllids are present in early May.
Information from Penn State University. Go to http://woodypests.cas.psu.edu/factsheets/insectfactsheets/html/Boxwood_Psyllid.html to view the factsheet with images.
Boxwood Psyllid. Photo by Nancy Gregory, Extension Plant Diagnostician, UD
Boxwood Psyllid Damage. Photo by Brian Kunkel, UD Ornamental IPM Extension Specialist.The Boxwood Psyllid, Cacopsylla busi (Linnaeus) occurs wherever boxwoods are grown. It causes the cupping of leaves and may affect twig growth, but the damage caused is purely aesthetic and not as destructive as other boxwood pests.
Plants Attacked
Boxwood psyllid is a common pest of all boxwoods, but the American boxwood (Buxus sempervirens) is most susceptible.
Insect Identification
The small, orange eggs are laid between the bud scales with only the tip of the egg protruding past the edge of the scale. The nymphs are yellowish and covered in a white waxy exudate. The
Life History
Winter: Over-winters as a tiny, orange egg deposited in the bud scales.
Spring: The eggs hatch when the buds of the host plant open. The nymphs immediately begin to feed and develop a white flocculent material over their bodies. Winged adults appear by early June.
Summer: After mating, the female deposits her eggs between the bud scales of the host plant.
There is one generation each year in Delaware.
Damage Symptoms
The nymph stage damages the host plant by feeding on newly developing foliage, causing the leaves to become cupped. This cupping conceals the psyllid, and provides protection while feeding. Damage to the host plant is purely aesthetic.
Management Options
Insecticides should be directed towards the nymph in early May before leaf cupping occurs. Formulations of acetamiprid, azadirachtin (Ornazin 3% EC only), Beauveria bassiana, bifenthrin (Bifenthrin Pro Multi-Insecticide, Talstar F, Talstar Lawn & Tree Flowable, and TalstarOne Multi-Insecticide only), carbaryl, chlorpyrifos (Dursban 50W only), cyfluthrin and imidacloprid, deltamethrin (5SC only), horticultural oil (for immature psyllids), imidacloprid, insecticidal soap, and pyrethrins and piperonyl butoxide are labeled for psyllid management. Marathon 1% G and Marathon 60 WP are labeled for use only on plants grown in containers, flats, benches, or beds.
Management Hints: Treat when young psyllids are present in early May.
Information from Penn State University. Go to http://woodypests.cas.psu.edu/factsheets/insectfactsheets/html/Boxwood_Psyllid.html to view the factsheet with images.
Landscape and Nursery - Psyllid Damage to River Birch
The following is information of psyllid damage on river birch. Psyllids or 'jumping plant lice' are small phloem feeding insects (feed on food transporting vessels in plants) and can cause considerable damage.
River birch has been recommended as a nearly problem free tree, and in most cases that is true. We have, however, had a few come into the UD Plant Diagnostic Clinic in the past couple of weeks, with psyllid damage. The damage is seen as a darkening of young terminal shoots and a twisting or distortion of the leaves, first suspected to be disease. Upon examination with a hand lens or stereoscope, psyllids and sometimes aphids were noted. Control may not be necessary. Plants can tolerate feeding and populations will decline naturally, although distorted leaves will persist. Psyllids may be controlled by spraying with neem oil, hort oil, or insecticidal soap.
Nancy Gregory, Extension Plant Diagnostician, UD
River birch has been recommended as a nearly problem free tree, and in most cases that is true. We have, however, had a few come into the UD Plant Diagnostic Clinic in the past couple of weeks, with psyllid damage. The damage is seen as a darkening of young terminal shoots and a twisting or distortion of the leaves, first suspected to be disease. Upon examination with a hand lens or stereoscope, psyllids and sometimes aphids were noted. Control may not be necessary. Plants can tolerate feeding and populations will decline naturally, although distorted leaves will persist. Psyllids may be controlled by spraying with neem oil, hort oil, or insecticidal soap.
Nancy Gregory, Extension Plant Diagnostician, UD
Thursday, May 22, 2008
Nursery and Landscape - Azalea Lace Bug
Azalea lace bug is the most common pest that attacks Azaleas in Delaware. The following is some information on this pest and its control.
AZALEA LACE BUG: Adults will become active by mid-late May, feeding and laying eggs on the underside of azalea foliage. Leaves appear stippled and offcolored. Look for black fecal spots on the underside of foliage or for the lacy winged adults. Spiny black nymphs will also be noticeable by the end of the month. Azaleas planted in full sun and under drought stress exhibit the worst damage. Control with acephate (Orthene) when active life stages are first seen. Note that while insecticidal soap has offered good (>85%) control, obtaining contact with lace bugs on the underside of foliage may prove daunting on small plants. Field studies have shown that Imidichloprid (Merit) will provide excellent control for at least a full calendar season. Hence, it may be unnecessary to apply Merit to the same plant every year.
Reprinted from the May 1, 2008 Edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition, Rutgers University.
AZALEA LACE BUG: Adults will become active by mid-late May, feeding and laying eggs on the underside of azalea foliage. Leaves appear stippled and offcolored. Look for black fecal spots on the underside of foliage or for the lacy winged adults. Spiny black nymphs will also be noticeable by the end of the month. Azaleas planted in full sun and under drought stress exhibit the worst damage. Control with acephate (Orthene) when active life stages are first seen. Note that while insecticidal soap has offered good (>85%) control, obtaining contact with lace bugs on the underside of foliage may prove daunting on small plants. Field studies have shown that Imidichloprid (Merit) will provide excellent control for at least a full calendar season. Hence, it may be unnecessary to apply Merit to the same plant every year.
Reprinted from the May 1, 2008 Edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition, Rutgers University.
Landscape and Nursery - Pine Sawflies
Two defoliating species of pine sawflies are of concern to landscape and nursery professionals in our area. Both species prefer two and three needled pines such as mugo, Scots, red, and Austrian. The following is some information on these pests.
The European pine sawfly has one generation per year and larvae hatch from overwintered eggs laid in slits along needles. They feed until late May or early June. The red-headed pine sawfly has two generations. It overwinters as a mature larva and then quickly completes its life cycle in early spring. The first generation occurs in May-Early June and a second generation occurs in July-August.
These sawflies are chewing insects that look like caterpillars at first glance. However, don't use B.t. to control them! Sawflies are immature wasps/hornets and are not susceptible to B.t. sprays.
A quick way to tell the difference between “maggots” (immature flies), caterpillars (immature butterflies/moths) and sawflies (most plant feeding wasps) is by looking at the number of fleshy stumps called “prolegs” present along their abdomen. All maggots and slug sawflies (i.e. rose slug, pear slug) have no prolegs. Caterpillars will have 3-5 pairs of prolegs with tiny hooks on them called “crochets” because they resemble knitting needles. Most sawflies have 6-9 pairs of prolegs and no crochets such is the case with both red-headed and European sawflies.
Control sawflies by hand removal of infected terminals or by pesticide sprays. Two reduced-risk products, Azadirachtin (Neem many trade names) and Spinosad (Conserve, Entrust) have very good sawfly efficacy. Numerous biological controls such as birds, squirrels and beneficial insects exist for sawflies and often keep their populations low naturally,
Casey Sclar, IPM Coordinator, Longwood Gardens
The European pine sawfly has one generation per year and larvae hatch from overwintered eggs laid in slits along needles. They feed until late May or early June. The red-headed pine sawfly has two generations. It overwinters as a mature larva and then quickly completes its life cycle in early spring. The first generation occurs in May-Early June and a second generation occurs in July-August.
These sawflies are chewing insects that look like caterpillars at first glance. However, don't use B.t. to control them! Sawflies are immature wasps/hornets and are not susceptible to B.t. sprays.
A quick way to tell the difference between “maggots” (immature flies), caterpillars (immature butterflies/moths) and sawflies (most plant feeding wasps) is by looking at the number of fleshy stumps called “prolegs” present along their abdomen. All maggots and slug sawflies (i.e. rose slug, pear slug) have no prolegs. Caterpillars will have 3-5 pairs of prolegs with tiny hooks on them called “crochets” because they resemble knitting needles. Most sawflies have 6-9 pairs of prolegs and no crochets such is the case with both red-headed and European sawflies.
Control sawflies by hand removal of infected terminals or by pesticide sprays. Two reduced-risk products, Azadirachtin (Neem many trade names) and Spinosad (Conserve, Entrust) have very good sawfly efficacy. Numerous biological controls such as birds, squirrels and beneficial insects exist for sawflies and often keep their populations low naturally,
Casey Sclar, IPM Coordinator, Longwood Gardens
Wednesday, May 21, 2008
Nursery, Landscape, and Greenhouse - Wet Weather Means Slugs
Wet weather has increased slug activity in landscapes. The following is information on these pests and their control from the University of Maryland.
In wet seasons slugs and snails, invertebrates with soft bodies in the phylum mollusca, can cause major losses of plants or a reduction in the quality of plant material in nurseries and can damage plants in the landscape. The high humidity environment of production beds is well-suited for supporting populations of slugs and snails. Several native and imported slugs and snails have been reported damaging foliage of annuals and herbaceous perennial plants.
Damage to Monitor
Plant damage occurs by the rasping action of the mouthparts. Damage to leaves appears as irregularly shaped holes with smooth edges. They can chew off succulent plant parts and growing tips that are close to the ground. Seedling plants can be completely consumed. A slime trail is nearly always associated with fresh feeding injury.
Control
Metaldehyde baits have been shown to attract slugs up to 3 feet away. The toxic effects of metaldehyde seem to be primarily due to dehydration as it elicits excessive mucus production (mucus is 98% water and 2% mucoproteins.) Thus in dry weather, metaldehyde is more effective. In wet weather, slugs sometimes can absorb enough moisture to compensate for the water lost in mucus production and therefore recover from the effects of metaldehyde. However, if slugs consume too much metaldehyde, they do not recover. Slugs seem to become more susceptible to carbamate pesticides as they mature. Copper sulfate is toxic to slugs and slugs will not crawl across a barrier of copper metal or wooden surfaces treated with copper sulfate. Mesurol is labeled for slug and snail control in greenhouses, and it also kills thrips. The problem is that Mesurol has a 24 hour REI.
Reprinted from the May 9, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the
University of Maryland Cooperative Extension
In wet seasons slugs and snails, invertebrates with soft bodies in the phylum mollusca, can cause major losses of plants or a reduction in the quality of plant material in nurseries and can damage plants in the landscape. The high humidity environment of production beds is well-suited for supporting populations of slugs and snails. Several native and imported slugs and snails have been reported damaging foliage of annuals and herbaceous perennial plants.
Damage to Monitor
Plant damage occurs by the rasping action of the mouthparts. Damage to leaves appears as irregularly shaped holes with smooth edges. They can chew off succulent plant parts and growing tips that are close to the ground. Seedling plants can be completely consumed. A slime trail is nearly always associated with fresh feeding injury.
Control
Metaldehyde baits have been shown to attract slugs up to 3 feet away. The toxic effects of metaldehyde seem to be primarily due to dehydration as it elicits excessive mucus production (mucus is 98% water and 2% mucoproteins.) Thus in dry weather, metaldehyde is more effective. In wet weather, slugs sometimes can absorb enough moisture to compensate for the water lost in mucus production and therefore recover from the effects of metaldehyde. However, if slugs consume too much metaldehyde, they do not recover. Slugs seem to become more susceptible to carbamate pesticides as they mature. Copper sulfate is toxic to slugs and slugs will not crawl across a barrier of copper metal or wooden surfaces treated with copper sulfate. Mesurol is labeled for slug and snail control in greenhouses, and it also kills thrips. The problem is that Mesurol has a 24 hour REI.
Reprinted from the May 9, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the
University of Maryland Cooperative Extension
Landscape - Oriental Bittersweet, an Invasive Plant
The following is information on oriental bittersweet which has become an invasive plant that you want to control on properties where it has escaped. Information is from the University of Maryland.
Oriental bittersweet, Celastrus orbiculatus, often called Asiatic bittersweet, is a deciduous woody perennial plant which grows very prolifically in this area. A problem of nursery and landscape settings, this fast growing vine can grow as tall as fifty feet or more in one year, with a stem diameter of up to four inches. The leaves will be alternate, round in shape, with a finely toothed margin. Damage from this weed can be from breakage of the desired plant as it will grow into the canopy and create either weight or potential storm damage. The spirally habit can also choke other desired plants. Oriental bittersweet is very similar to American bittersweet, and can be distinguished by the location of the flowers and fruit. Berry location on the American bittersweet is only at the tips of the vines where with the Oriental bittersweet, the berries occur all along the vines.
Oriental bittersweet is an invasive plant. One reason for concern is the color and great numbers of berries produced. As birds are one of the prime methods of dissemination, a brighter red color is very attractive to the birds and with greater numbers of berries to be found, the potential of spread is much higher. To add insult to this problem, the seeds also seem to have a higher germination percentage than that of American bittersweet. Control of Oriental bittersweet can be accomplished through either mechanical or chemical means. Cutting near the base can be effective with small plants. As plants mature, the use of a stem application after cutting with the immediate use of triclopyr (Garlon 4) or glyphosate (Roundup and others) at a 25% solution. Use caution not to apply the herbicide to the desired plant material, as thin barked species can be damaged or killed. In open settings, where possible apply triclopyr and glyphosate. If possible mow the site first to create the cut stem. Repeated applications may be necessary. The use of a basal oil and a penetrant may be beneficial to increase the effectiveness. Use eye protection when doing stem applications, as some products are salt based and may cause eye damage.
Information from Chuck Schuster in the May 9, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Oriental bittersweet, Celastrus orbiculatus, often called Asiatic bittersweet, is a deciduous woody perennial plant which grows very prolifically in this area. A problem of nursery and landscape settings, this fast growing vine can grow as tall as fifty feet or more in one year, with a stem diameter of up to four inches. The leaves will be alternate, round in shape, with a finely toothed margin. Damage from this weed can be from breakage of the desired plant as it will grow into the canopy and create either weight or potential storm damage. The spirally habit can also choke other desired plants. Oriental bittersweet is very similar to American bittersweet, and can be distinguished by the location of the flowers and fruit. Berry location on the American bittersweet is only at the tips of the vines where with the Oriental bittersweet, the berries occur all along the vines.
Oriental bittersweet is an invasive plant. One reason for concern is the color and great numbers of berries produced. As birds are one of the prime methods of dissemination, a brighter red color is very attractive to the birds and with greater numbers of berries to be found, the potential of spread is much higher. To add insult to this problem, the seeds also seem to have a higher germination percentage than that of American bittersweet. Control of Oriental bittersweet can be accomplished through either mechanical or chemical means. Cutting near the base can be effective with small plants. As plants mature, the use of a stem application after cutting with the immediate use of triclopyr (Garlon 4) or glyphosate (Roundup and others) at a 25% solution. Use caution not to apply the herbicide to the desired plant material, as thin barked species can be damaged or killed. In open settings, where possible apply triclopyr and glyphosate. If possible mow the site first to create the cut stem. Repeated applications may be necessary. The use of a basal oil and a penetrant may be beneficial to increase the effectiveness. Use eye protection when doing stem applications, as some products are salt based and may cause eye damage.
Information from Chuck Schuster in the May 9, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Tuesday, May 20, 2008
Landscape and Nursery - Some Leafminers to Look For
The following is information on some leafminers that may be active in the landscape now or in the near future.
Birch Leafminer and Hawthorn Leafminer
Common lilac is in bloom and this is the time that we generally see birch leafminer and hawthorn leafminer adult activity. The insects overwintered as pupae. The adults will be searching foliage and females will oviposit into foliage over the next couple of weeks. The eggs are laid through slits in the foliage. Your customers will see blotch mines form in the foliage in June. There are 3 - 4 generations per year.
Control: European birch is most susceptible to birch leafminer. Paper birch and gray birch are also susceptible. River birch can have the foliage damaged but it is usually a few leaves and the damage is very tolerable. Systemics such as imidacloprid and dinotefuran can be applied to the soil of susceptible trees to protect foliage.
Holly Leafminers
American hollies are about 10 –14 days away from flowering. Adult holly leafminers emerge just about the time of flowering of American holly. Adults are gray to black colored flies. The adults are out for several days before they mate and females start laying eggs.
Control: Soil applications of imidacloprid (Merit in Landscape and Marathon in Nursery), thiamexthoxam (Flagship) applied as a soil drench or dinotefuran (Safari) applied as soil application gives very effective control.
Reprinted from the May 16, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Birch Leafminer and Hawthorn Leafminer
Common lilac is in bloom and this is the time that we generally see birch leafminer and hawthorn leafminer adult activity. The insects overwintered as pupae. The adults will be searching foliage and females will oviposit into foliage over the next couple of weeks. The eggs are laid through slits in the foliage. Your customers will see blotch mines form in the foliage in June. There are 3 - 4 generations per year.
Control: European birch is most susceptible to birch leafminer. Paper birch and gray birch are also susceptible. River birch can have the foliage damaged but it is usually a few leaves and the damage is very tolerable. Systemics such as imidacloprid and dinotefuran can be applied to the soil of susceptible trees to protect foliage.
Holly Leafminers
American hollies are about 10 –14 days away from flowering. Adult holly leafminers emerge just about the time of flowering of American holly. Adults are gray to black colored flies. The adults are out for several days before they mate and females start laying eggs.
Control: Soil applications of imidacloprid (Merit in Landscape and Marathon in Nursery), thiamexthoxam (Flagship) applied as a soil drench or dinotefuran (Safari) applied as soil application gives very effective control.
Reprinted from the May 16, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.
Greenhouse - Bacterial Blight on Geranium
The following is a short article on bacterial blight of geranium from the University of Maryland.
Geranium bacterial blight, caused by Xanthomonas campestris pv. pelargonii, was observed this week. Symptoms of this important disease of geranium include small brown leaf spots, yellow and/or brown wedge-shaped areas on the leaves, and wilting and eventual plant death. There is no cure for infected plants – sanitation and early detection are the most effective management strategies. The pathogen can be spread through infected cuttings and splashing irrigation water, and can lead to significant losses. Because other diseases and disorders can mimic bacterial blight symptoms, it is important to have symptomatic plants checked by a diagnostic laboratory. More information on this disease can be found at the following Penn State University website: http://www.ppath.cas.psu.edu/extension/plant_disease/bactbl_g.html
Reprinted from the May 16, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension.
Geranium bacterial blight, caused by Xanthomonas campestris pv. pelargonii, was observed this week. Symptoms of this important disease of geranium include small brown leaf spots, yellow and/or brown wedge-shaped areas on the leaves, and wilting and eventual plant death. There is no cure for infected plants – sanitation and early detection are the most effective management strategies. The pathogen can be spread through infected cuttings and splashing irrigation water, and can lead to significant losses. Because other diseases and disorders can mimic bacterial blight symptoms, it is important to have symptomatic plants checked by a diagnostic laboratory. More information on this disease can be found at the following Penn State University website: http://www.ppath.cas.psu.edu/extension/plant_disease/bactbl_g.html
Reprinted from the May 16, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension.
Monday, May 19, 2008
Nursery and Landscape - What to do About Fire Blight Infections
Fire blight strikes are evident in landscape plantings. Fire blight affects rose family plants, most commonly apple and pear, but also crabapple, hawthorn, mountain ash, cotoneaster, pyracantha, and spirea. What should be done with fire blight infections? The following are recommendations.
Growers and landscapers dealing with infected trees are often tempted to remove fire blight infected branches as soon as they see them. In many cases, this would be the wrong strategy, because removing branches can encourage new shoots to develop and these new shoots would also be susceptible to new infections. If fire blight strikes are discovered early, before leaves have turned completely brown, timely removal of infected shoots can help slow the spread of the disease. However, most growers do not discover the disease early enough for this to be helpful. So what is to be done with infected trees now?
Growers should just let the disease run its course, allowing the tree defenses to stop fire blight spread within the tree. Dead shoots and branches should be removed later in summer, after the plant has stopped the infection or better in winter when there is little chance of spreading the disease.
Some growers may feel compelled to cut out fire blight infections, possibly for cosmetic or aesthetic reasons. What then? If pruning is begun after obvious symptoms appear, cut back in the direction of a healthy internode of at least two-year-old wood, leaving a stub several inches long. Rely on the tree's natural defenses to prevent further movement into the branch. If needed, paint the stub with bright paint to make it more obvious. This stub can then be safely removed in the winter. Leaving infected stubs rather than pruning all the way back to the main branch reduces the chances for development of undesirable water sprouts in response to pruning.
The reason not to prune infected branches back to a spur or crotch in summer is because it may not be noticed in winter and could be overlooked. It should not be necessary to sterilize cutting tools between cuts if only blighted shoots are being removed.
Do not engage in normal summer pruning and training at the same time as fire blight removal without wiping the cutters with sterilizing solutions like Lysol, 70% alcohol or 10% bleach. Don't forget to remove the infected stubs along with dead shoots and cankers next winter.
Do not apply chemical controls such as streptomycin. They are only effective if used during the normal bloom period. Remove trailing blooms to prevent late spring and summer infections.
Fire Blight Symptoms. Photo by Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.
Adapted from "FIRE BLIGHT-WHAT NOW?" By John Hartman in the May 31, 2005 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Growers and landscapers dealing with infected trees are often tempted to remove fire blight infected branches as soon as they see them. In many cases, this would be the wrong strategy, because removing branches can encourage new shoots to develop and these new shoots would also be susceptible to new infections. If fire blight strikes are discovered early, before leaves have turned completely brown, timely removal of infected shoots can help slow the spread of the disease. However, most growers do not discover the disease early enough for this to be helpful. So what is to be done with infected trees now?
Growers should just let the disease run its course, allowing the tree defenses to stop fire blight spread within the tree. Dead shoots and branches should be removed later in summer, after the plant has stopped the infection or better in winter when there is little chance of spreading the disease.
Some growers may feel compelled to cut out fire blight infections, possibly for cosmetic or aesthetic reasons. What then? If pruning is begun after obvious symptoms appear, cut back in the direction of a healthy internode of at least two-year-old wood, leaving a stub several inches long. Rely on the tree's natural defenses to prevent further movement into the branch. If needed, paint the stub with bright paint to make it more obvious. This stub can then be safely removed in the winter. Leaving infected stubs rather than pruning all the way back to the main branch reduces the chances for development of undesirable water sprouts in response to pruning.
The reason not to prune infected branches back to a spur or crotch in summer is because it may not be noticed in winter and could be overlooked. It should not be necessary to sterilize cutting tools between cuts if only blighted shoots are being removed.
Do not engage in normal summer pruning and training at the same time as fire blight removal without wiping the cutters with sterilizing solutions like Lysol, 70% alcohol or 10% bleach. Don't forget to remove the infected stubs along with dead shoots and cankers next winter.
Do not apply chemical controls such as streptomycin. They are only effective if used during the normal bloom period. Remove trailing blooms to prevent late spring and summer infections.
Fire Blight Symptoms. Photo by Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.Adapted from "FIRE BLIGHT-WHAT NOW?" By John Hartman in the May 31, 2005 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Landscape and Nursery - Juniper Tip Blights
Twig and branch tip dieback is a common sight in many juniper plantings in Delaware this spring. While other factors can cause these general symptoms, two fungal diseases are frequently responsible for the dieback. These fungi (Phomopsis juniperovora and Kabatina juniperi) attack several species of Juniperus, including red cedar, common juniper and creeping juniper. Arborvitae is also susceptible. In the spring, Kabatina twig blight is most noticeable. The following is information on these diseases.
Kabatina Twig Blight.
Brown shoots scattered within the healthy green foliage are being seen now. The disease is especially noticeable in beds of creeping juniper. These shoots, green all winter, have only recently turned brown. In early spring, as junipers begin to green up, infected twigs from the previous season's growth begin to fade to a pale green and then turn brown in contrast to healthy green tissues nearby. Grayish lesions with numerous gray-black fruiting bodies appear at the bases of blighted shoots. Kabatina twig blight infections begin through a wound caused by insects or mechanical injury and are thought to begin the previous fall.
Disease Management: 1) Prune out and destroy infected twig tips. Pruning should be done when the foliage is dry in order to minimize fungal spread. 2) Use an approved insecticide to control insect pests. It is possible that insects, such as the juniper midge, create the wounds necessary for Kabatina infections. 3) Avoid planting highly susceptible cultivars. Instead, select varieties that are known to be tolerant to Kabatina.
Phomopsis Twig Blight.
In late spring and in summer, as new shoots are developing, they can become infected with this pathogen during periods of moist weather. This disease begins as an infection of newly developing needles which then spreads to and kills stem tissues. As with Kabatina tip blight, a tan lesion with fungal fruiting bodies (pycnidia) develop after infection.
Disease Management: 1) Fungicides can be used in spring and summer to prevent infections of new growth. Applications of fungicides containing thiophanate-methyl, azoxystrobin, propiconazole, mancozeb, or fixed copper can protect twigs from infection. 2) Prune out and destroy infected twig tips when foliage is dry. 3) Avoid overhead irrigation, especially late in the evening.
Because these two diseases are so similar in appearance, the time of symptom development can be helpful in distinguishing between the two. Kabatina twig blight symptoms generally develop early in the spring before new growth begins. Phomopsis twig blight symptoms, on the other hand, are more likely to develop any time during the growing season. If twig blight symptoms are evident now on junipers that appeared healthy in the fall, Kabatina is likely responsible.
Most junipers are not immune to tip blight diseases.
Kabatina tolerant juniper (that are not known to be susceptible to Phomopsis) cultivars across several species include: Aurea Gold Coast, Blue Mountain, Burkii, Cologreen, Emerald Sentinal, Expansa, Henryii, Hetzii, Hetzii glauca, Hibernica, Hornbrooki, Keteleeri, Manhattan Blue, Marcellus, Mas, McFarland, Mint Julep, Mountbatten, Nana, Perfecta, Prostrata glauca, Robusta Green, Saybrook Gold, Sargentii viridis, Sargentii glauca, Silver Globe, Sutherland, Variegata.
Phomopsis tolerant juniper (that are not known to be susceptible to Kabatina) cultivars across several species include Arcadia, Ashfordii, Aureo-Globosa, Aureo-spica, Buffalo, Calgary Carpet, Campbellii, Cinerascens, Depressa, Douglassii, Expansa, Fargesii, Fastigiata, Femina, Globosa, Hetzii, Hibernica, Hillii, Iowa, Keteleeri, Knap Hill, Meyeri, Mint Julep, Mountbatten, Oblonga Pendula, Pfitzeriana, Pfitzeriana aurea, Prostrata aurea, Pumila, Pyramidalis, Repanda, Reptans, Robusta Green, Sargentii, Sargentii glauca, Saxatilis, Saybrook Gold, Shoosmith, Silver King, Skandia, Suecia, Tripartita,
Avoid the cultivars Adpressa, Albospica, Alpina, Argentea, Bar Harbor, Blue Chip, Blue Haven, Blue Horizon, Blue Mat, Blue Pacific, Broadmoor, Columnaris, Emerald Sea, Emerson Creeper, Eximius, Horizontalis, Japonica, Pendula, Platinum, Plumosa Compacta, Prince of Wales, Procumbens, Sky Rocket, Spartan, Torulosa Hollywood, Variegata, Welchii, Wiltonii, and Wichita Blue.
Information from the May 23, 2008 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Kabatina Twig Blight.
Brown shoots scattered within the healthy green foliage are being seen now. The disease is especially noticeable in beds of creeping juniper. These shoots, green all winter, have only recently turned brown. In early spring, as junipers begin to green up, infected twigs from the previous season's growth begin to fade to a pale green and then turn brown in contrast to healthy green tissues nearby. Grayish lesions with numerous gray-black fruiting bodies appear at the bases of blighted shoots. Kabatina twig blight infections begin through a wound caused by insects or mechanical injury and are thought to begin the previous fall.
Disease Management: 1) Prune out and destroy infected twig tips. Pruning should be done when the foliage is dry in order to minimize fungal spread. 2) Use an approved insecticide to control insect pests. It is possible that insects, such as the juniper midge, create the wounds necessary for Kabatina infections. 3) Avoid planting highly susceptible cultivars. Instead, select varieties that are known to be tolerant to Kabatina.
Phomopsis Twig Blight.
In late spring and in summer, as new shoots are developing, they can become infected with this pathogen during periods of moist weather. This disease begins as an infection of newly developing needles which then spreads to and kills stem tissues. As with Kabatina tip blight, a tan lesion with fungal fruiting bodies (pycnidia) develop after infection.
Disease Management: 1) Fungicides can be used in spring and summer to prevent infections of new growth. Applications of fungicides containing thiophanate-methyl, azoxystrobin, propiconazole, mancozeb, or fixed copper can protect twigs from infection. 2) Prune out and destroy infected twig tips when foliage is dry. 3) Avoid overhead irrigation, especially late in the evening.
Because these two diseases are so similar in appearance, the time of symptom development can be helpful in distinguishing between the two. Kabatina twig blight symptoms generally develop early in the spring before new growth begins. Phomopsis twig blight symptoms, on the other hand, are more likely to develop any time during the growing season. If twig blight symptoms are evident now on junipers that appeared healthy in the fall, Kabatina is likely responsible.
Most junipers are not immune to tip blight diseases.
Kabatina tolerant juniper (that are not known to be susceptible to Phomopsis) cultivars across several species include: Aurea Gold Coast, Blue Mountain, Burkii, Cologreen, Emerald Sentinal, Expansa, Henryii, Hetzii, Hetzii glauca, Hibernica, Hornbrooki, Keteleeri, Manhattan Blue, Marcellus, Mas, McFarland, Mint Julep, Mountbatten, Nana, Perfecta, Prostrata glauca, Robusta Green, Saybrook Gold, Sargentii viridis, Sargentii glauca, Silver Globe, Sutherland, Variegata.
Phomopsis tolerant juniper (that are not known to be susceptible to Kabatina) cultivars across several species include Arcadia, Ashfordii, Aureo-Globosa, Aureo-spica, Buffalo, Calgary Carpet, Campbellii, Cinerascens, Depressa, Douglassii, Expansa, Fargesii, Fastigiata, Femina, Globosa, Hetzii, Hibernica, Hillii, Iowa, Keteleeri, Knap Hill, Meyeri, Mint Julep, Mountbatten, Oblonga Pendula, Pfitzeriana, Pfitzeriana aurea, Prostrata aurea, Pumila, Pyramidalis, Repanda, Reptans, Robusta Green, Sargentii, Sargentii glauca, Saxatilis, Saybrook Gold, Shoosmith, Silver King, Skandia, Suecia, Tripartita,
Avoid the cultivars Adpressa, Albospica, Alpina, Argentea, Bar Harbor, Blue Chip, Blue Haven, Blue Horizon, Blue Mat, Blue Pacific, Broadmoor, Columnaris, Emerald Sea, Emerson Creeper, Eximius, Horizontalis, Japonica, Pendula, Platinum, Plumosa Compacta, Prince of Wales, Procumbens, Sky Rocket, Spartan, Torulosa Hollywood, Variegata, Welchii, Wiltonii, and Wichita Blue.
Information from the May 23, 2008 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Sunday, May 18, 2008
Turf - Summer Patch
Summer patch is a disease that we find primarily on bluegrass turf in Delaware. It starts showing up in June. Ther following is information on this disease.
Kentucky bluegrass (Poa pratensis), annual bluegrass (Poa annua), and fescues (Festuca sp.) can be affected during the summer by an interaction of environmental factors and a root and/or crown rot caused by the fungus Magnaporthe poae. This diseases is known as Summer Patch. Bentgrasses (Agrostis sp.) may also become infected but show few symptoms and may continue to perform where other grasses decline.
Summer Patch occurs between June and September. It can be difficult to diagnose this disease by symptoms alone in the early stages. The disease begins as scattered small round patches of thin, wilted or slow growing turf. Initially, affected patches may be only 3-8 cm in diameter, but thay may enlarge to about 30 cm in diameter (about 12 inches) and range from gray-green to light tan or straw-colored. In rarer circumstances, they may get to be twice that size. As patches enlarge, they may coalesce, and form crescents of yellow or tan turf. Where turf within the center of a patch begins to recover, necrotic rings may become evident.
Because Necrotic Ring Spot disease may exhibit similar symptoms, microscopic examination is often necessary to determine the cause of the problem. The roots, crowns and stolons of infected plants may appear to be dark brown as the dark mycelium of the funugus invades the tissue. As the disease progresses, the cortex may begin to rot, and plants may die.
Summer Patch blighted areas often occur on lawn sites that receive direct sun and are on south-facing slopes, or near sidewalks, driveways, buildings, or other "hot spots" or otherwise stresed areas in the yard or on golf courses. In the cool weather of autumn, the grass may begin to grow into these dead areas again. The disease, however, is likely to reappear in previously affected areas the following summer, and to increase in intensity. Summer patch usually occurs during the hotter periods (June, July, August) of the year. Summer patch is less of a problem during cool summers with adequate rainfall.
Disease Cycle
The fungus, Magnaporthe poae, survives unfavorable conditions as mycelium in infected plant tissue or plant debris. The optimum temperature for fungal growth is 28°C. Infection takes place in late spring when soil temperatures reach 19-20°C. Spread during the growing season occurs as the fungus grows between roots. Symptoms may not be evident until the temperature increases very drastically during wet weather. The pathogen may also be spread by movement of infected plant material and on mechanical equipment.
Management Strategies
The primary stresses that influence disease development include excesses of thatch, fertilizer, and turf canopy temperature, as well as incorrect timing of fertilizer applications, low mowing height, and pH extremes. Each of these stresses can be reduced through appropriate cultural practices described below. Disease severity may worsen at a higher pH, so try to maintain the pH of the soil and Rhizosphere at 5.5 to 6.0. Use an acidifying fertilizer where the pH is above 6.0, and try to avoid the use of products that may raise the pH.
For most bluegrass lawns, two to five lbs of nitrogen/1000 sq.ft. is sufficient. Apply this in a fertilizer balanced by phosphorus and potassium. Do not apply even small amounts of fertilizer during the June-August stress period because this will tend to stimulate the disease. Therefore, fertilize only in autumn (September through November) and in late spring (May). Deep watering is essential for proper root growth. Water the soil under disease-prone areas to a depth of 15 to 20 cm every 7-10 days during the dry periods of the summer. Soaker hoses are very useful for supplementary watering on steeper slopes where other sprinklers are inefficient. The harmful effects of excessive temperature can be reduced by a light sprinkling of the surface at mid-day. Proneness to disease in turf is increased as the cutting height is decreased. Cut lawns at 5 to 10 cm height, and often enough so that less than 1/3 of the leaf blade is removed during each mowing. Thatch (the layer of organic matter between the mineral soil and the green grass) should be no more than 1.5 cm (1/2 inches) in thickness. Thatch can be removed by vertical slicing machines and/or aeration during the spring and early fall. Over a longer period thatch will be reduced by using the cultural practices discussed above.
Kentucky bluegrass cultivars such as Adelphi, America, Aspen, Columbia, Eclipse, Glade, Midnight, Nassau, Parade, Ram I, Sydsport, Touchdown, Vantage, Windsor, and Victa are less susceptible to summer patch than others. Blend seed of resistant cultivars with that of one or more otherwise desirable cultivars.
Chemical treatment is efficient only when the previously mentioned cultural practices are first used. Furthermore, applications must be made before the crown rot develops sufficiently to cause visual symptoms of the disease. Fungicides containing the active ingredients azoxystrobin, cyproconazole, fenarimol, propiconazole, iprodione, thiophanate-methyl, trifloxystrobin or triadimefon are available for control of summer patch in commercial applications. Other products containing azoxystrobin, myclobutanil, thiophanate-methyl, or triadimefon may be available for use on home lawns by homeowners to manage this disease. Thoroughly water (applying 2 to 3 cm of water) areas with a history of this disease several days before applying the fungicide. To determine the best time to treat, monitor soil temperature to a depth of 2 inches, and make the first application when the soil temperature reaches 55°F. or about 13°C. Additional applications may be required for certain fungicides. Always adhere to the rates and procedures recommended on the fungicide package label.
Reprinted in part from "SUMMER PATCH ON TURFGRASS" a Cornell University Plant Disease Diagnostic Clinic factsheet http://plantclinic.cornell.edu/factsheets/summerpatch/summer_patch.htm
Kentucky bluegrass (Poa pratensis), annual bluegrass (Poa annua), and fescues (Festuca sp.) can be affected during the summer by an interaction of environmental factors and a root and/or crown rot caused by the fungus Magnaporthe poae. This diseases is known as Summer Patch. Bentgrasses (Agrostis sp.) may also become infected but show few symptoms and may continue to perform where other grasses decline.
Summer Patch occurs between June and September. It can be difficult to diagnose this disease by symptoms alone in the early stages. The disease begins as scattered small round patches of thin, wilted or slow growing turf. Initially, affected patches may be only 3-8 cm in diameter, but thay may enlarge to about 30 cm in diameter (about 12 inches) and range from gray-green to light tan or straw-colored. In rarer circumstances, they may get to be twice that size. As patches enlarge, they may coalesce, and form crescents of yellow or tan turf. Where turf within the center of a patch begins to recover, necrotic rings may become evident.
Because Necrotic Ring Spot disease may exhibit similar symptoms, microscopic examination is often necessary to determine the cause of the problem. The roots, crowns and stolons of infected plants may appear to be dark brown as the dark mycelium of the funugus invades the tissue. As the disease progresses, the cortex may begin to rot, and plants may die.
Summer Patch blighted areas often occur on lawn sites that receive direct sun and are on south-facing slopes, or near sidewalks, driveways, buildings, or other "hot spots" or otherwise stresed areas in the yard or on golf courses. In the cool weather of autumn, the grass may begin to grow into these dead areas again. The disease, however, is likely to reappear in previously affected areas the following summer, and to increase in intensity. Summer patch usually occurs during the hotter periods (June, July, August) of the year. Summer patch is less of a problem during cool summers with adequate rainfall.
Disease Cycle
The fungus, Magnaporthe poae, survives unfavorable conditions as mycelium in infected plant tissue or plant debris. The optimum temperature for fungal growth is 28°C. Infection takes place in late spring when soil temperatures reach 19-20°C. Spread during the growing season occurs as the fungus grows between roots. Symptoms may not be evident until the temperature increases very drastically during wet weather. The pathogen may also be spread by movement of infected plant material and on mechanical equipment.
Management Strategies
The primary stresses that influence disease development include excesses of thatch, fertilizer, and turf canopy temperature, as well as incorrect timing of fertilizer applications, low mowing height, and pH extremes. Each of these stresses can be reduced through appropriate cultural practices described below. Disease severity may worsen at a higher pH, so try to maintain the pH of the soil and Rhizosphere at 5.5 to 6.0. Use an acidifying fertilizer where the pH is above 6.0, and try to avoid the use of products that may raise the pH.
For most bluegrass lawns, two to five lbs of nitrogen/1000 sq.ft. is sufficient. Apply this in a fertilizer balanced by phosphorus and potassium. Do not apply even small amounts of fertilizer during the June-August stress period because this will tend to stimulate the disease. Therefore, fertilize only in autumn (September through November) and in late spring (May). Deep watering is essential for proper root growth. Water the soil under disease-prone areas to a depth of 15 to 20 cm every 7-10 days during the dry periods of the summer. Soaker hoses are very useful for supplementary watering on steeper slopes where other sprinklers are inefficient. The harmful effects of excessive temperature can be reduced by a light sprinkling of the surface at mid-day. Proneness to disease in turf is increased as the cutting height is decreased. Cut lawns at 5 to 10 cm height, and often enough so that less than 1/3 of the leaf blade is removed during each mowing. Thatch (the layer of organic matter between the mineral soil and the green grass) should be no more than 1.5 cm (1/2 inches) in thickness. Thatch can be removed by vertical slicing machines and/or aeration during the spring and early fall. Over a longer period thatch will be reduced by using the cultural practices discussed above.
Kentucky bluegrass cultivars such as Adelphi, America, Aspen, Columbia, Eclipse, Glade, Midnight, Nassau, Parade, Ram I, Sydsport, Touchdown, Vantage, Windsor, and Victa are less susceptible to summer patch than others. Blend seed of resistant cultivars with that of one or more otherwise desirable cultivars.
Chemical treatment is efficient only when the previously mentioned cultural practices are first used. Furthermore, applications must be made before the crown rot develops sufficiently to cause visual symptoms of the disease. Fungicides containing the active ingredients azoxystrobin, cyproconazole, fenarimol, propiconazole, iprodione, thiophanate-methyl, trifloxystrobin or triadimefon are available for control of summer patch in commercial applications. Other products containing azoxystrobin, myclobutanil, thiophanate-methyl, or triadimefon may be available for use on home lawns by homeowners to manage this disease. Thoroughly water (applying 2 to 3 cm of water) areas with a history of this disease several days before applying the fungicide. To determine the best time to treat, monitor soil temperature to a depth of 2 inches, and make the first application when the soil temperature reaches 55°F. or about 13°C. Additional applications may be required for certain fungicides. Always adhere to the rates and procedures recommended on the fungicide package label.
Reprinted in part from "SUMMER PATCH ON TURFGRASS" a Cornell University Plant Disease Diagnostic Clinic factsheet http://plantclinic.cornell.edu/factsheets/summerpatch/summer_patch.htm
Nursery and Landscape - Newer Insecticides and Their Use.
Over the last 4-5 years, many new insecticides have been registered for use in horticultural applications. The following are some of these as well as informtion on some new uses for older insecticides.
Tristar (acetamiprid). This is a neonicotinoid insecticide available as a foliar spray for control of aphids, mealybugs, caterpillars, scales, whiteflies, thrips, leaf-eating beetles and leafminers. Nursery and landscape.
Safari (dinotefuran). A neonicotinoid insecticide used as a foliar spray or soil drench for control of whiteflies, aphids, scales, leafminers, mealybugs and other insects. Nursery and Landscape.
Celero (clothianidin). A new neonicotinoid insecticide for aphids, whiteflies and mealybugs in ornamental crops. The same active ingredient is labeled as Arena for use in turfgrass. Arena provided great control of grubs in turf, even surpassing Merit in our trials last year. Nursery and Landscape.
Discus (imidacloprid + cyfluthrin). Soil directed sprays in late June or July should be lightly covered with soil or watered-in immediately after application for optimum control of grubs. Discus is also excellent for aphid control and will help suppress scale insects and mealybugs. Allow four weeks after soil application for uptake by roots and movement into the leaves. Foliar sprays will control a wide spectrum of insects because of the cyfluthrin. Nurseries.
Flagship (thiamethoxam). Soil-directed sprays in June followed by rain or irrigation will control Fletcher scale and other scale insects and aphids. This insecticide seems to work better for soft scale insects than imidacloprid. June applications will also provide grub control, although July is the optimum timing for grubs. Nurseries
Distance (pyriproxyfen). Although not a new product, recent research tests in Indiana showed that Distance gave the highest level of control of euonymus scale of any product tested. This means it should also work well as a crawler spray for pine needle scale, oystershell scale and any armored scale insects. Nursery or landscape.
Reprinted from the June 10, 2005 edition of the Michigan Landscape Alert newsletter from Michigan State University.
Tristar (acetamiprid). This is a neonicotinoid insecticide available as a foliar spray for control of aphids, mealybugs, caterpillars, scales, whiteflies, thrips, leaf-eating beetles and leafminers. Nursery and landscape.
Safari (dinotefuran). A neonicotinoid insecticide used as a foliar spray or soil drench for control of whiteflies, aphids, scales, leafminers, mealybugs and other insects. Nursery and Landscape.
Celero (clothianidin). A new neonicotinoid insecticide for aphids, whiteflies and mealybugs in ornamental crops. The same active ingredient is labeled as Arena for use in turfgrass. Arena provided great control of grubs in turf, even surpassing Merit in our trials last year. Nursery and Landscape.
Discus (imidacloprid + cyfluthrin). Soil directed sprays in late June or July should be lightly covered with soil or watered-in immediately after application for optimum control of grubs. Discus is also excellent for aphid control and will help suppress scale insects and mealybugs. Allow four weeks after soil application for uptake by roots and movement into the leaves. Foliar sprays will control a wide spectrum of insects because of the cyfluthrin. Nurseries.
Flagship (thiamethoxam). Soil-directed sprays in June followed by rain or irrigation will control Fletcher scale and other scale insects and aphids. This insecticide seems to work better for soft scale insects than imidacloprid. June applications will also provide grub control, although July is the optimum timing for grubs. Nurseries
Distance (pyriproxyfen). Although not a new product, recent research tests in Indiana showed that Distance gave the highest level of control of euonymus scale of any product tested. This means it should also work well as a crawler spray for pine needle scale, oystershell scale and any armored scale insects. Nursery or landscape.
Reprinted from the June 10, 2005 edition of the Michigan Landscape Alert newsletter from Michigan State University.
Saturday, May 17, 2008
Landscape - Ticks
Workers in the landscape industry should be aware of how to deal with ticks. The following is some information on the subject.
Q: Where do ticks come from and how can I avoid them?
A: Ticks thrive in woods, uncut fields and brush. They climb onto lower portions of vegetation and attach to a suitable host passing by. To reduce tick encounters, follow these precautions:
1. Don't walk through uncut fields, brush, and overgrown areas, especially during April-July. When working in tick-infested areas, wear light-colored clothing and long pants tucked into boots or socks, and consider using tick repellent.
2. Workers should have someone inspect them after being in tick prone areas. Ticks often attach at the waist, armpit, neck and scalp, but can attach virtually anywhere. Promptly remove any ticks, using the method discussed below.
3. Keep grass and shrubs trimmed, and clear overgrown vegetation from edges of a property. Ticks and their wild hosts will not normally infest areas that are well maintained. Treating the property with insecticides is of little benefit since mowed areas are not normally infested. If insecticides are used, treatment should be concentrated mainly along borders and fences, and between overgrown areas and the lawn. A good way to confirm if ticks are present is to drag a white flannel cloth or sheet through suspected areas. Ticks will attach and be visible against the white background.
Insecticide sprays containing pyrethroid active ingredients permethrin, cyfluthrin, bifenthrin or lambda-cyhalothrin or carbaryl (Sevin) are effective. One to two applications during late April/May and perhaps mid-summer is often all that's required.
Lyme Disease
Lyme disease is a disease caused by a bacteria vectored by the deer tick. It is sometimes referred to as ‘the great imitator' since symptoms of the disease are common to many other diseases. It is initially flu-like but if not treated can develop into rheumatoid arthritis-type conditions. It is not usually fatal but can be debilitating and difficult to treat if not detected early. Humans, our pets, wild and domestic animals may get the disease.
Lyme disease is caused by a bacteria transmitted by the deer tick Ixodes dammini. This tick is found in grassy areas, open fields and especially the margin where fields and wooded areas join. Incidence of the disease is increasing in Delaware.
Description and Life Cycle
After hatching from an egg in late spring, deer ticks go through three life stages: larva, nymph, and adult. Each stage requires a different host animal. During each stage a tick feeds only once. It is a 2 year life cycle. Larvae - are very small (about the size of a pin head) and tan in color. They feed in late summer (near ground level) on mice, shrews, chipmunks, voles, and other small animals. Larvae pick up the disease bacteria feeding on an infected animal.
Nymphs are the size of a poppy seed. They are beige in color, sometimes appearing transparent with a dark head. Nymphs feed from May through August on larger animals; including birds, raccoons, opossum, squirrels, cats, dogs and human beings.
Adults ticks are tiny only the size of a sesame seed. Males are black; females have a brick-red abdomen and a black shield near the head. Females may swell to 1/4 inch when fully engorged after feeding. Adults are found from September through November, and again in March and April. Adults feed primarily on deer, but will also attack cattle, horses, dogs, etc. Human beings are accidental hosts of nymphs or adults.
Disease Cycle
The risk of being bitten by an infected deer tick is greatest in the summer months of June and July when the nymph stage is active. This is the time of year when people (and notably children) are most active outdoors. About 25% of the deer ticks in Delaware (depending on where they are found) are infected with, and able to transmit Lyme Disease. Newly hatched deer tick larvae do not initially carry this disease; they pick it up from an infected animal usually the white-footed mouse, the primary carrier/source of the Lyme Disease bacterium. After feeding, a tick that picks up the bacterium passes it to the next life stage, and is able to infect future host animals.
The early signs of Lyme Disease are:
• Headache
• Flu-like symptoms
• Spreading "bull's-eye" rash
• Swelling and pain in the joints
Lyme Disease symptoms mimic many other diseases. About 80 percent of Lyme Disease victims develop a rash at the site of the tick bite within 2 days to 4 weeks. If untreated, more severe symptoms may develop--sometimes months to years later. If you suspect Lyme Disease, consult a physician immediately.
Tick Removal
If you find a tick on your body, remove it AS SOON AS POSSIBLE. For feeding ticks, use tweezers ONLY; do NOT use nail polish, Vaseline, matches, or other methods that may traumatize the tick and cause it to regurgitate its gut contents. Grasp the tick with tweezers around its head, close to the skin and pull it outward slowly and firmly. Disinfect the bite afterwards with antiseptic.
Tick Prevention
1. Avoiding Ticks Outdoors
o Avoid tall grass and shrubby areas
o Wear slacks tucked into socks
o Wear light colored clothing (to help locate ticks easily)
o Stay close to the center of hiking trails (avoid brushing against vegetation)
o Check companions and children frequently for ticks
2. Use a repellent
• Apply to shoes, socks, and pants:
• PERMANONE* (permethrin) - kills ticks on contact - Labeled for clothing only, it will last through two or three washings.
• N,N-Diethyl-meta-toluamide commonly known as DEET. ("DEET,""Off," "Cutter," "Muskol")--repels ticks labeled for skin or clothing.
Q: Where do ticks come from and how can I avoid them?
A: Ticks thrive in woods, uncut fields and brush. They climb onto lower portions of vegetation and attach to a suitable host passing by. To reduce tick encounters, follow these precautions:
1. Don't walk through uncut fields, brush, and overgrown areas, especially during April-July. When working in tick-infested areas, wear light-colored clothing and long pants tucked into boots or socks, and consider using tick repellent.
2. Workers should have someone inspect them after being in tick prone areas. Ticks often attach at the waist, armpit, neck and scalp, but can attach virtually anywhere. Promptly remove any ticks, using the method discussed below.
3. Keep grass and shrubs trimmed, and clear overgrown vegetation from edges of a property. Ticks and their wild hosts will not normally infest areas that are well maintained. Treating the property with insecticides is of little benefit since mowed areas are not normally infested. If insecticides are used, treatment should be concentrated mainly along borders and fences, and between overgrown areas and the lawn. A good way to confirm if ticks are present is to drag a white flannel cloth or sheet through suspected areas. Ticks will attach and be visible against the white background.
Insecticide sprays containing pyrethroid active ingredients permethrin, cyfluthrin, bifenthrin or lambda-cyhalothrin or carbaryl (Sevin) are effective. One to two applications during late April/May and perhaps mid-summer is often all that's required.
Lyme Disease
Lyme disease is a disease caused by a bacteria vectored by the deer tick. It is sometimes referred to as ‘the great imitator' since symptoms of the disease are common to many other diseases. It is initially flu-like but if not treated can develop into rheumatoid arthritis-type conditions. It is not usually fatal but can be debilitating and difficult to treat if not detected early. Humans, our pets, wild and domestic animals may get the disease.
Lyme disease is caused by a bacteria transmitted by the deer tick Ixodes dammini. This tick is found in grassy areas, open fields and especially the margin where fields and wooded areas join. Incidence of the disease is increasing in Delaware.
Description and Life Cycle
After hatching from an egg in late spring, deer ticks go through three life stages: larva, nymph, and adult. Each stage requires a different host animal. During each stage a tick feeds only once. It is a 2 year life cycle. Larvae - are very small (about the size of a pin head) and tan in color. They feed in late summer (near ground level) on mice, shrews, chipmunks, voles, and other small animals. Larvae pick up the disease bacteria feeding on an infected animal.
Nymphs are the size of a poppy seed. They are beige in color, sometimes appearing transparent with a dark head. Nymphs feed from May through August on larger animals; including birds, raccoons, opossum, squirrels, cats, dogs and human beings.
Adults ticks are tiny only the size of a sesame seed. Males are black; females have a brick-red abdomen and a black shield near the head. Females may swell to 1/4 inch when fully engorged after feeding. Adults are found from September through November, and again in March and April. Adults feed primarily on deer, but will also attack cattle, horses, dogs, etc. Human beings are accidental hosts of nymphs or adults.
Disease Cycle
The risk of being bitten by an infected deer tick is greatest in the summer months of June and July when the nymph stage is active. This is the time of year when people (and notably children) are most active outdoors. About 25% of the deer ticks in Delaware (depending on where they are found) are infected with, and able to transmit Lyme Disease. Newly hatched deer tick larvae do not initially carry this disease; they pick it up from an infected animal usually the white-footed mouse, the primary carrier/source of the Lyme Disease bacterium. After feeding, a tick that picks up the bacterium passes it to the next life stage, and is able to infect future host animals.
The early signs of Lyme Disease are:
• Headache
• Flu-like symptoms
• Spreading "bull's-eye" rash
• Swelling and pain in the joints
Lyme Disease symptoms mimic many other diseases. About 80 percent of Lyme Disease victims develop a rash at the site of the tick bite within 2 days to 4 weeks. If untreated, more severe symptoms may develop--sometimes months to years later. If you suspect Lyme Disease, consult a physician immediately.
Tick Removal
If you find a tick on your body, remove it AS SOON AS POSSIBLE. For feeding ticks, use tweezers ONLY; do NOT use nail polish, Vaseline, matches, or other methods that may traumatize the tick and cause it to regurgitate its gut contents. Grasp the tick with tweezers around its head, close to the skin and pull it outward slowly and firmly. Disinfect the bite afterwards with antiseptic.
Tick Prevention
1. Avoiding Ticks Outdoors
o Avoid tall grass and shrubby areas
o Wear slacks tucked into socks
o Wear light colored clothing (to help locate ticks easily)
o Stay close to the center of hiking trails (avoid brushing against vegetation)
o Check companions and children frequently for ticks
2. Use a repellent
• Apply to shoes, socks, and pants:
• PERMANONE* (permethrin) - kills ticks on contact - Labeled for clothing only, it will last through two or three washings.
• N,N-Diethyl-meta-toluamide commonly known as DEET. ("DEET,""Off," "Cutter," "Muskol")--repels ticks labeled for skin or clothing.
Information from the University of Kentucky and the University of Delaware.
Turf - Should You Clean or Sanitize Mowers Between Properties?
Anything that slows down the ability of a lawn care company to get from one property to another will result in reduced profits. One question that gets asked is should mowers be cleaned, washed, or sanitized between properties? The following is some information.
From time to time, the question comes up as to whether mowing equipment can transport microorganisms that cause disease (called pathogens). The answer is, "Yes, it certainly can". Inoculum is any pathogen structure that can initiate disease. Microscopic fungal spores are the most common form of inoculum in turfgrass ecosystems. Another important form of inoculum is bits of diseased grass that are cut off by the mower blade.
So if you think for a moment and imagine a microscopic fungal spore, it is easy to imagine that it can attach temporarily to the mower blade, the wheels, the carriage of the mower, etc. Furthermore, anyone who mows grass also knows that fragments of cut leaves also attach to mowers. If these cut fragments are diseased, the disease-causing agent will also be readily transported. So yes, mowers clearly can move fungal inoculum from one property to another.
Does it matter? Well, that is the key question, and the answer, at least for Delaware conditions, is "No". Most of the diseases of significance in Delaware turfgrasses are caused by fungi that are easily transported as windblown spores or are common residents of our soils. Movement of inoculum of on lawn-maintenance equipment doesn't really move inoculum any more effectively that Mother Nature already has.
In my assessment, there seems to be no reason to sanitize lawn maintenance equipment when going from one property to the next. Lawn care operators can breathe a sigh of relief, because if sanitation were biologically important to do so, I can imagine it would be very difficult to implement an effective and economical program for sanitation of mowing equipment in a commercial lawn care operation.
There can be a case made with the transport of weed seeds. If you are in the lawn maintenance business, you do not want to transport problem weeds from one site to another. Having an air tank on the truck to blow off the tops of mower decks and do quick removal of materials stuck to the the underside of mower decks can go a long way toward reducing spread of weeds. If properties are relatively weed free, this will not be necessary.
Information from "DO MOWERS SPREAD DISEASE-CAUSING AGENTS FROM ONE LAWN TO ANOTHER?" By Paul Vincelli in the May 12, 2008 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture. Comments on weeds by Gordon Johnson, Extension Agriculture Agent, UD, Kent County.
From time to time, the question comes up as to whether mowing equipment can transport microorganisms that cause disease (called pathogens). The answer is, "Yes, it certainly can". Inoculum is any pathogen structure that can initiate disease. Microscopic fungal spores are the most common form of inoculum in turfgrass ecosystems. Another important form of inoculum is bits of diseased grass that are cut off by the mower blade.
So if you think for a moment and imagine a microscopic fungal spore, it is easy to imagine that it can attach temporarily to the mower blade, the wheels, the carriage of the mower, etc. Furthermore, anyone who mows grass also knows that fragments of cut leaves also attach to mowers. If these cut fragments are diseased, the disease-causing agent will also be readily transported. So yes, mowers clearly can move fungal inoculum from one property to another.
Does it matter? Well, that is the key question, and the answer, at least for Delaware conditions, is "No". Most of the diseases of significance in Delaware turfgrasses are caused by fungi that are easily transported as windblown spores or are common residents of our soils. Movement of inoculum of on lawn-maintenance equipment doesn't really move inoculum any more effectively that Mother Nature already has.
In my assessment, there seems to be no reason to sanitize lawn maintenance equipment when going from one property to the next. Lawn care operators can breathe a sigh of relief, because if sanitation were biologically important to do so, I can imagine it would be very difficult to implement an effective and economical program for sanitation of mowing equipment in a commercial lawn care operation.
There can be a case made with the transport of weed seeds. If you are in the lawn maintenance business, you do not want to transport problem weeds from one site to another. Having an air tank on the truck to blow off the tops of mower decks and do quick removal of materials stuck to the the underside of mower decks can go a long way toward reducing spread of weeds. If properties are relatively weed free, this will not be necessary.
Information from "DO MOWERS SPREAD DISEASE-CAUSING AGENTS FROM ONE LAWN TO ANOTHER?" By Paul Vincelli in the May 12, 2008 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture. Comments on weeds by Gordon Johnson, Extension Agriculture Agent, UD, Kent County.
Friday, May 16, 2008
Greenhouse - Black Root Rot
Thielaviopsis root rot, also called black root rot is a problem in bedding plants such as annual vinca. It is often seen as chlorosis of young leaves and leads to losses in greenhouse and planting beds. Once established it can be very difficult to control, due to resistant spores in soil. The following is some information on this disease of greenhouse plants.
Black root rot is a common and destructive fungal disease on greenhouse floral crops. The disease is widespread, having been reported on many different plants including poinsettia, geranium, fuchsia, pansy, vincas, petunia, etc. The fungus is soil-borne and is capable of living in soils as a saprophyte (without causing disease) and surviving in soil and dust for years via tiny, thick-walled spores called chlamydospores. Plants may be infected but not show symptoms until the plant undergoes some form of stress.
Symptoms
Black root rot is commonly confused with Pythium root rot. Above-ground symptoms of both diseases include yellowing, stunting and under certain conditions wilting or death of the plant. Sometimes, plants affected with black root rot may have black stem lesions at or near the soil line. A close examination of the roots will reveal different symptoms for each disease. Pythium usually attacks roots from the ends or tips, causing a soft, brown rotting as it progresses. Oospores of Pythium can be seen in the infected roots with a microscope. Black root rot begins by attacking the middle of the root and forms cankers. The black root cankers can be seen relatively easily by washing roots free of growing media and then viewing them carefully with a hand lens. A plant diagnostic lab can be consulted if you suspect black root rot. Be sure and tell them you think black root rot may be involved so that the lab will examine the roots through a microscope. If Thielaviopsis is there, the black, barrel-shaped spores will be easily seen. There are also methods to culture the fungus from the tissue. Since the pathogen grows slowly onto the culture plate, culturing is rarely done in a diagnostic lab.
Causal Fungus and Disease Development
Black root rot is caused by the fungus, Thielaviopsis basicola. As mentioned earlier, the fungus is very common and widespread. It has a wide host range and affects many other hosts besides greenhouse floral crops. Thielaviopsis can spread between greenhouses or between crops within a greenhouse in many ways. Long distance spread between greenhouses occurs via the movement of infested (but not necessarily diseased) plant material. Many of our specialized plug producers control crop stresses so well that an infestation of their material goes undetected by all parties until the plants are stressed in shipment or transplanting.
Infested plugs are not the only way your crop can get black root rot. Thielaviopsis also has the potential to enter a greenhouse via wind blown dust or in growing media. Once within a greenhouse, there are many situations that can result in the pathogen becoming a long term resident. Thielaviopsis has a broad host range, and its saprophytic nature may allow it to continue to grow, spread and survive on many plants in the greenhouse that may appear symptomless or nearly so.
Thielaviopsis produces resistant "resting" spores on infected host tissue in tremendous numbers. These spores can be splashed about or blown about in dust in the air. They will be present on flats, pots, or trays that may be brought into a work area for reuse. In addition, the pathogen produces a second type of spore that is spread by splashing water. It may be the spread of these small spores that allows the disease to develop so quickly once it gets started. All in all, the black root rot pathogen is well suited to becoming a permanent, though unwelcome, resident in your greenhouse.
Disease Management
Avoid Plant Stress. Almost any factor that stresses the host plant can lead to further parasitic development of this disease. On the other hand, correcting plant stress can allow infested plants to "outgrow" the disease and eventually recover.
Crops grown under conditions that are too cool or too warm are often subject to this disease. Nutritional imbalances are also frequently associated with disease development. Excess of ammonia nitrogen appears to be particularly troublesome for pansy growers dealing with black root rot. Growing media with a pH above 5.5-6.0 are also conducive to black root rot development.
A well-drained medium provides an environment favorable for the seedling and somewhat less favorable for the pathogen. Carefully executed watering practices are very important. When the medium is irrigated thoroughly and less often, conditions at or near the surface of the medium tend to remain slightly drier and are less favorable for growth of the pathogen. Plug trays must be kept evenly moist and sufficiently warm to enable seed to germinate rapidly and seedlings to emerge promptly.
Sanitation
Thielaviopsis is well adapted to survival in the greenhouse. Some relatively simple practices are crucial for controlling this disease. Do not reuse containers or trays. Do not create dust, especially when the dust can settle on piles of growing media nearby. Disinfesting potting media will eliminate the organism and should be carried out if there is any topsoil or sand to be used in the growing media. Sanitize benches when possible.
Chemicals
There are quit a few good chemicals with efficacy against Thielaviopsis. Routine, monthly drenches at labeled rates with chemicals such as Cleary's 3336, Domain, Banner, and Terragard will help protect your crops. With bedding plants, you must have the fungicide present at seeding. Plug crops can be infected within only a few days after seeding. Continue a regular monthly schedule throughout transplanting and finishing the crop.
Reprinted from "Black Root Rot of Greenhouse Floral Crops" by Stephen Nameth, Ohio State University Extension Fact Sheet HYG-3066-96, Plant Pathology
Black root rot is a common and destructive fungal disease on greenhouse floral crops. The disease is widespread, having been reported on many different plants including poinsettia, geranium, fuchsia, pansy, vincas, petunia, etc. The fungus is soil-borne and is capable of living in soils as a saprophyte (without causing disease) and surviving in soil and dust for years via tiny, thick-walled spores called chlamydospores. Plants may be infected but not show symptoms until the plant undergoes some form of stress.
Symptoms
Black root rot is commonly confused with Pythium root rot. Above-ground symptoms of both diseases include yellowing, stunting and under certain conditions wilting or death of the plant. Sometimes, plants affected with black root rot may have black stem lesions at or near the soil line. A close examination of the roots will reveal different symptoms for each disease. Pythium usually attacks roots from the ends or tips, causing a soft, brown rotting as it progresses. Oospores of Pythium can be seen in the infected roots with a microscope. Black root rot begins by attacking the middle of the root and forms cankers. The black root cankers can be seen relatively easily by washing roots free of growing media and then viewing them carefully with a hand lens. A plant diagnostic lab can be consulted if you suspect black root rot. Be sure and tell them you think black root rot may be involved so that the lab will examine the roots through a microscope. If Thielaviopsis is there, the black, barrel-shaped spores will be easily seen. There are also methods to culture the fungus from the tissue. Since the pathogen grows slowly onto the culture plate, culturing is rarely done in a diagnostic lab.
Causal Fungus and Disease Development
Black root rot is caused by the fungus, Thielaviopsis basicola. As mentioned earlier, the fungus is very common and widespread. It has a wide host range and affects many other hosts besides greenhouse floral crops. Thielaviopsis can spread between greenhouses or between crops within a greenhouse in many ways. Long distance spread between greenhouses occurs via the movement of infested (but not necessarily diseased) plant material. Many of our specialized plug producers control crop stresses so well that an infestation of their material goes undetected by all parties until the plants are stressed in shipment or transplanting.
Infested plugs are not the only way your crop can get black root rot. Thielaviopsis also has the potential to enter a greenhouse via wind blown dust or in growing media. Once within a greenhouse, there are many situations that can result in the pathogen becoming a long term resident. Thielaviopsis has a broad host range, and its saprophytic nature may allow it to continue to grow, spread and survive on many plants in the greenhouse that may appear symptomless or nearly so.
Thielaviopsis produces resistant "resting" spores on infected host tissue in tremendous numbers. These spores can be splashed about or blown about in dust in the air. They will be present on flats, pots, or trays that may be brought into a work area for reuse. In addition, the pathogen produces a second type of spore that is spread by splashing water. It may be the spread of these small spores that allows the disease to develop so quickly once it gets started. All in all, the black root rot pathogen is well suited to becoming a permanent, though unwelcome, resident in your greenhouse.
Disease Management
Avoid Plant Stress. Almost any factor that stresses the host plant can lead to further parasitic development of this disease. On the other hand, correcting plant stress can allow infested plants to "outgrow" the disease and eventually recover.
Crops grown under conditions that are too cool or too warm are often subject to this disease. Nutritional imbalances are also frequently associated with disease development. Excess of ammonia nitrogen appears to be particularly troublesome for pansy growers dealing with black root rot. Growing media with a pH above 5.5-6.0 are also conducive to black root rot development.
A well-drained medium provides an environment favorable for the seedling and somewhat less favorable for the pathogen. Carefully executed watering practices are very important. When the medium is irrigated thoroughly and less often, conditions at or near the surface of the medium tend to remain slightly drier and are less favorable for growth of the pathogen. Plug trays must be kept evenly moist and sufficiently warm to enable seed to germinate rapidly and seedlings to emerge promptly.
Sanitation
Thielaviopsis is well adapted to survival in the greenhouse. Some relatively simple practices are crucial for controlling this disease. Do not reuse containers or trays. Do not create dust, especially when the dust can settle on piles of growing media nearby. Disinfesting potting media will eliminate the organism and should be carried out if there is any topsoil or sand to be used in the growing media. Sanitize benches when possible.
Chemicals
There are quit a few good chemicals with efficacy against Thielaviopsis. Routine, monthly drenches at labeled rates with chemicals such as Cleary's 3336, Domain, Banner, and Terragard will help protect your crops. With bedding plants, you must have the fungicide present at seeding. Plug crops can be infected within only a few days after seeding. Continue a regular monthly schedule throughout transplanting and finishing the crop.
Reprinted from "Black Root Rot of Greenhouse Floral Crops" by Stephen Nameth, Ohio State University Extension Fact Sheet HYG-3066-96, Plant Pathology
Turf - Sulfentrazone Herbicide Injury on Tall Fescue
Sulfentrazone is a relatively new herbicide material that is sold in several products for weed control in turf. There have been reports of injury to tall fescue when using this product with urea nitrogen fertilizer. The following is an article on the subject by Dr. Steve Hart from Rutgers University.
HERBICIDE INJURY ALERT. On May 8 I was informed by my counterpart, Dr. Fred Yelverton, at North Carolina State University, that professional Lawn Care Operators were complaining that the herbicides containing the active ingredientm sulfentrazone applied in combination with urea fertilizer was causing significant injury to Tall Fescue. Dr. Yelverton has since confirmed the potential for this injury to occur in replicated research trials. As of yet I have not been informed of any injury problems with herbicides containing sulfentrazone in Delaware or New Jersey.
Sulfentrazone is currently marketed as Dismiss and is also a component of the herbicides Echelon, Surge and Q4. We have extensively tested these herbicides applied without urea fertilizer at Rutgers and found them to be safe to desired turfgrass but these studies have predominantly been conducted on perennial ryegrass and to a lesser extent Kentucky bluegrass. As of yet, we have not tested any of these herbicides on tall fescue. Until we learn more, I would recommend that these herbicides not be applied to sites containing tall fescue. If these herbicides are utilized on Kentucky bluegrass, perennial ryegrarss, or creeping bentgrass I would recommend that they not be applied in any tank-mix combination with fertilizers, other pesticides, or spray adjuvants (surfactants).
Stephen Hart, Extension Turf and Ornamental Weed Specialist, Rutgers University.
HERBICIDE INJURY ALERT. On May 8 I was informed by my counterpart, Dr. Fred Yelverton, at North Carolina State University, that professional Lawn Care Operators were complaining that the herbicides containing the active ingredientm sulfentrazone applied in combination with urea fertilizer was causing significant injury to Tall Fescue. Dr. Yelverton has since confirmed the potential for this injury to occur in replicated research trials. As of yet I have not been informed of any injury problems with herbicides containing sulfentrazone in Delaware or New Jersey.
Sulfentrazone is currently marketed as Dismiss and is also a component of the herbicides Echelon, Surge and Q4. We have extensively tested these herbicides applied without urea fertilizer at Rutgers and found them to be safe to desired turfgrass but these studies have predominantly been conducted on perennial ryegrass and to a lesser extent Kentucky bluegrass. As of yet, we have not tested any of these herbicides on tall fescue. Until we learn more, I would recommend that these herbicides not be applied to sites containing tall fescue. If these herbicides are utilized on Kentucky bluegrass, perennial ryegrarss, or creeping bentgrass I would recommend that they not be applied in any tank-mix combination with fertilizers, other pesticides, or spray adjuvants (surfactants).
Stephen Hart, Extension Turf and Ornamental Weed Specialist, Rutgers University.
Thursday, May 15, 2008
Landscape and Turf - Salt Water Inundation Along the Coast
Coastal communitites throughout Delaware were flooded in areas with tidal surges during the recent storm. Soils in these areas were inundated with salt water. This will create saline soil conditions. The following is information on soils and salinity.
Concentrated sodium (Na), a component of salt, can damage plant tissue whether it contacts above or below ground parts. High salt levels also damage plants by osmotic effects, drawing moisture out of plants. High salinity can reduce plant growth and may even cause plant death. Care should be taken to avoid excessive salt accumulation from any source on tree and shrub roots, leaves or stems. Sites with saline (salty) soils present challenges to landscapers and homeowners.
Saline Soils
Saline soils occur when salts accumulate in the soil. Significant aline soils do occur in specific situations such as: along the coastline where seawater may overwash, and where salt from spray may collect in the soil (this happened during the recent storm; along brackish tidal rivers and estuaries. Flooding during storms and high tides can deposit salt in low-lying areas. Wooded wetlands are frequently found in these locations (again, this happened during the recent storm; and in areas with high groundwater tables where salt water has intruded from the bay or marsh areas.
How do saline soils affect trees and shrubs?
Plant root cells contain a membrane which allows water to pass through, but which prevents salt from entering. As the soil's salt content increases, it becomes more difficult for water to pass through the membrane into the root. In addition, if salt levels get high enough they may actually dehydrate roots or cause "salt burn" by drawing water out of root cells. Sodium from sea water also has direct toxic effects on many plants.
High levels of soluble salts also cause changes to soil structure, resulting in compacted soils that are problematic for plants. Because salts bind with soil clays, causing them to swell, compaction occurs more frequently in clayey soils than in sandy soils. Compaction causes reduction of pore spaces between soil particles, reducing water and oxygen penetration into the soil, and water drainage from the soil. As a result, water and oxygen availability to plant roots, and consequently plant growth and pest resistance, is affected.
Plants vary in their ability to grow in salty soils. Plants that grow only in saline soils are called "halophytic" or salt loving. Halophytic plants are generally found in coastal areas, in salt-water marshes, and in brackish (moderately saline) wetlands. The presence of some of these plants (such as spartina and sea oats) is generally indicative of a saline soil.
Most landscape plants are sensitive to soil salinity. Seedling trees and shrubs and young transplants can be particularly sensitive to salt exposure. The severity of salt damage to plants depends upon the amount and duration of exposure, and the concentration of salt. For example, coastal areas that receive consistent salt spray may always have elevated levels of soil salinity. Areas subject to flooding by brackish water or overwash from the Delaware Bay may only be affected by salinity following storms and high tides.
If there is adequate precipitation to leach the salt out of these areas soon after the initial exposure, the amount and duration of salt exposure will be brief. If salt exposure persists, or is repeated, damage will be more severe. There is a direct relationship between the amount and duration of salt exposure and potential damage to plants. The higher the amount of salt in the soil, the greater the impact on plants. Salt damage is generally more severe during periods of hot, dry weather.
Measuring soil salinity
The amount of salt in the soil can be measured with a soil test. The Delaware Cooperative Extension Service Soil Test Laboratory can test for soluble salt levels. With the exception of very salt sensitive plants, most landscape plants can tolerate salt concentrations in the medium or low ranges.
Symptoms of saline soil damage
Plant damage due to saline soils becomes evident more slowly than plant damage due to salt spray. At elevated levels, soil salts are harmful to seed germination and plant growth. General symptoms include stunted growth and reduced yields. All parts of the plant, including leaves, stems, roots and fruits, may be reduced in size. The signs and symptoms displayed by deciduous and broad-leaved trees and shrubs include leaf necrosis (death), marginal leaf or needle burn, leaf drop, and eventual plant death. Entire leaves can be affected and drop prematurely. Buds may fail to open or grow, and branches may die. Sometimes deciduous trees may exhibit early fall color and leaf drop. Salt damage on deciduous trees and shrubs usually becomes evident in late summer following the growing season, or during periods of hot, dry weather (summer drought).
On conifers (firs, junipers, pines, spruces), damage appears as brown needle tips. The brown discoloration progresses toward the base of the needles as salt exposure increases. Salt damage on evergreen trees and shrubs [both conifers and broadleaf (hollies, photinia, southern magnolia)] usually first appears in late winter to early spring and becomes more extensive during the growing season. In extreme situations, trees and shrubs will die due to soil salt damage.
When trying to diagnose plant damage, keep in mind that all of the above signs and symptoms can also be caused by a variety of other factors including root damage, drought, diseases, chemical misuse, etc. Try to eliminate these other possibilities, and use tools such as soil and water analyses, and weather data to help you arrive at a correct damage diagnosis.
Reducing soil salinity or soil salt damage
Numerous options exist for reducing salt damage including:
Improving soil structure, drainage and moisture holding capacity by adding organic matter.
Planting salt sensitive plants uphill or on berms where salty water will not drain or accumulate.
Leaching the soil with thorough irrigation after salt exposure. Flush salt through the soil by applying 2 inches of water over a 2-3 hour period, stopping if runoff occurs. Repeat this treatment three days later if salt levels are still high.
Irrigating thoroughly (deeply) rather than watering lightly (shallow watering). For established landscapes, one inch of water applied once a week is generally adequate.
Mulching to prevent evaporation and subsequent build-up of salt in the soil.
Keeping plants healthy because healthy plants are more tolerant of salt damage.
Selecting and planting salt tolerant trees and shrubs.
Adapted from "Trees and Shrubs that Tolerate Saline Soils and Salt Spray Drift"
Authors: Bonnie Appleton, Extension Specialist; Vickie Greene, Graduate Student; Aileen Smith, Graduate Student; Hampton Roads AREC, Virginia Tech; and Susan French, Virginia Cooperative Extension, Virginia Beach from Virginia Tech Cooperative Extension.
Concentrated sodium (Na), a component of salt, can damage plant tissue whether it contacts above or below ground parts. High salt levels also damage plants by osmotic effects, drawing moisture out of plants. High salinity can reduce plant growth and may even cause plant death. Care should be taken to avoid excessive salt accumulation from any source on tree and shrub roots, leaves or stems. Sites with saline (salty) soils present challenges to landscapers and homeowners.
Saline Soils
Saline soils occur when salts accumulate in the soil. Significant aline soils do occur in specific situations such as: along the coastline where seawater may overwash, and where salt from spray may collect in the soil (this happened during the recent storm; along brackish tidal rivers and estuaries. Flooding during storms and high tides can deposit salt in low-lying areas. Wooded wetlands are frequently found in these locations (again, this happened during the recent storm; and in areas with high groundwater tables where salt water has intruded from the bay or marsh areas.
How do saline soils affect trees and shrubs?
Plant root cells contain a membrane which allows water to pass through, but which prevents salt from entering. As the soil's salt content increases, it becomes more difficult for water to pass through the membrane into the root. In addition, if salt levels get high enough they may actually dehydrate roots or cause "salt burn" by drawing water out of root cells. Sodium from sea water also has direct toxic effects on many plants.
High levels of soluble salts also cause changes to soil structure, resulting in compacted soils that are problematic for plants. Because salts bind with soil clays, causing them to swell, compaction occurs more frequently in clayey soils than in sandy soils. Compaction causes reduction of pore spaces between soil particles, reducing water and oxygen penetration into the soil, and water drainage from the soil. As a result, water and oxygen availability to plant roots, and consequently plant growth and pest resistance, is affected.
Plants vary in their ability to grow in salty soils. Plants that grow only in saline soils are called "halophytic" or salt loving. Halophytic plants are generally found in coastal areas, in salt-water marshes, and in brackish (moderately saline) wetlands. The presence of some of these plants (such as spartina and sea oats) is generally indicative of a saline soil.
Most landscape plants are sensitive to soil salinity. Seedling trees and shrubs and young transplants can be particularly sensitive to salt exposure. The severity of salt damage to plants depends upon the amount and duration of exposure, and the concentration of salt. For example, coastal areas that receive consistent salt spray may always have elevated levels of soil salinity. Areas subject to flooding by brackish water or overwash from the Delaware Bay may only be affected by salinity following storms and high tides.
If there is adequate precipitation to leach the salt out of these areas soon after the initial exposure, the amount and duration of salt exposure will be brief. If salt exposure persists, or is repeated, damage will be more severe. There is a direct relationship between the amount and duration of salt exposure and potential damage to plants. The higher the amount of salt in the soil, the greater the impact on plants. Salt damage is generally more severe during periods of hot, dry weather.
Measuring soil salinity
The amount of salt in the soil can be measured with a soil test. The Delaware Cooperative Extension Service Soil Test Laboratory can test for soluble salt levels. With the exception of very salt sensitive plants, most landscape plants can tolerate salt concentrations in the medium or low ranges.
Symptoms of saline soil damage
Plant damage due to saline soils becomes evident more slowly than plant damage due to salt spray. At elevated levels, soil salts are harmful to seed germination and plant growth. General symptoms include stunted growth and reduced yields. All parts of the plant, including leaves, stems, roots and fruits, may be reduced in size. The signs and symptoms displayed by deciduous and broad-leaved trees and shrubs include leaf necrosis (death), marginal leaf or needle burn, leaf drop, and eventual plant death. Entire leaves can be affected and drop prematurely. Buds may fail to open or grow, and branches may die. Sometimes deciduous trees may exhibit early fall color and leaf drop. Salt damage on deciduous trees and shrubs usually becomes evident in late summer following the growing season, or during periods of hot, dry weather (summer drought).
On conifers (firs, junipers, pines, spruces), damage appears as brown needle tips. The brown discoloration progresses toward the base of the needles as salt exposure increases. Salt damage on evergreen trees and shrubs [both conifers and broadleaf (hollies, photinia, southern magnolia)] usually first appears in late winter to early spring and becomes more extensive during the growing season. In extreme situations, trees and shrubs will die due to soil salt damage.
When trying to diagnose plant damage, keep in mind that all of the above signs and symptoms can also be caused by a variety of other factors including root damage, drought, diseases, chemical misuse, etc. Try to eliminate these other possibilities, and use tools such as soil and water analyses, and weather data to help you arrive at a correct damage diagnosis.
Reducing soil salinity or soil salt damage
Numerous options exist for reducing salt damage including:
Improving soil structure, drainage and moisture holding capacity by adding organic matter.
Planting salt sensitive plants uphill or on berms where salty water will not drain or accumulate.
Leaching the soil with thorough irrigation after salt exposure. Flush salt through the soil by applying 2 inches of water over a 2-3 hour period, stopping if runoff occurs. Repeat this treatment three days later if salt levels are still high.
Irrigating thoroughly (deeply) rather than watering lightly (shallow watering). For established landscapes, one inch of water applied once a week is generally adequate.
Mulching to prevent evaporation and subsequent build-up of salt in the soil.
Keeping plants healthy because healthy plants are more tolerant of salt damage.
Selecting and planting salt tolerant trees and shrubs.
Adapted from "Trees and Shrubs that Tolerate Saline Soils and Salt Spray Drift"
Authors: Bonnie Appleton, Extension Specialist; Vickie Greene, Graduate Student; Aileen Smith, Graduate Student; Hampton Roads AREC, Virginia Tech; and Susan French, Virginia Cooperative Extension, Virginia Beach from Virginia Tech Cooperative Extension.
Landscape - Salt Spray Damage From Recent Storm
The recent storms produced salt spray that was blown inland along the coast of the Delaware Bay. Symptoms are just now showing up in plants. The following is information on salt spray damage from Virginia Tech and from UD Extension.
The aerial drift of salt-laden water droplets that are deposited on trees and shrubs causes salt spray damage. When droplets evaporate, the salt's sodium and chlorine ions can penetrate stems, buds and leaves, causing direct damage. Salt spray damage to trees and shrubs is most frequently seen on seaside plants and near sidewalks and roads where de-icing salts are applied. Additional stresses in these areas, including wind, sun, heat, exposure, heavy traffic and saline soils, increase the likelihood of damage.
How does salt spray affect trees and shrubs?
Exposure to salt spray can cause stem and foliage disfigurement, reduced growth, and often plant death. Because aerial salt spray damage may appear similar to damage caused by other stresses, a tree or shrub's location and damage symptoms should be carefully evaluated to correctly identify the damage's cause. Consider the distance from salty water sources and the severity of storms and winds that carry aerial salt drift inland.
Symptoms of salt spray damage
Examine injury patterns on trees and shrubs. On foliage, salt spray causes leaf burn or scorch, or needle browning. Direct signs such as white salt residue are a strong indication that salt spray may be injuring landscape plants. For seashore areas, salt spray damage is seen soon after storms, and occurs inland if salt spray is carried farther by strong winds.
Reducing salt spray or salt spray damage
Numerous options exist for reducing salt damage including:
Carefully designing planting areas to reduce exposure of trees and shrubs to aerial salt spray. Establish windbreaks to prevent "wind tunnels" that can carry aerial salts farther and at higher wind speeds. Use salt-tolerant shrubs or herbaceous borders (especially denser evergreens) as windbreaks to help intercept aerial salt drift before it reaches sensitive plants.
Grouping tree and shrub species to shield them from wind and drift, with the most tolerant species in higher exposure areas to shield moderately tolerant species.
Maintaining appropriate soil fertility and moisture conditions to reduce additional stresses, and to help combat desiccation.
If feasible, rinse salt spray off trees and shrubs after storms and high winds.
As with saline soils, selecting and planting salt spray tolerant trees and shrubs. Avoid plants, such as azaleas, that are considered especially sensitive to salt spray.
White pines are very sensitive to salt spray and air pollution. Salt spray damage will be a problem after recent storms. Salt spray from the Delaware Bay, carried by strong Northeast winds, will affect trees inland for a number of miles. Eastern white pine will be one of the trees with noticeable salt spray damate. The eastern side of the trees will look “burnt”. Other nearby trees and grass may not be affected. Unfortunately, many of the trees will lose most of the browning needles. The candles or new needles (new growth) are just coming out. Normally pines keep last year’s needles, plus this years and will shed the three year old needles in late fall. White pines will look bare from the extra needle loss, but should live.
Information adapted from a Virginia Tech Factsheet on salt tolerant plants and an article by Derby Walker, Extension Agriculture Agent, Retired, UD.
The aerial drift of salt-laden water droplets that are deposited on trees and shrubs causes salt spray damage. When droplets evaporate, the salt's sodium and chlorine ions can penetrate stems, buds and leaves, causing direct damage. Salt spray damage to trees and shrubs is most frequently seen on seaside plants and near sidewalks and roads where de-icing salts are applied. Additional stresses in these areas, including wind, sun, heat, exposure, heavy traffic and saline soils, increase the likelihood of damage.
How does salt spray affect trees and shrubs?
Exposure to salt spray can cause stem and foliage disfigurement, reduced growth, and often plant death. Because aerial salt spray damage may appear similar to damage caused by other stresses, a tree or shrub's location and damage symptoms should be carefully evaluated to correctly identify the damage's cause. Consider the distance from salty water sources and the severity of storms and winds that carry aerial salt drift inland.
Symptoms of salt spray damage
Examine injury patterns on trees and shrubs. On foliage, salt spray causes leaf burn or scorch, or needle browning. Direct signs such as white salt residue are a strong indication that salt spray may be injuring landscape plants. For seashore areas, salt spray damage is seen soon after storms, and occurs inland if salt spray is carried farther by strong winds.
Reducing salt spray or salt spray damage
Numerous options exist for reducing salt damage including:
Carefully designing planting areas to reduce exposure of trees and shrubs to aerial salt spray. Establish windbreaks to prevent "wind tunnels" that can carry aerial salts farther and at higher wind speeds. Use salt-tolerant shrubs or herbaceous borders (especially denser evergreens) as windbreaks to help intercept aerial salt drift before it reaches sensitive plants.
Grouping tree and shrub species to shield them from wind and drift, with the most tolerant species in higher exposure areas to shield moderately tolerant species.
Maintaining appropriate soil fertility and moisture conditions to reduce additional stresses, and to help combat desiccation.
If feasible, rinse salt spray off trees and shrubs after storms and high winds.
As with saline soils, selecting and planting salt spray tolerant trees and shrubs. Avoid plants, such as azaleas, that are considered especially sensitive to salt spray.
White pines are very sensitive to salt spray and air pollution. Salt spray damage will be a problem after recent storms. Salt spray from the Delaware Bay, carried by strong Northeast winds, will affect trees inland for a number of miles. Eastern white pine will be one of the trees with noticeable salt spray damate. The eastern side of the trees will look “burnt”. Other nearby trees and grass may not be affected. Unfortunately, many of the trees will lose most of the browning needles. The candles or new needles (new growth) are just coming out. Normally pines keep last year’s needles, plus this years and will shed the three year old needles in late fall. White pines will look bare from the extra needle loss, but should live.
Information adapted from a Virginia Tech Factsheet on salt tolerant plants and an article by Derby Walker, Extension Agriculture Agent, Retired, UD.
Wednesday, May 14, 2008
Turf - Dealing With Flooded Lawns
What can you do when turf is flooded - either by heavy rains or the outflow of streams or rivers? The following is some information.
In the early spring before lawns begin active growth and the ground is still thawing, lawn grasses can withstand several days of being submerged without suffering serious damage. However, during summertime, periods of high temperatures and high light conditions, any water that ponds on a lawn surface can cause significant damage or loss even within a few hours. Ponding occurs in areas of poor drainage or results from water being left behind in valleys and depressions when floodwaters recede. Noting these locations and correcting any surface or subsurface drainage problems is prudent for creating a healthy lawn environment for the future. Areas where the grass has been completely lost will need to be restored through reseeding or resodding.
Spring flooded lawn areas, where the water has risen and then receded rapidly, are not likely to experience extensive injury. The more significant effect of flooding is likely to be the deposit of sediment, primarily silt, over lawn surfaces. This can lead to serious soil layering problems and even death of existing grass if deposits are deep enough.
Once floodwaters recede, don't start working in the area immediately. Wait until it isn't soggy under foot. The drying process may take several weeks. Damage assessment and recovery of the existing lawn may not be possible for a few weeks. Once the lawn has dried, thoroughly aerify it by going over it 3 times with a core type aerifier. Repeat the process in early September and again the following spring.
Aerification is especially important where silt is deposited over the lawn. If silt depth is barely detectable over the surface, thorough aerification may be sufficient. The lawn may be completely covered with silt and the grass plants barely visible or completely buried. REMOVING SILT IS WORK and can be very damaging to the existing grass plants. Therefore, you may want to establish a new lawn
Perform necessary overseeding at the time of aerification or delay seeding until late August through September. To prepare a smooth seed bed, break up the aerification cores with a lawn rake or power rake. Sodding can be done successfully throughout the growing season. Another problem with silt deposits is the introduction of potentially new and different weeds to the lawn. Pre-and/or post-emergence herbicides may be used where appropriate. Remember, if you are dealing with a flooded lawn, wait until the soil is sufficiently dry to perform any maintenance activities.
Information reprinted from "Repairing Flooded Lawns" from the University of Minnesota Cooperative Extension.
In the early spring before lawns begin active growth and the ground is still thawing, lawn grasses can withstand several days of being submerged without suffering serious damage. However, during summertime, periods of high temperatures and high light conditions, any water that ponds on a lawn surface can cause significant damage or loss even within a few hours. Ponding occurs in areas of poor drainage or results from water being left behind in valleys and depressions when floodwaters recede. Noting these locations and correcting any surface or subsurface drainage problems is prudent for creating a healthy lawn environment for the future. Areas where the grass has been completely lost will need to be restored through reseeding or resodding.
Spring flooded lawn areas, where the water has risen and then receded rapidly, are not likely to experience extensive injury. The more significant effect of flooding is likely to be the deposit of sediment, primarily silt, over lawn surfaces. This can lead to serious soil layering problems and even death of existing grass if deposits are deep enough.
Once floodwaters recede, don't start working in the area immediately. Wait until it isn't soggy under foot. The drying process may take several weeks. Damage assessment and recovery of the existing lawn may not be possible for a few weeks. Once the lawn has dried, thoroughly aerify it by going over it 3 times with a core type aerifier. Repeat the process in early September and again the following spring.
Aerification is especially important where silt is deposited over the lawn. If silt depth is barely detectable over the surface, thorough aerification may be sufficient. The lawn may be completely covered with silt and the grass plants barely visible or completely buried. REMOVING SILT IS WORK and can be very damaging to the existing grass plants. Therefore, you may want to establish a new lawn
Perform necessary overseeding at the time of aerification or delay seeding until late August through September. To prepare a smooth seed bed, break up the aerification cores with a lawn rake or power rake. Sodding can be done successfully throughout the growing season. Another problem with silt deposits is the introduction of potentially new and different weeds to the lawn. Pre-and/or post-emergence herbicides may be used where appropriate. Remember, if you are dealing with a flooded lawn, wait until the soil is sufficiently dry to perform any maintenance activities.
Information reprinted from "Repairing Flooded Lawns" from the University of Minnesota Cooperative Extension.
Landscape - Flooding Effects on Trees
Some areas in the state were flooded for a period of time during the the recent storms. Some areas remain waterlogged. The following is information on flooding effects on trees.
Although the impact of flooding on humans is almost immediate, how flooding affects trees is less obvious. There are several factors to take into account when considering the impact of flood stress on a particular tree. These include: 1) Species tolerance to flooding, 2) overall tree health, 3) length of flood and 4) sediment accumulation around tree roots.
Some species of trees are better able to adapt to flooded conditions. Trees that have evolved in a floodplain ecosystem have mechanisms to cope with the periodic flooding that may occur and are better able to handle flooding. However, urban areas that end up flooded are not usually forested by trees that are adapted to flooding. There are some notable urban exceptions: boxelder, silver maple, hackberry, green ash and hawthorn are all considered relatively tolerant to flooding stress. It should be noted that the pines and oaks (with the exception of eastern pin oak and swamp white oak) are all relatively intolerant of flooded conditions.
When examining flood damaged trees, keep in mind that urban life is stressful to many species of trees, making them particularly susceptible to flood-related damage. Flooding compounds these stresses, leaving trees highly predisposed to additional mortality due to insect and disease attacks. If death does not occur outright, then it may be due to secondary agents of plant disease. Those trees that weren’t killed in the initial flood event are considered predisposed, and can die quickly due to the combination of physical injury and rapid invasion from insects or diseases. Conversely, well-maintained and healthy trees can and do recover quickly. Most trees fall within these two extremes. How well a tree copes with flooding and the secondary agents of plant disease depends upon how vigorous the tree was prior to flooding, and how long the flooding occurs.
Symptoms of flood stress
It is important to remember that plants respond differently to flooding and that this response depends on tree species, health and site. For this reason, trees that are flood stressed exhibit a range of symptoms that include: leaf chlorosis and subsequent defoliation, reduced leaf size, development of epicormic shoots (watersprouts or small shoots emerging from the main stem), and crown dieback. These stresses may produce early fall coloration and leaf drop. It also is not uncommon for declining trees to produce either large seed crops or no seed crops in years following a flood. Symptoms may develop over a period of several years or they may abate as the tree recovers. Finally, it is important to remember that the symptoms may progress and ultimately result in tree death. However, this tree death may occur several years after the flood. It is very difficult to link a flood from several years ago as the cause of tree death years later.
Secondary Agents of Plant Disease
You need to be on alert for the possibility that flood-stressed trees may become invaded by insects or infected with disease. The likelihood of this occurring depends upon the severity of the flood and tree health. A tree that is already predisposed because of stressful urban conditions can have this stress compounded by flood. This tree should be considered a prime target for opportunistic insects and disease causing agents. These opportunists invade or infect only those hosts that are predisposed by stress. In this case, the insect or pathogens are actually secondary agents of tree disease. Flooding could act as the predisposing agent or an inciting agent of plant disease if the flood period is prolong or intense. Although not well understood, it is generally believed that predisposed plants emit a biochemical signal which attract secondary agents of plant diseases.
Flood stressed trees are especially susceptible to collar and root rot diseases caused by species of Phytophthora and Pythium, which are considered "water molds" and are not "true" fungi. Free-standing water aids in both the reproduction and dissemination of these fungi. Oxygen starvation, wounding and loss of cell permeability due to flooding provide ideal infection sites for these organisms to colonize.
Symptoms of Phytophthora collar rot of flood damaged trees include brown to reddish water-soaked lesions with abrupt margins underneath the bark. A reddish brown liquid sometimes exudes from the canker margin. Cankers may not be noticed until foliar symptoms develop, which include sparse, chlorotic(yellow) leaves, premature fall color and dieback. Pythium root rot produces less distinctive diagnostic symptoms that included root rot and dieback.
Even trees that have appeared to recover are still at risk for infection by a group of opportunistic pathogens, members of the genus Armillaria. These fungi are the causal agents of shoestring root rot. There are hundreds of species of Armillaria, some of which are virulent pathogens and others of which only act as contributing factors to tree death. Although drought is usually considered the inciting agent that allows Armillaria to establish itself and infect, flooding has been implicated as a factor of Armillaria root rot in oak, chestnut and larch.
Symptoms of Armillaria infection include leaf chlorosis, defoliation, reduction in leaf and shoot growth, dieback, and/or death. Key diagnostic signs of this disease are white mycelial fans under the bark; black, shoestring-like rhizomorphs attached to roots, and the fall development of honey-colored mushrooms growing in clumps at the tree base.
Flooding is but one of the many injurious factors trees face over the course of their lives. Proactive maintenance of tree health is the best way to contend with periodic flooding. As the tree recovers, it needs to replenish food reserves. To increase tree vigor, the US Forest Service recommends application with a low nitrogen fertilizer, aerating the soil, mulching, and watering if soil conditions become excessively dry after the flood. Dead or cankered branches should be removed. Prune trees only when bark surfaces are dry or during the dormant season to minimize infection by opportunistic pathogens. In the absence of tree maintenance, flooding and other environmental extremes leave trees susceptible to further injury or death. How well a tree copes with these stresses is dependent upon how healthy the tree was prior to the flood.
Reprinted in part from "Flood Damage Effects On Trees" by Janna Beckerman, Extension Plant Pathologist, University of Minnesota.
Although the impact of flooding on humans is almost immediate, how flooding affects trees is less obvious. There are several factors to take into account when considering the impact of flood stress on a particular tree. These include: 1) Species tolerance to flooding, 2) overall tree health, 3) length of flood and 4) sediment accumulation around tree roots.
Some species of trees are better able to adapt to flooded conditions. Trees that have evolved in a floodplain ecosystem have mechanisms to cope with the periodic flooding that may occur and are better able to handle flooding. However, urban areas that end up flooded are not usually forested by trees that are adapted to flooding. There are some notable urban exceptions: boxelder, silver maple, hackberry, green ash and hawthorn are all considered relatively tolerant to flooding stress. It should be noted that the pines and oaks (with the exception of eastern pin oak and swamp white oak) are all relatively intolerant of flooded conditions.
When examining flood damaged trees, keep in mind that urban life is stressful to many species of trees, making them particularly susceptible to flood-related damage. Flooding compounds these stresses, leaving trees highly predisposed to additional mortality due to insect and disease attacks. If death does not occur outright, then it may be due to secondary agents of plant disease. Those trees that weren’t killed in the initial flood event are considered predisposed, and can die quickly due to the combination of physical injury and rapid invasion from insects or diseases. Conversely, well-maintained and healthy trees can and do recover quickly. Most trees fall within these two extremes. How well a tree copes with flooding and the secondary agents of plant disease depends upon how vigorous the tree was prior to flooding, and how long the flooding occurs.
Symptoms of flood stress
It is important to remember that plants respond differently to flooding and that this response depends on tree species, health and site. For this reason, trees that are flood stressed exhibit a range of symptoms that include: leaf chlorosis and subsequent defoliation, reduced leaf size, development of epicormic shoots (watersprouts or small shoots emerging from the main stem), and crown dieback. These stresses may produce early fall coloration and leaf drop. It also is not uncommon for declining trees to produce either large seed crops or no seed crops in years following a flood. Symptoms may develop over a period of several years or they may abate as the tree recovers. Finally, it is important to remember that the symptoms may progress and ultimately result in tree death. However, this tree death may occur several years after the flood. It is very difficult to link a flood from several years ago as the cause of tree death years later.
Secondary Agents of Plant Disease
You need to be on alert for the possibility that flood-stressed trees may become invaded by insects or infected with disease. The likelihood of this occurring depends upon the severity of the flood and tree health. A tree that is already predisposed because of stressful urban conditions can have this stress compounded by flood. This tree should be considered a prime target for opportunistic insects and disease causing agents. These opportunists invade or infect only those hosts that are predisposed by stress. In this case, the insect or pathogens are actually secondary agents of tree disease. Flooding could act as the predisposing agent or an inciting agent of plant disease if the flood period is prolong or intense. Although not well understood, it is generally believed that predisposed plants emit a biochemical signal which attract secondary agents of plant diseases.
Flood stressed trees are especially susceptible to collar and root rot diseases caused by species of Phytophthora and Pythium, which are considered "water molds" and are not "true" fungi. Free-standing water aids in both the reproduction and dissemination of these fungi. Oxygen starvation, wounding and loss of cell permeability due to flooding provide ideal infection sites for these organisms to colonize.
Symptoms of Phytophthora collar rot of flood damaged trees include brown to reddish water-soaked lesions with abrupt margins underneath the bark. A reddish brown liquid sometimes exudes from the canker margin. Cankers may not be noticed until foliar symptoms develop, which include sparse, chlorotic(yellow) leaves, premature fall color and dieback. Pythium root rot produces less distinctive diagnostic symptoms that included root rot and dieback.
Even trees that have appeared to recover are still at risk for infection by a group of opportunistic pathogens, members of the genus Armillaria. These fungi are the causal agents of shoestring root rot. There are hundreds of species of Armillaria, some of which are virulent pathogens and others of which only act as contributing factors to tree death. Although drought is usually considered the inciting agent that allows Armillaria to establish itself and infect, flooding has been implicated as a factor of Armillaria root rot in oak, chestnut and larch.
Symptoms of Armillaria infection include leaf chlorosis, defoliation, reduction in leaf and shoot growth, dieback, and/or death. Key diagnostic signs of this disease are white mycelial fans under the bark; black, shoestring-like rhizomorphs attached to roots, and the fall development of honey-colored mushrooms growing in clumps at the tree base.
Flooding is but one of the many injurious factors trees face over the course of their lives. Proactive maintenance of tree health is the best way to contend with periodic flooding. As the tree recovers, it needs to replenish food reserves. To increase tree vigor, the US Forest Service recommends application with a low nitrogen fertilizer, aerating the soil, mulching, and watering if soil conditions become excessively dry after the flood. Dead or cankered branches should be removed. Prune trees only when bark surfaces are dry or during the dormant season to minimize infection by opportunistic pathogens. In the absence of tree maintenance, flooding and other environmental extremes leave trees susceptible to further injury or death. How well a tree copes with these stresses is dependent upon how healthy the tree was prior to the flood.
Reprinted in part from "Flood Damage Effects On Trees" by Janna Beckerman, Extension Plant Pathologist, University of Minnesota.
Tuesday, May 13, 2008
Landscape - Volutella Blight of Pachysandra
Volutella blight is a common disease of Pachysandra in Delaware. The following is information on this disease in the landscape.
Volutella blight (also called Pachysandra leaf and stem blight) is easy to spot. Plants infected with the fungus Volutella exhibit characteristically large, “bulls-eye” leaf spots and elongate cankers on petioles and stems. Within several weeks, highly diagnostic, pink-colored fruiting bodies form on affected tissue. This disease can be very destructive in beds, causing circular patches of dying plants to form and enlarge rapidly. Like many diseases in the landscape, Volutella blight cannot be sufficiently managed by only using fungicides. There are cultural factors that contribute to disease severity. First, water is essential in the disease infection process, so “managing the moisture” helps to manage the disease. Avoid practices that encourage excessive moisture (such as including heavy mulching and over watering). Periodically thin the beds to increase light and air circulation. Avoid watering during times of the day, such as late afternoon, when the beds are apt to remain wet for long periods. Consider that heavy shade may also contribute to longer periods of leaf wetness. Winter injury and wounding predispose pachysandra to this disease. Common things to watch out for include mechanical injury (foot traffic, pets, or children playing in beds), scale insects, and poor nutrition. Fungicides labeled for control of this disease include chlorothalonil, copper (Badge, hydroxide, metallic, oxychloride, salts, sulfate), Junction, mancozeb, Spectro, or Zyban. Please follow label directions when applying pesticides.
Volutella blight on Pachysandra. Photo by Jody Fetzer, New York Botanical Garden, Bugwood.org
Reprinted from "Diseases of Landscape Ornamentals in the Springtime, Part II" by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the April 17, 2008 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition, from the Rutgers New Jersey Agricultural Experiment Station - Cooperative Extension.
Volutella blight (also called Pachysandra leaf and stem blight) is easy to spot. Plants infected with the fungus Volutella exhibit characteristically large, “bulls-eye” leaf spots and elongate cankers on petioles and stems. Within several weeks, highly diagnostic, pink-colored fruiting bodies form on affected tissue. This disease can be very destructive in beds, causing circular patches of dying plants to form and enlarge rapidly. Like many diseases in the landscape, Volutella blight cannot be sufficiently managed by only using fungicides. There are cultural factors that contribute to disease severity. First, water is essential in the disease infection process, so “managing the moisture” helps to manage the disease. Avoid practices that encourage excessive moisture (such as including heavy mulching and over watering). Periodically thin the beds to increase light and air circulation. Avoid watering during times of the day, such as late afternoon, when the beds are apt to remain wet for long periods. Consider that heavy shade may also contribute to longer periods of leaf wetness. Winter injury and wounding predispose pachysandra to this disease. Common things to watch out for include mechanical injury (foot traffic, pets, or children playing in beds), scale insects, and poor nutrition. Fungicides labeled for control of this disease include chlorothalonil, copper (Badge, hydroxide, metallic, oxychloride, salts, sulfate), Junction, mancozeb, Spectro, or Zyban. Please follow label directions when applying pesticides.
Volutella blight on Pachysandra. Photo by Jody Fetzer, New York Botanical Garden, Bugwood.orgReprinted from "Diseases of Landscape Ornamentals in the Springtime, Part II" by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the April 17, 2008 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition, from the Rutgers New Jersey Agricultural Experiment Station - Cooperative Extension.
Landscape and Turf - Wet Weather and Drainage
Recent heavy rainfall and flooding bring the topic of drainage in the landscape to mind. The following are some thoughts on the subject.
Drainage problems are evident throughout the state with the recent heavy rains. Excess water reduces oxygen levels in the soil (suffocating roots), causes nitrogen losses through leaching and denitrification, and sets up conditions favoring certain diseases. Turf areas with poor drainage may start to turn yellow. Landscape plants with damaged root systems from last year’s drought will be more susceptible to injury from flooding or waterlogging of root systems and may show wilting once the sun comes out.
Plan now to manage drainage problems. Map poorly drained areas, note water paths and runoff sources, and evaluate outlets. Evaluate underlying soil conditions including restrictive layers and compaction. Consider traditional drainage methods such as swales, drainage tiles, or French drains. Consider diverting runoff water away from poorly drained areas into rain gardens, engineered infiltration basins, or bioretention areas. These systems become fixed landscape features that allow runoff water to accumulate and drain slowly, serving as a filter. Consider tools to deal with soil restriction such as subsoilers or deep aerators. Use core aeration or verticutting to increase aeration in turf once soil has dried. Evaluate current plantings in poorly drained areas and consider alternatives that do better in wet soils or soils with variable drainage.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Drainage problems are evident throughout the state with the recent heavy rains. Excess water reduces oxygen levels in the soil (suffocating roots), causes nitrogen losses through leaching and denitrification, and sets up conditions favoring certain diseases. Turf areas with poor drainage may start to turn yellow. Landscape plants with damaged root systems from last year’s drought will be more susceptible to injury from flooding or waterlogging of root systems and may show wilting once the sun comes out.
Plan now to manage drainage problems. Map poorly drained areas, note water paths and runoff sources, and evaluate outlets. Evaluate underlying soil conditions including restrictive layers and compaction. Consider traditional drainage methods such as swales, drainage tiles, or French drains. Consider diverting runoff water away from poorly drained areas into rain gardens, engineered infiltration basins, or bioretention areas. These systems become fixed landscape features that allow runoff water to accumulate and drain slowly, serving as a filter. Consider tools to deal with soil restriction such as subsoilers or deep aerators. Use core aeration or verticutting to increase aeration in turf once soil has dried. Evaluate current plantings in poorly drained areas and consider alternatives that do better in wet soils or soils with variable drainage.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Monday, May 12, 2008
Turf - Core Aeration in the Spring?
Core aeration is an important tool to maintain the health of turf. We generally core aerate in late summer or early fall. However, there are times when a spring core aeration will be beneficial. The following is an article on the subject.
The spring rollercoaster of wet and dry conditions continues to persist across much of Delaware. For those areas that received a nice dumping of rain this last week, you may notice that in poorly drained areas where the soil may be staying saturated for several days, the turf may be looking a little brownish or yellow. There are several reasons for the discoloration , but one of the main reasons is impairment of the root system. It doesn’t take long once the soil is saturated for soil oxygen levels to decline and root hairs to begin to die. As the turf’s root system becomes impaired nutrient extraction and water uptake will be limited and the turf won’t look emerald green anymore.
The solutions, of course, are rather simple assuming you can do some earth movement or cut in drain lines to help take the water away. However, in some situations neither of these options may seem realistic. One simple practice that can help the turf in these areas, but will probably not completely eliminate the problem, is core aeration. Of course, before you start thinking of a core aerifier going submersible in these soggy areas, you need to let them dry out. Core aeration will help get air and, most importantly, oxygen to the roots and it may also help water infiltrate quicker into the soil thereby preventing puddle formation.
Typically the “best” time of year to core aerate lawns is in the autumn because it is more likely the soil will not be too moist and it also gives the turf plenty of time to recover from this rather invasive procedure during the cooler temperatures of the autumn. However, for those trying to manage turf on soils that have a high clay content, I often recommend that they core aerate both in the spring and the fall and maybe even in the summer if the weather conditions are not too extreme in terms of heat and drought. Core aeration will increase oxygen in the soil, facilitate rooting, improve water infiltration, and can gradually over time reduce thatch.
Things to keep in mind before coring any turf area: Do you have an in-ground irrigation system? Be sure to know where the sprinkler heads are located. Also be aware of any other underground lines, e.g., invisible dog fence wire. Normally, these lines should be buried deep enough to avoid any trouble, but it never hurts to double check.
Reprinted with minor changes from "Airing out the turf" by Kevin Frank, Crop & Soil Sciences, Michigan State University Cooperative Extension, in the May 11, 2007 edition of the Michigan State University Landscape Alert newletter.
The spring rollercoaster of wet and dry conditions continues to persist across much of Delaware. For those areas that received a nice dumping of rain this last week, you may notice that in poorly drained areas where the soil may be staying saturated for several days, the turf may be looking a little brownish or yellow. There are several reasons for the discoloration , but one of the main reasons is impairment of the root system. It doesn’t take long once the soil is saturated for soil oxygen levels to decline and root hairs to begin to die. As the turf’s root system becomes impaired nutrient extraction and water uptake will be limited and the turf won’t look emerald green anymore.
The solutions, of course, are rather simple assuming you can do some earth movement or cut in drain lines to help take the water away. However, in some situations neither of these options may seem realistic. One simple practice that can help the turf in these areas, but will probably not completely eliminate the problem, is core aeration. Of course, before you start thinking of a core aerifier going submersible in these soggy areas, you need to let them dry out. Core aeration will help get air and, most importantly, oxygen to the roots and it may also help water infiltrate quicker into the soil thereby preventing puddle formation.
Typically the “best” time of year to core aerate lawns is in the autumn because it is more likely the soil will not be too moist and it also gives the turf plenty of time to recover from this rather invasive procedure during the cooler temperatures of the autumn. However, for those trying to manage turf on soils that have a high clay content, I often recommend that they core aerate both in the spring and the fall and maybe even in the summer if the weather conditions are not too extreme in terms of heat and drought. Core aeration will increase oxygen in the soil, facilitate rooting, improve water infiltration, and can gradually over time reduce thatch.
Things to keep in mind before coring any turf area: Do you have an in-ground irrigation system? Be sure to know where the sprinkler heads are located. Also be aware of any other underground lines, e.g., invisible dog fence wire. Normally, these lines should be buried deep enough to avoid any trouble, but it never hurts to double check.
Reprinted with minor changes from "Airing out the turf" by Kevin Frank, Crop & Soil Sciences, Michigan State University Cooperative Extension, in the May 11, 2007 edition of the Michigan State University Landscape Alert newletter.
Nursery and Greenhouse - Weed Control Guides
The following is information on two good weed control guides for nurseries and outdoor production areas of greenhouse operations.
Nursery and greenhouse growers who need some resources for identification of weeds that impact their production will find these two publications helpful. "Weeds of Container Nurseries in the United States" by Joseph C. Neal, North Carolina State University and Jeffrey F. Derr, Virginia Tech. This link has a great list and photos of weeds that impact container nurseries: http://ppwsipm.contentsrvr.net/weeds_container_nurseries.php.
Another useful publication is from Michigan State University, MSU publication E-2982 "An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes" (available from the MSU Extension Bulletin Office at 517-353-6740) you should be able to identify most weeds that show up in the nursery container area. This guide is also available on-line at: http://www.ipm.msu.edu/weeds-nursery/contents.htm Proper identification is the first step to controlling weeds in the nursery. Please contact your local UD Extension horticulture educator for the latest weed control recommendations.
Information adapted for Delaware from "Weed identification guides for field and container nurseries" by Thomas Dudek, District Extension Horticulture and Marketing Educator, Michigan State University Cooperative Extension, in the May 9, 2008 edition of the MSU Landscape Alert newsletter.
Nursery and greenhouse growers who need some resources for identification of weeds that impact their production will find these two publications helpful. "Weeds of Container Nurseries in the United States" by Joseph C. Neal, North Carolina State University and Jeffrey F. Derr, Virginia Tech. This link has a great list and photos of weeds that impact container nurseries: http://ppwsipm.contentsrvr.net/weeds_container_nurseries.php.
Another useful publication is from Michigan State University, MSU publication E-2982 "An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes" (available from the MSU Extension Bulletin Office at 517-353-6740) you should be able to identify most weeds that show up in the nursery container area. This guide is also available on-line at: http://www.ipm.msu.edu/weeds-nursery/contents.htm Proper identification is the first step to controlling weeds in the nursery. Please contact your local UD Extension horticulture educator for the latest weed control recommendations.
Information adapted for Delaware from "Weed identification guides for field and container nurseries" by Thomas Dudek, District Extension Horticulture and Marketing Educator, Michigan State University Cooperative Extension, in the May 9, 2008 edition of the MSU Landscape Alert newsletter.
Sunday, May 11, 2008
Nursery and Landscape - Anthracnose Diseases in Trees
The cool, wet weather we have had recently will favor the fungi that cause anthracnose diseases in landscape trees. The following is information on several of these anthracnose diseases.
Anthracnose diseases are not all caused by the same fungus. Each host plant has its own anthracnose fungus, so, for example, don't assume that anthracnose of sycamore or grape is a threat to nearby dogwoods. The incidence and severity of anthracnose diseases of landscape trees varies with the season, and this year, symptoms appear to be at moderate levels.
Ash anthracnose. Brown blotches along leaflet edges have been visible for the past week or so on new ash foliage. Many of these infected leaflets will begin to drop soon and carpet the walks and lawns nearby. Ash anthracnose is not normally a threat to ash tree survival, however, and the ash trees will simply put out a new set of leaves. The ash anthracnose fungus is a species of Discula.
Dogwood anthracnose. Caused by the fungus Discula destructiva, dogwood anthracnose is appearing this spring in many flowering dogwoods (Cornus florida). Dogwood anthracnose causes leaf spots, leaf blight, and lower branch dieback and is most commonly observed in forested regions where native understory dogwood trees are threatened. This spring, anthracnose is also present in landscape trees, especially those growing in shaded locations.
Maple anthracnose. Symptoms can range from leaf spots to shoot blight and shoot cankers. Maple anthracnose may be caused by Discula sp. or by Kabatiella apocrypta. There is considerable variation in maple susceptibility to anthracnose. In some cases, sugar maple leaf spotting may be heavy on one tree while the adjacent tree is barely affected.
Oak anthracnose. This disease is less common and is caused by the fungus Apiognomonia quercina.
Sycamore anthracnose. Anthracnose symptoms on infected green, expanding leaves, look for irregular dark, necrotic blotching centered along the leaf veins or leaf edges. These dark blotches may turn a tan color as the diseased areas of the leaves dry out. In the same trees, tips of young shoots with newly expanding leaves are wilting and dying because of twig or shoot infection. With continued rainy weather, the disease should continue to spread in the foliage. Symptoms are not as severe as we see some years when trees are heavily defoliated by now. As the weather gets warmer and drier, sycamores normally put out new, healthy foliage. However, the legacy of crooked branches (because lateral shoots take over when terminals are killed by anthracnose) and multiple shoots arising from the base of a killed branch may still be visible many years later. Sycamore anthracnose is caused by the fungus Apiognomonia veneta, and the fungus attacks both sycamore and London plane.
Delaware growers and gardeners should know how to grow and maintain healthy landscape trees. For most trees, anthracnose disease is not lethal, but it can be for dogwoods. Good growing practices are important in reducing the effects of anthracnose and in preventing loss of dogwoods from anthracnose. Consider the following:
Rake up and compost fallen leaves. Leaves can be a source of inoculum.
Prune out and destroy dead twigs and branches, because for many of the anthracnose fungi, branches harbor fungal inoculum. Although it is difficult to prune large trees, small trees are at greater risk, so prune out dead twigs and branches from them. For dogwoods, pruning out dead branches and water sprouts is especially important where anthracnose might be a threat.
Avoid unnecessary wounding and avoid construction or other activities which could injure the roots or the branches.
Provide mulch as needed. Maintain a 2-3 inch layer of mulch over the root zone of the tree (but not against the trunk) to help maintain soil moisture and to protect trees from lawnmower injury.
Protect trees from drought by watering at least once a week during dry periods. Do not use overhead sprinklers for watering; wet foliage favors infection.
Do not transplant dogwood trees from the wild. Purchase healthy trees from a reputable nursery.
Anthracnose is favored by a moist environment. Select a planting site with a sunny eastern exposure to promote rapid foliage drying early in the day.
Diagnose and treat insect and disease problems appropriately.
Plant disease resistant dogwoods such as C. florida 'Appalachian Spring' or oriental dogwoods (Cornus kousa) for high risk sites such as those with heavy shade and nearby diseased trees.
Although most anthracnose diseases can be controlled using fungicides, the attempt is usually more costly than the benefit. Dogwoods which are threatened by anthracnose may benefit from early spring fungicide applications.
Adapted for Delaware from "ANTHRACNOSE DISEASE SYMPTOMS APPEARING IN LANDSCAPE TREES" By John Hartman in the May 22, 2006 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Anthracnose diseases are not all caused by the same fungus. Each host plant has its own anthracnose fungus, so, for example, don't assume that anthracnose of sycamore or grape is a threat to nearby dogwoods. The incidence and severity of anthracnose diseases of landscape trees varies with the season, and this year, symptoms appear to be at moderate levels.
Ash anthracnose. Brown blotches along leaflet edges have been visible for the past week or so on new ash foliage. Many of these infected leaflets will begin to drop soon and carpet the walks and lawns nearby. Ash anthracnose is not normally a threat to ash tree survival, however, and the ash trees will simply put out a new set of leaves. The ash anthracnose fungus is a species of Discula.
Dogwood anthracnose. Caused by the fungus Discula destructiva, dogwood anthracnose is appearing this spring in many flowering dogwoods (Cornus florida). Dogwood anthracnose causes leaf spots, leaf blight, and lower branch dieback and is most commonly observed in forested regions where native understory dogwood trees are threatened. This spring, anthracnose is also present in landscape trees, especially those growing in shaded locations.
Maple anthracnose. Symptoms can range from leaf spots to shoot blight and shoot cankers. Maple anthracnose may be caused by Discula sp. or by Kabatiella apocrypta. There is considerable variation in maple susceptibility to anthracnose. In some cases, sugar maple leaf spotting may be heavy on one tree while the adjacent tree is barely affected.
Oak anthracnose. This disease is less common and is caused by the fungus Apiognomonia quercina.
Sycamore anthracnose. Anthracnose symptoms on infected green, expanding leaves, look for irregular dark, necrotic blotching centered along the leaf veins or leaf edges. These dark blotches may turn a tan color as the diseased areas of the leaves dry out. In the same trees, tips of young shoots with newly expanding leaves are wilting and dying because of twig or shoot infection. With continued rainy weather, the disease should continue to spread in the foliage. Symptoms are not as severe as we see some years when trees are heavily defoliated by now. As the weather gets warmer and drier, sycamores normally put out new, healthy foliage. However, the legacy of crooked branches (because lateral shoots take over when terminals are killed by anthracnose) and multiple shoots arising from the base of a killed branch may still be visible many years later. Sycamore anthracnose is caused by the fungus Apiognomonia veneta, and the fungus attacks both sycamore and London plane.
Delaware growers and gardeners should know how to grow and maintain healthy landscape trees. For most trees, anthracnose disease is not lethal, but it can be for dogwoods. Good growing practices are important in reducing the effects of anthracnose and in preventing loss of dogwoods from anthracnose. Consider the following:
Rake up and compost fallen leaves. Leaves can be a source of inoculum.
Prune out and destroy dead twigs and branches, because for many of the anthracnose fungi, branches harbor fungal inoculum. Although it is difficult to prune large trees, small trees are at greater risk, so prune out dead twigs and branches from them. For dogwoods, pruning out dead branches and water sprouts is especially important where anthracnose might be a threat.
Avoid unnecessary wounding and avoid construction or other activities which could injure the roots or the branches.
Provide mulch as needed. Maintain a 2-3 inch layer of mulch over the root zone of the tree (but not against the trunk) to help maintain soil moisture and to protect trees from lawnmower injury.
Protect trees from drought by watering at least once a week during dry periods. Do not use overhead sprinklers for watering; wet foliage favors infection.
Do not transplant dogwood trees from the wild. Purchase healthy trees from a reputable nursery.
Anthracnose is favored by a moist environment. Select a planting site with a sunny eastern exposure to promote rapid foliage drying early in the day.
Diagnose and treat insect and disease problems appropriately.
Plant disease resistant dogwoods such as C. florida 'Appalachian Spring' or oriental dogwoods (Cornus kousa) for high risk sites such as those with heavy shade and nearby diseased trees.
Although most anthracnose diseases can be controlled using fungicides, the attempt is usually more costly than the benefit. Dogwoods which are threatened by anthracnose may benefit from early spring fungicide applications.
Adapted for Delaware from "ANTHRACNOSE DISEASE SYMPTOMS APPEARING IN LANDSCAPE TREES" By John Hartman in the May 22, 2006 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.
Landscape and Nursery - Southern Red Mite
This is the time of the year that Southern Red Mite (Oligonychus ilicis) is out and active. The following is an article on this pest.
Southern red mite. Photo by John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org
Be on the look out for southern red on Japanese holly, camelia, laurel, azaleas, and pyracantha. You may be able to find eggs, immature mites and some mature mites. This mite is one of the most destructive mites of broad leaved evergreen plants. It feeds using piercing mouthparts to damage plant cells and causes a stippling to the foliage that can be noticed as the population increases. Examine foliage of plants in hot, sunny locations for mite activity. Dry wather will increase activity of this mite.
Monitoring: Examine the undersides of foliage of Japanese holly, camellia, laurel, azaleas, and pyracantha. These guys are small so you may want to beat foliage over a white piece of paper and look for small reddish “spots” crawling around.
Control: Since southern red mite just hatched you have the options of using mite growth regulators such as Hexygon. Most arborists mix 1 % horticultural oil with Hexygon. Other good materials to use include Forbid, Akari, Floramite, or Avid.
Information adapted from an article in the May 12, 2006 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension
Southern red mite. Photo by John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.orgBe on the look out for southern red on Japanese holly, camelia, laurel, azaleas, and pyracantha. You may be able to find eggs, immature mites and some mature mites. This mite is one of the most destructive mites of broad leaved evergreen plants. It feeds using piercing mouthparts to damage plant cells and causes a stippling to the foliage that can be noticed as the population increases. Examine foliage of plants in hot, sunny locations for mite activity. Dry wather will increase activity of this mite.
Monitoring: Examine the undersides of foliage of Japanese holly, camellia, laurel, azaleas, and pyracantha. These guys are small so you may want to beat foliage over a white piece of paper and look for small reddish “spots” crawling around.
Control: Since southern red mite just hatched you have the options of using mite growth regulators such as Hexygon. Most arborists mix 1 % horticultural oil with Hexygon. Other good materials to use include Forbid, Akari, Floramite, or Avid.
Information adapted from an article in the May 12, 2006 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension
Saturday, May 10, 2008
Landscape - Borers in Trees
The following is a short article on borer pests that can attack trees in Delaware that will be active soon.
Three serious pests of landscape trees - dogwood borer, bronze birch borer, and flatheaded appletree borer - soon will be emerging. The dogwood borer is the most serious pest of ornamental dogwoods, especially stressed trees in full sun. The bronze birch borer is a severe pest of white or paper birch, especially cultivated trees under stress. Flatheaded appletree borers are major pests of red maples, hawthorns, flowering crabapple, and several other hardwoods, especially those which are newly transplanted or under stress. Mated females of all three species fly to host trees and lay eggs on the bark.
Management -- Borers rarely injure healthy trees or shrubs growing in their natural environments. When transplanted into landscape settings, every effort should be made to minimize plant stresses such as drought, soil compaction, sun scald, lawn mower/weed trimmer injuries, etc. Because newly planted trees are under considerable stress, preventive sprays are advisable during the first 2-3 growing seasons after planting. Timing is crucial in order to have a lethal residue of insecticide on the bark to intercept newly-hatched larvae before they burrow into the tree. Mid-May to late May is about the time to apply protectant sprays for all three species. Dursban (chlorpyrifos) and Lindane are no longer available, but professionals can use Onyx (bifenthrin) or Astro (permethrin).
Adapted for Delaware from "BORER ALERT" By Mike Potter in the May 5, 2008 edition of the Kentucky Pest News from the University of Kentucky College of Agriculture.
Three serious pests of landscape trees - dogwood borer, bronze birch borer, and flatheaded appletree borer - soon will be emerging. The dogwood borer is the most serious pest of ornamental dogwoods, especially stressed trees in full sun. The bronze birch borer is a severe pest of white or paper birch, especially cultivated trees under stress. Flatheaded appletree borers are major pests of red maples, hawthorns, flowering crabapple, and several other hardwoods, especially those which are newly transplanted or under stress. Mated females of all three species fly to host trees and lay eggs on the bark.
Management -- Borers rarely injure healthy trees or shrubs growing in their natural environments. When transplanted into landscape settings, every effort should be made to minimize plant stresses such as drought, soil compaction, sun scald, lawn mower/weed trimmer injuries, etc. Because newly planted trees are under considerable stress, preventive sprays are advisable during the first 2-3 growing seasons after planting. Timing is crucial in order to have a lethal residue of insecticide on the bark to intercept newly-hatched larvae before they burrow into the tree. Mid-May to late May is about the time to apply protectant sprays for all three species. Dursban (chlorpyrifos) and Lindane are no longer available, but professionals can use Onyx (bifenthrin) or Astro (permethrin).
Adapted for Delaware from "BORER ALERT" By Mike Potter in the May 5, 2008 edition of the Kentucky Pest News from the University of Kentucky College of Agriculture.
Landscape - Spring Diseases
Periodic rainy days and nights have been occurring recently in Delaware. Wet weather leading to prolonged leaf wetness as new foliage is emerging is very favorable for many landscape tree diseases. Symptoms of scab, rust, and anthracnose diseases are already beginning to appear in many landscapes.
Apple scab. Unsprayed, susceptible flowering crabapples and some backyard apples are already showing symptoms of leaf infections by the scab fungus, Venturia inaequalis. Long (15-18 hours) periods of leaf wetness are were favorable for new apple scab infections in. If trees were not already infected, expect symptoms developing from recent infections to appear in 10-12 days.
Cedar apple rust and cedar quince rust. The causal fungi, Gymnosporangium juniperi-virginianae and Gymnosporangium clavipes are still active on infected cedar trees. Symptoms on flowering crabapple and apple are already visible in some locations.
Fire blight (Erwinia amylovora). The primary infection season on flowering pears and crabapples and backyard apples and pears is over since most blooms have dropped flower petals by now. Depending on location, landscapes in Delaware were exposed to one or two fire blight primary infection periods based on favorable weather conditions this spring. If fire blight infections occurred earlier this season, symptoms in the fruiting spurs should be visible now. Look for blossom blight symptoms in the form of blackened, dead fruitlets in the fruit spurs throughout the tree. If there are not too many of them, infected clusters can be broken out by hand. Shoot blight symptoms, if they are going to occur, will appear in the coming weeks.
Anthracnose diseases. Where cool, rainy weather has prevailed, it is likely that sycamore (Apiognomonia veneta), oak (Apiognomonia quercina), maple (Discula sp. or Kabatiella apocrypta), and dogwood (Discula destructiva) anthracnose diseases will be active.
Adapted for Delaware from "SPRINGTIME DISEASES IN THE LANDSCAPE" By John Hartman in the May 5, 2008 edition of the Kentucky Pest News from the University of Kentucky College of Agriculture.
Apple scab. Unsprayed, susceptible flowering crabapples and some backyard apples are already showing symptoms of leaf infections by the scab fungus, Venturia inaequalis. Long (15-18 hours) periods of leaf wetness are were favorable for new apple scab infections in. If trees were not already infected, expect symptoms developing from recent infections to appear in 10-12 days.
Cedar apple rust and cedar quince rust. The causal fungi, Gymnosporangium juniperi-virginianae and Gymnosporangium clavipes are still active on infected cedar trees. Symptoms on flowering crabapple and apple are already visible in some locations.
Fire blight (Erwinia amylovora). The primary infection season on flowering pears and crabapples and backyard apples and pears is over since most blooms have dropped flower petals by now. Depending on location, landscapes in Delaware were exposed to one or two fire blight primary infection periods based on favorable weather conditions this spring. If fire blight infections occurred earlier this season, symptoms in the fruiting spurs should be visible now. Look for blossom blight symptoms in the form of blackened, dead fruitlets in the fruit spurs throughout the tree. If there are not too many of them, infected clusters can be broken out by hand. Shoot blight symptoms, if they are going to occur, will appear in the coming weeks.
Anthracnose diseases. Where cool, rainy weather has prevailed, it is likely that sycamore (Apiognomonia veneta), oak (Apiognomonia quercina), maple (Discula sp. or Kabatiella apocrypta), and dogwood (Discula destructiva) anthracnose diseases will be active.
Adapted for Delaware from "SPRINGTIME DISEASES IN THE LANDSCAPE" By John Hartman in the May 5, 2008 edition of the Kentucky Pest News from the University of Kentucky College of Agriculture.
Friday, May 9, 2008
Turf - Fungicide Resistance
By the early 1900’s fungicides were being used extensively on turfgrass for disease control. With widespread use has come fungicide resistance with some disease strains. The following is an article on the subject.
Early fungicides provided protection by chemically modifying basic biological processes. The deactivation of these processes resulted in the shut down of several vital cell functions and caused death to the fungus. Broad spectrum chemical modifications of this sort were usually achieved with a metal like zinc or copper and were not specific to fungi. They were also found to be phytotoxic to plant material, so they were modified to be confined to the outsides of the plants. In order for them to be effective fungicides they had to be placed on the plant before the fungus was present to prevent the establishment of an infection. There are similar materials still on the market that we refer to as contacts.
In the 1960’s materials with the capability to enter plants and theoretically cure active infections were being developed and brought to market. In order to overcome the problem of non-specific biological activity caused by the early fungicides, the toxic effects of the newer materials needed to be confined to the target fungus. Consequently, the toxic effect of these new products usually focused on a single or narrow range of metabolic processes in the fungus. This single site toxicosis is often overcome by changes in the fungus. Reports of fungicide resistance quickly followed the introduction of the new materials.
Fungicide resistance is a stable, inheritable adjustment by the fungal population to the toxic effects of the fungicide. The changes in the fungal cell that bring about resistance are sometimes regulated by a single gene. This phenomenon is called monogenic resistance. In some fungi the changes are regulated by multiple genes, which is known as polygenic resistance. Fungicides that are at the highest risk of resistance problems are those that affect a single metabolic site in the fungus and those in which the resistance factor is governed by a single gene.
It is possible that any fungus has the ability to resist two or more fungicides. This phenomenon is known as cross resistance. Cross resistance usually occurs in closely related compounds in the same chemical classes. For instance, fungal populations resistant to propiconizole are often resistant to triadimefon and fenarimol. All of these materials are found in the same chemical class (sterole demethylation inhibitors).
Fungicide resistance does not develop spontaneously. In normal fungal populations, resistant biotypes are always present. Increases in the population of these resistant biotypes are brought on by the fungicide program. If the material one uses only attacks sensitive biotypes, then over time, the resistant biotypes dominate the population and control efforts fail. This generally occurs when a single material or materials in the same chemical class are repeatedly used over a period of time. It is also not uncommon for resistance to occur if less than optimal rates of the materials are used. This allows a broader range of tolerant biotypes to survive and prosper. The point at which satisfactory disease control is no longer provided in the field by your program is called practical resistance.
Be aware that all fungicide failures are not due to practical resistance. Improper diagnosis, improper dilution rates, poor selection of materials, bad timing, tank incompatibilities, improper calibration and bad nozzle choices are just a few of the possibilities.
That being said, we have seen several cases in the Rutgers Plant Diagnostic Laboratory last summer of practical resistance to dollar spot and anthracnose. If you suspect practical resistance and have ruled out other reasons for your disease control failures, then we suggest screening for fungicides in the following chemical classes: sterole demethylation inhibitors, the strobilurins, and benzamidazoles. In order to screen for resistance, we isolate the causal agents from diseased plant material and grow them on mycological media amended with a fungicide in each of the mentioned chemical classes. We use different concentrations of the materials in each media. The concentrations range from below to well above field rates. Over a period of several days we compare the growth rates of the target fungus on the fungicide amended media to an isolate of the fungus on a non-amended media. If the growth rates are similar, we determine the sample to be insensitive or laboratory resistant to the material we are testing for. If this is the case, adjustments to your fungicide program are in order.
Adapted from "Practical Fungicide Resistance in Turf Stands, Part I" by Richard Buckley, Director, Soil Testing and Plant Diagnostic Services, Rutgers University in the April 17, 2008 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition, Rutgers University Ag. Experiment Station and Cooperative Extension.
Early fungicides provided protection by chemically modifying basic biological processes. The deactivation of these processes resulted in the shut down of several vital cell functions and caused death to the fungus. Broad spectrum chemical modifications of this sort were usually achieved with a metal like zinc or copper and were not specific to fungi. They were also found to be phytotoxic to plant material, so they were modified to be confined to the outsides of the plants. In order for them to be effective fungicides they had to be placed on the plant before the fungus was present to prevent the establishment of an infection. There are similar materials still on the market that we refer to as contacts.
In the 1960’s materials with the capability to enter plants and theoretically cure active infections were being developed and brought to market. In order to overcome the problem of non-specific biological activity caused by the early fungicides, the toxic effects of the newer materials needed to be confined to the target fungus. Consequently, the toxic effect of these new products usually focused on a single or narrow range of metabolic processes in the fungus. This single site toxicosis is often overcome by changes in the fungus. Reports of fungicide resistance quickly followed the introduction of the new materials.
Fungicide resistance is a stable, inheritable adjustment by the fungal population to the toxic effects of the fungicide. The changes in the fungal cell that bring about resistance are sometimes regulated by a single gene. This phenomenon is called monogenic resistance. In some fungi the changes are regulated by multiple genes, which is known as polygenic resistance. Fungicides that are at the highest risk of resistance problems are those that affect a single metabolic site in the fungus and those in which the resistance factor is governed by a single gene.
It is possible that any fungus has the ability to resist two or more fungicides. This phenomenon is known as cross resistance. Cross resistance usually occurs in closely related compounds in the same chemical classes. For instance, fungal populations resistant to propiconizole are often resistant to triadimefon and fenarimol. All of these materials are found in the same chemical class (sterole demethylation inhibitors).
Fungicide resistance does not develop spontaneously. In normal fungal populations, resistant biotypes are always present. Increases in the population of these resistant biotypes are brought on by the fungicide program. If the material one uses only attacks sensitive biotypes, then over time, the resistant biotypes dominate the population and control efforts fail. This generally occurs when a single material or materials in the same chemical class are repeatedly used over a period of time. It is also not uncommon for resistance to occur if less than optimal rates of the materials are used. This allows a broader range of tolerant biotypes to survive and prosper. The point at which satisfactory disease control is no longer provided in the field by your program is called practical resistance.
Be aware that all fungicide failures are not due to practical resistance. Improper diagnosis, improper dilution rates, poor selection of materials, bad timing, tank incompatibilities, improper calibration and bad nozzle choices are just a few of the possibilities.
That being said, we have seen several cases in the Rutgers Plant Diagnostic Laboratory last summer of practical resistance to dollar spot and anthracnose. If you suspect practical resistance and have ruled out other reasons for your disease control failures, then we suggest screening for fungicides in the following chemical classes: sterole demethylation inhibitors, the strobilurins, and benzamidazoles. In order to screen for resistance, we isolate the causal agents from diseased plant material and grow them on mycological media amended with a fungicide in each of the mentioned chemical classes. We use different concentrations of the materials in each media. The concentrations range from below to well above field rates. Over a period of several days we compare the growth rates of the target fungus on the fungicide amended media to an isolate of the fungus on a non-amended media. If the growth rates are similar, we determine the sample to be insensitive or laboratory resistant to the material we are testing for. If this is the case, adjustments to your fungicide program are in order.
Adapted from "Practical Fungicide Resistance in Turf Stands, Part I" by Richard Buckley, Director, Soil Testing and Plant Diagnostic Services, Rutgers University in the April 17, 2008 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition, Rutgers University Ag. Experiment Station and Cooperative Extension.
Greenhouse, Nursery, Landscape, and Turf - Proper Fungicide Use
Fungicides are used extensively to control diseases in greenhouses, nurseries, landscapes, and turf areas. The following is an article on considerations in applying fungicides.
1. Apply fungicides prior to the development of disease. Most fungicides do not have a “kick back” action. That is, they do not effectively eradicate diseases after they have started. And by the time a single disease lesion is observed, many more lesions too small to observe are already working on your plants. Even those fungicides with systemic activity and some curative action are much better applied before the disease is present.
2. Use shorter spray intervals during weather conducive to plant disease. Each plant disease has its own “personality” and thus prefers different weather. However, most plant diseases require leaf wetness. Therefore, during periods of rain and heavy dews, more frequent fungicide applications are a good idea. The normal range of spray applications is every 7 to 14 days during the period the disease is active. Use disease forecasting tools where available to schedule applications.
3. Apply fungicides before a rain if possible. Water is necessary for most fungal spores to infect a leaf or stem and for the splash dispersal of many spores. Therefore apply fungicides before a rain if it appears that the fungicide will have a chance to dry before the rain. It is not necessary to apply fungicides again after every rain. Most modern fungicides have a good sticker and will persist through rains pretty well.
4. Avoid applying fungicides in the heat of the day. It is possible for any foliar applied chemical to cause some plant damage if applied under conditions of heat and direct sunshine. Also remember that if fungicides and insecticides are applied together, make the applications so that bees are unharmed.
5. Timing of fungicide applications and coverage is more important than nozzle type and spray pressure. Studies have found that nozzle type and spray pressure don’t make as much difference as we once thought.
6. Some diseases cannot be managed by foliar sprays. Problems caused by soil borne fungi or nematodes cannot be controlled with foliar fungicides. No amount of fungicide will improve a problem caused by soil fertility.
7. Do not apply foliar fungicides to the soil. Although fungicides may kill or inhibit the growth of fungi which cause plant diseases, the application of those same fungicides to the soil will be wasteful and off label. Foliar fungicides are designed to protect the surfaces of plants. Only use fungicides labeled for soil treament
8. Make certain the fungicide matches the crop and disease. That is, READ THE LABEL. The label is the law. Plus, considerable time and money was spent to test each fungicide with a particular crop and disease. Off label applications also waste your time and money.
9. Double – check the label for the current rate. Rates may vary widely based on label changes and different formulations. While you are checking the rate, also check to make sure your application method is labeled. For example, some fungicides are labeled for greenhouse use, others only for use outside
10. Play it safe. Always adhere to the Re-Entry Intervals and Worker Protection Standards listed in the label. No one wants an accident or lawsuit. Besides, the label is the law.
11. Rotate fungicide chemistries to avoid the development of fungicide resistant strains of the diseases.
Adapted from an article by Dr. Dan Egel, Purdue University
1. Apply fungicides prior to the development of disease. Most fungicides do not have a “kick back” action. That is, they do not effectively eradicate diseases after they have started. And by the time a single disease lesion is observed, many more lesions too small to observe are already working on your plants. Even those fungicides with systemic activity and some curative action are much better applied before the disease is present.
2. Use shorter spray intervals during weather conducive to plant disease. Each plant disease has its own “personality” and thus prefers different weather. However, most plant diseases require leaf wetness. Therefore, during periods of rain and heavy dews, more frequent fungicide applications are a good idea. The normal range of spray applications is every 7 to 14 days during the period the disease is active. Use disease forecasting tools where available to schedule applications.
3. Apply fungicides before a rain if possible. Water is necessary for most fungal spores to infect a leaf or stem and for the splash dispersal of many spores. Therefore apply fungicides before a rain if it appears that the fungicide will have a chance to dry before the rain. It is not necessary to apply fungicides again after every rain. Most modern fungicides have a good sticker and will persist through rains pretty well.
4. Avoid applying fungicides in the heat of the day. It is possible for any foliar applied chemical to cause some plant damage if applied under conditions of heat and direct sunshine. Also remember that if fungicides and insecticides are applied together, make the applications so that bees are unharmed.
5. Timing of fungicide applications and coverage is more important than nozzle type and spray pressure. Studies have found that nozzle type and spray pressure don’t make as much difference as we once thought.
6. Some diseases cannot be managed by foliar sprays. Problems caused by soil borne fungi or nematodes cannot be controlled with foliar fungicides. No amount of fungicide will improve a problem caused by soil fertility.
7. Do not apply foliar fungicides to the soil. Although fungicides may kill or inhibit the growth of fungi which cause plant diseases, the application of those same fungicides to the soil will be wasteful and off label. Foliar fungicides are designed to protect the surfaces of plants. Only use fungicides labeled for soil treament
8. Make certain the fungicide matches the crop and disease. That is, READ THE LABEL. The label is the law. Plus, considerable time and money was spent to test each fungicide with a particular crop and disease. Off label applications also waste your time and money.
9. Double – check the label for the current rate. Rates may vary widely based on label changes and different formulations. While you are checking the rate, also check to make sure your application method is labeled. For example, some fungicides are labeled for greenhouse use, others only for use outside
10. Play it safe. Always adhere to the Re-Entry Intervals and Worker Protection Standards listed in the label. No one wants an accident or lawsuit. Besides, the label is the law.
11. Rotate fungicide chemistries to avoid the development of fungicide resistant strains of the diseases.
Adapted from an article by Dr. Dan Egel, Purdue University
Thursday, May 8, 2008
Research - Looking for Euonymus Scales
Brian Kunkel, Extension Ornamental IPM Specialist at the University of Delaware is conducting a euonymus scale evaluation trial this summer. If you have euonymus scale infestations please contact him or send a sample to one of the county offices. He is looking for samples of euonymus scales with either active crawlers or scales to infest plants.
Contact Information:
Dr. Brian A. Kunkel
Extension Specialist, Ornamental IPM
Phone: (302) 831-3641
FAX: (302) 831-8889
Email: bakunkel@udel.edu
Euonymus Scales, Photo from Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
Contact Information:
Dr. Brian A. Kunkel
Extension Specialist, Ornamental IPM
Phone: (302) 831-3641
FAX: (302) 831-8889
Email: bakunkel@udel.edu
Euonymus Scales, Photo from Clemson University - USDA Cooperative Extension Slide Series, Bugwood.orgGreenhouse - Biological Controls for Spider Mites
There are effective biological controls for spider mites in greenhouses. The following is a short article on the subject.
Spider mites may be introduced into your greenhouses on incoming plant material, or may move from weeds onto your crops. If hot spots of mite activity are detected early by regular scouting, biological control may be an option.
A fast acting predatory mite that is commercially available is Phytoseiulus persimilis. This predatory mite only feeds upon spider mites, and will disperse or starve with no prey. The adult P. persimilis is bright red in color, pear shaped, long-legged and slightly larger and more active than spider mites.
It is best released when mite populations are first noticed, in hot spots of mite activity. Relative humidity should be greater than 75% and temperatures above 68F for some hours of the day. (At low relative humidity (less than 60%), eggs shrivel and do not hatch.) Spider mite colonies should be reduced in two to three weeks.
The spider mite predator Neoseilus californicus is slower acting than P. persimilis, but can survive longer in the absence of prey. It is useful for keeping low spider mite populations under control. In certain situations where high temperature or relative humidity variations can occur, N. californicus may be an option. N. californicus is active at temperatures between 46°F to 95°F, 40-80% relative humidity. At low pest densities, it declines less than P. persmilis, for N. californicus can survive on other mites, thrips, molds and nectar. N. californicus can also be introduced preventively and is compatible with P. persimilis.
Some suppliers offer a mix of different species of predatory mites. Additional species are available that are adapted to outdoor use.
Article by Leanne Pundt, Extension Educator, University of Connecticut in the May 1 edition of the New England Greenhouse Update http://www.negreenhouseupdate.info/greenhouse_update/index.php
Spider mites may be introduced into your greenhouses on incoming plant material, or may move from weeds onto your crops. If hot spots of mite activity are detected early by regular scouting, biological control may be an option.
A fast acting predatory mite that is commercially available is Phytoseiulus persimilis. This predatory mite only feeds upon spider mites, and will disperse or starve with no prey. The adult P. persimilis is bright red in color, pear shaped, long-legged and slightly larger and more active than spider mites.
It is best released when mite populations are first noticed, in hot spots of mite activity. Relative humidity should be greater than 75% and temperatures above 68F for some hours of the day. (At low relative humidity (less than 60%), eggs shrivel and do not hatch.) Spider mite colonies should be reduced in two to three weeks.
The spider mite predator Neoseilus californicus is slower acting than P. persimilis, but can survive longer in the absence of prey. It is useful for keeping low spider mite populations under control. In certain situations where high temperature or relative humidity variations can occur, N. californicus may be an option. N. californicus is active at temperatures between 46°F to 95°F, 40-80% relative humidity. At low pest densities, it declines less than P. persmilis, for N. californicus can survive on other mites, thrips, molds and nectar. N. californicus can also be introduced preventively and is compatible with P. persimilis.
Some suppliers offer a mix of different species of predatory mites. Additional species are available that are adapted to outdoor use.
Article by Leanne Pundt, Extension Educator, University of Connecticut in the May 1 edition of the New England Greenhouse Update http://www.negreenhouseupdate.info/greenhouse_update/index.php
Wednesday, May 7, 2008
Turf - Bermudagrass Control in Cool Season Turf
Bermudagrass can be a troublesome weed in cool season turf. It will be greening up starting the middle of May. Note browned out areas in turf where bermudagrass infestations were last year and watch for signs of greenup. Control programs should begin once greenup has completed. The following is an article on the subject.
Bermudagrass (Cynodon dactylon) is a warm season perennial grass that is used extensively for turf in southern states and along the coast in Delaware. It is also finding a place on athletic fields in the state. However, common bermudagrass, often know as wiregrass, is a troublesome summer weed in cool season turfgrass. Bermuda grass is recognized by its wiry appearance, short leaves, creeping stolons, and underground rhizomes. It can be distinguished from similar looking grasses (nimblewill and bentgrass) by looking at the ligules which will be hair-like and not membranous.
Several approaches can be taken to control bermudagrass in cool season turf. Avoid spring and summer applications of nitrogen fertilizer. This favors bermudagrass growth over cool season turf. Bermudagrass control can be achieved by use of the non-selective herbicide glyphosate applied 2-3 times at 3 week intervals followed by reseeding or sodding (desirable turf will be killed). This is effective for smaller patches and spots. For larger infestations in cool season turf, bermudagrass suppression has been achieved by applications of Acclaim extra (fexoxaprop-p-ethyl) applied at 0.46 fl. oz. per 1000 sq. ft. every 4-5 weeks (maximum of 6 applications) starting at bermudagrass first greenup in May. Acclaim extra mixed in combination with Prograss (ethofumisate) or Turflon Ester (triclopyr) has given better bermudagrass control (do not use Prograss on fine fescues) and fewer applications may be needed. Both Prograss and Turflon Ester both have some bermudagrass activity when used alone. In tall fescue turf only, bermudagrass can be suppressed by 2 applications of fluazifop-P-butyl (Ornamec, Fusilade II, refer to labels for rates and restrictions), one at first bermudagrass greenup in May, the second in late summer (September). Do not apply during hot summer months. Some tall fescue yellowing can be expected and severe damage to tall fescue can occur where spray is overlapped. Basamid G (dazomet) a granular soil fumigant (numerous restrictions, must be watered in), has been used with some success to kill out bermudagrass followed by complete renovation. Control of bermudagrass in landscape beds is best accomplished by post-emergence applications of a grass herbicide: sethoxidim (Vantage, Sethoxydim G-Pro), fluazifop-P-butyl (Ornamec, Fusilade II), or clethodim (Envoy plus, others).
Gordon Johnson, Extension Horticulture Agent, UD, Kent County.
Bermudagrass (Cynodon dactylon) is a warm season perennial grass that is used extensively for turf in southern states and along the coast in Delaware. It is also finding a place on athletic fields in the state. However, common bermudagrass, often know as wiregrass, is a troublesome summer weed in cool season turfgrass. Bermuda grass is recognized by its wiry appearance, short leaves, creeping stolons, and underground rhizomes. It can be distinguished from similar looking grasses (nimblewill and bentgrass) by looking at the ligules which will be hair-like and not membranous.
Several approaches can be taken to control bermudagrass in cool season turf. Avoid spring and summer applications of nitrogen fertilizer. This favors bermudagrass growth over cool season turf. Bermudagrass control can be achieved by use of the non-selective herbicide glyphosate applied 2-3 times at 3 week intervals followed by reseeding or sodding (desirable turf will be killed). This is effective for smaller patches and spots. For larger infestations in cool season turf, bermudagrass suppression has been achieved by applications of Acclaim extra (fexoxaprop-p-ethyl) applied at 0.46 fl. oz. per 1000 sq. ft. every 4-5 weeks (maximum of 6 applications) starting at bermudagrass first greenup in May. Acclaim extra mixed in combination with Prograss (ethofumisate) or Turflon Ester (triclopyr) has given better bermudagrass control (do not use Prograss on fine fescues) and fewer applications may be needed. Both Prograss and Turflon Ester both have some bermudagrass activity when used alone. In tall fescue turf only, bermudagrass can be suppressed by 2 applications of fluazifop-P-butyl (Ornamec, Fusilade II, refer to labels for rates and restrictions), one at first bermudagrass greenup in May, the second in late summer (September). Do not apply during hot summer months. Some tall fescue yellowing can be expected and severe damage to tall fescue can occur where spray is overlapped. Basamid G (dazomet) a granular soil fumigant (numerous restrictions, must be watered in), has been used with some success to kill out bermudagrass followed by complete renovation. Control of bermudagrass in landscape beds is best accomplished by post-emergence applications of a grass herbicide: sethoxidim (Vantage, Sethoxydim G-Pro), fluazifop-P-butyl (Ornamec, Fusilade II), or clethodim (Envoy plus, others).
Gordon Johnson, Extension Horticulture Agent, UD, Kent County.
Turf - Reconsider Zoysiagrass
Zoysiagrass invokes strong emotions by homeowners, property managers, and turf professionals. Some like the texture, density, and color of the lush turf it produces. Others hate that it browns out all winter and how it invades areas. The following are some reasons to reconsider zoysias and what varieties are recommended.
Zoysiagrass is a warm season grass that can be very successfully grown as a lawn in Delaware. It produces a dense, attractive turf that is drought resistant and heat tolerant. As a warm season grass it greens up in May and goes dormant in October (turns straw colored). It is slower to fill in than Bermdagrass and less wear tolerant but is more cold hardy and shade tolerant . It requires a very sharp mower blade to cut properly. Originally, only vegetatively propagated varieties were available; however, excellent seed varieties are now on the market. Recommended varieties are Meyer (vegetative), Zenith and Compadre (both seeded types).
Newer promising vegetatively propagated (V) and seeded (S) zoysiagrass varieties include: Cavalier (V), Companion (S), Himeno (V), J-14 (S), J-36 (S), J-37 (S), Marquis (V), Sunburst (V), Zorro (V), ZEN-400 (S), and ZEN-500 (S).
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Zoysiagrass is a warm season grass that can be very successfully grown as a lawn in Delaware. It produces a dense, attractive turf that is drought resistant and heat tolerant. As a warm season grass it greens up in May and goes dormant in October (turns straw colored). It is slower to fill in than Bermdagrass and less wear tolerant but is more cold hardy and shade tolerant . It requires a very sharp mower blade to cut properly. Originally, only vegetatively propagated varieties were available; however, excellent seed varieties are now on the market. Recommended varieties are Meyer (vegetative), Zenith and Compadre (both seeded types).
Newer promising vegetatively propagated (V) and seeded (S) zoysiagrass varieties include: Cavalier (V), Companion (S), Himeno (V), J-14 (S), J-36 (S), J-37 (S), Marquis (V), Sunburst (V), Zorro (V), ZEN-400 (S), and ZEN-500 (S).
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Tuesday, May 6, 2008
Nursery and Landscape - Watch for Rhabdocline Needlecast in Douglas Fir
Rhabdocline needlecast is often seen in plantings of Douglas firs. The following is an article on the subject.
Rhabdocline needlecast is an important disease to know and control if you grow Douglas fir or have properties with Douglas fir. Only Douglas fir is susceptible to this needlecast. Badly infected trees will lose a considerable number of one and two year old needles, which renders the plants unsaleable come Nov. and Dec. in nurseries and Christmas tree plantings. The plant tissue covering the spore bearing structures is just splitting and the buds are emerging in this area, so the timing is right for a treatment in the next few days. Now would be a good time to scout plantings for symptoms and treat if the disease is seen. Bravo Weather Stik or other labeled formulation of Bravo or Daconil (chlorothalonil) is the least expensive and effective if applied at the proper time.
Cultural Control
>Control vegetation around base of trees to increase air circulation and reduce moisture conditions necessary for infection.
>Plant healthy stock.
>Identify disease early to minimize losses.
>Shear trees in healthy plantations first to avoid contamination of these plantations by workers' clothing and equipment.
>Sterilize tools by dipping in denatured alcohol for 3 minutes after shearing infected plantations.
Chemical Control
Trees should be sprayed with chlorothalonil (Bravo or Daconil 2787). Foliage should be completely covered. Three fungicide applications are generally recommended. The first should be made when at least 50% of the buds have broken and the new growth is 1/2 inch long. Make two more applications at two to three week intervals after the first.
Information from Bob Mulrooney, Extension Plant Pathologist, UD.
Rhabdocline needlecast is an important disease to know and control if you grow Douglas fir or have properties with Douglas fir. Only Douglas fir is susceptible to this needlecast. Badly infected trees will lose a considerable number of one and two year old needles, which renders the plants unsaleable come Nov. and Dec. in nurseries and Christmas tree plantings. The plant tissue covering the spore bearing structures is just splitting and the buds are emerging in this area, so the timing is right for a treatment in the next few days. Now would be a good time to scout plantings for symptoms and treat if the disease is seen. Bravo Weather Stik or other labeled formulation of Bravo or Daconil (chlorothalonil) is the least expensive and effective if applied at the proper time.
Cultural Control
>Control vegetation around base of trees to increase air circulation and reduce moisture conditions necessary for infection.
>Plant healthy stock.
>Identify disease early to minimize losses.
>Shear trees in healthy plantations first to avoid contamination of these plantations by workers' clothing and equipment.
>Sterilize tools by dipping in denatured alcohol for 3 minutes after shearing infected plantations.
Chemical Control
Trees should be sprayed with chlorothalonil (Bravo or Daconil 2787). Foliage should be completely covered. Three fungicide applications are generally recommended. The first should be made when at least 50% of the buds have broken and the new growth is 1/2 inch long. Make two more applications at two to three week intervals after the first.
Information from Bob Mulrooney, Extension Plant Pathologist, UD.
Business - Child Labor Laws
Horticultural businesses often hire high school students. Younger family members and relatives are also often used in the business. Remember that children are protected by child labor laws and you should be aware of the requirements when hiring minors.
You might ask, “What does child labor have to do with my business”?
The National Institute for Occupational Safety and Health (NIOSH) distributed a timely Alert titled “Preventing Deaths and Injuries of Adolescent Workers” that should be reviewed by all employers. It is especially pertinent to horticultural employers who routinely hire young workers to assist with the added workload in the spring and summer months. The report addressed concern over the disproportionately high number of injuries and deaths to adolescent workers. They estimate that approximately 70 adolescents die from injuries at work and nearly 200,000 suffer work-related injuries each year.
The sad commentary is that agriculture accounted for 2 out of every 3 deaths. The retail industry came in second followed by construction and the service industries. The activities accounting for most of the adolescent deaths included motor vehicles, tractors and other heavy equipment, electrical hazards, working at jobs with a high risk of homicide and fall hazards. The fact that many of these workers were performing hazardous work prohibited under the Federal Child Labor Laws raises some serious concerns.
Horticultural and other employers need to be aware of the work restrictions for adolescent workers and also remember that training is essential. According to the NIOSH study, more than 50% of the young workers reported they had not received any training. The Federal Child Labor Laws prohibit children under 16 years of age from performing certain hazardous jobs without training. These provisions do not apply to youth working in businesses of their parents or guardians, but nevertheless the training is still essential.
Some of the hazardous jobs not open to youth include: operating a tractor over 20-belt horsepower; operating or assisting with the operation of certain pieces of farm machinery; and operating or assisting with trenchers, fork lifts, chain saws, or other types of dangerous machines. Other jobs excluded include working at high elevations, handling hazardous materials, working in logging operations, transporting passengers in buses, tractors, trucks and autos or riding on a tractor as a passenger or helper.
Violations of Federal Child Labor Laws are too common and have been associated with serious injury and deaths. Research on work-related deaths of adolescents has found that in recent years as high as 86% of deaths of adolescents have been associated with prohibited activities.
Although work does provide many benefits for the development of adolescents and may be financially necessary, the potential for serious injury and death must be recognized and addressed. The disproportionate number of adolescents killed and seriously injured at work each year cannot be tolerated. Employers and parents of adolescents, school counselors, teachers and young workers must be aware of the risks, the law and injury prevention techniques. Educating our youth and employers to recognize the hazards and take steps to reduce risks is the key.
Adapted from an article by Ron Jester; UD Extension Safety Specialist (retired).
You might ask, “What does child labor have to do with my business”?
The National Institute for Occupational Safety and Health (NIOSH) distributed a timely Alert titled “Preventing Deaths and Injuries of Adolescent Workers” that should be reviewed by all employers. It is especially pertinent to horticultural employers who routinely hire young workers to assist with the added workload in the spring and summer months. The report addressed concern over the disproportionately high number of injuries and deaths to adolescent workers. They estimate that approximately 70 adolescents die from injuries at work and nearly 200,000 suffer work-related injuries each year.
The sad commentary is that agriculture accounted for 2 out of every 3 deaths. The retail industry came in second followed by construction and the service industries. The activities accounting for most of the adolescent deaths included motor vehicles, tractors and other heavy equipment, electrical hazards, working at jobs with a high risk of homicide and fall hazards. The fact that many of these workers were performing hazardous work prohibited under the Federal Child Labor Laws raises some serious concerns.
Horticultural and other employers need to be aware of the work restrictions for adolescent workers and also remember that training is essential. According to the NIOSH study, more than 50% of the young workers reported they had not received any training. The Federal Child Labor Laws prohibit children under 16 years of age from performing certain hazardous jobs without training. These provisions do not apply to youth working in businesses of their parents or guardians, but nevertheless the training is still essential.
Some of the hazardous jobs not open to youth include: operating a tractor over 20-belt horsepower; operating or assisting with the operation of certain pieces of farm machinery; and operating or assisting with trenchers, fork lifts, chain saws, or other types of dangerous machines. Other jobs excluded include working at high elevations, handling hazardous materials, working in logging operations, transporting passengers in buses, tractors, trucks and autos or riding on a tractor as a passenger or helper.
Violations of Federal Child Labor Laws are too common and have been associated with serious injury and deaths. Research on work-related deaths of adolescents has found that in recent years as high as 86% of deaths of adolescents have been associated with prohibited activities.
Although work does provide many benefits for the development of adolescents and may be financially necessary, the potential for serious injury and death must be recognized and addressed. The disproportionate number of adolescents killed and seriously injured at work each year cannot be tolerated. Employers and parents of adolescents, school counselors, teachers and young workers must be aware of the risks, the law and injury prevention techniques. Educating our youth and employers to recognize the hazards and take steps to reduce risks is the key.
Adapted from an article by Ron Jester; UD Extension Safety Specialist (retired).
Monday, May 5, 2008
Landscape - Landscape Fabric Problems
I have seen many issues in the landscape with the use of landscape fabrics. While they do have some limited applications and are a necessity in greenhouses and container nurseries, they can cause problems in landscape settings. The following is an article on the subject from Washington State University.
Increased concern over the use of herbicides has caused landscape professionals and consumers to look closely at non-chemical alternatives to weed control. Mulches are increasing in popularity as weed control strategies and have a number of additional benefits, including water retention and soil protection. Mulches may be organic, inorganic, or synthetic and often can bring an aesthetic quality in tandem with their principal role in plant health maintenance. Synthetic mulches, including geotextiles, are of interest to many consumers and professionals because they are perceived as nonbiodegradable, permanent solutions to weed control.
Initially developed for agricultural use, geotextiles have found their way into ornamental installations as landscape fabrics. These fabrics, a vast improvement over the impermeable black plastics still (unfortunately) used for weed control, are woven in such a way that water and gas exchange can occur but light penetration is significantly reduced. Hence, they are effective in reducing weed seed germination in areas where soil disturbance would otherwise induce germination of a horde of weeds. Such fabrics have been so effective in reducing weeds in vegetable and ornamental crop production that they have been applied to more permanent landscape installations.
The Reality
Like the perpetual dieter searching for a permanent weight loss pill, so we as landscape professionals and consumers continue to seek permanent weed control solutions. Unfortunately, there is no such permanent fix. We must remain “ever vigilant” in our battle with weeds and cannot rely on a product to do this passively. The fact is that weed control fabrics are not permanent and will decompose, especially when exposed to sunlight. Such fabrics are effective in agricultural situations, in annual planting beds, or where the landscape is regularly disturbed and the fabrics can be replaced when needed. For permanent landscapes, however, they are not a long term solution and in fact can hinder landscape plant health.
Some of the documented drawbacks of these fabrics are listed below.
• Geotextiles degrade in the landscape in as little as one year if unprotected from sunlight.
• Any organic matter or soil on top of the fabrics will hasten their colonization by weeds; this precludes covering the fabric with anything but inorganic mulch like pebbles. It also requires continual maintenance to keep the fabric free of debris.
• Weeds will eventually grow on top of and through these fabrics, making their removal difficult.
• Landscape plant roots can also colonize fabrics, and they are damaged when the fabrics are removed.
• The aesthetic quality of landscape fabrics is minimal; it becomes worse as the materials begin to degrade.
The Bottom Line
• Geotextiles are not effective weed control solutions for permanent landscapes
• Landscape fabrics used in permanent landscape installations will eventually become a high maintenance issue in terms of appearance, weed control, and landscape plant health
• Organic mulches are preferred alternatives for permanent landscape installations as they can be reapplied throughout the life of the landscape without damaging the existing plantings
Adapted from "The Myth of Landscape Fabric:Landscape fabric provides permanent weed control for ornamental landscapes" by Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor, Puyallup Research and Extension Center, Washington State University. For more information, please visit Dr. Chalker-Scott’s web page at http://www.theinformedgardener.com.
Increased concern over the use of herbicides has caused landscape professionals and consumers to look closely at non-chemical alternatives to weed control. Mulches are increasing in popularity as weed control strategies and have a number of additional benefits, including water retention and soil protection. Mulches may be organic, inorganic, or synthetic and often can bring an aesthetic quality in tandem with their principal role in plant health maintenance. Synthetic mulches, including geotextiles, are of interest to many consumers and professionals because they are perceived as nonbiodegradable, permanent solutions to weed control.
Initially developed for agricultural use, geotextiles have found their way into ornamental installations as landscape fabrics. These fabrics, a vast improvement over the impermeable black plastics still (unfortunately) used for weed control, are woven in such a way that water and gas exchange can occur but light penetration is significantly reduced. Hence, they are effective in reducing weed seed germination in areas where soil disturbance would otherwise induce germination of a horde of weeds. Such fabrics have been so effective in reducing weeds in vegetable and ornamental crop production that they have been applied to more permanent landscape installations.
The Reality
Like the perpetual dieter searching for a permanent weight loss pill, so we as landscape professionals and consumers continue to seek permanent weed control solutions. Unfortunately, there is no such permanent fix. We must remain “ever vigilant” in our battle with weeds and cannot rely on a product to do this passively. The fact is that weed control fabrics are not permanent and will decompose, especially when exposed to sunlight. Such fabrics are effective in agricultural situations, in annual planting beds, or where the landscape is regularly disturbed and the fabrics can be replaced when needed. For permanent landscapes, however, they are not a long term solution and in fact can hinder landscape plant health.
Some of the documented drawbacks of these fabrics are listed below.
• Geotextiles degrade in the landscape in as little as one year if unprotected from sunlight.
• Any organic matter or soil on top of the fabrics will hasten their colonization by weeds; this precludes covering the fabric with anything but inorganic mulch like pebbles. It also requires continual maintenance to keep the fabric free of debris.
• Weeds will eventually grow on top of and through these fabrics, making their removal difficult.
• Landscape plant roots can also colonize fabrics, and they are damaged when the fabrics are removed.
• The aesthetic quality of landscape fabrics is minimal; it becomes worse as the materials begin to degrade.
The Bottom Line
• Geotextiles are not effective weed control solutions for permanent landscapes
• Landscape fabrics used in permanent landscape installations will eventually become a high maintenance issue in terms of appearance, weed control, and landscape plant health
• Organic mulches are preferred alternatives for permanent landscape installations as they can be reapplied throughout the life of the landscape without damaging the existing plantings
Adapted from "The Myth of Landscape Fabric:Landscape fabric provides permanent weed control for ornamental landscapes" by Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor, Puyallup Research and Extension Center, Washington State University. For more information, please visit Dr. Chalker-Scott’s web page at http://www.theinformedgardener.com.
Turf - Irrigating Lawns
A frequently publicized rule of thumb for irrigating lawn turf is to apply 1 to 2 inches of water per week. Although this may keep turf green during most of the summer, it may be wasteful or ineffective, particularly where thick thatch layers, heavy clay soils, or "hard pans" exist. In general, it is much more effective to water turf by need and not by rule.
The best time to irrigate the lawn is when turf just begins to show signs of wilt. This of course is not always easy to determine. However, there are two prominent symptoms exhibited by turf as it begins to wilt: (1) foot printing, and (2) turf develops a blue-green or blue-gray leaf color. After walking across drought stressed turf, leaves of the walked upon plants remain depressed for several minutes, providing the "foot printing" effect. When turf exhibits foot printing or develops a blue-gray color, it is very important that the turf be irrigated to avoid permanent wilting of leaves, and induction of summer dormancy (i.e. browning of the turf). During periods of extreme heat and drought stress dormant plants may die. Some professional managers use instruments that measure soil moisture levels, but most rely on the visual symptoms expressed by drought stressed turf, and frequent soil probing to determine moisture levels.
The lawn should be deeply watered as soon as it has been determined that turf is under drought stress. The duration and quantity of water applied should be sufficient to wet the soil to a depth of 4 to 6 inches. Deep watering encourages the roots of grass plants to grow deeper into soil. This indirectly enhances the drought resistance of turfgrasses by providing a greater reservoir of soil water for plants to draw upon.
The duration and quantity of water needed depends greatly upon soil texture and structure, and thickness of the thatch. In many housing developments, lawns are grown on sub-soils deposited during excavation that have higher clay content. This type of soil resists water penetration and the downward movement of water (percolation) through the soil. In many situations, it is extremely difficult to get water percolation to a 4 to 6 inch depth. Hence, on heavy, clay soils or where hard pans and dense layers of thatch exist, water must be applied slowly. If the rate of water applied exceeds the rate at which water infiltrates soil, water will run off and be wasted.
Sprinklers will have to be moved as water begins to run off onto sidewalks or the driveway. The sprinkler must be continually moved back and forth on rapid run-off areas at 30 to 90 minute intervals or as needed until water has penetrated to the desired depth. Installed underground systems will require zoning, turning one zone on, the turning it of and turning another zone on, back and forth until fully watered. The same principles and practices apply when irrigating turf on slopes or other rapid run-off areas. Probing the soil will enable an individual to determine soil moisture depth. This is best achieved using a probe that removes soil plugs. Probing with a screwdriver also may provide a good indication of depth of soil wetness.
Night irrigation is discouraged because it may encourage diseases, particularly when night temperatures exceed 68 F. Night irrigation, however, is a standard practice on golf courses and other large recreational turfs. Night irrigation is preferred in the aforementioned situations because it does not interfere with daily management operations or recreational activities, and it reduces the potential for soil compaction in turf areas with heavy traffic. The best time to irrigate is during the coolest part of the day when there is no wind. These conditions usually occur during early morning or late afternoon, and help conserve water by reducing evaporation. Conversely, mid-day irrigation during hot, sunny or windy days should be avoided because of increased evaporative losses of water. Furthermore, water that collects in low areas and inundates the turf for an extended period may cause scald injury during sunny, hot periods. Contrary to a popular misconception, scald will not occur if water is applied properly on hot days when turf is under heat and drought stress. Scald will only occur when turf has been inundated by water for an extended period of time on sunny and hot days.
Excessive or frequent irrigation can be just as detrimental to turf as inadequate watering. Turfgrass plants that are subjected to frequent irrigation become lush and succulent. These lush plant tissues are more susceptible to injury from heat, drought, and wear stress, and are more prone to disease injury. Frequent irrigation also discourages roots from growing deeper into soil thereby limiting the soil volume from which plants obtain water and nutrients. Excessively irrigated turf is more prone to invasion by moss and algae, and wet soils are more easily compacted by traffic. Soil compaction is common on homelawns, particularly those lawns where children play frequently. Turf growing in compacted areas will have restricted root systems, and lose vigor as a result of poor aeration. Because of the harmful effects of compaction, turf growing in these areas has a tendency to wilt more rapidly during dry periods, and normally thins-out allowing crabgrass, knotweed and other weeds to invade the area. Compaction can be minimized by not subjecting turf to traffic, and other heavy uses when soil is wet. Compaction can be alleviated by aeration, but only rototilling, adding soil amendments (if necessary), and reseeding or sodding the area will cure the problem.
Light and frequent irrigation also restricts rooting, reduces stress tolerance, enhances germination of weed seed (especially crabgrass, goosegrass and white clover seed), and encourages diseases. Many homeowners get into the habit of applying small amounts of water to their lawns on a frequent basis. These homeowners often return to a brown lawn after taking a one or two week vacation during hot, summer months. Grasses in these brown lawns are usually not dead, but in a state of dormancy. However, in extreme cases of drought coupled with a past history of light and frequent irrigations, large areas of the lawn may die. Homeowners who are likely to take vacations longer than one week in the summer are best advised to begin restrictive, deep and infrequent irrigation several weeks in advance of their vacation. Light and frequent, or excessive watering prior to leaving on vacation is likely to cause more severe injury than not applying any water at all. This is particularly true where Kentucky bluegrass or perennial ryegrass are the predominant turf species.
Adapted from "Irrigation and Water Conservation on Home Lawns", Agronomy Memo 88, from the University of Maryland
The best time to irrigate the lawn is when turf just begins to show signs of wilt. This of course is not always easy to determine. However, there are two prominent symptoms exhibited by turf as it begins to wilt: (1) foot printing, and (2) turf develops a blue-green or blue-gray leaf color. After walking across drought stressed turf, leaves of the walked upon plants remain depressed for several minutes, providing the "foot printing" effect. When turf exhibits foot printing or develops a blue-gray color, it is very important that the turf be irrigated to avoid permanent wilting of leaves, and induction of summer dormancy (i.e. browning of the turf). During periods of extreme heat and drought stress dormant plants may die. Some professional managers use instruments that measure soil moisture levels, but most rely on the visual symptoms expressed by drought stressed turf, and frequent soil probing to determine moisture levels.
The lawn should be deeply watered as soon as it has been determined that turf is under drought stress. The duration and quantity of water applied should be sufficient to wet the soil to a depth of 4 to 6 inches. Deep watering encourages the roots of grass plants to grow deeper into soil. This indirectly enhances the drought resistance of turfgrasses by providing a greater reservoir of soil water for plants to draw upon.
The duration and quantity of water needed depends greatly upon soil texture and structure, and thickness of the thatch. In many housing developments, lawns are grown on sub-soils deposited during excavation that have higher clay content. This type of soil resists water penetration and the downward movement of water (percolation) through the soil. In many situations, it is extremely difficult to get water percolation to a 4 to 6 inch depth. Hence, on heavy, clay soils or where hard pans and dense layers of thatch exist, water must be applied slowly. If the rate of water applied exceeds the rate at which water infiltrates soil, water will run off and be wasted.
Sprinklers will have to be moved as water begins to run off onto sidewalks or the driveway. The sprinkler must be continually moved back and forth on rapid run-off areas at 30 to 90 minute intervals or as needed until water has penetrated to the desired depth. Installed underground systems will require zoning, turning one zone on, the turning it of and turning another zone on, back and forth until fully watered. The same principles and practices apply when irrigating turf on slopes or other rapid run-off areas. Probing the soil will enable an individual to determine soil moisture depth. This is best achieved using a probe that removes soil plugs. Probing with a screwdriver also may provide a good indication of depth of soil wetness.
Night irrigation is discouraged because it may encourage diseases, particularly when night temperatures exceed 68 F. Night irrigation, however, is a standard practice on golf courses and other large recreational turfs. Night irrigation is preferred in the aforementioned situations because it does not interfere with daily management operations or recreational activities, and it reduces the potential for soil compaction in turf areas with heavy traffic. The best time to irrigate is during the coolest part of the day when there is no wind. These conditions usually occur during early morning or late afternoon, and help conserve water by reducing evaporation. Conversely, mid-day irrigation during hot, sunny or windy days should be avoided because of increased evaporative losses of water. Furthermore, water that collects in low areas and inundates the turf for an extended period may cause scald injury during sunny, hot periods. Contrary to a popular misconception, scald will not occur if water is applied properly on hot days when turf is under heat and drought stress. Scald will only occur when turf has been inundated by water for an extended period of time on sunny and hot days.
Excessive or frequent irrigation can be just as detrimental to turf as inadequate watering. Turfgrass plants that are subjected to frequent irrigation become lush and succulent. These lush plant tissues are more susceptible to injury from heat, drought, and wear stress, and are more prone to disease injury. Frequent irrigation also discourages roots from growing deeper into soil thereby limiting the soil volume from which plants obtain water and nutrients. Excessively irrigated turf is more prone to invasion by moss and algae, and wet soils are more easily compacted by traffic. Soil compaction is common on homelawns, particularly those lawns where children play frequently. Turf growing in compacted areas will have restricted root systems, and lose vigor as a result of poor aeration. Because of the harmful effects of compaction, turf growing in these areas has a tendency to wilt more rapidly during dry periods, and normally thins-out allowing crabgrass, knotweed and other weeds to invade the area. Compaction can be minimized by not subjecting turf to traffic, and other heavy uses when soil is wet. Compaction can be alleviated by aeration, but only rototilling, adding soil amendments (if necessary), and reseeding or sodding the area will cure the problem.
Light and frequent irrigation also restricts rooting, reduces stress tolerance, enhances germination of weed seed (especially crabgrass, goosegrass and white clover seed), and encourages diseases. Many homeowners get into the habit of applying small amounts of water to their lawns on a frequent basis. These homeowners often return to a brown lawn after taking a one or two week vacation during hot, summer months. Grasses in these brown lawns are usually not dead, but in a state of dormancy. However, in extreme cases of drought coupled with a past history of light and frequent irrigations, large areas of the lawn may die. Homeowners who are likely to take vacations longer than one week in the summer are best advised to begin restrictive, deep and infrequent irrigation several weeks in advance of their vacation. Light and frequent, or excessive watering prior to leaving on vacation is likely to cause more severe injury than not applying any water at all. This is particularly true where Kentucky bluegrass or perennial ryegrass are the predominant turf species.
Adapted from "Irrigation and Water Conservation on Home Lawns", Agronomy Memo 88, from the University of Maryland
Sunday, May 4, 2008
Landscape - Mugwort Control in Landscape Beds
The following is information on the control of Mugwort, a problem weed in landscape beds.
Mugwort (Artemesia vulgaris), also know as wild chrysanthemum, is a perennial weed of landscape plantings that is difficult to control due to its ability to spread by underground rhizomes. It is in the Artemesia genus of the Aster family which contains numerous herb and ornamentals species. At a glance, leaves are similar to appearance as chrysanthemum. They are 2-4 inches long, 1-3 inches wide, simple, alternate, deeply lobed, and have a distinctive aroma. Leaf undersides are covered with soft, white to gray hairs. Mugwort has vigorous underground rhizomes and is commonly introduced as a weed with nursery stock.
Control with hand weeding requires removal of all the underground rhizomes, which is often difficult, if not impossible, in landscape beds. Spring application (directed) of non-selective herbicides such as glyphosate (Roundup Pro and several others) will provide some suppression but not full control. Better results have been obtained with two applications of glyphosate applied several weeks apart in late summer and early fall. Dichlobenil (Casoron) granular herbicide, winter applied, has given good mugwort control in beds with woody plants such as junipers; however, Casoron is not labeled for all species and injury can occur on newly planted trees and shrubs. Research has also been done on the use of Lontrel (clopyralid) for mugwort control, but results have often been disappointing. One fit for Lontrel may be suppression of mugwort in ornamental grasses where it can be used as an over-the-top application
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Mugwort (Artemesia vulgaris), also know as wild chrysanthemum, is a perennial weed of landscape plantings that is difficult to control due to its ability to spread by underground rhizomes. It is in the Artemesia genus of the Aster family which contains numerous herb and ornamentals species. At a glance, leaves are similar to appearance as chrysanthemum. They are 2-4 inches long, 1-3 inches wide, simple, alternate, deeply lobed, and have a distinctive aroma. Leaf undersides are covered with soft, white to gray hairs. Mugwort has vigorous underground rhizomes and is commonly introduced as a weed with nursery stock.
Control with hand weeding requires removal of all the underground rhizomes, which is often difficult, if not impossible, in landscape beds. Spring application (directed) of non-selective herbicides such as glyphosate (Roundup Pro and several others) will provide some suppression but not full control. Better results have been obtained with two applications of glyphosate applied several weeks apart in late summer and early fall. Dichlobenil (Casoron) granular herbicide, winter applied, has given good mugwort control in beds with woody plants such as junipers; however, Casoron is not labeled for all species and injury can occur on newly planted trees and shrubs. Research has also been done on the use of Lontrel (clopyralid) for mugwort control, but results have often been disappointing. One fit for Lontrel may be suppression of mugwort in ornamental grasses where it can be used as an over-the-top application
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Landscape - Herbicide Damage to Trees
Two common herbicides, 2,4-D and dicamba are used extensively for control of broadleaf weeds in turf and are commonly included in broadleaf herbicide formulations. Unfortunately, they can also damage nearby trees and shrubs if not used correctly. The following is information on these two herbicides and the damage they can cause.
2,4-D is one of the most common herbicides used in the home landscape and is often associated with plant injury. The most common symptoms are a twisting of the petiole which results in the leaf turning upside down. There are sucking insects whose feeding activity will also result in a leaf to curl or twist but their feeding will not cause the petiole to twist. The lowest residue that will produce symptoms in susceptible tree species is 0.02 ppm. The species that are the most sensitive to 2,4-D injury include boxelder, birch, hackberry, green ash, honeylocust, walnut, poplar, littleleaf linden and elm.
Dicamba is another frequent herbicide associated with plant injury. Dicamba will produce similar symptoms to 2,4-D at low concentrations but in addition to the leaf curling or twisting there is often a proliferation of short shoots. Oftentimes there will be a swelling of the shoot. Dicamba injury frequently occurs from root uptake as applicators ignore the precaution that this herbicide should not be applied within the dripline of trees. The dripline is considered to be the edge of the tree’s canopy, the furthest extent of the roots, but the root system can extend out a distance equal to the tree’s height. Since the concern about applications within this zone is possible uptake by the roots it is best to restrict applications to a distance further than the height of the tree. The lowest residue that will produce symptoms in susceptible tree species is 0.03 ppm. Tree species that are most sensitive to dicamba include: boxelder, birch, catalpa, honeylocust, apple (and crabapple), spruce, poplar, oaks, littleleaf linden and lilacs.
Reprinted in part from the January 2008 Pest Update from South Dakota State University
2,4-D is one of the most common herbicides used in the home landscape and is often associated with plant injury. The most common symptoms are a twisting of the petiole which results in the leaf turning upside down. There are sucking insects whose feeding activity will also result in a leaf to curl or twist but their feeding will not cause the petiole to twist. The lowest residue that will produce symptoms in susceptible tree species is 0.02 ppm. The species that are the most sensitive to 2,4-D injury include boxelder, birch, hackberry, green ash, honeylocust, walnut, poplar, littleleaf linden and elm.
Dicamba is another frequent herbicide associated with plant injury. Dicamba will produce similar symptoms to 2,4-D at low concentrations but in addition to the leaf curling or twisting there is often a proliferation of short shoots. Oftentimes there will be a swelling of the shoot. Dicamba injury frequently occurs from root uptake as applicators ignore the precaution that this herbicide should not be applied within the dripline of trees. The dripline is considered to be the edge of the tree’s canopy, the furthest extent of the roots, but the root system can extend out a distance equal to the tree’s height. Since the concern about applications within this zone is possible uptake by the roots it is best to restrict applications to a distance further than the height of the tree. The lowest residue that will produce symptoms in susceptible tree species is 0.03 ppm. Tree species that are most sensitive to dicamba include: boxelder, birch, catalpa, honeylocust, apple (and crabapple), spruce, poplar, oaks, littleleaf linden and lilacs.
Reprinted in part from the January 2008 Pest Update from South Dakota State University
Saturday, May 3, 2008
Turf - Black Medic
Black medic is now flowering in turf areas. The following is information on this weed.
Black Medic (Medicago lupulina) is a yellowed flowered leguminous weed of turf and minimally maintained areas. It is related to alfalfa and has compound leaves that are arranged alternately with three, wedge to oval shaped leaflets. The center leaflet is stalked and the side leaflets occur close to the stem. The yellow flower is ball shaped but is smaller than white clover. Black Medic commonly occurs as a summer annual but can survive the winter as a tender perennial. It is common in compacted soils such as high traffic areas near sidewalks and is more prevalent in sites that receive limited nitrogen fertilization.
Many broadleaf post emergence herbicides have activity against Black Medic in turf; however 2,4-D will not provide control. Use of a product with triclopyr, dicamba, fluroxypyr, or clopyralid as an active ingredient is recommended. Drive (quinclorac), is effective against Black Medic and is also a good crabgrass herbicide. Spring applications made before the end of May are most effective. Black medic can be difficult to kill when under water stress and multiple applications may be needed in summer.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Black Medic (Medicago lupulina) is a yellowed flowered leguminous weed of turf and minimally maintained areas. It is related to alfalfa and has compound leaves that are arranged alternately with three, wedge to oval shaped leaflets. The center leaflet is stalked and the side leaflets occur close to the stem. The yellow flower is ball shaped but is smaller than white clover. Black Medic commonly occurs as a summer annual but can survive the winter as a tender perennial. It is common in compacted soils such as high traffic areas near sidewalks and is more prevalent in sites that receive limited nitrogen fertilization.
Many broadleaf post emergence herbicides have activity against Black Medic in turf; however 2,4-D will not provide control. Use of a product with triclopyr, dicamba, fluroxypyr, or clopyralid as an active ingredient is recommended. Drive (quinclorac), is effective against Black Medic and is also a good crabgrass herbicide. Spring applications made before the end of May are most effective. Black medic can be difficult to kill when under water stress and multiple applications may be needed in summer.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Greenhouse - Botrytis Control
Botrytis is the most common disease of flowering greenhouse plants. The following is an article on this disease and its control from the New England Greenhouse Update newsletter.
Closely spaced plants, overcast cloudy weather, and flower drop from overhead hanging baskets have encouraged Botrytis Blight on New Guinea Impatiens, Garden Impatiens, geraniums and many other susceptible ornamental crops. Botrytis infections often begin when spent flowers drop from hanging baskets above susceptible crops. The flowers provide a source of food for the developing fungus. Tender flowers, leaves, and stems are often infected.
The familiar fuzzy grayish-brown spores are easily spread on air currents and by water splash. Botrytis is best managed by combining proper sanitation practices with environmental controls.
Promptly remove infected plants, keep weeds under control, and place cull piles as far away from your greenhouse as possible. Keep garbage cans covered so spores are not released into the greenhouse via air currents. Some growers place netting below hanging baskets to catch the spent flowers.
Water early in the day, so foliage can dry rapidly. As plants are sold, provide more space to your existing crops to reduce humidity levels within your crops. Reduce humidity by heating and venting several times in the evening and in the morning.
Apply preventative fungicides before cleaning up plants so spores are not released as workers handle plants. On ornamental crops, a number of fungicides are labeled for use against Botrytis. The New England Recommendation Guide lists the following fungicides under Botrytis Management: trifloxystrobin(MOA Group 11) (Compass), fenhazamid (MOA Group 17)(Decree), iprodione (MOA Group 2) (26GT), chlorothalonil (MOA Group 5)(Daconil Weather Stik) or (Daconil Ultrex), mancozeb (MOA Group 3) (Dithane Rainshield WF), azoxystrobin (MOA Group 11) (Heritage), fludioxonil (MOA Group 12) (Medallion), Protect T/O (MOA Group 3), triflumizole (MOA Group 3)(Terraguard) or iprodione (MOA Group 2)(Sextant).
(Before treatment, read labels carefully to see if there is potential damage to flowers and other safety precautions to avoid potential phytotoxicity!)
Reprinted from the May 2006 edition of the New England Greenhouse Update.
Closely spaced plants, overcast cloudy weather, and flower drop from overhead hanging baskets have encouraged Botrytis Blight on New Guinea Impatiens, Garden Impatiens, geraniums and many other susceptible ornamental crops. Botrytis infections often begin when spent flowers drop from hanging baskets above susceptible crops. The flowers provide a source of food for the developing fungus. Tender flowers, leaves, and stems are often infected.
The familiar fuzzy grayish-brown spores are easily spread on air currents and by water splash. Botrytis is best managed by combining proper sanitation practices with environmental controls.
Promptly remove infected plants, keep weeds under control, and place cull piles as far away from your greenhouse as possible. Keep garbage cans covered so spores are not released into the greenhouse via air currents. Some growers place netting below hanging baskets to catch the spent flowers.
Water early in the day, so foliage can dry rapidly. As plants are sold, provide more space to your existing crops to reduce humidity levels within your crops. Reduce humidity by heating and venting several times in the evening and in the morning.
Apply preventative fungicides before cleaning up plants so spores are not released as workers handle plants. On ornamental crops, a number of fungicides are labeled for use against Botrytis. The New England Recommendation Guide lists the following fungicides under Botrytis Management: trifloxystrobin(MOA Group 11) (Compass), fenhazamid (MOA Group 17)(Decree), iprodione (MOA Group 2) (26GT), chlorothalonil (MOA Group 5)(Daconil Weather Stik) or (Daconil Ultrex), mancozeb (MOA Group 3) (Dithane Rainshield WF), azoxystrobin (MOA Group 11) (Heritage), fludioxonil (MOA Group 12) (Medallion), Protect T/O (MOA Group 3), triflumizole (MOA Group 3)(Terraguard) or iprodione (MOA Group 2)(Sextant).
(Before treatment, read labels carefully to see if there is potential damage to flowers and other safety precautions to avoid potential phytotoxicity!)
Reprinted from the May 2006 edition of the New England Greenhouse Update.
Friday, May 2, 2008
Landscape and Turf - Weed Control in Landscape Beds and More
The following is information from Dr. Steve Hart, extension weed specialist from Rutgers, on weed control options in landscape beds and turf as well as newer herbicide products coming to market.
In landscape beds, it is important to place herbicides in the proper location with respect to mulch. Ronstar, Goal, Rout and OH2 require light to be effective and must be placed on top of mulch. Devrinol, Treflan and Snapshot have the potential to volatilize, therefore must be placed below mulch. Gallery, Pennant and Surflan can go under or on top of mulch.
Some landscapers like to use landscape fabric under mulch to reduce weeds in landscape beds. Fabric can work in shrub beds, but is not effective for annuals and perennials, when too many holes are punched in the fabric. Spun-bonded fabric is better for weed control than woven fabric, but it has limited friction and will not hold mulch on a slope.
Snapshot, Rout and OH2 are great on annual grasses (They also are effective on a wide range of annual broadleaf weeds) and should be applied as a preemergent in early spring and late summer. Ronstar and Casoran are other preemergent products. Casoran is especially useful for controlling really tough perennial weeds, like Canada thistle and mugwort in an existing groundcover, like blue rug juniper. But, Casoran is tricky to use. Only apply Casoran when it is cold because it is highly volatile. The ideal time to apply is in February, when there is a layer of snow on the ground. As the snow melts, it carries the herbicide into the soil.
When applying a granular herbicide, don’t let the granules collect leaf whorls. Some landscapers effectively use leaf blowers to blow granules off plants and onto the soil where they belong. Allow soil to settle around newly planted perennials before applying herbicide. Air pockets become flow channels and you will loose the herbicide from the zone where it provides control. Pennant is a good preemergent to use for yellow nutsedge control.
Post emergent products for landscape beds include Sedgehammer (new name for Manage), Basagran, and Lontrel for broadleaf control; Acclaim, Fusilade, Vantage and Envoy for grass control; and Roundup and Finale for non-selective control. Basagran is good for Canada thistle and yellow nutsedge. Fusilade is the best grass herbicide to use for bermudagrass in beds. The grass herbicides can generally be used over the top when beds contain broadleaved plants.
Many suppliers now carry a glyphosate product. Fortunately, the formulations are all 41% active ingredient (except Glypro). All manufacturers have also followed the convention of calling their product “pro” or “plus” if it contains a surfactant. When people complain about poor control with glyphosate, it is usually a timing issue. Spraying glyphosate in April on tough weeds will kill topgrowth but since there is very little translocation to the roots at this time of year, the plant is not completely killed. If you are managing difficult weeds like mugwort, the best thing to do is to keep the mugwort in check until about July 15 (but you won’t be able to kill it). Then allow it to grow to about 6 inches. Control with an application of glyphosate on August 15 (with a second application in September).
Steve Hart’s recommendation for control of bermuda grass in lawns is to apply 3-4% Round Up Pro mixed with a post emergence grass herbicide. Then wait four weeks to see what comes back. Retreat (maybe as many as two-three times) and reseed in August.
Yellow nutsedge is another difficult to control weed. Glyphosate usually just burns the tops without killing roots. The product formerly called Manage, is now Sedgehammer, and can be used by professionals for excellent nutsedge control. You need a significant amount of foliage present to get good control. Sedgehammer failures are usually due to one of the following reasons: lack of high quality non-ionic surfactant – you must add a surfactant when using Sedgehammer for nutsedge control; degradation in solution – Sedgehammer degrades in solution with a complete breakdown in 5-7 days. That means if you mix a tank, don’t use it all, save it for 5 days and try to use then, it won’t work.
Mugwort, another difficult weed, can be controlled with glyphosate in late fall. Lontrel and Casoran (applied during winter) can also control mugwort.
Phragmites can be controlled with Rodeo (the aquatic formulation of glyphosate) but you need to use a high rate and apply in the fall. Renovate has an aquatic label, contains triclopyr and has good activity on phragmites if applied in late June.
Glyphosate will control poison ivy, but only with a fall application. Use a rubber glove, covered by a cotton glove and brush a 10% glyphosate solution on the plant.
Some new products for weed control include:
mesotrione – This product will replace Tupersan. It provides a longer window for crabgrass control by providing early postermergent activity. Unfortunately, it turns foliage white for about 2 weeks before it kills the weed. It will control creeping bentgrass and nimblewill in cool season turf and has some activity on zoysia and bermudagrass in cool season turf. For commercial nursery production, it may have a use as a preemergent to control yellow nutsedge.
Mesotrione is currently labeled as Tenacity but is only registered on golf courses and sod farms.
Dismiss – This is a new nutsedge material. It controls other sedges as well and has rapid activity.
Quicksilver – This product provides more rapid injury and will control moss and Star-of- Bethlehem (at high rates).
Spotlight – This new formulation removed clopyralid since clopyralid can’t be used on material destined for compost (i.e. lawn clippings).
Information compiled by Susan Barton, Extension Horticulture Specialist, UD
In landscape beds, it is important to place herbicides in the proper location with respect to mulch. Ronstar, Goal, Rout and OH2 require light to be effective and must be placed on top of mulch. Devrinol, Treflan and Snapshot have the potential to volatilize, therefore must be placed below mulch. Gallery, Pennant and Surflan can go under or on top of mulch.
Some landscapers like to use landscape fabric under mulch to reduce weeds in landscape beds. Fabric can work in shrub beds, but is not effective for annuals and perennials, when too many holes are punched in the fabric. Spun-bonded fabric is better for weed control than woven fabric, but it has limited friction and will not hold mulch on a slope.
Snapshot, Rout and OH2 are great on annual grasses (They also are effective on a wide range of annual broadleaf weeds) and should be applied as a preemergent in early spring and late summer. Ronstar and Casoran are other preemergent products. Casoran is especially useful for controlling really tough perennial weeds, like Canada thistle and mugwort in an existing groundcover, like blue rug juniper. But, Casoran is tricky to use. Only apply Casoran when it is cold because it is highly volatile. The ideal time to apply is in February, when there is a layer of snow on the ground. As the snow melts, it carries the herbicide into the soil.
When applying a granular herbicide, don’t let the granules collect leaf whorls. Some landscapers effectively use leaf blowers to blow granules off plants and onto the soil where they belong. Allow soil to settle around newly planted perennials before applying herbicide. Air pockets become flow channels and you will loose the herbicide from the zone where it provides control. Pennant is a good preemergent to use for yellow nutsedge control.
Post emergent products for landscape beds include Sedgehammer (new name for Manage), Basagran, and Lontrel for broadleaf control; Acclaim, Fusilade, Vantage and Envoy for grass control; and Roundup and Finale for non-selective control. Basagran is good for Canada thistle and yellow nutsedge. Fusilade is the best grass herbicide to use for bermudagrass in beds. The grass herbicides can generally be used over the top when beds contain broadleaved plants.
Many suppliers now carry a glyphosate product. Fortunately, the formulations are all 41% active ingredient (except Glypro). All manufacturers have also followed the convention of calling their product “pro” or “plus” if it contains a surfactant. When people complain about poor control with glyphosate, it is usually a timing issue. Spraying glyphosate in April on tough weeds will kill topgrowth but since there is very little translocation to the roots at this time of year, the plant is not completely killed. If you are managing difficult weeds like mugwort, the best thing to do is to keep the mugwort in check until about July 15 (but you won’t be able to kill it). Then allow it to grow to about 6 inches. Control with an application of glyphosate on August 15 (with a second application in September).
Steve Hart’s recommendation for control of bermuda grass in lawns is to apply 3-4% Round Up Pro mixed with a post emergence grass herbicide. Then wait four weeks to see what comes back. Retreat (maybe as many as two-three times) and reseed in August.
Yellow nutsedge is another difficult to control weed. Glyphosate usually just burns the tops without killing roots. The product formerly called Manage, is now Sedgehammer, and can be used by professionals for excellent nutsedge control. You need a significant amount of foliage present to get good control. Sedgehammer failures are usually due to one of the following reasons: lack of high quality non-ionic surfactant – you must add a surfactant when using Sedgehammer for nutsedge control; degradation in solution – Sedgehammer degrades in solution with a complete breakdown in 5-7 days. That means if you mix a tank, don’t use it all, save it for 5 days and try to use then, it won’t work.
Mugwort, another difficult weed, can be controlled with glyphosate in late fall. Lontrel and Casoran (applied during winter) can also control mugwort.
Phragmites can be controlled with Rodeo (the aquatic formulation of glyphosate) but you need to use a high rate and apply in the fall. Renovate has an aquatic label, contains triclopyr and has good activity on phragmites if applied in late June.
Glyphosate will control poison ivy, but only with a fall application. Use a rubber glove, covered by a cotton glove and brush a 10% glyphosate solution on the plant.
Some new products for weed control include:
mesotrione – This product will replace Tupersan. It provides a longer window for crabgrass control by providing early postermergent activity. Unfortunately, it turns foliage white for about 2 weeks before it kills the weed. It will control creeping bentgrass and nimblewill in cool season turf and has some activity on zoysia and bermudagrass in cool season turf. For commercial nursery production, it may have a use as a preemergent to control yellow nutsedge.
Mesotrione is currently labeled as Tenacity but is only registered on golf courses and sod farms.
Dismiss – This is a new nutsedge material. It controls other sedges as well and has rapid activity.
Quicksilver – This product provides more rapid injury and will control moss and Star-of- Bethlehem (at high rates).
Spotlight – This new formulation removed clopyralid since clopyralid can’t be used on material destined for compost (i.e. lawn clippings).
Information compiled by Susan Barton, Extension Horticulture Specialist, UD
Turf - Perennial Grass Weeds in Cool Season Turf
Undesirable perennial grasses in turf-type tall fescue include coarse pasture varieties of tall fescue such as KY31, orchardgrass (Dactylis glomerata), rough bluegrass (Poa trivialis), and creeping bentgrass (Agrostis palustris). The following is an article on the subject.
Pasture types of tall fescue will be coarser, more bunching, and taller, with wider leaves than turf varieties. Orchardgrass is a coarse pasture grass. It can be distinguished by its flattened sheaths, blue-green color, and leaf blades 1/4 to 1/2 inch wide. It grows in bunches and is upright. Rough bluegrass is a perennial bluegrass that spreads by stolons and seed. Leaves are light green, 1/8 inch wide, with the typical boat-shaped tip of bluegrasses. The seedhead is a panicle similar to other bluegrass species. It is larger that annual bluegrass, growing in patches, and can be differentiated by the presence of stolons. Creeping bentgass has blue-green leaves that are flat, 1/8 inch wide, with pointed tips and prominent veins. Seed heads are purplish, compressed panicles occurring in mid spring. It spreads by vigorous stolons and forms dense patches of fine-textured grass. These perennial grasses are introduced from contaminated seed sources, plants in seed at adjacent sites, or seed carried by mowers, workers, and equipment.
Unfortunately, there currently are no registered postemergence selective herbicides for the control of these perennial grass weeds in turf-type tall fescue for residential lawns, recreation areas, or commercial turf areas. Small patches of bunch grasses such as pasture-type tall fescue and orchardgrass should be dug out with a shovel and then the holes filled and reseeded. For larger infested areas, spot application of non-selective glyphosate herbicide is recommended for control followed by reseeding. Control of the spreading grasses, rough bluegrass and creeping bentgrass, is accomplished by two or more sequential applications of glyphosate followed by reseeding after full control. This may take several months. Applications should be made to young, fully green, actively growing plants that are not under stress. For severely infested turf, complete renovation of the whole area with multiple applications of glyphosate followed by reseeding may be required.
A new herbicide was be registered in 2008 for use in turf called Tenacity. It contains mesotrione as the active ingredient and will be an excellent selective control for creeping bentgrass in turf-type tall fescue. However, it is only labelled for golf courses and sod farms. If the label is expanded, we will inform you.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County.
Pasture types of tall fescue will be coarser, more bunching, and taller, with wider leaves than turf varieties. Orchardgrass is a coarse pasture grass. It can be distinguished by its flattened sheaths, blue-green color, and leaf blades 1/4 to 1/2 inch wide. It grows in bunches and is upright. Rough bluegrass is a perennial bluegrass that spreads by stolons and seed. Leaves are light green, 1/8 inch wide, with the typical boat-shaped tip of bluegrasses. The seedhead is a panicle similar to other bluegrass species. It is larger that annual bluegrass, growing in patches, and can be differentiated by the presence of stolons. Creeping bentgass has blue-green leaves that are flat, 1/8 inch wide, with pointed tips and prominent veins. Seed heads are purplish, compressed panicles occurring in mid spring. It spreads by vigorous stolons and forms dense patches of fine-textured grass. These perennial grasses are introduced from contaminated seed sources, plants in seed at adjacent sites, or seed carried by mowers, workers, and equipment.
Unfortunately, there currently are no registered postemergence selective herbicides for the control of these perennial grass weeds in turf-type tall fescue for residential lawns, recreation areas, or commercial turf areas. Small patches of bunch grasses such as pasture-type tall fescue and orchardgrass should be dug out with a shovel and then the holes filled and reseeded. For larger infested areas, spot application of non-selective glyphosate herbicide is recommended for control followed by reseeding. Control of the spreading grasses, rough bluegrass and creeping bentgrass, is accomplished by two or more sequential applications of glyphosate followed by reseeding after full control. This may take several months. Applications should be made to young, fully green, actively growing plants that are not under stress. For severely infested turf, complete renovation of the whole area with multiple applications of glyphosate followed by reseeding may be required.
A new herbicide was be registered in 2008 for use in turf called Tenacity. It contains mesotrione as the active ingredient and will be an excellent selective control for creeping bentgrass in turf-type tall fescue. However, it is only labelled for golf courses and sod farms. If the label is expanded, we will inform you.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County.
Thursday, May 1, 2008
Landscape - Carpenter Bees
Large, black bees have begun hovering around eaves, decks, and wood siding of clients' homes and outbuildings. These are probably carpenter bees searching for mates and nesting sites. Carpenter bees cause cosmetic and structural damage to wood. They can also be intimidating and have the potential to inflict painful stings.
The Problem- Carpenter bees are similar in appearance to bumblebees, but have different nesting habits. Bumblebees generally nest in the ground, whereas carpenter bees tunnel into wood to lay their eggs. Bare, unpainted, weathered softwoods are preferred especially redwood, cedar, cypress and pine. Painted or pressure-treated wood is much less susceptible to attack. Common nesting sites include eaves, fascia boards, siding, wooden shake roofs, decks and outdoor furniture.
Carpenter bees overwinter as adults in old nest tunnels. After mating, the fertilized females excavate galleries in wood, laying their eggs within a series of small cells. The cells are provisioned with a ball of pollen on which the larvae feed, emerging as adults in late summer. The entrance hole and tunnels are perfectly round and about the diameter of your finger. Coarse sawdust, the color of fresh cut wood, is often seen beneath the entry hole, and burrowing sounds may be heard within the wood. Female carpenter bees may excavate new tunnels or enlarge and reuse old ones. Serious damage can result when the same piece of wood is worked year after year.
Males are often aggressive, hovering in front of people who are around the nests. The males are harmless, however, since they lack stingers. Female carpenter bees can inflict a painful sting, but seldom will unless handled or molested.
The Solution- The best time to control carpenter bees is before the tunnels are fully excavated. Sprays of Sevin or a pyrethroid can be applied directly into nest openings, or broadcast sprayed as a deterrent onto wood surfaces attracting large numbers of bees. The broadcast spray approach is often warranted when carpenter bees are riddling siding on a barn, wood shake roofs, decking or similar large expanses of wood. Broadcast treatment is best accomplished with a pump up or hose end sprayer, targeting wood surfaces that are most favored by the bees (fascia boards, joist ends of redwood decks, etc.). Residual effectiveness of such applications is only about 1-3 weeks, so the treatment may need to be repeated. Individual holes which are already present also can be treated with a wasp and hornet aerosol spray or insecticide dust directed into the nest opening. Although carpenter bees are less aggressive than wasps, female bees provisioning their nests will sting. Consider treating at dusk or while wearing protective clothing.
Leave the holes open for a few days after treatment to allow the bees to contact and distribute the insecticide throughout the nest tunnel. Then plug the entrance hole with a piece of wooden dowel coated with carpenter's glue, wood putty, or other suitable sealant. This will protect against future bees using the old tunnels, as well as moisture intrusion and wood decay.
Carpenter bees normally will not tunnel into painted wood. Therefore a more permanent solution is to paint unfinished wood surfaces, especially those with a history of being attacked. Wood stains and preservatives are less reliable than painting, but may provide some degree of repellence versus bare wood. To further discourage nesting, garages and outbuildings should be kept closed when carpenter bees are actively searching for nesting sites. The annoying flying and nesting habit usually subsides by the end of May.
Reprinted from "CARPENTER BEES ARE FLYING" By Mike Potter in the April 14, 2008 edition of the Kentucky Pest News.
The Problem- Carpenter bees are similar in appearance to bumblebees, but have different nesting habits. Bumblebees generally nest in the ground, whereas carpenter bees tunnel into wood to lay their eggs. Bare, unpainted, weathered softwoods are preferred especially redwood, cedar, cypress and pine. Painted or pressure-treated wood is much less susceptible to attack. Common nesting sites include eaves, fascia boards, siding, wooden shake roofs, decks and outdoor furniture.
Carpenter bees overwinter as adults in old nest tunnels. After mating, the fertilized females excavate galleries in wood, laying their eggs within a series of small cells. The cells are provisioned with a ball of pollen on which the larvae feed, emerging as adults in late summer. The entrance hole and tunnels are perfectly round and about the diameter of your finger. Coarse sawdust, the color of fresh cut wood, is often seen beneath the entry hole, and burrowing sounds may be heard within the wood. Female carpenter bees may excavate new tunnels or enlarge and reuse old ones. Serious damage can result when the same piece of wood is worked year after year.
Males are often aggressive, hovering in front of people who are around the nests. The males are harmless, however, since they lack stingers. Female carpenter bees can inflict a painful sting, but seldom will unless handled or molested.
The Solution- The best time to control carpenter bees is before the tunnels are fully excavated. Sprays of Sevin or a pyrethroid can be applied directly into nest openings, or broadcast sprayed as a deterrent onto wood surfaces attracting large numbers of bees. The broadcast spray approach is often warranted when carpenter bees are riddling siding on a barn, wood shake roofs, decking or similar large expanses of wood. Broadcast treatment is best accomplished with a pump up or hose end sprayer, targeting wood surfaces that are most favored by the bees (fascia boards, joist ends of redwood decks, etc.). Residual effectiveness of such applications is only about 1-3 weeks, so the treatment may need to be repeated. Individual holes which are already present also can be treated with a wasp and hornet aerosol spray or insecticide dust directed into the nest opening. Although carpenter bees are less aggressive than wasps, female bees provisioning their nests will sting. Consider treating at dusk or while wearing protective clothing.
Leave the holes open for a few days after treatment to allow the bees to contact and distribute the insecticide throughout the nest tunnel. Then plug the entrance hole with a piece of wooden dowel coated with carpenter's glue, wood putty, or other suitable sealant. This will protect against future bees using the old tunnels, as well as moisture intrusion and wood decay.
Carpenter bees normally will not tunnel into painted wood. Therefore a more permanent solution is to paint unfinished wood surfaces, especially those with a history of being attacked. Wood stains and preservatives are less reliable than painting, but may provide some degree of repellence versus bare wood. To further discourage nesting, garages and outbuildings should be kept closed when carpenter bees are actively searching for nesting sites. The annoying flying and nesting habit usually subsides by the end of May.
Reprinted from "CARPENTER BEES ARE FLYING" By Mike Potter in the April 14, 2008 edition of the Kentucky Pest News.
Landscape and Nursery - Fusiform Rust of Pine
The following is information on a rust disease we are currently seeing in pines.
Fusiform rust of pine is caused by the fungus Cronartium fusiforme, and is widely distributed in southern states up to Maryland and Delaware. Infections result in swollen, spindle-shaped (or oval) galls on branches of the pines with orange spore production in the spring. Loblolly and slash pine are both very susceptible. The disease may kill trees less than ten years of age, and cause deformed branches on older trees. This fungus requires an alternate host, oak, and there are usually oaks in the vicinity of infected pines. Black and red oaks are the most susceptible and symptoms occur only on the leaves. The best control is the use of resistant varieties. Pruning of infected branches or rouging out of infected pines will reduce infection. Some years may be worse than others for infection and sporulation. Do not fertilize infected trees and stimulate excess growth.
Nancy Gregory, Extension Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware
Fusiform rust of pine is caused by the fungus Cronartium fusiforme, and is widely distributed in southern states up to Maryland and Delaware. Infections result in swollen, spindle-shaped (or oval) galls on branches of the pines with orange spore production in the spring. Loblolly and slash pine are both very susceptible. The disease may kill trees less than ten years of age, and cause deformed branches on older trees. This fungus requires an alternate host, oak, and there are usually oaks in the vicinity of infected pines. Black and red oaks are the most susceptible and symptoms occur only on the leaves. The best control is the use of resistant varieties. Pruning of infected branches or rouging out of infected pines will reduce infection. Some years may be worse than others for infection and sporulation. Do not fertilize infected trees and stimulate excess growth.
Nancy Gregory, Extension Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware
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