The following is some information on weed control in container nurseries from a presentation by Dr. Stephen Hart at Rutgers.
The weeds that are found in container nurseries are different than in field grown nurseries. Major weed species are bittercress, Oxalis, and common groundsel. These are normally winter annuals but due to the use of irrigation and covered houses, the growth cycle is year round. These and other weeds of containers can have multiple generations per year. Bittercress and oxalis have forceful dehiscence, that is the pods expel the seeds when mature. Grounsel produces fluffy seeds that are easily wind borne.
The first key to weed control in containers is sanitation. You should start out with no seed bank. Because containers are placed on landscape fabric with or without gravel, there should be complete vegetation control. The goal is to prevent the occurrence of weed seeds in containers. Weeds can come in on infested liners, can blow in from surrounding areas, or can come from media that is infested with seed. All media and containers should be stored in a manner to avoid any contamination with weed seeds. Do not reuse containers unless thoroughly cleaned and disinfested. Cover media piles and do not let any stray weeds grow on media piles. Use non-selective herbicide spot sprays to kill any weeds that come up in surrounding nursery areas - roads, between blocks, alleyways, along the sides of overwintering houses, around potting facilities, and other similar areas.
For container weed control, timing of herbicide applications is critical. Scout containers and eliminate any infested with perennial weeds. Do no attempt to save any containers that have weeds such as nutsedge or mugwort. Before applying herbicides, hand weed any annuals that you find. Irrigate prior to herbicide application to settle the soil. Apply granular herbicides after foliage had dried. Irrigate immediately after herbicides have been applied to container plants to remove any herbicides that is stuck on foliage.
Herbicides labelled for containers include pendimethalin (Pendulum), prodiamine (Factor), trifluralin (Treflan), oryazalin (Surflan), isoxaben (Gallery), oxadiozon (Ronstar), and flumioxazon (Broadstar). Combination products for use in containers include Snapshot (isoxaben plus trifluralin), OH2 (oxyfluorfen + pendimethalin), Rout (oxyfluorfen + oryazalin), and Showcase (isoxaben + oxyfluorfen). Most are in granular formulation.
Herbicides such as Rout, OH2, Showcase and Ronstar are very effective for those container plants they are labelled on. The also will provide some control of existing liverworts and some emerged seedling broadleaf weeds. Unfortunately they have a relatively narrow label (the plants they can be used on). Granular formulations of Snapshot, Treflan, and Pendulum have very wide labels and good crop safety. Factor and Gallery are two other herbicides with wide container crop labels. Broadstar is also labeled on some plants and is very effective. You may consider applying sequential applications of these herbicides at reduced rates.
Showcase, Rout, and OH2 are the most effective on bittercress; Rout and Broadstar are most effective on groundsel, and Snapshot, Showcase, Rout, and Broadstar are the most effective on Oxalis.
Summarized by Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Friday, November 16, 2007
Thursday, November 15, 2007
Landscape - Winter Injury on Landscape Plants
With winter fast approaching, landscapers should take some time to familiarize themselves with winter injury symptoms on ornamental plants and plants that commonly show winter injury. The following is an article on this subject.
Winter injury is a result of many environmental factors. The causal factors are diverse and include late spring frost, a cool summer followed by a warm fall or a sudden drop in temperature, excessive or late season fertilization, excessive temperature fluctuations, abnormally cold temperatures during winter, drying winds, and lack of snow cover. Growing plants out of their hardiness zone reduces their ability to survive low temperatures during the winter.
Excessive drying (winter desiccation) is one type of winter injury. This is quite common in evergreens and occurs when water evaporates from leaves or needles on windy or warm sunny days during the winter or early spring. Drying occurs because this water is not replaced since the roots cannot take up enough water from cold or frozen soil. Winter desiccation is prevalent on broadleaved evergreens such as rhododendron and holly and on needled evergreens such as hemlock and pine. Rhododendron leaves affected by winter desiccation turn brown along the margins and roll longitudinally along the mid-vein. Desiccated needled evergreens exhibit browning of the tips of needles, needle drop, and twig dieback.
Periods of fluctuating winter temperatures combined with sunny calm days can cause sunscald (or sunscorch). Sunscald becomes evident when bark splitting occurs on stems or branches, most often on the southwest side of the tree. Other symptoms include dried buds, scorching or shriveling and dying of newly emerged foliage, twig dieback, scalding of bark, stunted annual twig development, and reduced plant growth. Smooth, thinbarked deciduous trees and shrubs are most prone to sun scald injury. Examples include flowering cheery and almond, Japanese and red maple, and flowering plum and peach.
Keep in mind that, unfortunately, symptoms of winter injury are not often evident until the following spring or summer. Winter injury will predispose plants to secondary infections by insects and diseases caused by living organisms.
Extracted from "Landscape and Ornamental Plant Stress: Factors, Symptoms, Diagnosis, and Management" by Gladis Zinati, Ph.D., Extension Specialist in Nursery Management, Ann Brooks Gould, Ph.D. Extension Specialist in Ornamental Plant Pathology, Richard Buckley, Coordinator Plant Diagnostic Laboratory, and Rich Obal, Monmouth County Agricultural Agent, Rutgers University.
Winter injury is a result of many environmental factors. The causal factors are diverse and include late spring frost, a cool summer followed by a warm fall or a sudden drop in temperature, excessive or late season fertilization, excessive temperature fluctuations, abnormally cold temperatures during winter, drying winds, and lack of snow cover. Growing plants out of their hardiness zone reduces their ability to survive low temperatures during the winter.
Excessive drying (winter desiccation) is one type of winter injury. This is quite common in evergreens and occurs when water evaporates from leaves or needles on windy or warm sunny days during the winter or early spring. Drying occurs because this water is not replaced since the roots cannot take up enough water from cold or frozen soil. Winter desiccation is prevalent on broadleaved evergreens such as rhododendron and holly and on needled evergreens such as hemlock and pine. Rhododendron leaves affected by winter desiccation turn brown along the margins and roll longitudinally along the mid-vein. Desiccated needled evergreens exhibit browning of the tips of needles, needle drop, and twig dieback.
Periods of fluctuating winter temperatures combined with sunny calm days can cause sunscald (or sunscorch). Sunscald becomes evident when bark splitting occurs on stems or branches, most often on the southwest side of the tree. Other symptoms include dried buds, scorching or shriveling and dying of newly emerged foliage, twig dieback, scalding of bark, stunted annual twig development, and reduced plant growth. Smooth, thinbarked deciduous trees and shrubs are most prone to sun scald injury. Examples include flowering cheery and almond, Japanese and red maple, and flowering plum and peach.
Keep in mind that, unfortunately, symptoms of winter injury are not often evident until the following spring or summer. Winter injury will predispose plants to secondary infections by insects and diseases caused by living organisms.
Extracted from "Landscape and Ornamental Plant Stress: Factors, Symptoms, Diagnosis, and Management" by Gladis Zinati, Ph.D., Extension Specialist in Nursery Management, Ann Brooks Gould, Ph.D. Extension Specialist in Ornamental Plant Pathology, Richard Buckley, Coordinator Plant Diagnostic Laboratory, and Rich Obal, Monmouth County Agricultural Agent, Rutgers University.
Nursery - Weed Control in Field Grown Nurseries
The following is some information on weed control in field grown nurseries from a presentation by Dr. Stephen Hart at Rutgers
Weed management challenges in field grown nurseries are:
Weed management challenges in field grown nurseries are:
- Year round weed control is required
- There is a lack of crop competition with weeds (not a lot of shading)
- Tillage is only done at establishment normally
- These are perennial crops so perennial weeds are often a problem
- There is a wide diversity of plants being produced so no one herbicide program will fit all
- There is a relatively small number of herbicides registered
Programs rely on preemergence herbicides with low water solubility and long residual and spot treatments of non-selectives for perennial weed control and annual escapes. Often extensive labor is needed, especially for post spot herbicide applications.
Major weed problems are summer annual grasses and broaleaf weeds with marestail becomming more of an issue (due to glyphosate resistance) and morningglory due to its late season germination. Perennial weed problems include yellow nutsedge, mugwort, bindweeds, and Canada thistle.
Preemergence herbicides that are extensively used extensively according to chemical class are:
- Dinitroanalines: Pendimethalin (Pendulum), prodiamine (Factor, Barricade), trifluralin (Treflan), oryazalin (Surflan). These give annual grass control and some small seeded broadleaf control and have good safety across ornamental species.
- Acid Amides: Metolachor (Pennant Magnum) is the main one in this group. Pennant provides nutsedge and grass control. It is labelled mainly on woody species.
- Triazines: Simazine (Princep) is the main herbicide used in this group. It has annual broadleaf and some grass control. It is low cost. It is limited to woody ornamentals.
- Diphenylethers: Some of the most effective nursery herbicides fall into this class which includes oxyfluorfen (Goal), oxadiazon (Ronstar), and flumioxizon (SureGuard and Broadstar). This group controls annual broadleaf weeds and some annual grasses.
- Others: Isoxaben (Gallery) is the main one here. It is an annual broadleaf weed material. It is safe on a wide range of ornamentals including many herbaceous perennials but is relatively high cost.
Selective postemergence nursery herbicides for nurseries include the grass products sethoxydim (Vantage), fluazifop (Fusilade), and Clethodim (Envoy) that are save on most ornamentals (except ornamental grasses). There are only a few postemergence broadleaf materials for nurseries. Chlopyralid (Lontrel, Stinger) is the main one and is very limited in the species it can be used on.
Non selective herbicides for postemergence spot weed control mainly include the glyphosate products (Roundup and many others) and Finale. Finale is mainly used for control of weeds that glyphosate does not work well on. This includes glyphosate resistant marestail and morningglory. One issue with Finale is that it can cause bark splitting.
Where they are labelled, SureGuard/Broadstar and Goal have provided superior annual weed control in field grown nurseries in spring applied programs. Pennant Magnum is often added to give grass and nutsedge control. In fall applications, the grass materials would be Pendulum, Factor, Surflan, or Devrinol mixed with the broadleaf materials SureGuard/Broadstar, Princep, or Gallery. Goal is not recommended for fall due to lack of marestail activity.
Summarized by Gordon Johnson, Extension Agriculture Agent, UD, Kent County
Wednesday, November 14, 2007
Greenhouse - A Biological Control for Thrips and Whiteflies
The following is an article on a successful biological control (predator) for thrips and whiteflies in the greenhouse .
Thrips and Whitefly Control Using Amblyseius swirskii Predators
Swirskii-mite is a voracious predatory mite which controls both thrips and whitefly. It has also demonstrated the ability to provide added control with spider mite infestations in conjunction with other predatory mites. It controls both greenhouse and tobacco whitefly species. It preys on the eggs and 1st larval stages of whiteflies, and on the 1st larval stages of thrips. It has a very high rate of reproduction. Swirskii-mite is not susceptible to diapause, and can be introduced in winter months. It also may be introduced in high temperatures. Without prey it can establish onpollen.
Mode of Action/ Life Cycle: Predatory mites pierce their prey and suck out the body contents, resulting in immediate control. Their eggs are deposited on the underside of leaves, often on the leaf hairs near the veins. Total development from egg to adult takes 5 to 6 days depending on temperature and humidity.
Release Technique: Rates vary with plant size and infestation level. From 2 to 5 mites are recommended per square foot. Two release methods are available. Loose mites are suspended in media that is placed directly on the plant. Sachets with 250 mites are hung on the plant and the sachets release mites for about 4-6 weeks.
Article from the March 23, 2007 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension.
Thrips and Whitefly Control Using Amblyseius swirskii Predators
Swirskii-mite is a voracious predatory mite which controls both thrips and whitefly. It has also demonstrated the ability to provide added control with spider mite infestations in conjunction with other predatory mites. It controls both greenhouse and tobacco whitefly species. It preys on the eggs and 1st larval stages of whiteflies, and on the 1st larval stages of thrips. It has a very high rate of reproduction. Swirskii-mite is not susceptible to diapause, and can be introduced in winter months. It also may be introduced in high temperatures. Without prey it can establish onpollen.
Mode of Action/ Life Cycle: Predatory mites pierce their prey and suck out the body contents, resulting in immediate control. Their eggs are deposited on the underside of leaves, often on the leaf hairs near the veins. Total development from egg to adult takes 5 to 6 days depending on temperature and humidity.
Release Technique: Rates vary with plant size and infestation level. From 2 to 5 mites are recommended per square foot. Two release methods are available. Loose mites are suspended in media that is placed directly on the plant. Sachets with 250 mites are hung on the plant and the sachets release mites for about 4-6 weeks.
Article from the March 23, 2007 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension.
Monday, November 12, 2007
Turf - Liming Material Comparisons
Liquid calcium materials are being marketed as liming alternatives. The following is an article on comparisons of one such product with regular lime.
Turf managers not only need to be able to diagnose problems as they arise, but to decide on what products and practices to use in correcting these problems. The maintenance of a desired soil pH level is a crucial part of the establishment and maintenance of a healthy stand of turf and varies with the type of turf being maintained. In the Northeast, managers must frequently monitor and adjust pH levels in acidic soils. Agricultural limestone has long been the standard used for this purpose, but frequently we are presented with alternative or new products and are not sure what benefit they will provide or if they will work in solving the problem at hand.
One such product, Solu-Cal, has been suggested as an alternative to limestone. We conducted a study at Rutgers University to compare the effects of Solu-Cal on the chemistry of an infertile sandy loam soil, with an initial pH of 4.9, to that of common liming agents. According to the product label, Solu-Cal is derived from calcium carbonate and calcium oxide with no calcium carbonate equivalent (CCE) listed on the label. The product appears as gray pellets with a 1-4mm size range. Solu-Cal was compared to both Baker’s Pulverized Dolomitic Limestone and Pelleted Pro Limestone. The pH was checked after two different time intervals, 71 and 137 days. At the end soil samples were taken and analyzed. The pH, on both dates, showed the greatest increase by Baker’s, followed by Pelleted Pro, and lastly by Solu-Cal. The final soil test results at the application rate of 459 lb/1000ft²(10 tons/A), showed Baker’s treated soil had a pH of 7.2, Pelleted Pro 6.3, and Solu-Cal 5.5. Although the Solu-Cal product was less effective at neutralizing acidity, the soil test results showed that the amount of calcium supplied to the soil was comparable to that of the other two liming agents. Solu-Cal did little to increase exchangeable magnesium in the soil, by comparison. The study results indicate that although Solu-Cal proved less effective than traditional liming materials in raising the pH of an acidic soil, it can be useful as a calcium source.
Extracted from "Solu-Cal as an Alternative for Soil Amendment" by Mary C. Provance-Bowley, Research Assistant and Joseph Heckman, Ph.D., Specialist in Soil Fertility, Rutgers University in the April 6, 2006 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition.
Reference: Provance-Bowley, M.C. and J.R. Heckman. 2006. Evaluation of Solu-Cal as a Soil Amendment for pH Adjustment. Proceedings of the Fifteenth Annual Rutgers Turfgrass Symposium.
Turf managers not only need to be able to diagnose problems as they arise, but to decide on what products and practices to use in correcting these problems. The maintenance of a desired soil pH level is a crucial part of the establishment and maintenance of a healthy stand of turf and varies with the type of turf being maintained. In the Northeast, managers must frequently monitor and adjust pH levels in acidic soils. Agricultural limestone has long been the standard used for this purpose, but frequently we are presented with alternative or new products and are not sure what benefit they will provide or if they will work in solving the problem at hand.
One such product, Solu-Cal, has been suggested as an alternative to limestone. We conducted a study at Rutgers University to compare the effects of Solu-Cal on the chemistry of an infertile sandy loam soil, with an initial pH of 4.9, to that of common liming agents. According to the product label, Solu-Cal is derived from calcium carbonate and calcium oxide with no calcium carbonate equivalent (CCE) listed on the label. The product appears as gray pellets with a 1-4mm size range. Solu-Cal was compared to both Baker’s Pulverized Dolomitic Limestone and Pelleted Pro Limestone. The pH was checked after two different time intervals, 71 and 137 days. At the end soil samples were taken and analyzed. The pH, on both dates, showed the greatest increase by Baker’s, followed by Pelleted Pro, and lastly by Solu-Cal. The final soil test results at the application rate of 459 lb/1000ft²(10 tons/A), showed Baker’s treated soil had a pH of 7.2, Pelleted Pro 6.3, and Solu-Cal 5.5. Although the Solu-Cal product was less effective at neutralizing acidity, the soil test results showed that the amount of calcium supplied to the soil was comparable to that of the other two liming agents. Solu-Cal did little to increase exchangeable magnesium in the soil, by comparison. The study results indicate that although Solu-Cal proved less effective than traditional liming materials in raising the pH of an acidic soil, it can be useful as a calcium source.
Extracted from "Solu-Cal as an Alternative for Soil Amendment" by Mary C. Provance-Bowley, Research Assistant and Joseph Heckman, Ph.D., Specialist in Soil Fertility, Rutgers University in the April 6, 2006 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition.
Reference: Provance-Bowley, M.C. and J.R. Heckman. 2006. Evaluation of Solu-Cal as a Soil Amendment for pH Adjustment. Proceedings of the Fifteenth Annual Rutgers Turfgrass Symposium.
Turf - Some Traits Being Bred Into Tall Fescue
There is a lot of breeding work going on with turf type tall fescue. The following is an article on two traits being worked on.
Rhizome activity in tall fescue is not equivalent to that in Kentucky bluegrass, yet there is a spreading characteristic present in tall fescue that breeders are working to enhance.
There are two varieties that are being aggressively marketed as having rhizomes: Labrynth and Grande II. Of these two, Grande II has the best turf quality - I would recommend this one. Labrynth isn’t attractive (very coarse textured, poor density, and yellow-green color). And accordingly Labrynth is being sold in blends or mixes with better looking varieties to mask this appearance while Labrynth provides the sod knitting ability. These blends and mixtures with Labrynth would be the only way I would recommend using Labrynth, but realize that the turf quality of Labrynth will not be totally masked and could be a negative to many property owners.
Some anecdotal evidence suggest that the variety Titan Ltd. has good spreading and sod knitting ability, presumably by rhizomes. The breeding program at Rutgers is working diligently on improving this trait in tall fescue. So it is fair to say that you will be hearing more on this issue in the coming years. And I am optimistic that this characteristic will be prevalent in more varieties in the near future.
Cold weather (winter) performance is another trait that is being worked on. This improvement would a great boost to the sports turf industry, since winter is a period of downtime for fields. Current varieties are too slow growing during the mild weather of winter; improvement of winter vigor could enable turf managers to achieve some degree of recovery during winter and early spring that is currently not possible.
Extracted from an article by James Murphy, Ph.D., Specialist in Turf Management, Rutgers University in the April 6, 2006 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf edition.
Rhizome activity in tall fescue is not equivalent to that in Kentucky bluegrass, yet there is a spreading characteristic present in tall fescue that breeders are working to enhance.
There are two varieties that are being aggressively marketed as having rhizomes: Labrynth and Grande II. Of these two, Grande II has the best turf quality - I would recommend this one. Labrynth isn’t attractive (very coarse textured, poor density, and yellow-green color). And accordingly Labrynth is being sold in blends or mixes with better looking varieties to mask this appearance while Labrynth provides the sod knitting ability. These blends and mixtures with Labrynth would be the only way I would recommend using Labrynth, but realize that the turf quality of Labrynth will not be totally masked and could be a negative to many property owners.
Some anecdotal evidence suggest that the variety Titan Ltd. has good spreading and sod knitting ability, presumably by rhizomes. The breeding program at Rutgers is working diligently on improving this trait in tall fescue. So it is fair to say that you will be hearing more on this issue in the coming years. And I am optimistic that this characteristic will be prevalent in more varieties in the near future.
Cold weather (winter) performance is another trait that is being worked on. This improvement would a great boost to the sports turf industry, since winter is a period of downtime for fields. Current varieties are too slow growing during the mild weather of winter; improvement of winter vigor could enable turf managers to achieve some degree of recovery during winter and early spring that is currently not possible.
Extracted from an article by James Murphy, Ph.D., Specialist in Turf Management, Rutgers University in the April 6, 2006 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf edition.
Saturday, November 10, 2007
Greenhouse - Use of Fascination on Poinsettias
There are several tools to control plant height in poinsettias. However, some of the growth regulators can reduce bract size. The following is a report on research using Fascination, a hormone product that can maintain good bract size and can be used to counteract the effect of excess growth regulators.
During poinsettia production various plant growth regulators (PGR’s) are typically used to control stem elongation. A potential negative side effect of PGR usage is the reduction of bract size. This is especially possible when PGR’s are applied late in the season or when an overdose occurs.
Fascination (Valent USA) is the brand name of a product that has been available for many years and is composed of the naturally occurring plant hormones, gibberellins and cytokinin. A couple of years ago this material received an EPA label registration for use on poinsettia crops. It has proven to be an effective material for increasing poinsettia stem elongation and bract size, especially after an overdose of a PGR. It also provides a counteracting option for those growers who have the tendency to produce consistently short and compact poinsettia crops each year. The objectives of the Michigan State University experiments were to determine the effects of Fascination rates and timing on poinsettia stem elongation and bract area size. In addition, a study was performed comparing the affects of Fascination applications to poinsettia plants provided with and without a Bonzi (growth retardant) drench.
Experimental Conclusions
Poinsettia growers can increase plant height by 1 to 2 inches by spraying a single application of Fascination at the 3 to 5-ppm rate. Maximum plant height increases are achieved when sprays are timed 7 to 10 days after initial bract color is observed. This spray timing will also promote some increase in bract area. To achieve the greatest increase in bract area size, spray Fascination 20 to 30 days after initial bract color. This later spray timing results in limited stem elongation.
Important Precautions to Consider
The optimum Fascination rates and timing depends on desired expectations and specific physical and environmental factors. Various cultural practices including temperature, light conditions, potting media, fertilization and watering will all affect the final impact from different Fascination spray rates. Dissimilarities in response can also occur with different poinsettia varieties. To determine optimum use rates, conduct trials on a small number of plants under actual use conditions using the lowest indicated rate.
The application of Fascination to poinsettia during the period of time between start of short days to two weeks after first bract color can promote delayed coloration. Therefore, increased bench time can postpone proposed shipping dates. Furthermore, when Fascination increases bract expansion the dilution of leaf pigmentation causes the color of bracts to appear lighter. As bract maturity continues to develop with time the color will also improve. However, often times the treated bracts will never reach the same dark coloration as non-sprayed plants. Multiple applications will exacerbate the lightening of bract color.
Extracted from the "Greenhouse Research Summary" by Steven K. Rettke, Rutgers Cooperative Extension in the January 2007 edition of the Northeast Floriculture IPM Notes from Rutgers and Cornell Universities.
During poinsettia production various plant growth regulators (PGR’s) are typically used to control stem elongation. A potential negative side effect of PGR usage is the reduction of bract size. This is especially possible when PGR’s are applied late in the season or when an overdose occurs.
Fascination (Valent USA) is the brand name of a product that has been available for many years and is composed of the naturally occurring plant hormones, gibberellins and cytokinin. A couple of years ago this material received an EPA label registration for use on poinsettia crops. It has proven to be an effective material for increasing poinsettia stem elongation and bract size, especially after an overdose of a PGR. It also provides a counteracting option for those growers who have the tendency to produce consistently short and compact poinsettia crops each year. The objectives of the Michigan State University experiments were to determine the effects of Fascination rates and timing on poinsettia stem elongation and bract area size. In addition, a study was performed comparing the affects of Fascination applications to poinsettia plants provided with and without a Bonzi (growth retardant) drench.
Experimental Conclusions
Poinsettia growers can increase plant height by 1 to 2 inches by spraying a single application of Fascination at the 3 to 5-ppm rate. Maximum plant height increases are achieved when sprays are timed 7 to 10 days after initial bract color is observed. This spray timing will also promote some increase in bract area. To achieve the greatest increase in bract area size, spray Fascination 20 to 30 days after initial bract color. This later spray timing results in limited stem elongation.
Important Precautions to Consider
The optimum Fascination rates and timing depends on desired expectations and specific physical and environmental factors. Various cultural practices including temperature, light conditions, potting media, fertilization and watering will all affect the final impact from different Fascination spray rates. Dissimilarities in response can also occur with different poinsettia varieties. To determine optimum use rates, conduct trials on a small number of plants under actual use conditions using the lowest indicated rate.
The application of Fascination to poinsettia during the period of time between start of short days to two weeks after first bract color can promote delayed coloration. Therefore, increased bench time can postpone proposed shipping dates. Furthermore, when Fascination increases bract expansion the dilution of leaf pigmentation causes the color of bracts to appear lighter. As bract maturity continues to develop with time the color will also improve. However, often times the treated bracts will never reach the same dark coloration as non-sprayed plants. Multiple applications will exacerbate the lightening of bract color.
Extracted from the "Greenhouse Research Summary" by Steven K. Rettke, Rutgers Cooperative Extension in the January 2007 edition of the Northeast Floriculture IPM Notes from Rutgers and Cornell Universities.
Landscape - Tree Salt Tolerance
Salt Damage on MapleImage from "Salt Damage and Trees" from the University of Massachusetts Extension
Winter deicing season is coming and there is potential for salt damage to landscape plants. The following is a list of some landscape trees and their salt tolerance
Moderately Tolerant Deciduous Trees
black cherry
black locust
box elder
bur oak
callery pear
English oak
golden willow
green ash
honey locust
horse-chestnut
Norway maple
red oak
Russian olive
Siberian crabapple
Siberian elm
tree-of-heaven
weeping willow
white oak
white poplar
Intolerant Deciduous Trees
American elm
American linden
apple
basswood
beech
box elder
boxwood
flowering quince
ginkgo
ironwood
hickory
hornbeam
little-leaf linden
mimosa
red maple
shagbark hickory
silver maple
sugar maple
sycamore
Moderately Tolerant Evergreens
Austrian pine
Colorado blue spruce
Japanese black pine
mugo pine
pitch pine
red cedar
white spruce
Intolerant Evergreens
balsam fir
Canadian hemlock
Douglas-fir
Eastern white pine
red pine
List from an article by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the March 16, 2006 issue of the Plant and Pest Advisory, Landcape, Nursery, and Turf Edition.
Landscape - Winter Deicing Compounds and Salt Injury
De-icing salt injury along route 206 in Sussex County, NJ. Photo credit: Spence Davis. (bottomthird of pines on right are brown.)
Winter is just around the corner and the first snowfalls cannot be far away. One issue that comes with winter storms is the effect of deicing compounds on plants and potential salt injury. The following is an article on the subject.
Roadside vegetation will be exposed to de-icing compounds in upcoming winter storms. Runoff from treated pavement contains dissolved salts that can injure adjacent vegetation. In plants sensitive to excessive salt, affected foliage may appear “scorched” and drop prematurely. In severe cases, the death of twigs, branches, and sometimes the entire plant, may occur.
Why are De-icing salts used?
Deicing salts make roadways, driveways, and sidewalks safer by melting snow and ice. These compounds are usually applied during snow storms before the snow can accumulate. The salt dissolves in water to form a brine that has a freezing point lower than water. The brine melts ice and helps to prevent the formation of more ice as temperatures drop. The two most commonly applied de-icing salts are sodium chloride (rock salt) and calcium chloride. To improve traction, de-icing salts are usually mixed with abrasives. These abrasives, which include sand, cinders, gravel, and sawdust, can accumulate along roadways and cause problems with drainage.
How does salt affect vegetation?
Plants become injured when salt-laden water contacts roots and foliage. The foliage on roadside vegetation is injured when salted water sprays up from the pavement by passing vehicles. Salt-laden water can also percolate down through the soil profile, coming into contact with soil particles, soil microbes, and plant roots. Salt injures vegetation by:
● Increasing water stress. In the root zone, water molecules are held very tightly by salt ions, making it difficult for roots to absorb sufficient quantities of water. In sensitive species, this “physiological drought” may result in depressed growth and yield.
● Affecting soil quality. The sodium ion component in salt becomes attached to soil particles and displaces soil elements such as potassium and phosphorus. As a result, soil density and compaction increases and drainage and aeration are reduced. Plant growth and vigor are poor under these conditions.
● Affecting mineral nutrition. When the concentration of both the sodium and chloride components of salt in the root zone is excessive, plants preferentially absorb these ions instead of nutrients such as potassium and phosphorus. When this occurs, plants may suffer from potassium and phosphorus deficiency.
● Accumulating to toxic levels within plants. The chloride component of salt is absorbed by roots and foliage and becomes concentrated in actively growing tissue. Plants repeatedly exposed to salt over long periods of time may accumulate chloride ions to toxic levels, resulting in leaf burn and twig die-back.
How do plants respond to excessive salt?
Unlike animals, plants do not have mechanisms to excrete excess salt from tissues and can only “shed” salt in dead leaves and needles. Because conifers do not shed leaves on a yearly basis, they tend to suffer damage from accumulated salt more easily than do deciduous trees.
Plant species vary in their tolerance to salt exposure. Plants that are tolerant of salt grow as well in saline soils as they do under normal conditions. Many herbaceous plants such as grasses adapt fairly readily to high salt levels. Among woody plants, tolerance varies with the species. Plant species with waxy foliage are generally more tolerant of salt spray. In salt-sensitive plants, exposure to salt can result in poor growth, stunted leaves, heavy seed loads, twig and branch die-back, leaf scorch, and premature leaf drop. Plants stressed by excessive salt are also more susceptible to biotic diseases and insect pests. The extent of injury a plant sustains in response to salt depends on:
● The kind and amount of salt applied. Sodium chloride (rock salt) can be very damaging to plants. De-icing compounds without chloride, such as urea, are safer for vegetation.
● The volume of fresh water applied. Although salts are easily leached by water in well-drained soils, they tend to accumulate in poorly-drained soils, so the potential for damage to vegetation in these soils is high. High volumes of water, whether from rainfall or melting snow, will decrease the possibility of injury. Rainfall also washes salt from foliage surfaces.
● The distance plants are situated from treated pavements. Plants within the “spray zone” of moving vehicles are more likely to sustain salt injury. Injury is usually most evident on the side of the plant that faces the highway.
● The direction of surface-water flow. The channeling of drainage water away from susceptible plants will prevent salt from coming into contact with plant roots. If plants are situated up-slope or away from drainage areas, they are less likely to be affected.
● The time of year salt is applied. Salt applied in late winter and early spring is more likely to damage vegetation than salt applied earlier in the winter season. This is because there is less time for winter snow and precipitation to leach salt from the root zone before growth resumes in the spring.
How can we minimize salt injury?
The best solution to the de-icing salt problem is to prevent contamination. Clear snow first, and then use abrasives instead of salt to treat driveways and walkways. If vegetation is located in areas where salt spray occurs, erect barriers or screens to protect plants during the winter months. Anti-desiccants may also help prevent injury when applied to evergreen foliage where de-icing salt will be used. County, state, and municipal officials can help prevent salt injury by carefully training equipment operators and frequently calibrating equipment.
Once soil becomes contaminated with salt, damage can be reduced by leaching the salt with fresh water as soon as possible after exposure. Under certain circumstances, incorporation of gypsum at the rate of 50 lb/1000 sq ft into the top six inches of soil at the drip-line of trees may also be helpful. Furthermore, foliage exposed to salt spray may be washed with salt-free water to remove deposited salt.
When landscaping, place trees and shrubs that are sensitive to salt as far as possible from problem areas consider the following: Select planting sites that are not subject to salt-contaminated waters, and place shallow diversion ditches between roadways and plantings. When vegetation must be placed near roadways, utilize salt-tolerant plants.
Article by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the March 16, 2006 issue of the Plant and Pest Advisory, Landcape, Nursery, and Turf Edition.
Roadside vegetation will be exposed to de-icing compounds in upcoming winter storms. Runoff from treated pavement contains dissolved salts that can injure adjacent vegetation. In plants sensitive to excessive salt, affected foliage may appear “scorched” and drop prematurely. In severe cases, the death of twigs, branches, and sometimes the entire plant, may occur.
Why are De-icing salts used?
Deicing salts make roadways, driveways, and sidewalks safer by melting snow and ice. These compounds are usually applied during snow storms before the snow can accumulate. The salt dissolves in water to form a brine that has a freezing point lower than water. The brine melts ice and helps to prevent the formation of more ice as temperatures drop. The two most commonly applied de-icing salts are sodium chloride (rock salt) and calcium chloride. To improve traction, de-icing salts are usually mixed with abrasives. These abrasives, which include sand, cinders, gravel, and sawdust, can accumulate along roadways and cause problems with drainage.
How does salt affect vegetation?
Plants become injured when salt-laden water contacts roots and foliage. The foliage on roadside vegetation is injured when salted water sprays up from the pavement by passing vehicles. Salt-laden water can also percolate down through the soil profile, coming into contact with soil particles, soil microbes, and plant roots. Salt injures vegetation by:
● Increasing water stress. In the root zone, water molecules are held very tightly by salt ions, making it difficult for roots to absorb sufficient quantities of water. In sensitive species, this “physiological drought” may result in depressed growth and yield.
● Affecting soil quality. The sodium ion component in salt becomes attached to soil particles and displaces soil elements such as potassium and phosphorus. As a result, soil density and compaction increases and drainage and aeration are reduced. Plant growth and vigor are poor under these conditions.
● Affecting mineral nutrition. When the concentration of both the sodium and chloride components of salt in the root zone is excessive, plants preferentially absorb these ions instead of nutrients such as potassium and phosphorus. When this occurs, plants may suffer from potassium and phosphorus deficiency.
● Accumulating to toxic levels within plants. The chloride component of salt is absorbed by roots and foliage and becomes concentrated in actively growing tissue. Plants repeatedly exposed to salt over long periods of time may accumulate chloride ions to toxic levels, resulting in leaf burn and twig die-back.
How do plants respond to excessive salt?
Unlike animals, plants do not have mechanisms to excrete excess salt from tissues and can only “shed” salt in dead leaves and needles. Because conifers do not shed leaves on a yearly basis, they tend to suffer damage from accumulated salt more easily than do deciduous trees.
Plant species vary in their tolerance to salt exposure. Plants that are tolerant of salt grow as well in saline soils as they do under normal conditions. Many herbaceous plants such as grasses adapt fairly readily to high salt levels. Among woody plants, tolerance varies with the species. Plant species with waxy foliage are generally more tolerant of salt spray. In salt-sensitive plants, exposure to salt can result in poor growth, stunted leaves, heavy seed loads, twig and branch die-back, leaf scorch, and premature leaf drop. Plants stressed by excessive salt are also more susceptible to biotic diseases and insect pests. The extent of injury a plant sustains in response to salt depends on:
● The kind and amount of salt applied. Sodium chloride (rock salt) can be very damaging to plants. De-icing compounds without chloride, such as urea, are safer for vegetation.
● The volume of fresh water applied. Although salts are easily leached by water in well-drained soils, they tend to accumulate in poorly-drained soils, so the potential for damage to vegetation in these soils is high. High volumes of water, whether from rainfall or melting snow, will decrease the possibility of injury. Rainfall also washes salt from foliage surfaces.
● The distance plants are situated from treated pavements. Plants within the “spray zone” of moving vehicles are more likely to sustain salt injury. Injury is usually most evident on the side of the plant that faces the highway.
● The direction of surface-water flow. The channeling of drainage water away from susceptible plants will prevent salt from coming into contact with plant roots. If plants are situated up-slope or away from drainage areas, they are less likely to be affected.
● The time of year salt is applied. Salt applied in late winter and early spring is more likely to damage vegetation than salt applied earlier in the winter season. This is because there is less time for winter snow and precipitation to leach salt from the root zone before growth resumes in the spring.
How can we minimize salt injury?
The best solution to the de-icing salt problem is to prevent contamination. Clear snow first, and then use abrasives instead of salt to treat driveways and walkways. If vegetation is located in areas where salt spray occurs, erect barriers or screens to protect plants during the winter months. Anti-desiccants may also help prevent injury when applied to evergreen foliage where de-icing salt will be used. County, state, and municipal officials can help prevent salt injury by carefully training equipment operators and frequently calibrating equipment.
Once soil becomes contaminated with salt, damage can be reduced by leaching the salt with fresh water as soon as possible after exposure. Under certain circumstances, incorporation of gypsum at the rate of 50 lb/1000 sq ft into the top six inches of soil at the drip-line of trees may also be helpful. Furthermore, foliage exposed to salt spray may be washed with salt-free water to remove deposited salt.
When landscaping, place trees and shrubs that are sensitive to salt as far as possible from problem areas consider the following: Select planting sites that are not subject to salt-contaminated waters, and place shallow diversion ditches between roadways and plantings. When vegetation must be placed near roadways, utilize salt-tolerant plants.
Article by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the March 16, 2006 issue of the Plant and Pest Advisory, Landcape, Nursery, and Turf Edition.
Friday, November 9, 2007
Greenhouse - Bulb Forcing 1
This is the first in a series on bulb forcing for greenhouse growers
Basic Principles
Given that geophyte (bulbing flower) storage organs evolved in response to adverse climatic conditions, it is logical that the most important variable to consider in geophyte production is temperature; thus, for many bulb plants, it is necessary to mimic the natural temperature sequences of the environment to which a geophyte is naturally adapted in order for the plant to flower properly. Spring-flowering bulbs develop flower primordia inside the bulb during the summer, are planted outside in the fall, overwinter under low temperatures and then flower in the warmth of spring. For forcing, it is necessary to give these geophytes a warm-cool-warm temperature sequence.
Phases
Five phases comprise horticultural production of geophytes (bulb flowers):
1. bulb (storage organ) production
2. bulb (storage organ) programming
3. greenhouse flower forcing
4. marketing
5. the consumer (after care)
The bulb production phase involves the production of bulbs for subsequent forcing or use in the garden. These two bulb markets are referred to as the forcing market and the dry-sale market. Forcing bulbs are sold to greenhouse forcers for production of cut flowers, flowering potted plants, and growing potted plants. These bulbs go through programming and forcing regimes to accelerate or delay flowering. Dry-sale bulbs are sold after the production phase for use in outdoor gardens and landscaping; thus, these bulbs skip the programming and forcing phases.
The bulb programming phase involves all temperature treatments given to bulbs from the time they are harvested until they are placed in the greenhouse. Again, the basis of this phase is the need to provide the proper temperature sequence to ensure proper flowering. The most common method for providing these artificial growing conditions involves a temperature-controlled rooting room; however, not all geophytes require a rooting room for programming. Those that do not are forced entirely in the greenhouse.
The greenhouse forcing stage begins when bulbs are moved from the rooting room into the greenhouse or, in the case of non-rooting room bulbs, when bulbs enter the greenhouse upon arrival from the bulb producer. It ends when the cut flowers, flowering potted plants or growing potted plants are sent to market.
For successful marketing, it is essential that consumers of bulb flowers and plants receive the products at the proper developmental stage to allow for maximum enjoyment. In order to optimize this process, the cooperation of all stages of the flower bulb industry is essential. If producers, wholesalers, and retailers work together, they can increase customer satisfaction and profits for all.
Finally, it is important to consider the consumer stage because interior conditions and the level of care given by the consumer have a major impact on quality.
Extracted from "Geophyte Horticulture" from the Cornell University Flower Bulb Research Program. For more information on research on bulb crops go to http://www.hort.cornell.edu/miller/bulb/index.html
Basic Principles
Given that geophyte (bulbing flower) storage organs evolved in response to adverse climatic conditions, it is logical that the most important variable to consider in geophyte production is temperature; thus, for many bulb plants, it is necessary to mimic the natural temperature sequences of the environment to which a geophyte is naturally adapted in order for the plant to flower properly. Spring-flowering bulbs develop flower primordia inside the bulb during the summer, are planted outside in the fall, overwinter under low temperatures and then flower in the warmth of spring. For forcing, it is necessary to give these geophytes a warm-cool-warm temperature sequence.
Phases
Five phases comprise horticultural production of geophytes (bulb flowers):
1. bulb (storage organ) production
2. bulb (storage organ) programming
3. greenhouse flower forcing
4. marketing
5. the consumer (after care)
The bulb production phase involves the production of bulbs for subsequent forcing or use in the garden. These two bulb markets are referred to as the forcing market and the dry-sale market. Forcing bulbs are sold to greenhouse forcers for production of cut flowers, flowering potted plants, and growing potted plants. These bulbs go through programming and forcing regimes to accelerate or delay flowering. Dry-sale bulbs are sold after the production phase for use in outdoor gardens and landscaping; thus, these bulbs skip the programming and forcing phases.
The bulb programming phase involves all temperature treatments given to bulbs from the time they are harvested until they are placed in the greenhouse. Again, the basis of this phase is the need to provide the proper temperature sequence to ensure proper flowering. The most common method for providing these artificial growing conditions involves a temperature-controlled rooting room; however, not all geophytes require a rooting room for programming. Those that do not are forced entirely in the greenhouse.
The greenhouse forcing stage begins when bulbs are moved from the rooting room into the greenhouse or, in the case of non-rooting room bulbs, when bulbs enter the greenhouse upon arrival from the bulb producer. It ends when the cut flowers, flowering potted plants or growing potted plants are sent to market.
For successful marketing, it is essential that consumers of bulb flowers and plants receive the products at the proper developmental stage to allow for maximum enjoyment. In order to optimize this process, the cooperation of all stages of the flower bulb industry is essential. If producers, wholesalers, and retailers work together, they can increase customer satisfaction and profits for all.
Finally, it is important to consider the consumer stage because interior conditions and the level of care given by the consumer have a major impact on quality.
Extracted from "Geophyte Horticulture" from the Cornell University Flower Bulb Research Program. For more information on research on bulb crops go to http://www.hort.cornell.edu/miller/bulb/index.html
Greenhouse - Easter Lily Forcing Update
Easter lily forcing schedules are much earlier this year due to an earlier Easter. The following is information on this topic.
Easter Lily Update
Easter is very early next year on March 23rd. This is 16 days earlier than 2007 and a whopping 24 days earlier than 2006. Schedule your crops accordingly! This means that right now we are at about 19 weeks before Easter. The following information is based on guidelines published by William Miller, Cornell Flower Bulb Research Program: At this point growers should be starting their fourth week of cooling at 40° F. Watch for sprouting. If you are seeing widespread sprouting lower the temperature a few degrees, but do not go below 35° F.
Modified from an article in the November 2, 2007 edition of the Greenhouse TPM/IPM Weekly Report, University of Maryland Cooperative Extension
Easter Lily Update
Easter is very early next year on March 23rd. This is 16 days earlier than 2007 and a whopping 24 days earlier than 2006. Schedule your crops accordingly! This means that right now we are at about 19 weeks before Easter. The following information is based on guidelines published by William Miller, Cornell Flower Bulb Research Program: At this point growers should be starting their fourth week of cooling at 40° F. Watch for sprouting. If you are seeing widespread sprouting lower the temperature a few degrees, but do not go below 35° F.
Modified from an article in the November 2, 2007 edition of the Greenhouse TPM/IPM Weekly Report, University of Maryland Cooperative Extension
Thursday, November 8, 2007
Landscape - Recommended Plants for Kent County
This is the first in a series on recommended landscape plants for Kent County. Green Giant Arborvitae is a good choice for a screen, border planting or windbreak. It is a good replacement for Leyland Cypress.
'Green Giant' arborvitae (Thuja standishii x plicata) is a National Arboretum introduction. It comes from a single selection originating from a cross between Japanese Arborvitae and Giant Arborvitae. ‘Green Giant’ is adapted to our Mid-Atlantic climate (heat and humidity), is tolerant of a wide variety of soils, is low maintenance, and is disease resistant. One possible concern would be bagworms. Green Giant arborvitae has a broad pyramid growth habit with mature size of 30-40 feet. It can be used as an evergreen screen, windbreak, or hedge and as specimen plant. It is somewhat tolerant of shade and is deer resistant. Growth rate is 1-2 feet per year with growth after 10 years on 20 feet in height and 8 feet in width. It roots readily from cuttings for nursery propagation. It is a good replacement for Leyland Cypress.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
'Green Giant' arborvitae (Thuja standishii x plicata) is a National Arboretum introduction. It comes from a single selection originating from a cross between Japanese Arborvitae and Giant Arborvitae. ‘Green Giant’ is adapted to our Mid-Atlantic climate (heat and humidity), is tolerant of a wide variety of soils, is low maintenance, and is disease resistant. One possible concern would be bagworms. Green Giant arborvitae has a broad pyramid growth habit with mature size of 30-40 feet. It can be used as an evergreen screen, windbreak, or hedge and as specimen plant. It is somewhat tolerant of shade and is deer resistant. Growth rate is 1-2 feet per year with growth after 10 years on 20 feet in height and 8 feet in width. It roots readily from cuttings for nursery propagation. It is a good replacement for Leyland Cypress.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Join the DNLA
The Delaware Nursery and Landscape Association is an important voice for the green industry in the state. It also provides educational opportunities for its members and the ability to obtain professional credentials through its Certified Nursery Professional program. The following is some information on the DNLA.
The Delaware Nursery & Landscape Association (DNLA) is a non-profit association of green industry professionals. Our members include retail nurseries and garden centers; wholesale growers; landscape architects, designers & contractors; landscape maintenance & irrigation firms; arborists; golf courses; state & county facilities and agencies; and allied suppliers. Member organizations continuously strive to increase their knowledge and enhance their skills in the horticulture industry. DNLA members service their customers with professionalism, and provide them with high quality products and services.
The Delaware Nursery & Landscape Association, a leader in Delaware's $745 million Green Industry, is a non-profit trade organization serving Delaware's horticultural related businesses and the companies that supply them. The DNLA's mission is to advance the common interest of its members and to promote the use, and enhance the quality, of the products and skills of the green industry. Our organization strives to attain these goals, in part, through annual conferences, trade shows, and certification programs. The DNLA also works in cooperation with the Delaware Department of Agriculture and Delaware Cooperative Extension to shape legislative and administrative policies and procedures on matters which are of interest to Delaware's Green Industry.
Be a part of the largest horticulture industry association in Delaware and take advantage of the many benefits D.N.L.A. offers:
The Delaware Nursery & Landscape Association (DNLA) is a non-profit association of green industry professionals. Our members include retail nurseries and garden centers; wholesale growers; landscape architects, designers & contractors; landscape maintenance & irrigation firms; arborists; golf courses; state & county facilities and agencies; and allied suppliers. Member organizations continuously strive to increase their knowledge and enhance their skills in the horticulture industry. DNLA members service their customers with professionalism, and provide them with high quality products and services.
The Delaware Nursery & Landscape Association, a leader in Delaware's $745 million Green Industry, is a non-profit trade organization serving Delaware's horticultural related businesses and the companies that supply them. The DNLA's mission is to advance the common interest of its members and to promote the use, and enhance the quality, of the products and skills of the green industry. Our organization strives to attain these goals, in part, through annual conferences, trade shows, and certification programs. The DNLA also works in cooperation with the Delaware Department of Agriculture and Delaware Cooperative Extension to shape legislative and administrative policies and procedures on matters which are of interest to Delaware's Green Industry.
Be a part of the largest horticulture industry association in Delaware and take advantage of the many benefits D.N.L.A. offers:
- RecognitionMembership in the D.N.L.A. identifies your business as "a cut above the rest."
- Delaware Certified Nursery Professional (CNP) Program
- Members receive discounts on training manuals and exams.
- Educational Programs, Expo Enrollment Discounts & Pesticide CNP Recertification Credits
- Delaware Horticulture Industry Expo
- Summer Turf and Nursery Expo
- Delaware Ornamental & Turf Workshop
- Landscape Awards
- Up-to-Date Information in the D.N.L.A. News
- Legislative Action & Updates
- Representation on the Water Supply Coordinating Council, Delaware Nutrient Management Commission, Delaware Invasive Species Council, Delaware Council of Farm Organizations, Delaware Community Forestry Council, Delaware Nuisance Plant Committee
- Membership in the DNLA is open to all persons/businesses engaged in a working relationship with the Green Industry.
Visit their websit at http://www.dnlaonline.org/index.php
Wednesday, November 7, 2007
Turf - Controlled Release Fertilizers in Turf
The following is a power point lesson from the turfgrass science class at North Carolina State University on slow release fertilizers. It explains the release patterns for different slow release fertilizers used on turf.
Double click on slide to go to gallery for larger images or to advance manually.
Double click on slide to go to gallery for larger images or to advance manually.
Understanding Slow Release Fertilizers
Slow release fertilizers release their nutrients in different ways. An understanding of the factors affecting nutrient release is needed to understand how to use these fertilizers in greenhouse or nursery production, in a landscape or to fertilize a turf area. The following is an article on the subject.
Many types of slow release fertilizers are available to the commercial horticulture industry. Slow release fertilizers are a great advantage over soluble fertilizers in that they can offer a complete nutritional package for a season or longer. Release rates vary from weeks to years. Some products have slow release nitrogen only, and some contain slow release N-P-K. They may be incorporated or topdressed. It's up to the greenhouse or nursery grower, landscaper, or turf manager to decide which product fits into the production plan best.
The following are some of the slow release materials available.
Non-coated products
Urea formaldehyde (UF) and methylene urea (MU) are polymeric forms of nitrogen. UF is a condensation product of urea and formaldehyde MU of methylene and urea. About one third of the total N in UF or MU is available in the first few weeks, another third in a few months, and the remaining portion in 1 to 2 years. There is an initial flush of nitrogen released that lasts about 6-8 weeks. The remainder of nitrogen releases very slowly over time can help even out the nutritional program, or provide long term nitrogen nutrition. UF and MU nitrogen is released primarily by microbial action; increasing temperature and low pH values in the medium increase the release rate. There are both solid and liquid products using UF and MU.
Isobutylidene-diurea (IBDU) is a condensation product of urea and isobutyraldehyde. The nitrogen in IBDU is released by a chemical hydrolysis reaction, and in contrast to UF nitrogen, the microbial degradation is minimal. Particle size, hardness, and the amount of water passing through the media have the biggest effect on the fertilizer release. Low pH increases hydrolysis, but temperature is not a critical factor. Commercial IBDU fertilizers contain multiple particle sizes to achieve an even release rate. The maximum duration of release for IBDU particles is about 5-6 months. In the some products, IBDU nitrogen is combined with a plastic coating technology to produce fertilizers that release over periods longer than 5-6 months.
Magnesium-ammonium phosphate (Mag-Amp, e.g., 7-40-6). Nutrients from Mag-Amp are released as the compound solubilizes; release is controlled much as described for IBDU. Compared to other slow release fertilizers, Mag-Amp is low in nitrogen content, and very high in phosphorus. Perhaps it is more properly considered a slow-release phosphorus.
Coated fertilizers.
Nursery and greenhouse growers often use one or more slow-release fertilizers with either a sulfur or synthetic polymer coating.
Sulfur-coated ureas (SCU). Sulfur-coated urea has long been popular and economical for incorporation and top-dressing. The release rate is controlled primarily by the thickness of the coating and medium temperature. The sulfur in the coating is often an advantage because it lowers the pH of the medium. A disadvantage of the traditional SCU products is that a significant portion of the total nitrogen is released early and rapidly due to cracks and imperfections in the coating.
This early release feature has been eliminated and a much more even release pattern has been achieved in the next generation in sulfur coatings, the polymer-coated SCUs. The polymer-coated SCUs are but one type of plastic coated fertilizers.
Polymer-coated fertilizers. Polymer coating technologies allow manufacturers to carefully manipulate release characteristics and to provide fertilizers that release over periods up to two years in duration. Really only cost limits the manufacturer's creativity. To initiate release from plastic-coated materials, moisture must first diffuse through the coating and solubilizes the fertilizer inside. Temperature is the key factor in the nutrient release from all of these products.
Polymer coated urea has a solid urea nitrogen core, coated with various plastic polymer coatings. Differences in coating chemistry affects membrane properties and release rate. Release is due to controlled diffusion, which is fairly constant over time and depends on coat thickness, chemistry, temperature, and moisture.
Osmocote has been an industry standard for years. The original Osmocote was a resin-coated prill containing N, P, and K. Release rates are controlled by coating thickness and temperature. As water diffused into the prill, the coating swelled and the membrane became thinner. Coating imperfections in Osmocote contributed to an initial flush of nutrients in the first week after application. There are now a range of products under the Osmocote label with mixtures of release technologies including the original Osmocote.
Newer coating technologies were developed that did not swell to the degree that Osmocote did. An example is Polyon fertilizers that contain polyurethane-coated urea. Like Osmocote, coating thickness and medium temperature control release.
In contrast to Osmocote and Polyon, The release of nutrients from polyolefin-coated fertilizers is affected by temperature, but not coating thickness. The amount of a surfactant added to the coating determines how rapidly the nutrients are released; more surfactant produces a faster release. Polyolefin resin chemistry came from Japan. Nutricote is an example of a fertilizer with this coating technology. Polyolefin-coated fertilizers do not provide an initial flush of nutrients that some slow-release fertilizers have.
Many products contain more than one of the above technologies in a blend to give different release patterns along with soluble sources. These blends often will have both quick release and slow release properties.
Modified from "Slow release fertilizers for container nursery production" by Mary Ann Rose, Commercial Landscape& Nursery Specialist, The Ohio State University
Many types of slow release fertilizers are available to the commercial horticulture industry. Slow release fertilizers are a great advantage over soluble fertilizers in that they can offer a complete nutritional package for a season or longer. Release rates vary from weeks to years. Some products have slow release nitrogen only, and some contain slow release N-P-K. They may be incorporated or topdressed. It's up to the greenhouse or nursery grower, landscaper, or turf manager to decide which product fits into the production plan best.
The following are some of the slow release materials available.
Non-coated products
Urea formaldehyde (UF) and methylene urea (MU) are polymeric forms of nitrogen. UF is a condensation product of urea and formaldehyde MU of methylene and urea. About one third of the total N in UF or MU is available in the first few weeks, another third in a few months, and the remaining portion in 1 to 2 years. There is an initial flush of nitrogen released that lasts about 6-8 weeks. The remainder of nitrogen releases very slowly over time can help even out the nutritional program, or provide long term nitrogen nutrition. UF and MU nitrogen is released primarily by microbial action; increasing temperature and low pH values in the medium increase the release rate. There are both solid and liquid products using UF and MU.
Isobutylidene-diurea (IBDU) is a condensation product of urea and isobutyraldehyde. The nitrogen in IBDU is released by a chemical hydrolysis reaction, and in contrast to UF nitrogen, the microbial degradation is minimal. Particle size, hardness, and the amount of water passing through the media have the biggest effect on the fertilizer release. Low pH increases hydrolysis, but temperature is not a critical factor. Commercial IBDU fertilizers contain multiple particle sizes to achieve an even release rate. The maximum duration of release for IBDU particles is about 5-6 months. In the some products, IBDU nitrogen is combined with a plastic coating technology to produce fertilizers that release over periods longer than 5-6 months.
Magnesium-ammonium phosphate (Mag-Amp, e.g., 7-40-6). Nutrients from Mag-Amp are released as the compound solubilizes; release is controlled much as described for IBDU. Compared to other slow release fertilizers, Mag-Amp is low in nitrogen content, and very high in phosphorus. Perhaps it is more properly considered a slow-release phosphorus.
Coated fertilizers.
Nursery and greenhouse growers often use one or more slow-release fertilizers with either a sulfur or synthetic polymer coating.
Sulfur-coated ureas (SCU). Sulfur-coated urea has long been popular and economical for incorporation and top-dressing. The release rate is controlled primarily by the thickness of the coating and medium temperature. The sulfur in the coating is often an advantage because it lowers the pH of the medium. A disadvantage of the traditional SCU products is that a significant portion of the total nitrogen is released early and rapidly due to cracks and imperfections in the coating.
This early release feature has been eliminated and a much more even release pattern has been achieved in the next generation in sulfur coatings, the polymer-coated SCUs. The polymer-coated SCUs are but one type of plastic coated fertilizers.
Polymer-coated fertilizers. Polymer coating technologies allow manufacturers to carefully manipulate release characteristics and to provide fertilizers that release over periods up to two years in duration. Really only cost limits the manufacturer's creativity. To initiate release from plastic-coated materials, moisture must first diffuse through the coating and solubilizes the fertilizer inside. Temperature is the key factor in the nutrient release from all of these products.
Polymer coated urea has a solid urea nitrogen core, coated with various plastic polymer coatings. Differences in coating chemistry affects membrane properties and release rate. Release is due to controlled diffusion, which is fairly constant over time and depends on coat thickness, chemistry, temperature, and moisture.
Osmocote has been an industry standard for years. The original Osmocote was a resin-coated prill containing N, P, and K. Release rates are controlled by coating thickness and temperature. As water diffused into the prill, the coating swelled and the membrane became thinner. Coating imperfections in Osmocote contributed to an initial flush of nutrients in the first week after application. There are now a range of products under the Osmocote label with mixtures of release technologies including the original Osmocote.
Newer coating technologies were developed that did not swell to the degree that Osmocote did. An example is Polyon fertilizers that contain polyurethane-coated urea. Like Osmocote, coating thickness and medium temperature control release.
In contrast to Osmocote and Polyon, The release of nutrients from polyolefin-coated fertilizers is affected by temperature, but not coating thickness. The amount of a surfactant added to the coating determines how rapidly the nutrients are released; more surfactant produces a faster release. Polyolefin resin chemistry came from Japan. Nutricote is an example of a fertilizer with this coating technology. Polyolefin-coated fertilizers do not provide an initial flush of nutrients that some slow-release fertilizers have.
Many products contain more than one of the above technologies in a blend to give different release patterns along with soluble sources. These blends often will have both quick release and slow release properties.
Modified from "Slow release fertilizers for container nursery production" by Mary Ann Rose, Commercial Landscape& Nursery Specialist, The Ohio State University
Tuesday, November 6, 2007
Turf and Landscape - Nitrogen and Phosphorus Winter Application Restrictions
Turf managers and landscapers are reminded that regulations in Delaware state that no nitrogen or phosphorus fertilizers may be applied to impervious surfaces, frozen ground, or between December 7 and February 15. The following is the regulation from the Delaware Department of Agriculture and the Delaware Nutrient Management Commission.
6.0 Nutrient Handling Requirements
6.1 As required by 3 Del.C §2201 et.al, Nitrogen and Phosphorus fertilizers shall be applied according to a Nutrient Management plan.
6.2 For land areas not required to have a Nutrient Management plan, applications of Nitrogen and Phosphorus fertilizers by anyone holding a commercial nutrient handler or nutrient consultant certification, or anyone required to be certified at said level pursuant to 3 Del.C. §2242 and section 4.0 herein, are prohibited when one of the following conditions exist:
6.2.1 The surface area of application is impervious such as sidewalks, roads and other paved areas and the misdirected fertilizer is not removed on the same day of application;
6.2.2 The surface area is covered by snow or frozen; or
6.2.3 The date of application is between December 7 and February 15.
6.0 Nutrient Handling Requirements
6.1 As required by 3 Del.C §2201 et.al, Nitrogen and Phosphorus fertilizers shall be applied according to a Nutrient Management plan.
6.2 For land areas not required to have a Nutrient Management plan, applications of Nitrogen and Phosphorus fertilizers by anyone holding a commercial nutrient handler or nutrient consultant certification, or anyone required to be certified at said level pursuant to 3 Del.C. §2242 and section 4.0 herein, are prohibited when one of the following conditions exist:
6.2.1 The surface area of application is impervious such as sidewalks, roads and other paved areas and the misdirected fertilizer is not removed on the same day of application;
6.2.2 The surface area is covered by snow or frozen; or
6.2.3 The date of application is between December 7 and February 15.
Greenhouse and Nursery - Controlling Liverworts
LiverwortsPhoto from the Biological Sciences Greenhouse Facility, The Ohio State University
Liverworts can be a problem pest in greenhouses and nurseries, especially in long term perennial production areas. The following is an article on this subject.
Liverworts, Marchantia polymorpha, are bryophytes that are green plants without roots that can establish themselves and become a persistent problem in a commercial greenhouse. Most people accidentally introduce liverworts by bringing in a crop plant with the liverwort present. Liverworts produce spores that can persist in a greenhouse for one year or longer. Once established it is very difficult to control in greenhouses. Removal of liverwort by hand is labor intensive and often damages the crop in the process. If this plant becomes established in a greenhouse all infested plants should be discarded and all floors, benches, structures and glazing should be sanitized using a disinfectant. For perennial crops in a greenhouse, an application of Ronstar or Surflan can be applied to substrate surfaces to prevent the spores from germinating. If young liverwort plants start to grow then try applications of ZeroTol (hydrogen dioxide), TerraCyte (sodium perocarbonate) or Physan 20 (quaternary ammonium chloride salt). These materials act as biocides and will burn back young liverwort plants. The sodium in the TerraCyte causes liverworts to desiccate and you can generally kill back about 70 % of the plants. The sprays are more effective against younger plants. Placing a layer of coarse pine bark or coca shell will keep the surface dry and make conditions less conducive for liverwort growth. The best advice is to keep liverwort infested plants out of your greenhouse. Once it is introduced it will be a difficult battle to get rid of this persistent pest.
Extracted from the November 30, 2006 issue of the Greenhouse TPM/IPM Weekly Report University of Maryland Cooperative Extension
Landscape - Natural Enemies are Key Players in Pest Management
It is critical to understand how natural controls affect pest populations in the landscape. The following is the first in a series on this subject.
Natural enemies are predators, parasitoids, and pathogens that attack and kill pests. Common predators include lady beetles and assassin bugs, parasitoids are often tiny wasps or flies, and pathogens that kill insects include specific species of nematodes, bacteria, or fungi. Natural enemies are ubiquitous in our natural and managed ecosystems. There is an abundance of data that demonstrate natural enemies are very important in preventing plant feeding insects (herbivores) from reaching population densities that cause aesthetic and/or economic damage to plants in our landscape and production systems. In managed systems we often implement practices that eliminate or reduce the populations of natural enemies so they no longer can keep herbivore populations from reaching pest outbreak levels. As plant managers the best way to prevents pests from damaging our plants is to avoid practices that are harmful to natural enemies and implement practices that will attract and/or retain natural enemies into our landscapes and production systems. This includes the wise use of pesticides: selecting products that have the least toxic effect on natural enemies, and applying pesticides at a time or by a method that reduces the likelihood of exposure of natural enemies to pesticides. Also maintain managed systems that provide natural enemies with: refuge from unfavorable environmental conditions and hiding places from their natural enemies, and an abundance of food resources (nectar, pollen, and alternative prey). This includes adding flowering plants that provide season long floral resources and adding structural complexity such as plants at varying vegetational strata (ex. over and under story trees, shrubs, herbaceous plants, and ground covers).
Extracted from "Natural Enemies are Key Players in Pest Management" by Paula Shrewsbury, Extension IPM Specialist with the University of Maryland in the March 30, 2007 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers, University of Maryland Cooperative Extension
Natural enemies are predators, parasitoids, and pathogens that attack and kill pests. Common predators include lady beetles and assassin bugs, parasitoids are often tiny wasps or flies, and pathogens that kill insects include specific species of nematodes, bacteria, or fungi. Natural enemies are ubiquitous in our natural and managed ecosystems. There is an abundance of data that demonstrate natural enemies are very important in preventing plant feeding insects (herbivores) from reaching population densities that cause aesthetic and/or economic damage to plants in our landscape and production systems. In managed systems we often implement practices that eliminate or reduce the populations of natural enemies so they no longer can keep herbivore populations from reaching pest outbreak levels. As plant managers the best way to prevents pests from damaging our plants is to avoid practices that are harmful to natural enemies and implement practices that will attract and/or retain natural enemies into our landscapes and production systems. This includes the wise use of pesticides: selecting products that have the least toxic effect on natural enemies, and applying pesticides at a time or by a method that reduces the likelihood of exposure of natural enemies to pesticides. Also maintain managed systems that provide natural enemies with: refuge from unfavorable environmental conditions and hiding places from their natural enemies, and an abundance of food resources (nectar, pollen, and alternative prey). This includes adding flowering plants that provide season long floral resources and adding structural complexity such as plants at varying vegetational strata (ex. over and under story trees, shrubs, herbaceous plants, and ground covers).
Extracted from "Natural Enemies are Key Players in Pest Management" by Paula Shrewsbury, Extension IPM Specialist with the University of Maryland in the March 30, 2007 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers, University of Maryland Cooperative Extension
Monday, November 5, 2007
Greenhouse and Nursery - Downy Mildew
Downy mildew is becoming more of a problem in greenhouses and perennial nurseries. Greenhouse growers, perennial growers, and garden centers should be aware of this disease. The following is a presentation on downy mildew in common annual and perennial plants.
Click to go to gallery for larger images and to manually view.
From a presentation by Bob Mulrooney, Extension Plant Pathologist, University of Delaware at the 2007 Greenhouse Session at Delaware Agriculture Week.
Click to go to gallery for larger images and to manually view.
From a presentation by Bob Mulrooney, Extension Plant Pathologist, University of Delaware at the 2007 Greenhouse Session at Delaware Agriculture Week.
Building the Next Generation of Customers
Horticultural businesses such as greenhouses, nurseries, garden centers, and landscapers should consider ways to connect to youth who will become the next generation of customers. The following is a presentation that I gave on this subject.
Click to enlarge or go to album.
Powerpoint presentation by Gordon Johnson
Click to enlarge or go to album.
Powerpoint presentation by Gordon Johnson
Diseases - How Plants Defend Themselves Against Diseases
One of the issues with plant diseases during and following a drought year is that there is reduced resistance to plant diseases due to reduced plant defences. The following is a list of the different ways plants defend against disease.
How plants defend themselves against diseases
Constitutive (passive) plant defenses
Structural
- bark
- bud scales
- collenchyma/sclerenchyma (protect vascular bundles)
- defense trichomes (hairs)
- position, size, and shape of stomata on lower leaf surface
- the suberized outer layers of bulbs, corms, and tubers
- waxy cuticle
- suberin (similar to waxy cuticle) on primary roots (however, root hairs and root apical meristems are extremely vulnerable to attack)
Chemical (these are secondary metabolites, which are not necessary for growth of the plant)
- cyanogenic glucosides (cyanide bound to sugar molecules)
- phenolic glucosides (phenols bound to sugar molecules)
Induced (active) plant defenses
Structural
- abscission layers (infected portions of leaves drop out and block further invasion of the pathogen)
- cork layers (block further invasion of the pathogen)
- gums or resins (create barriers against invading pathogens in wounds or vascular tissue)
- papillae of callose (thickenings that prevent entry of a pathogen into a cell)
- thickening or lignification of cell walls
- tyloses
Chemical
- pathogenesis-related (PR) proteins (enzymes and other proteins produced as defense compounds)
- phytoalexins (defense compounds toxic specifically to the pathogens of the host plant)
Information from "The Relationship of Plant Stress to Plant Disease" by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the May 31, 2007 issue of the Plant and Pest Advisory, Landscape, Nursery, and Turf edition.
How plants defend themselves against diseases
Constitutive (passive) plant defenses
Structural
- bark
- bud scales
- collenchyma/sclerenchyma (protect vascular bundles)
- defense trichomes (hairs)
- position, size, and shape of stomata on lower leaf surface
- the suberized outer layers of bulbs, corms, and tubers
- waxy cuticle
- suberin (similar to waxy cuticle) on primary roots (however, root hairs and root apical meristems are extremely vulnerable to attack)
Chemical (these are secondary metabolites, which are not necessary for growth of the plant)
- cyanogenic glucosides (cyanide bound to sugar molecules)
- phenolic glucosides (phenols bound to sugar molecules)
Induced (active) plant defenses
Structural
- abscission layers (infected portions of leaves drop out and block further invasion of the pathogen)
- cork layers (block further invasion of the pathogen)
- gums or resins (create barriers against invading pathogens in wounds or vascular tissue)
- papillae of callose (thickenings that prevent entry of a pathogen into a cell)
- thickening or lignification of cell walls
- tyloses
Chemical
- pathogenesis-related (PR) proteins (enzymes and other proteins produced as defense compounds)
- phytoalexins (defense compounds toxic specifically to the pathogens of the host plant)
Information from "The Relationship of Plant Stress to Plant Disease" by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers University in the May 31, 2007 issue of the Plant and Pest Advisory, Landscape, Nursery, and Turf edition.
Insects - Multicolored Asian Lady Beetle
Multicolored Asian Lady BeetlePhoto by Bill Ree, Texas A&M University, Bugwood.org
One of the fall nuisance pests is the multicolored Asian lady beetle. It congregates on the walls of houses and can enter to overwinter in houses. However, this is also a beneficial insect and populations have increases recently as it is one of the natural controls for soybean aphid in soybean fields. The following is an article on this insect.
The multicolored Asian lady beetle is one of several species of lady beetles in Delaware . Adult multicolored Asian lady beetles exhibit the familiar oval lady beetle shape. Slightly larger than most of our native species – about 1/4" long by 3/16" wide – they are variable in color. Adults may be yellow, orange or red with black spots of various sizes on the wing covers. Beetles with 2, 4, 6, 10 and up to 19 spots have been found; some have no spots. The pronotum often has a "M"-like shape of black on the white- or cream-colored exoskeleton. When viewed from above, the head is concealed by the pronotum.
The life cycle from egg to adult takes about 36 days, beginning in mid-spring while the weather is still cool. The eggs are laid on the undersides of leaves of low-growing ornamentals, roses, wheat, tobacco, and other crops. Eggs clustered with 10 to 20 in one spot are yellow-orange and stand upright on lower leaf surfaces. They take from 3 to 5 days to hatch. The larvae are elongate and flattened with the familiar "alligator" shape of immature lady beetles.
The multicolored Asian lady beetle prefers to feed on host insects that live within trees. Favorite feeding hosts include maple, walnut, willow, and oak. Both larvae and adults feed on various aphids, certain scales, and a few other insects. It is an effective predator of aphids on pecan and apple trees, in evergreens, on ornamental shrubs, roses, and other plants. Beetle populations tend to explode when there is an abundance of aphids, often to the detriment of local aphid populations.
Although the multicolored Asian lady beetle is an important biological control agent, it can become a nuisance when adults aggregate in large numbers on homes or other buildings during autumn. It is sometimes called the "Halloween" beetle because it shows up in homes in late October. The massed beetles typically cluster on sunny, southwest sides of light-colored houses, barns, farm silos, rock outcroppings or structures where nearby crevices serve as overwintering sites.
Homeowners complain when hundreds/thousands of beetles are observed clustering on the side of their house. As daytime temperatures cool the beetles seek to enter by crawling through openings such as uncaulked window frames. Once inside, they cluster together. They do not bite, sting, or carry human diseases, they do not feed on wood, clothing, or food, nor do they breed indoors, but there sheer numbers can be a nuisance. They also create problems when they become active in February and March during warm, sunny days and attempt to return outside. During this time, they show up at windows as they attempt to leave the house.
Prevention is the key to managing nuisance populations of the multicolored Asian lady beetles. The easiest way to dispose of live/dead beetles inside the home during the fall or winter is with a vacuum cleaner or broom. Most beetles emerge from over winter hibernation during a 3- to 6-week period and will not survive more than a few days indoors. As they attempt to escape to their natural habitat outdoors, some inadvertently disperse into living areas. Since the beetles are attracted to light, they are often seen around windows and lighting fixtures. As the weather continues to warm, the beetles disperse outdoors and they cease to be a nuisance.
The multicolored Asian lady beetle is one of several species of lady beetles in Delaware . Adult multicolored Asian lady beetles exhibit the familiar oval lady beetle shape. Slightly larger than most of our native species – about 1/4" long by 3/16" wide – they are variable in color. Adults may be yellow, orange or red with black spots of various sizes on the wing covers. Beetles with 2, 4, 6, 10 and up to 19 spots have been found; some have no spots. The pronotum often has a "M"-like shape of black on the white- or cream-colored exoskeleton. When viewed from above, the head is concealed by the pronotum.
The life cycle from egg to adult takes about 36 days, beginning in mid-spring while the weather is still cool. The eggs are laid on the undersides of leaves of low-growing ornamentals, roses, wheat, tobacco, and other crops. Eggs clustered with 10 to 20 in one spot are yellow-orange and stand upright on lower leaf surfaces. They take from 3 to 5 days to hatch. The larvae are elongate and flattened with the familiar "alligator" shape of immature lady beetles.
The multicolored Asian lady beetle prefers to feed on host insects that live within trees. Favorite feeding hosts include maple, walnut, willow, and oak. Both larvae and adults feed on various aphids, certain scales, and a few other insects. It is an effective predator of aphids on pecan and apple trees, in evergreens, on ornamental shrubs, roses, and other plants. Beetle populations tend to explode when there is an abundance of aphids, often to the detriment of local aphid populations.
Although the multicolored Asian lady beetle is an important biological control agent, it can become a nuisance when adults aggregate in large numbers on homes or other buildings during autumn. It is sometimes called the "Halloween" beetle because it shows up in homes in late October. The massed beetles typically cluster on sunny, southwest sides of light-colored houses, barns, farm silos, rock outcroppings or structures where nearby crevices serve as overwintering sites.
Homeowners complain when hundreds/thousands of beetles are observed clustering on the side of their house. As daytime temperatures cool the beetles seek to enter by crawling through openings such as uncaulked window frames. Once inside, they cluster together. They do not bite, sting, or carry human diseases, they do not feed on wood, clothing, or food, nor do they breed indoors, but there sheer numbers can be a nuisance. They also create problems when they become active in February and March during warm, sunny days and attempt to return outside. During this time, they show up at windows as they attempt to leave the house.
Prevention is the key to managing nuisance populations of the multicolored Asian lady beetles. The easiest way to dispose of live/dead beetles inside the home during the fall or winter is with a vacuum cleaner or broom. Most beetles emerge from over winter hibernation during a 3- to 6-week period and will not survive more than a few days indoors. As they attempt to escape to their natural habitat outdoors, some inadvertently disperse into living areas. Since the beetles are attracted to light, they are often seen around windows and lighting fixtures. As the weather continues to warm, the beetles disperse outdoors and they cease to be a nuisance.
From the factsheet "Multicolored Asian Lady Beetle" by Dewey M. Caron, Extension Entomologist, University of Delaware
Sunday, November 4, 2007
Landscape and Turf - Controlling Bamboo
I recently received several questions on controlling bamboo. The following is an article that I wrote for our Ornamentals Hotline on the subject.
Bamboo has caused many disputes between neighbors due to the propensity of running types to invade adjoining properties. One recommendation is not to use invasive types of bamboo but plant clumping types such as Chinese Mountain Bamboo or Umbrella bamboo instead. Unfortunately, many clumping types are not well adapted to our Delaware climate. If a spreading type such as a Phyllostachys species is desired, then containment is necessary, especially if near a property line. A barrier made of metal, concrete, plastic, fiberglass, or treated wood should be installed at least 2 feet deep and slanted at an angle outward. This will deflect the bamboo rhizomes so when they hit the barrier they will turn upwards and the shoots can be controlled (physically removed) when they appear above the barrier. Inspect barriers at least 2 times a year for these escapes.
If bamboo has escaped, first, trench or use a spade to cut the rhizomes in the invading area off from the mother plant. Then cut the stand to the ground and allow to regrow. Frequent mowing will control bamboo so consider converting the area to turf. If the invaded area is in landscape beds, control is more difficult and involves physical removal of the rhizomes or herbicide treatment. Herbicides are limited in their ability to control bamboo. Czarnota and Derr (U Ga and Va Tech) conducted experiments on two Phyllostachys species. They found that “MSMA, quinclorac, dithiopyr, clethodim, fenoxaprop, and sethoxydim did not control either species” tested. “Glyphosate, glufosinate, and fluazifop significantly reduced bamboo-shoot fresh weight, although regrowth occurred after a single application.” In this same research, Bamboo control with dichlobenil (Casoron) was less than 23%. Glyphosate and imazapyr provided 76% and 98% bamboo control, respectively, at 58 weeks after treatment. Imazapyr (Arsenal, Sahara) is limited to use on forestry sites and right-of-ways. For horticultural uses, repeated spot applications of glyphosate (Roundup, others) will give the best control. However, as many as 4 applications may be needed.
To see pictures from the bamboo control research mentioned above go to the 9/4/07 post in the archives on this blog.
Article by Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Bamboo has caused many disputes between neighbors due to the propensity of running types to invade adjoining properties. One recommendation is not to use invasive types of bamboo but plant clumping types such as Chinese Mountain Bamboo or Umbrella bamboo instead. Unfortunately, many clumping types are not well adapted to our Delaware climate. If a spreading type such as a Phyllostachys species is desired, then containment is necessary, especially if near a property line. A barrier made of metal, concrete, plastic, fiberglass, or treated wood should be installed at least 2 feet deep and slanted at an angle outward. This will deflect the bamboo rhizomes so when they hit the barrier they will turn upwards and the shoots can be controlled (physically removed) when they appear above the barrier. Inspect barriers at least 2 times a year for these escapes.
If bamboo has escaped, first, trench or use a spade to cut the rhizomes in the invading area off from the mother plant. Then cut the stand to the ground and allow to regrow. Frequent mowing will control bamboo so consider converting the area to turf. If the invaded area is in landscape beds, control is more difficult and involves physical removal of the rhizomes or herbicide treatment. Herbicides are limited in their ability to control bamboo. Czarnota and Derr (U Ga and Va Tech) conducted experiments on two Phyllostachys species. They found that “MSMA, quinclorac, dithiopyr, clethodim, fenoxaprop, and sethoxydim did not control either species” tested. “Glyphosate, glufosinate, and fluazifop significantly reduced bamboo-shoot fresh weight, although regrowth occurred after a single application.” In this same research, Bamboo control with dichlobenil (Casoron) was less than 23%. Glyphosate and imazapyr provided 76% and 98% bamboo control, respectively, at 58 weeks after treatment. Imazapyr (Arsenal, Sahara) is limited to use on forestry sites and right-of-ways. For horticultural uses, repeated spot applications of glyphosate (Roundup, others) will give the best control. However, as many as 4 applications may be needed.
To see pictures from the bamboo control research mentioned above go to the 9/4/07 post in the archives on this blog.
Article by Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Landscape - Dormant Season Pruning Guidelines
The winter season is fast approaching. Landscape maintenance companies will schedule dormant pruning during this period. The following is an article on dormant season pruning. Although geared toward trees, the concepts equally apply to shrubs.
Under optimal growing conditions, the appropriate time to prune will depend on the type of plant, its condition and the desired results. During the winter months, a closer inspection of the interior growth habit, or skeleton, of the tree or shrub can often reveal several maintenance issues that might have otherwise gone undetected due to the cover of foliage. Dormant landscape pruning can be a very effective and cost efficient method in controlling the future growth and overall health of your landscape investment.
The need for proper pruning and decision-making cannot be overemphasized. Visualizing the end product of your actions can be extremely difficult. Periodically stepping back to inspect the form and structure while pruning can be an invaluable method in avoiding the chance of over-pruning. Under normal circumstances, no more than twenty-five percent of the current crown should be removed during a given year.
Pruning is by definition the controlled wounding of the plant for a specific purpose or desired effect. The specific type of pruning necessary to maintain a tree in a healthy, safe and attractive condition has recently been defined in a national set of standards. These classifications can easily be applied to shrubs and other ornamentals throughout the landscape.
>Crown Cleaning: The removal of dead, dying, diseased, crowded, weakly attached and low-vigor branches from the crown of the tree.
>Crown Thinning: The selective removal of branches to increase light penetration and air movement through the crown. Thinning opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape.
>Crown Raising: Removes the lower branches from a tree in order to provide clearance for buildings, vehicles, pedestrians, and vistas.
>Crown Reduction: Reduces the size of a tree, often for clearance for utility lines. Reducing the height or spread of a tree is best accomplished by pruning back the leaders and branch terminals to lateral branches that are large enough to assume terminal roles. This method replaces the unethical practice of topping, which is the indiscriminate reduction of a tree’s canopy.
Most routine pruning to remove a flush of growth, weak, diseased or dead limbs can be accomplished at any time of the year. However, there are several major benefits to timing routine or maintenance pruning during the winter months. Trees produce a dense crown of leaves to manufacture the sugar used as energy for growth and development. Pruning trees and shrubs during the dormant season does not interrupt this nutrient and growth cycle, and can result in an efficient re-direction of growth during the following spring. Dormant pruning reduces the number of buds or growing tips sharing the stored food reserves from the roots, so each remaining bud can grow more vigorously the following spring. Dormant pruning of summer flowering shrubs, whose flower buds are formed on new growth, will also encourage larger flowers.
Some trees, such as maples and birches, tend to “bleed” if pruned during the late winter or early spring. Though by itself of little consequence to the health of the tree, these unsightly stains and wounds may create an issue with some of your clients. Information provided prior to any late winter season pruning should address this issue.
Disease and pest management are also crucial in scheduling winter pruning. Oaks and elms are prime examples of where winter or dormant pruning may be preferred. Oak wilt diseases are active during the growing season, and fresh pruning wounds can allow spores access into the tree. Untreated saws can also inadvertently spread the disease from cut to cut. Wood borers that may be carrying Dutch Elm Disease spores will also utilize fresh spring pruning cuts as an entrance to previously unaffected trees. Winter pruning of evergreens will least likely attract borers. Timed properly, pruning may actually reduce the need for additional chemical pest control and disease suppression throughout the growing season. Knowing the biology of these and other pests and how they may interact with your pruning decisions and expertise will be the key to creating and maintaining a successful, healthy and aesthetically pleasing landscape for years to come.
Article reprinted from "Dormant Season Landscape Maintenance: The Benefits of Winter Pruning" by Nicholas Polanin, Agricultural Agent, Rutgers Cooperative Extension of Somerset County, in the March 15, 2007 edition of the Landscape, Nursery, and Turf edition of the Plant and Pest Advisory from Rutgers (NJ) Cooperative Extension.
Under optimal growing conditions, the appropriate time to prune will depend on the type of plant, its condition and the desired results. During the winter months, a closer inspection of the interior growth habit, or skeleton, of the tree or shrub can often reveal several maintenance issues that might have otherwise gone undetected due to the cover of foliage. Dormant landscape pruning can be a very effective and cost efficient method in controlling the future growth and overall health of your landscape investment.
The need for proper pruning and decision-making cannot be overemphasized. Visualizing the end product of your actions can be extremely difficult. Periodically stepping back to inspect the form and structure while pruning can be an invaluable method in avoiding the chance of over-pruning. Under normal circumstances, no more than twenty-five percent of the current crown should be removed during a given year.
Pruning is by definition the controlled wounding of the plant for a specific purpose or desired effect. The specific type of pruning necessary to maintain a tree in a healthy, safe and attractive condition has recently been defined in a national set of standards. These classifications can easily be applied to shrubs and other ornamentals throughout the landscape.
>Crown Cleaning: The removal of dead, dying, diseased, crowded, weakly attached and low-vigor branches from the crown of the tree.
>Crown Thinning: The selective removal of branches to increase light penetration and air movement through the crown. Thinning opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape.
>Crown Raising: Removes the lower branches from a tree in order to provide clearance for buildings, vehicles, pedestrians, and vistas.
>Crown Reduction: Reduces the size of a tree, often for clearance for utility lines. Reducing the height or spread of a tree is best accomplished by pruning back the leaders and branch terminals to lateral branches that are large enough to assume terminal roles. This method replaces the unethical practice of topping, which is the indiscriminate reduction of a tree’s canopy.
Most routine pruning to remove a flush of growth, weak, diseased or dead limbs can be accomplished at any time of the year. However, there are several major benefits to timing routine or maintenance pruning during the winter months. Trees produce a dense crown of leaves to manufacture the sugar used as energy for growth and development. Pruning trees and shrubs during the dormant season does not interrupt this nutrient and growth cycle, and can result in an efficient re-direction of growth during the following spring. Dormant pruning reduces the number of buds or growing tips sharing the stored food reserves from the roots, so each remaining bud can grow more vigorously the following spring. Dormant pruning of summer flowering shrubs, whose flower buds are formed on new growth, will also encourage larger flowers.
Some trees, such as maples and birches, tend to “bleed” if pruned during the late winter or early spring. Though by itself of little consequence to the health of the tree, these unsightly stains and wounds may create an issue with some of your clients. Information provided prior to any late winter season pruning should address this issue.
Disease and pest management are also crucial in scheduling winter pruning. Oaks and elms are prime examples of where winter or dormant pruning may be preferred. Oak wilt diseases are active during the growing season, and fresh pruning wounds can allow spores access into the tree. Untreated saws can also inadvertently spread the disease from cut to cut. Wood borers that may be carrying Dutch Elm Disease spores will also utilize fresh spring pruning cuts as an entrance to previously unaffected trees. Winter pruning of evergreens will least likely attract borers. Timed properly, pruning may actually reduce the need for additional chemical pest control and disease suppression throughout the growing season. Knowing the biology of these and other pests and how they may interact with your pruning decisions and expertise will be the key to creating and maintaining a successful, healthy and aesthetically pleasing landscape for years to come.
Article reprinted from "Dormant Season Landscape Maintenance: The Benefits of Winter Pruning" by Nicholas Polanin, Agricultural Agent, Rutgers Cooperative Extension of Somerset County, in the March 15, 2007 edition of the Landscape, Nursery, and Turf edition of the Plant and Pest Advisory from Rutgers (NJ) Cooperative Extension.
Saturday, November 3, 2007
Turf Weed Images - How Many Can You Identify?
Click Pictures for larger image or to go to album for manual advance.
Friday, November 2, 2007
Landscape and Turf - Compost Suppliers in Southern Delaware
I often recommend the use of compost in establishing or renovating landscapes and turf areas. A question that arises is where can you buy large quantities of compost. The following are some suppliers in Southern Delaware and nearby Maryland.
Blessing Greenhouses and Compost Facility, Bruce E. Blessing, PO Box 512, Milford, DE 19963
Phone: (302)-393-3273, E-mail: mailto:mblessingscompost@yahoo.com
Two types of compost: 20,000 tons/yr. Mixed organics from food processing and poultry plants. Municipal biosolids (composted separately). Certified by the Delaware Department of Agriculture as a soil amendment.
For sale: bulk and in bags, for pick-up.
Grizzly’s Landscape Supply and Services, Inc., Dick Pack, 20144 John J. Williams Hwy., Lewes, DE 19958-4339, Phone: (800) 355-4544 Fax: (302) 644-0654, Email: mailto:mgrizzly@dmv.com website: http://www.grizzlycompost.com/
Yard debris compost: 5,000 yd3/yr. Poultry litter compost: 3,000 yd3/yr. Blended topsoil, compost, composted wood fines: 7,000 yd3/yr. For sale: bulk or bagged for pick-up or delivery.
The City of Seaford has compost for sale. The compost can be used on lawns, gardens and ornamental plants. The cost is $10.00 per cubic yard. The compost may be picked up on Wednesdays and Fridays from the Composting Facility at 403 Nanticoke Avenue (across from the boat ramp). Call 629-0120 for more information.
The City of Dover has leaf compost that residents can have access to at times. Call the Public Works Department at 736-7025 for more information.
Coastal Supply Company, Inc., 1000 Main Street, Dagsboro, DE 19939, 302-732-6624, 1-800-235-7645. Has compost based soil mixes shipped from its Maryland facility.
I will be adding to this list in the future.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Blessing Greenhouses and Compost Facility, Bruce E. Blessing, PO Box 512, Milford, DE 19963
Phone: (302)-393-3273, E-mail: mailto:mblessingscompost@yahoo.com
Two types of compost: 20,000 tons/yr. Mixed organics from food processing and poultry plants. Municipal biosolids (composted separately). Certified by the Delaware Department of Agriculture as a soil amendment.
For sale: bulk and in bags, for pick-up.
Grizzly’s Landscape Supply and Services, Inc., Dick Pack, 20144 John J. Williams Hwy., Lewes, DE 19958-4339, Phone: (800) 355-4544 Fax: (302) 644-0654, Email: mailto:mgrizzly@dmv.com website: http://www.grizzlycompost.com/
Yard debris compost: 5,000 yd3/yr. Poultry litter compost: 3,000 yd3/yr. Blended topsoil, compost, composted wood fines: 7,000 yd3/yr. For sale: bulk or bagged for pick-up or delivery.
The City of Seaford has compost for sale. The compost can be used on lawns, gardens and ornamental plants. The cost is $10.00 per cubic yard. The compost may be picked up on Wednesdays and Fridays from the Composting Facility at 403 Nanticoke Avenue (across from the boat ramp). Call 629-0120 for more information.
The City of Dover has leaf compost that residents can have access to at times. Call the Public Works Department at 736-7025 for more information.
Coastal Supply Company, Inc., 1000 Main Street, Dagsboro, DE 19939, 302-732-6624, 1-800-235-7645. Has compost based soil mixes shipped from its Maryland facility.
I will be adding to this list in the future.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Turf - Critical Temperatures
Cool season and warm season turfgrasses respond differently to temperatures. The following is some information on this topic.
Temperatures Affecting Turfgrass
This info is from a report published by the North Carolina State University Turf Council (“Soil Temperature Reports Aid Managers” March 31, 2005) shows the impact of soil temperature on cool and warm season turf:
Excerpted from the report:
The following is a partial list of soil temperatures (F) at the 4-inch depth that should be of the association with certain biological events.
Cool Season Grasses (fescue, bluegrass, ryegrass):
Temperatures Affecting Turfgrass
This info is from a report published by the North Carolina State University Turf Council (“Soil Temperature Reports Aid Managers” March 31, 2005) shows the impact of soil temperature on cool and warm season turf:
Excerpted from the report:
The following is a partial list of soil temperatures (F) at the 4-inch depth that should be of the association with certain biological events.
Cool Season Grasses (fescue, bluegrass, ryegrass):
- 90°F Shoot growth ceases.
- 77°F Root growth ceases.
- 70°F Maximum temperature for root growth of any consequence.
- 70°F Time to plant grasses in late summer.
- 60°-75°F Optimum temperature for shoot growth.
- 50°-65°F Optimum temperature for root growth.
- 40°F Shoot growth ceases.
- 33°F Root growth ceases.
- 20°F Low temperature kill possible if temperature subsequently drops
rapidly below 20F
Warm Season Grasses (bermudagrass, zoysia):
- 120°F Shoot growth ceases.
- 110°F Root growth ceases.
- 80°-90°F Optimum shoot growth.
- 75°-85°F Optimum root growth.
- 74°F Optimum time to overseed bermudagrass with ryegrass in the fall.
Time to plant grasses in the spring. - 64°F Expected spring root decline is triggered and roots turn brown
and die within 1 or 2 days. - 50°F Root growth begins to slow below this temperature.
- 50°F Chilling injury resulting in discoloration is possible.
50°F Initiation of dormancy occurs resulting in discoloration. - 25°F Low temperature kill possible.
Thursday, November 1, 2007
Greenhouse - Conserving Energy
From an energy standpoint, greenhouse growers have been blessed with a warm fall. However, the heating season is now upon us. With the high cost of fuel, growers should consider all economical methods to reduce energy costs. The following are some suggestions.
Conserving Energy in Greenhouses
The Greenhouse Structure
Conserving Energy in Greenhouses
The Greenhouse Structure
- The first line of defense in efficient heating of a greenhouse is the structure itself. Losses vary depending on the greenhouse covering and the age of the structure. In general, newer structures will have better seals around the coverings and openings than older houses.
- Double poly - Double polyethylene (poly) coverings reduce heating costs about 50% compared to single poly coverings. Most greenhouses in Virginia that are used for winter production are inflated double poly houses. Different polyethylene films vary from 35% to 60% heat loss. Ask your supplier about the film's thermal value. Selecting films that reduce water condensation will enhance light transmission and improve heat retention. Maintaining proper inflation between double poly layers is critical to maximizing the insulation value of the covering.
- Retrofitting - A glass greenhouse can be covered with one or, preferably, a double, inflated layer of poly for extra insulation during the winter. A single layer of film over glass can reduce annual heating costs by 5% to 40% whereas a double (inflated) layer can reduce costs 40% to 60%. Remember that there is a tradeoff between increased energy efficiency and reduced light transmission with additional layers of poly.
- Winterize openings - A tight greenhouse with few air leaks around vents, fans or doors will cost less to heat. Repair any holes in the plastic, glass or doors. Keep doors closed and caulk or weatherstrip door frames and other openings.
Maximize the Insulation
- Endwalls - Insulate the endwalls of the greenhouse, especially the north endwall. In most parts of Virginia, the north endwall provides very little light for crop production. This wall can actually be constructed of a solid material like wood. Plywood (1/2-inch thick) will lose about the same amount of heat as a double poly wall. At least, insulate this wall for winter production. Reflective (foil backed) insulation boards provide better insulation than other rigid foam boards. Place them with the reflective side facing into the greenhouse. If possible, add windbreaks outside the greenhouse along the north wall. These may be conifers planted for screening or a temporary fence material to divert the wind over the greenhouse. The south endwall can be insulated with an extra layer of plastic.
- Foundations on new construction - On new construction, foundation heat loss can be reduced by half through the installation of 1 to 2 inches of polyurethane or polystyrene insulation. This insulation should be installed 1.5 to 2 feet deep around the foundation wall with care given not to leave gaps or openings. This is especially important when installing any type of floor heating system.
- Existing foundation and side walls - If the foundation of the greenhouse was not insulated during construction, make sure that all gaps or holes below the foundation board are filled or repaired. If the greenhouse has a concrete kneewall, insulating the inside of it with insulation board can significantly reduce heat loss. Reflective insulation boards can be added to the inside of any flat greenhouse wall but should not extend above the crop or bench height. Leave a small airspace between the insulation and the sidewall to prevent freezing of the greenhouse wall. Be sure that the reflective surfaces are not in contact with perimeter heating pipes. Sidewall insulation can reduce annual heating costs 5% to 10%.
Fans and vents - To reduce other air leaks, insulate secondary fans and vents to reduce heat loss through unused areas during the winter. Do not cover all of the vents; remember that winter ventilation is required for humidity control and to restore the oxygen/carbon dioxide balance in the greenhouse. Keep these vents in good working condition so that they close tightly when not in use.
Add a Thermal Blanket
- Up to 85% of the heat loss from a greenhouse occurs at night. Using a thermal blanket to retain heat at night can be a cost efficient investment. These blankets are easier to install and create less shading in gutter-connected houses than in a quonset house. Remember to use a porous curtain material so that condensation from the underside of the roof of the greenhouse will not pool above the plants. For greenhouse structures where an internal curtain cannot be installed, external curtains are available that can reduce radiation loss from the greenhouse at night.
- Reductions in heat loss - Blankets offered primarily for heat retention can reduce energy use by up to 50%, whereas blankets offered as combination thermal blanket and summer shade protection can reduce winter energy use 25% or more.
Recouping installation costs - With purchase and installation costs running $1.00 to $1.50 per square foot, these systems pay for themselves in one to two years or less under high fuel prices. - Installation details - Make sure that the blanket fits the greenhouse walls tightly to reduce heat loss above the blanket. Heating or water lines should be located below the blanket or be well insulated to reduce heat loss.
- Open slowly - Take care not to open the blankets too quickly over a chill-sensitive crop. On 10°F to 20°F nights, the temperature above the thermal blanket could be 30°F in a 60°F greenhouse. Open the blanket 6 to 12 inches for about 30 minutes to allow mixing of the air before opening it completely. Some growers wait until the sun has risen and warmed the air above the blanket before opening it and allowing that air to mix with the rest of the greenhouse air. That may be dictated by the light requirements of the crop.
Keep it open during snowstorms - In the case of snow storms, the blanket should be left open to allow the heat to reach the roof to prevent snow accumulation on the roof of the greenhouse.
Heating System Efficiencey
- Maintaining maximum heating efficiency of the existing heating system is critical to reducing heating costs in the greenhouse.
- Annual maintenance - Examine the equipment for physical damage to any parts of the system. Check the vent pipe and air inlet or discharge pipes for obstructions (i.e., bird nests). Furnaces should be cleaned and adjusted at least once per year. Check that the boiler, burner and backup systems are operating in peak efficiency. Clean the soot from inside the furnace. A 1/8-inch layer of soot can increase fuel consumption by as much as 10%.
- Fuel choice - Use the proper fuel for the system for maximum efficiency.
- Insulation - Insulate boiler or distribution pipes in areas where heat is not needed.
External air for combustion - Install an air inlet pipe for direct fired heaters to provide fresh air for combustion from outside the greenhouse. - Clean radiation surfaces - Clean heating pipes or other heat radiation surfaces frequently.
Motors and pumps - Keep all motors and pumps properly maintained for maximum efficiency. - WARNING: Do not inhibit the fresh air supply to the greenhouse heater. If you are using a heater that requires greenhouse air for combustion, be sure to leave about 1 square inch of opening for each 2,000 Btu/hr of heater output. If possible add an inlet pipe from outside air to serve the burner.
Add Horizontal Air Flow (HAF) Fans
- Reducing air leaks and heat loss in the greenhouse will make the house "tighter" which will also tend to increase the relative humidity. Regardless of the type of heating system used, install a sufficient number of horizontal air flow (HAF) fans to adequately circulate the air inside the greenhouse. Good air circulation will improve temperature and humidity uniformity in the greenhouse, which reduces the incidence of cold pockets in the greenhouse and improves plant quality and uniformity. Monitor the humidity level in the house, generally keeping it below 80% to minimize disease incidence, and vent when necessary.
- Air speed - Air circulation by the HAF fans should be maintained at 2 to 3 cubic feet per minute over the floor surface of the greenhouse. For example, a 28-foot x 96-foot greenhouse requires an airflow of 5,376 cubic feet per minute (28 x 96 x 2 cubic feet per min per square foot = 5,376 cubic feet per minute). This greenhouse would require four HAF fans capable of moving air at 1,440 cubic feet per minute. This could be provided by four 16-inch fans with 1/15-horsepower motors at 1,600 revolutions per minute. (See reference D. Ross, UMd Bulletin 351 for more details.) Horizontal air flow fans are generally available in two air flow capacities, but check the fan specifications to determine that they meet the calculated needs.
- Fan location - The HAF fans should be located 2 to 3 feet above the plants and aligned parallel to the sidewalls of the greenhouse so that the air is circulated around the house in a rotational pattern.
- Winter operation - The HAF fans should be run continuously during the winter to improve temperature and humidity uniformity in the greenhouse.
Environmental Control
- Use aspirated thermostats - Thermostats should be aspirated with greenhouse air and be placed near the plant canopy in locations representative of the rest of the greenhouse (not near sidewalls, fans, or doors). Aspirated thermostats save 2% to 3% of the total fuel bill by improving fan and heater operation.
- Electronic thermostats - Switching to solid-state electronic thermostats can also improve efficiency by reducing the differential between the on and off modes, usually down to 1°F instead of the 3°F to 4°F of mechanical thermostats.
- Calibrate sensors - Calibrate the sensors regularly to maintain proper environmental temperatures. If you are lowering greenhouse growing temperatures, sensors must be accurate to avoid chilling damage to the crop.
Information extracted from "Dealing with the High Cost of Energy for Greenhouse Operations" by Joyce G. Latimer, Extension Specialist, Greenhouse Crops; Virginia Tech
Greenhouse - Mealybugs and Their Control
Longtailed mealybugs have seventeen pairs of white waxy filaments around the periphery of the body (if you care to count them). The mature females have two tail-like projections projecting from their rear that are longer than the length of the body.
Citrus mealybug is recognized by a thin purple stripe that runs down the middle of the back. These mealybugs are densely covered with white wax and have very short tails.Mealybugs can be a problem pest in greenhouses, expecially on longer term greenhouse crops. Once established they are very hard to control. The following is an article on mealybugs.
When you find mealybugs in a greenhouse be decisive and take quick action. Nip the problem in the bud. As soon as mealybugs are detected, throw away the infested plants. The old saying “Let them have an inch and they’ll take a yard” rings true with this pest. Once mealybugs become established, expect to be spraying for a quite a long while. Mealybugs cost growers and retailers millions of dollars each year in control costs and crop damage and loss.
Mealybugs feed on plant juices and inject toxins that cause stunting and distortion of new growth. Infested plants usually have premature leaf drop and dieback in heavy infestations. In addition, this scale insect secretes a waste product, called honeydew. They do not digest the sugars they extract and excrete this as a sticky material. The syrupy liquid coats the leaves making them shiny and sticky. Often sooty mold grows on this honeydew making the foliage appear dirty and interfering with photosynthesis.
Many growers run to the savior of insecticides, imidacloprid, when they get a tough bug. You are going to have to use a variety of control methods and probably use insecticide rotation to clean up a mealybug population. Trying to control this pest quickly and relying just on chemical control is like running with sharp scissors – someone is going to get hurt. Cultural control of mealybugs is the best defense. This means closely inspecting incoming stock plants (like you have the time). But, if you don’t make the time, mealybugs may come back to haunt you. Rejecting infested plants now prevents a big disaster from occurring in your greenhouse. Certain plants are more prone to infestation such as rosemary, coleus, sage Swedish ivy, artemesia, and gardenia. The most susceptible plants should be monitored the closest.
Taking cuttings from infested plants is the kiss of death. Young, immature mealybugs prefer to move to tip growth to feed – exactly the part of the plant from which you take cuttings. Exposing cuttings to low temperatures (33 –35 °F for 24 –36 hours before sticking) will often help reduce mealybug survival. This is based on work by Casey Sclar at Longwood Gardens, Kennett Square, PA. Check to make sure that your plant material can withstand this lower temperature without suffering irreparable damage.
Mealybugs, are one of the most common scale insects attacking ornamental plants. Yes, mealybugs are members of the scale family Pseudococcidae. Mealybugs are different from most scales in that they are mobile in all of their life stages. They actually move when it suits them. The young are the most restless, wandering about the plant looking for good feeding sites. If they find a suitable feeding site they usually settle down, insert their mouthparts, and don’t budge until the feeding site taps out or it’s time to mate.
There are 275 species of mealybugs in the continental United States, and I believe 272 of these species hang out mainly in Florida and southern California. In most greenhouses and nurseries in the United States you will encounter mainly citrus mealybug (Planococcus citri), longtailed mealybug (Pseudococcus longispinus), Madeira mealybug (also unofficially known as false Mexican mealybug) (Phenococcus madeirensis), and root mealybug (Rhizoecus falcifer).
Most mealybugs have an oval body shape and some sort of white waxy coating on the body or extending from the edge or end of the insect. Each mealybug species is slightly different, but basically the female goes through 4 developmental stages (instars). An adult female will lay 500 – 600 eggs, usually in a cottony-like ovisac beneath her body. The eggs hatch in 7 –14 days and the 1st instar nymphs disperse- usually on wind currents in the greenhouse, attached to workers clothing, or by natural bridges created by closely spaced plant material. Some mealybugs are slightly different, like the longtailed mealybug, which does not lay eggs but rather gives live birth to nymphs. Male mealybugs go through 5 instars and only feed in the first two. Males pupate on leaves, pots, or benches and emerge as winged adults. They then have only 1 – 2 days to make a date and mate before they die.
Madeira mealybug looks a lot like citrus mealybug. They are generally a dull gray color under the white wax and lack the single purple stripe on their back that citrus mealybugs posses. Their egg sacs are longer and denser than citrus mealybug and male pupal cases may be found in equal numbers to the females. This is one nasty, hard to control mealybug. There will be more on this pest later.
Root mealybug is found only on the roots and not on the plant parts above ground. You will have to flip the plant over and pull the pot off. They commonly hang out at the edge of the root ball. This mealybug has a layer of dusty to granular white wax covering its body.
Toughest of the Tough Mealybugs
There is always an Olympic marathon among the pest population to grab your attention. When we have fairly good control methods available and one pest falls by the wayside, others quickly rise up to take their place. Such is the case with the Madeira mealybug. This pest has cropped up in greenhouses throughout the United States on a number of pot-grown plants and is rapidly moving to the head of the pack of greenhouse pests. If you thought citrus mealybug and longtailed mealybug were nasty, you haven't seen anything yet until you've experienced the new kid on the block, Phenacoccus madeirensis. There is no accepted common name for this pest, but some entomologists are calling it the Madeira or false Mexican mealybug. This mealybug will kill a mandevilla in a matter of 2 -3 weeks if left unchecked. It looks very much like a citrus mealybug, but boy is it different. To tell it apartshort of sending a sample to a specialist in coccidiology (a scale expert) - look for large number of pupal cases among the white wax.
With citrus mealybug, generally there are a lot more females present than males and males are the only ones that pupate. With Phenacoccus madeirensis, there is about an equal number of males and females, hence the larger number of pupal cases being found on the plant in the white wax. The other external macro characteristics are the egg sacs, which are long. One final feature is that citrus mealybug has a dark line running down the middle of its back, whereas Phenacoccus madeirensis does not. Nothing appears to really control a population once it’s ‘ripping’ on a plant. Ron Oetting at Georgia University had good (but not outstanding) results with Distance IGR (Pyriproxyfen), Dursguard (Chlorpyrifos) and Talstar (Bifenthrin). However, they found poor control with Marathon (Imidacloprid) and Flagship (Thiamethoxam – not EPA labeled yet).
Like you really needed another mealybug
Florida was invaded by the pink hibiscus mealybug from the Carribbean. In June of 2002 the pink hibisicus mealybug was detected in Broward and Miami-Dade counties. You can view this pest and obtain more information at www.doacs.state.fl.us/~pi/enpp/ento/pink.htm (a long URL, but worth the effort). Whenever Florida (the foliage plant capitol and plug producer of the world) gets a new pest, we all hold our breath hoping that they won’t spread it to the rest of us. In the fall of 2002 two parasitic insects, Anagyrus kamali and Gyranusoidea indica, were released in a 22 square mile area. These parasites were used in the Caribbean and in California during the 1990s with good results. The Florida Department of Agriculture is expecting a 95% or greater reduction in pink hibiscus mealybug with these parasite releases. The Department of Agriculture is trying hard to prevent this pest from spreading.
Biological Control of Mealybug
Mealybug destroyer (Cryptolaemus montrouzieri) can be an effective tool in controlling citrus and long-tailed mealybugs. Both the adults and the larvae of the mealybug destroyer feed on mealybugs. C. montrouzieri is a small, dark brown beetle with a tan head. Their wax-covered larvae resemble mealybugs, except they are twice as large as their prey. C. montrouzieri larvae feed on mealybug eggs, crawlers, and honeydew. Adults and young larvae prefer to feed on mealybug eggs, however older larvae will attack any stage.
Article reprinted from the Greenhouse TPM/IPM Weekly Report, November 15, 2006 issue, University of Maryland Cooperative Extension
Wednesday, October 31, 2007
Nursery and Landscape - Ornamental Plant Sensitivity to Different Herbicides
Herbicides are important weed management tools in nurseries and landscapes. However, certain herbicides can damage landscape plants. The following is an abstract of a talk by Jeff Derr of Virginia Tech on this subject.
Preememergence and postemergence herbicides are effective tools for managing weeds in nursery production. These chemicals can injury certain nursery crops, depending on the specific herbicide and formulation, specific nursery crop, ornamental growth stage, soil type, and weather conditions. This article will focus on ways to reduce the potential for injury associated with herbicide application.
Bedding plants and herbaceous perennials:
Certain herbicides cannot be used on most annual bedding plants and herbaceous perennials. This list includes the oxyfluorfen-containing products Goal, Rout, OH2, and Regal O-O. Dichlobenil (Casoron, Barrier), simazine (Princep, others), flumioxazin (BroadStar, SureGuard) and oxadiazon-containing herbicides (Ronstar, RegalStar, and Pre Pair) also cannot be used on most herbaceous ornamental species. Isoxaben-containing products (Gallery, Snapshot) can only be used on certain herbaceous perennials. Do not apply isoxaben to Danes rocket, oxeye daisy, the mustard family, sedum, ajuga, lambsear or Veronica. As with all herbicides, check the label for specific use restrictions.
Sprayable formulations of the dinitroaniline herbicides (pendimethalin, prodiamine, oryzalin, and trifluralin), especially oil-based (EC) formulations, can stunt bedding plants and reduce flowering. It is best to use granular forms of these products in bedding plants and herbaceous perennials. Pennant Magnum, an emulsifiable concentrate form of metolachlor, can burn tender foliage, especially in herbaceous ornamentals. Use directed sprays when possible and avoid applications during high temperature/high humidity conditions. Avoid herbicides altogether on Phlox paniculata. Currently no preemergence herbicides are registered for use in greenhouses or other enclosed structures such as over-wintering houses. Herbicide vapors could be trapped around ornamental foliage, resulting in nursery crop damage. Do not apply preemergence herbicides in enclosed structures; this applies to both herbaceous and woody ornamentals. The last application for the year should be applied at least 2 weeks prior to covering over-wintering houses.
Woody nursery crops:
The granular products containing oxyfluorfen, oxadiazon, or flumioxazin should not be applied to plants with wet foliage since they can cause a contact burn. Wet foliage causes the granules to stick and then release the herbicide, resulting in spotting of foliage. Since these chemicals are contact herbicides, these granules should not be applied to plants that could catch and funnel granules to their base, such as yucca. Avoid applications during budbreak since tender foliage is more susceptible to damage. Another concern with these products is injury following splashing of treated soil onto foliage. Applying a layer of mulch after application could make these products safer when applied to young plants growing in field soil. This could also be beneficial with herbicides that could cause injury through volatilization, such as oxyfluorfen.
Use lower rates when applying preemergence herbicide to sandy soils low in organic matter. Generally higher preemergence herbicide rates are needed in clay soils higher in organic matter. Emulsifiable concentrate formulations should not be applied overtop nursery crop foliage, especially during hot, humid weather. This applies to products such as Pendulum EC, Pennant Magnum, and the postemergence grass herbicides (Envoy, Fusilade/Ornamec, and Vantage). Avoid adding oil adjuvants to overtop applications during summer – use nonionic surfactants instead. For Fusilade/Ornamec, check the label for juniper, azalea and other cultivar restrictions Do not apply oryzalin (Surflan) to Douglas fir, hemlock, or true firs, especially on seedbeds, liner beds, and young plants. Isoxaben (Gallery) can injure dwarf burning bush (Euonymus alata compacta), hydrangea, and lilac. Simazine can injure dwarf burning bush, lilac, and mock orange.
BroadStar can injure wax myrtle, privet, butterfly bush, hydrangea, spiraea, and viburnum, although there may be differences in cultivar sensitivity and newly planted liners probably are more susceptible than older plantings. Do not apply SureGuard overtop broadleaf ornamentals; only conifers have tolerance to overtop application, and then primarily after new growth has hardened off or when plants are dormant. It is preferable to apply SureGuard or Goal to dormant shade trees. Dichlobenil (Casoron) can injure hemlock, fir, spruce or pines, especially if treated when young. Clopyralid (Lontrel, Stinger) can severely injure members of the aster, legume, and nightshade families, including such species as asters, mums, coreopsis, redbud, and locust, along with damaging English ivy. Certain species tend to be sensitive in general to herbicides. Test cultivar sensitivity using a few plants prior to widespread use for herbicide application to azalea, barberry, hydrangea, and dwarf burning bush.
From "You Better Watch Out!! – Herbicide/Ornamental Combinations to Avoid" by J.F. Derr, Virginia Tech in the 2006 Proceedings of the Annual Meeting of the Northeastern Weed Science Society meeting.
Preememergence and postemergence herbicides are effective tools for managing weeds in nursery production. These chemicals can injury certain nursery crops, depending on the specific herbicide and formulation, specific nursery crop, ornamental growth stage, soil type, and weather conditions. This article will focus on ways to reduce the potential for injury associated with herbicide application.
Bedding plants and herbaceous perennials:
Certain herbicides cannot be used on most annual bedding plants and herbaceous perennials. This list includes the oxyfluorfen-containing products Goal, Rout, OH2, and Regal O-O. Dichlobenil (Casoron, Barrier), simazine (Princep, others), flumioxazin (BroadStar, SureGuard) and oxadiazon-containing herbicides (Ronstar, RegalStar, and Pre Pair) also cannot be used on most herbaceous ornamental species. Isoxaben-containing products (Gallery, Snapshot) can only be used on certain herbaceous perennials. Do not apply isoxaben to Danes rocket, oxeye daisy, the mustard family, sedum, ajuga, lambsear or Veronica. As with all herbicides, check the label for specific use restrictions.
Sprayable formulations of the dinitroaniline herbicides (pendimethalin, prodiamine, oryzalin, and trifluralin), especially oil-based (EC) formulations, can stunt bedding plants and reduce flowering. It is best to use granular forms of these products in bedding plants and herbaceous perennials. Pennant Magnum, an emulsifiable concentrate form of metolachlor, can burn tender foliage, especially in herbaceous ornamentals. Use directed sprays when possible and avoid applications during high temperature/high humidity conditions. Avoid herbicides altogether on Phlox paniculata. Currently no preemergence herbicides are registered for use in greenhouses or other enclosed structures such as over-wintering houses. Herbicide vapors could be trapped around ornamental foliage, resulting in nursery crop damage. Do not apply preemergence herbicides in enclosed structures; this applies to both herbaceous and woody ornamentals. The last application for the year should be applied at least 2 weeks prior to covering over-wintering houses.
Woody nursery crops:
The granular products containing oxyfluorfen, oxadiazon, or flumioxazin should not be applied to plants with wet foliage since they can cause a contact burn. Wet foliage causes the granules to stick and then release the herbicide, resulting in spotting of foliage. Since these chemicals are contact herbicides, these granules should not be applied to plants that could catch and funnel granules to their base, such as yucca. Avoid applications during budbreak since tender foliage is more susceptible to damage. Another concern with these products is injury following splashing of treated soil onto foliage. Applying a layer of mulch after application could make these products safer when applied to young plants growing in field soil. This could also be beneficial with herbicides that could cause injury through volatilization, such as oxyfluorfen.
Use lower rates when applying preemergence herbicide to sandy soils low in organic matter. Generally higher preemergence herbicide rates are needed in clay soils higher in organic matter. Emulsifiable concentrate formulations should not be applied overtop nursery crop foliage, especially during hot, humid weather. This applies to products such as Pendulum EC, Pennant Magnum, and the postemergence grass herbicides (Envoy, Fusilade/Ornamec, and Vantage). Avoid adding oil adjuvants to overtop applications during summer – use nonionic surfactants instead. For Fusilade/Ornamec, check the label for juniper, azalea and other cultivar restrictions Do not apply oryzalin (Surflan) to Douglas fir, hemlock, or true firs, especially on seedbeds, liner beds, and young plants. Isoxaben (Gallery) can injure dwarf burning bush (Euonymus alata compacta), hydrangea, and lilac. Simazine can injure dwarf burning bush, lilac, and mock orange.
BroadStar can injure wax myrtle, privet, butterfly bush, hydrangea, spiraea, and viburnum, although there may be differences in cultivar sensitivity and newly planted liners probably are more susceptible than older plantings. Do not apply SureGuard overtop broadleaf ornamentals; only conifers have tolerance to overtop application, and then primarily after new growth has hardened off or when plants are dormant. It is preferable to apply SureGuard or Goal to dormant shade trees. Dichlobenil (Casoron) can injure hemlock, fir, spruce or pines, especially if treated when young. Clopyralid (Lontrel, Stinger) can severely injure members of the aster, legume, and nightshade families, including such species as asters, mums, coreopsis, redbud, and locust, along with damaging English ivy. Certain species tend to be sensitive in general to herbicides. Test cultivar sensitivity using a few plants prior to widespread use for herbicide application to azalea, barberry, hydrangea, and dwarf burning bush.
From "You Better Watch Out!! – Herbicide/Ornamental Combinations to Avoid" by J.F. Derr, Virginia Tech in the 2006 Proceedings of the Annual Meeting of the Northeastern Weed Science Society meeting.
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