University of Delaware Cooperative Extension, Kent Co., Commercial Horticulture Information

Landscape - Moisture Extremes and Tree Decline

2009-11-28T07:50:00.002-05:00

Wet years following drought years can cause problems with tree decline. The following is an article on the subject.

Of great concern are moisture extremes (excessive moisture in poorly drained areas as well as mid-season drought). Landscape trees throughout Delaware have been stressed in previous years by prolonged moisture extremes, and it often takes trees five or more years to recover. Not only does moisture stress impact the immediate growth and development of plants, it also predisposes them to other diseases (especially cankers caused by Cytospora, Botryosphaeria, and Nectria) and insect pests (such as borers). Keep this in mind during the next few years when monitoring landscape trees and shrubs for plant health.

Adapted from "Diseases of Ornamental Plants: End of Season Notes" Ann B. Gould, Ph.D., Specialist in Plant Pathology in the November 12, 2009 edition of the
Plant & Pest Advisory, Landscape, Nursery & Turf Edition, A Rutgers Cooperative Extension Publication http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln111209.pdf

Landscape and Turf - Don't Forget Soil Sampling Before the Ground Freezes

2009-11-27T07:39:00.000-05:00

The following is a reminder to take soil samples this fall if you have not yet done so.

The 2009 growing season is wrapping up, and landscaping chores mostly involve “cleaning up”. While you’re raking leaves, begin thinking about what tasks you can do now that can help you prepare for next season. One job you can do before the ground freezes is to take soil samples for testing. The nutrient levels that are analyzed for a fertility test will not change substantially between now and next March, and so the results and recommendations will allow you to learn what soil amendments you need to optimize soil fertility, plan your work efforts, and make your purchases well in advance.

Testing now also provides the advantage of rapid response time from the soil testing lab, since the sample load is relatively low. Often, landscapers may not think of soil testing until the weather warms up next spring, and they’ll all send their samples at the same time, wanting results in a hurry. However, this is the busiest time for most soil testing labs and turnaround time can be slow. Make soil testing a part of your late fall/winter garden routine to be better prepared and make next spring less hectic. Remember: soil testing helps you use your hard-earned dollars wisely by providing recommendations for the most appropriate fertilizer or amendment. And in addition to providing optimum conditions for your plants, proper fertilization prevents mis-use of nutrients that can cause environmental degradation. Always practice good landscape hygiene, cleaning up fertilizer granules, soil, grass clippings, and other plant detritus from impervious surfaces. Only water should be going into those storm sewers! So get back to those fall clean-up chores. For information on submitting soil samples, contact your County Extension office (Newark, Dover, or Georgetown).

Adapted from "It’s a Good Time to Test Your Soil!" in the November 12, 2009 edition of the
Plant & Pest Advisory, Landscape, Nursery & Turf Edition, A Rutgers Cooperative Extension Publication http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln111209.pdf

Greenhouse - Ethylene Damage to Poinsettias

2009-11-26T07:46:00.002-05:00

The following is information on ethylene damage to poinsettia plants.

Ethylene Damage

Ethylene (C2H4) is an odorless, colorless gas which acts as a plant hormone, a growth regulator, and a potentially harmful pollutant of ornamental crops. Poinsettias demonstrate an interesting wilt like appearance (epinasty) after exposure to ethylene gas. Leaf epinasty has been observed when poinsettias were exposed to 10 ppm ethylene. Epinasty can be observed on poinsettia plants when they are kept in their shipping sleeves for a prolonged time. Petioles of poinsettias naturally produce ethylene in response to sleeving. Deformed top growth can also occur during long term exposure to ethylene. Preventing economic losses due to ethylene can be achieved by avoiding exposure to engine exhaust from shipping trucks and other combustion engine vehicles, ripening fruit, senescing plant materials, smoke, welding fumes, and poorly maintained greenhouse furnaces. Annually servicing boilers and burners may reduce or prevent ethylene damage to floricultural crops. Gas leaks resulting from cracked heat exchangers may allow harmful concentrations of ethylene to be released into the greenhouse. Continual expansion and contraction of the metal in the heat exchanger of a furnace can stress the welds resulting in cracks. Leaks at joints and seams can be discovered by painting soapy water on them. Another method of detecting leaks is the placement of smoke bombs or furnace candles within the firebox. Light or smoke penetrating from the interior should cause alarm to growers.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Poor Bract Color or Bract Fading in Poinsettia

2009-11-25T07:04:00.002-05:00

The following is information on poor bract color or bract fading in poinsettias.

Poor bract color/Bract Fading

Varieties, particularly those red bracts, differ in the intensity of the pigmentation, but sometimes the color of the bracts on finished plants does not meet expectations. Bract color might be referred to as faded, though failure of the pigments to develop properly is perhaps more accurate. High night temperatures can be responsible for the lack of color intensity, and explains why night temperatures of approximately 60 to 62°F are recommended from early or mid-November until marketing. Bracts which are produced under crowded conditions, with low light levels, will usually be lighter in color than bracts in the upper canopy of the same plant.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Premature Cyathia Abscission in Poinsettia

2009-11-24T07:02:00.004-05:00

The following is information on premature cyathia abscission in poinsettias.

Premature cyathia abscission

The bracts are the conspicuous features of the poinsettia and the true flower parts in the center of the apex (the cyathia) are relatively unnoticed unless they are missing. Varieties differ in their ability to retain cyathia, and 'Gutbier V-10 Amy' was an example of one where the cyathia abscise rather quickly. Often, the cyathia fall off when the plants are still in the greenhouse. However, many of the newer cultivars have improved cyathia retention or there are few cyathia present, which limits the use of cyathia as an indicator of age.

A combination of high night temperatures (70°F or higher) and low-light intensities during the day, have been shown to increase the chances of premature cyathia abscission. Research has shown that such conditions result in an inadequate supply of carbohydrates, and cyathia do not have a high priority for the carbohydrates which are available. Inadequate water also increases the severity of the problem.

Maximum night temperatures of 65°F until early November, followed by temperatures of approximately 60°F, and proper spacing of the plants to allow light penetration into the interior of the bench are recommended procedures to reduce the incidence of cyathia abscission. Water stress should not be allowed to occur.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Landscape - Some Athyrium Ferns for Delaware

2009-11-23T07:44:00.003-05:00

The following are some Athyrium ferns recommended for used in Delaware Landscapes. All require part shade to full shade conditionas and moist soils.

Athyrium filix-femina 'Lady In Red', Lady fern
This is a delicate, lacy fern with arching fronds and red stems at maturity. It is a native fern species and is 1-1.5' in height.

Photograph of the Lady fern (Athyrium filix-femina en ssp. angustum 'Lady in Red'). Photo taken at the Mt. Cuba Center where it was identified. Photo by and (c)2007 Derek Ramsey (Ram-Man). the GFDL v.1.2 license applies http://www.gnu.org/copyleft/fdl.html.

Athyrium 'Ghost', Ghost fern
This fern is a bit taller at 2-2.5' in height. It is silvery-grey with stiffly upright fronds and is a slow spreading groundcover.

Athyrium niponicum 'Regal Red', Japanese painted fern
This Athyrium fern has silvery grey-green fronds and vase-shaped arching foliage. It is very elegant looking. It is 1-1.5' in height.

Athyrium niponicum 'Pictum', Japanese painted fern
This is a slightly larger Japanese painted fern 18-20" in height. It has silvery grey-green fronds with burgundy tones and was a perennial plant of year.

Athyrium 'Ocean's Fury', Crested painted fern
This 3' fern has upright fronds dusted in silver. It forms 2' wide clumps and is useful as a groundcover.

Greenhouse - Latex Eruptions in Poinsettia

2009-11-23T07:41:00.001-05:00

The following is information on latex eruptions on poinsettias.

Latex Eruptions

This disorder, once referred to as crud does not seem to be as prevalent as it was several years ago on varieties popular then, but occasional cases are reported. Latex, which erupts in the shoot apex when cyathia are forming, dries and seems to physically prevent the continued development of the flower parts. Malformed inflorescences reduce the quality and acceptability of the plants. Latex also can erupt from leaf surfaces, prompting a grower to consider mealybug damage, but damage to the shoot apex is much more serious. High relative humidity and generous amounts of water in the substrate seem to increase the chances for latex eruption, so avoidance of the disorder is geared to the control of these factors.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Landscape and Nursery - Some Sedge Species for Delaware

2009-11-22T07:41:00.002-05:00

The following are some sedge species to consider for Delaware.

Carex dolichostachya 'Kaga-nishiki', gold fountain sedge

Description: Gold fountain sedge prefers part shade to shade conditions and needs moist soil. It is 10-14" in height and has arching narrow green leaves edged in golden-yellow. This is a low maintenance plant.

Carex flaccosperma, thin fruit sedge

Description: This native plant has wide adaptation and will thrive in sun to shade conditions but needs constant moisture (do not let dry out. It is 8-10" in height, remains evergreen, and has attractive clumps of glass-like blue-green leaves.

Carex morrowii 'Silver Sceptre', Japanese sedge

Description: Japanese sedge prefers part shade to shaded conditions but is adapted to a wide range of soil moistures from dry to moist. One of the benefits of this sedge is that tolerates full sun and dry, drought conditions. It is 12" in height. Japanese sedge has narrow leaves with white margin.

Carex muskingumensis 'Little Midge', dwarf palm sedge

Description: This native plant needs moist soil conditions and is adapted to part shade or shaded conditions. It is 12-15" in height. It is fine textured and compact and is a great native substitute for dwarf bamboo.

Carex oshimensis 'Evergold' sedge

Description: This sedge requires part shade to shaded conditions and needs constant moisture and should not be let to dry out. It is 8-12" in height. This sedge has arching variegated yellow and green leaves and is an excellent groundcover that suppresses weeds.

Carex tenuiculmis 'Cappuccino', New Zealand hair sedge

Description: This sedge does well in sun to part shade in moist soils. It is 12-15" in height. New Zealand hair sedge has chocolate colored foliage and is great as an accent plant or in pots. To avoid winter damage plant this sedge in a protected site.

Greenhouse - Bract Edge Burn on Poinsettia

2009-11-22T07:36:00.004-05:00

The following is information on bract edge burn on poinsettias.

Bract necrosis/Bract Edge Burn

This disorder, which can be recognized by brown bract margins and eventual internal necrosis, and also referred to as bract burn occurs most frequently on the varieties 'Gutbier V-14 Glory' and 'Supjibi'. Generous fertilizer applications, particularly ammonium sources of nitrogen, continued into the late stages of the season, seem to increase the likelihood of bract burn. Research also has shown increased incidence of the problem when calcium was deficient. Excess soluble salts in the growing substrate causing root injury, reduced water absorption or stress from inadequate or excessive irrigation, damage from pesticides or pollutants, and high relative humidity are also associated with the disorder. Perhaps the greatest damage caused by bract necrosis in the increased chance for Botrytis infection of the damaged tissue, and then the need to control this persistent disease.

The following suggestions have been made:

1) Reduce fertilizer rates and frequencies as the crop matures.
2) Primarily use nitrate nitrogen, rather than fertilizer high in ammoniacal nitrogen.
3) Apply adequate amounts of calcium (calcium levels of 0.5% or less in the leaves are considered to be deficient). Consider supplemental calcium sprays (see: Calcium).
4) Do not use excessive amounts of slow-release forms of fertilizer, as nutrients cannot be withheld late in the season.
5) Avoid unnecessary irrigation which can result in soft bracts.
6) Try to avoid high relative humidity. This can be achieved by ventilating and heating late in the afternoon to remove moisture from the greenhouse atmosphere. A policy of not irrigating in the afternoon can also be helpful. Steps taken to reduce relative humidity will not only reduce the incidence of bract necrosis, but will also help control Botrytis if it does occur.
7)Use approved fungicides for Botrytis prevention or control.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Landscape - Assessing Potential for Winter Storm Damage to Trees

2009-11-21T07:32:00.003-05:00

With fall progressing, it brings to mind concerns about potential storm damage to trees. Vicious winds and ice storms, or heavy wet snow, have caused severe tree losses and property damage in the past. The following are some considerations in assessing potential for winter storm damage to trees.

It's often difficult to predict what will happen to trees in landscapes during storms. Healthy trees with no apparent potential problems can drop limbs or fall entirely during unusual weather. But the more common hazards from tree damage occur with trees that are unhealthy or stressed. If a tree has dropped big branches, or shows signs of interior rot when a branch falls, it definitely should be checked.

If a tree has a likelihood of falling, and has a target to hit if it falls, it may be considered a hazard tree.

Checklist for tree hazards:

1) Is there a history of trees falling near your home during bad storms?
2) Do certain trees look unhealthy compared to their neighbors?
3) Has there been construction activity near your trees in recent months or years?
4) Has nearby logging changed the growing conditions and exposed remaining trees to less shade, or stressed them in other ways?

Falling trees:

One very common reason for a tree to fall is because of some type of root problem. Consulting a qualified tree care professional makes good sense if you suspect the presence of a root disease, or if there have been many falling trees in your immediate neighborhood.

Roots that have decayed from fungi may no longer adequately anchor a tree. High winds combined with saturated ground may cause tree failure when root disease has developed.

Unfortunately, finding no signs of root diseases does not mean they are not present. However, close inspections of roots and trunks of fallen trees or drilling suspect trees to look for interior decay can be done by Certified Arborists and/or urban foresters that are familiar with root rots. Professional hazard evaluations are highly recommended for trees located near those that have died, fallen or appear to be dying.

Generally, roots aren't removed when hazard trees are cut down. If a root rot disease has been present, be certain not to replant susceptible trees in the same area.

Tree fall can also be caused by factors other than root rots. Trees may be rocked over by wind when soils are saturated with water. So in addition to root rot problems, there will be other possibilities checked by arborists when evaluating whether a tree is a hazard.

Checking trees for healthy appearance:

If you were to glance around at the trees in a neighborhood, the crowns will range from those with lush, full, healthy appearing foliage to those that have sparse, poor colored foliage. The crown is the part of the tree at the top, the branches that you see silhouetted against sky. The branch pattern and foliage pattern at the top of the tree will be the first area to show symptoms of tree disease. Trees that

With deciduous trees (those that drop their leaves in fall), such as maples, check for crown health when the trees still have all their summer leaves, before leaves begin to drop. The apparent thinning of leaf and twig health at the top of a deciduous tree is much more difficult to detect during and after leaf fall.

Often, a tree in distress will leaf out later than usual in the spring and have smaller leaves than are common. It may also set a very large, bountiful crop of seeds, though seed set needs to be looked at along with other factors in the tree.

Once a large tree begins to show severe symptoms, the situation isn't reversible. There generally are no cures for conifer trees that have root problems or that appear to be dying. Get advice from a qualified professional arborist.

Adapted from "Checking Tree Safety Before Winter Storms" by Mary Robson (Ret.), Area Extension Agent Regional Garden Column October 3, 1999, Washington State University.

Greenhouse - "Rabbit Tracks" on Poinsettia

2009-11-21T07:27:00.002-05:00

The following is information on the "rabbit track" disorder of poinsettia bracts.

Bilateral bract spots (Rabbit Tracks)

Many reasons have been proposed for this disorder, but the exact cause is still unknown. These spots, located on either side of the midrib of the bracts in late November and early December seem to occur more often on some varieties than on others. The disorder has been observed under every type of greenhouse covering, over a wide temperature range, and with several different fertilization programs and nutrient levels. High temperature and high nitrogen levels have been suspected as causes, but then the disorder will occur where neither of these conditions prevailed. Plants have been exposed to cool and warm air movements over the bracts and to high humidities, trying to produce rabbit tracks, but such experiments have usually failed. No pathogen or other pest has been found to be responsible for the spotting.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Poinsettia Wilting

2009-11-20T08:12:00.002-05:00

The following are some causes for wilting in poinsettias

Wilting/Epinasty in Poinsettia

The most common cause of wilting is a lack of water, and application of water should correct the problem. If plants remain wilted, the root systems should be inspected to determine if root injury has occurred because of excess soluble salts, root rot pathogens, or fungus gnat larvae. Growing medium testing laboratories and plant disease and insect clinics should be utilized for proper identification of the reasons for the wilting.

Flowering plants which have been sleeved and shipped to the retail outlet might show symptoms of wilting when sleeves are removed and the plants have been in the retail outlet for a couple of hours. The first response is for the florist or store personnel to apply water, but moisture might not be lacking. This wilting is referred to as epinasty. Varieties differ greatly in their susceptibility to wilting. Mechanical injury or bending of leaves during sleeving can increase the amount of ethylene being produced by the plant. Increased levels of ethylene can lead to droopy plants. Length of time in the sleeves also has an impact on the extent of the epinasty. Growers should avoid rough handling of the plants during sleeving and the amount of time that the plants stay in sleeves should be minimized.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Cold Weather and Poinsettias

2009-11-18T18:32:00.003-05:00

The following are some cold temperature effects on poinsettias.

Cool temperatures can delay initiation and development of flower parts. The impact of cool temperatures can readily be seen in a greenhouse where temperature control is not uniform and there are cold and hot areas within the greenhouse. Adequate heating facilities and horizontal air flow fans can reduce this variability.

Sales and delivery of plants during periods of extremely cold temperatures can be difficult because poinsettia bracts can be severely damaged by temperatures below 50°F. Red bracts develop a blue to a silver-white color and the extent of discoloration is dependent on length of exposure to such chilling temperatures. In some areas of the country, retail outlets are not accustomed to protecting poinsettias from chilling injury. Sleeving will help prevent chilling injury.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Poinsettia Bract Splitting

2009-11-17T06:16:00.003-05:00

The following is information on the bract splitting disorder of poinsettias.

Bract Splitting

The splitting disorder was first encountered with the variety 'Paul Mikkelsen', and it has been a problem with some other varieties since them. It can occur on stock plants or the finishing plants. It is especially frequent on stock plants if the shoots become long, with numerous leaves, before a pinch or removal of a cutting is made. It can occur even when the daylength is too long for floral initiation, but a floral primordium is produced and is then surrounded by lateral vegetative shoots. Splitting in stock plants is almost like an uncontrolled pinch, and growers should be wary of cuttings taken from such shoots. Cuttings taken early in the propagation season and grown too long as single-stem plants are more likely to split than those taken later.

Splitting can occur on plants which are to be sold as flowering plants, and can make the plants unacceptable. Again, this is more likely to occur on plants which are grown single-stem with a mature main axis, compared to plants of the same variety which are grown as pinched plants, with the younger lateral shoots.

Several ways have been recommended to reduce the changes of splitting. These methods are:

1. Select varieties which are known to be relatively free from splitting. (Unfortunately some of the longest lasting varieties and those that withstand shipping and handling the best are the ones most subject to splitting.)
2. Apply lights (extend the daylength or interrupt the dark period) to stock plants until mid-May, to keep plants vegetative.
3. Pinch shoots on stock plants regularly, so only short, young shoots are produced.
4. Try to avoid taking cuttings from the interior portions on the bench, where light intensity is low.
5. Do not propagate cuttings early for single-stem plant production.
6. If the variety is highly susceptible to splitting, apply lights until mid-September on finishing plants to make certain the shoots remain in the vegetative stage.
7. Make certain the dark period is not interrupted by lights, once initiation is desired, or splitting can be induced.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Poinsettia Leaf Distortion

2009-11-16T06:22:00.002-05:00

Leaf disortion is a common problem on poinsettias. The following is more information.

Leaf distortion

This disorder most often occurs in the early stages of the crop. Plants develop distorted or cupped leaves. Most poinsettias will outgrow this condition, but shoots with extreme distortion may not improve. It is unclear what causes this disorder. Some distorted leaves are very symptomatic of molybdenum deficiency in other crops, and some research studies have shown that a lack of this element early in the life of the plant can result in such leaf malformations. There have been reports that deformities occurred on some plants even when molybdenum had never been deficient, so other factors could also be responsible. Mechanical injury to very young leaves can cause leaf distortion. Wind, water stress, and insects (thrips) are also a few ways such injury could occur. Rapid changes in humidity, as what occurs early in the morning when the vent fans come on, can lead to an accumulation of salts along the leaf margins and veins - resulting in leaf injury. Leaf distortion becomes apparent as these injured leaves grow and expand.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Cloudy Weather and Calcium on Poinsettias

2009-11-15T06:15:00.001-05:00

The rainy weather for the last couple of weeks is making it tough for poinsettias to pull up calcium this fall. If you don’t get adequate uptake of calcium then you are likely to see bract edge burn. Many growers are making bi-weekly applications of calcium chloride to get the calcium into the foliage and bracts. The following is a chart from Paul Ecke Ranch on rates of
calcium applications.

Click on chart for a larger version in a new window.

Information from the November 13, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the Central Maryland Research and Education Center, University of Maryland Extension.

Greenhouse - Pythium on Poinsettias

2009-11-14T07:32:00.002-05:00

Pythium is a common root infection in poinsettias. The following is more information on this disease from the University of Maryland.

Pythium root rot is one of the most problematic diseases on poinsettias throughout the crop production cycle. The pathogen is really a number of species with different temperature requirements, so growers can see Pythium problems regardless of the season. Sanitation is critical to help reduce Pythium problems – the fungus-like pathogen is commonly associated with soil, dirty pots and untreated pond water. At this point in the poinsettia crop, Pythium can infect roots damaged from water stress or high soluble salts from too much fertilizer. Look for watersoaked, brown roots with vascular tissue intact (commonly called “rat-tailing”) as evidence of Pythium root rot infection. Infected plants may be smaller in size, with off-color leaves, and in extreme cases may show wilt symptoms even though the potting medium is moist. Plants with severe root rot should be discarded. Soil drench application of fungicides may be needed to protect uninfected plants against Pythium root rot. Products effective in managing this disease include FenStop (fenamidone), Banol (propamacarb), Banrot (etridiazole + thiophanate-methyl), Truban or Terrazole (etridiazole) and Subdue Maxx (mefenoxam). Some Pythium strains may be insensitive to Subdue Maxx. It is always a good idea to rotate products with different active ingredients to avoid resistance in Pythium populations.

Information from the current edition of the Greenhouse TPM/IPM Bi-Weekly Report from the Central Maryland Research and Education Center, University of Maryland Extension http://www.ipmnet.umd.edu/09Nov13G.pdf

Greenhouse - Pictures of Pythium on Poinsettias

2009-11-14T06:36:00.001-05:00

The following are pictures of Pythium, a common root rot organism on Poinsettias.

Darkened roots of Poinsettia cause by Pythium.

Poinsettia wilting caused by Pythium

Photos from the November 13, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the Central Maryland Research and Education Center, University of Maryland Extension http://www.ipmnet.umd.edu/09Nov13G.pdf

Greenhouse - Weak Side Stems and Stem Breakage in Poinsettia

2009-11-12T05:43:00.002-05:00

There are several possible reasons for the development of side stems which are so weak and thin that the inflorescences cannot be kept erect without staking. The following is more information.

Research has found that cutting quality plays a part in stem breakage. Larger sized cuttings do not tend to break as easily as smaller, weaker cuttings. Early in the production cycle the plants should also be spaced closer together so that the plants will grow more upright. Plants grown with a wider spacing are more likely to produce lateral shoots that can grow out horizontal over the edge of the pot. Support rings will help support the plant and prevent stem breakage, but the cost of the rings and the labor to install them has to be economically justified by the grower. Calcium deficiency also has been reported by some researchers as a cause of weak stems, as calcium is an important constituent of plant cell walls. Varieties can also differ in stem strength with 'Success' and 'Red Splendor' being varieties which are more resistant to breakage. Some of the free-branching varieties produce so many shoots that crowding and reduced light intensity occur. The number of shots can be controlled to a certain extent by limiting the number of nodes below the pinch to 5 or 6 or by the removal of some of the lateral shoots. The first method is practice more often, since pruning can be an expensive operation. Limiting the percentage of ammonical-nitrogen being applied may also help avoid stem breakage. Ammonical-nitrogen promotes vegetative growth that may lead to weaker stem. Since thicker, stronger stems generally result for growth regulator treatments, some growers apply growth regulators to improve stem strength as much as to control height.

Information from the Poinsettia Problem Diagnostic Key on Physiological Disorders from North Carolina State University http://www.ces.ncsu.edu/depts/hort/poinsettia/corrective/a11.html

Greenhouse - Fascination Growth Regulator on Poinsettia

2009-11-11T05:35:00.000-05:00

The following are conclusions from research at Michigan State University on using Fascination growth regulator to increase height and bract size in poinsettias.

Fascination can be used by poinsettia growers to increase plant height and promote bract expansion, especially on plants that have reduced bract size from an excessive or late growth retardant application. When warranted, we suggest applying Fascination as a spray at a rate of 3-5 ppm using a volume of 2 quarts per 100 sq.ft. The amount of stem elongation and bract expansion from a Fascination spray depended on the time of application. If an increase in plant height is desired, then Fascination could be used before or soon after first color. During this time, a single spray application at 3- 5 ppm increased plant height by 1-2 inches. A later application (20 or 30 days after bract color) produced little or no increase in plant height. If an increase in bract size is desired, our results indicate that the best time to apply Fascination is 20-30 days after bract color. This late application will also have a smaller effect on increasing plant height. In addition, we noticed that late applications of Fascination made bract surfaces appear smoother and reduced bract crinkling. We did not observe any effect on bract color, although growers have reported that Fascination can slightly lighten the bract color. In some cases, a second Fascination spray may be required to achieve the desired elongation effects. We suggest waiting at least 10 days between spray applications. Frequent applications and high rates can produce an undesirable spacing between the bracts. As with all plant growth regulators, we encourage growers to perform their own trials on a small scale to determine desirable rates for their growing conditions and for each poinsettia variety.

Information from Fascination on Poinsettia by Matthew Blanchard, Mike Olrich and Erik Runkle, Michigan State University
http://www.hrt.msu.edu/florAoE/PDF/Plant%20growth%20regulators/Fascination_on_poinsettia.pdf

Landscape - Winterberry Holly

2009-11-09T06:12:00.002-05:00

Winterberry holly is a great landscape plant for Delaware and adds significant winter interest with persistant berries. The following is more information.

Winterberry (Ilex verticillata) is a deciduous holly with very attractive red fruits that persist long into winter. The bright red (or in some varieties, orange) berries light up the winter landscape, especially when seen against a dark evergreen background. This native shrub has an upright form with multiple stems, reaching heights of 10-15 feet in the wild but most often maturing around 8 feet in gardens. Winterberry thrives in wet or moist soil that is high in organic matter; it also tolerates flooding. It is adaptable to many other types of soil but frequent drought does not suit it. Best fruit production occurs when the plant is grown in full sun to partial shade. There are many good cultivars on the market, but the one that tops the list is probably Winter Red®. Its bright red fruits do not fade in sunlight and persist for a very long time. This female holly will require a male pollinator to be planted nearby. Of course, wild growing male hollies in the nearby woods can also supply the necessary pollen for fruit production. When the soil is to its liking, Winterberry produces suckers that result in broad colonies of the plant. For a quicker natural effect, group three to five plants together for a mass planting. Look for ‘Red Sprite’, a compact, rounded form about 3 x 3, or ‘Sparkleberry’, a hybrid selection released by the US National Arboretum. All these deciduous hollies are deer resistant and provide shelter and food for birds. Once a few freezes have sweetened the berries, winter resident songbirds will visit for a snack.

Information from the January, 2007 edition of the Southeast District Commercial Horticulture Newsletter from the University of Georgia
http://apps.caes.uga.edu/urbanag/Industry/NewsLetters.cfm

Landscape - New Abelia Cultivars

2009-11-09T05:58:00.003-05:00

The following are some new Abelia cultivars from the University of Georgia breeding program that would do well in Delaware Landscapes

Abelia

They are not your grandmother’s Abelia anymore! Abelia, a foundation plant long used in American and European landscapes, is undergoing a facelift and three unique Abelia hybrids have been released as cultivars in 2006. These plants will add colorful excitement to an old garden standby. Plant Patents have been applied for and the cultivars have been licensed to Ball Horticultural.

‘Lavender Mist’ ‘Lavender Mist’ is a seedling selection of ‘Edward Goucher’ x. A. chinensis and develops into a dense, compact shrub with a slight spreading habit. This Abelia is a heavy and fragrant bloomer with clusters of lavender flowers and gray-green foliage, making it unique among Abelia cultivars. ‘Lavender Mist’ begins blooming in mid June and generally there are two heavy-blooming periods in June and August, with scattered blooms continuing into autumn. Sepals are straw-green color at the base, becoming rose at the tips. In the fall, the leaves on the shoot tips turn burgundy/purple while the others remain green. By mid-winter, the foliage is dark purple. After landscape establishment, a hard pruning is recommended in early spring to encourage compact growth and heavy blooming. ‘Lavender Mist’ is semi-deciduous in Georgia.
Common Name: Abelia Hardiness Zone: 6 to 9Height: 63”Exposure: Full Sun to Partial Shade
PPAF

‘Plum Surprise’ ‘Plum Surprise’ is a seedling selection from the cross ‘Edward Goucher’ x ‘Francis Mason’ and forms an unusual weeping, spreading mound with fine-textured foliage. In March and April, foliage is a yellow-green with scattered red/purple leaves. In late spring, the foliage becomes an emerald green and remains green throughout the summer. New stem growth is red, turning to a red-brown when older. The most striking features of ‘Plum Surprise’ are the fall and winter foliage color and the evergreen habit of the cultivar. As autumn progresses, the outer shoots and leaves transform to red/purple or crimson, while the inner foliage is a bright emerald green. Foliage is glossy in the winter, and a deep purple or burgundy color develops. ‘Plum Surprise’ is a relatively light bloomer, with flowers scattered individually or in pairs. The flowers appear white, but on close examination have a purple blush with a pale yellow throat. ‘Plum Surprise’ is noteworthy for its heat and drought tolerance.
Common Name: Abelia Hardiness Zone: 6 to 9Height: 36”Exposure: Full Sun to Partial Shade
PPAF

‘Raspberry Profusion’ ‘Raspberry Profusion’ is a seedling selection of ‘Edward Goucher’ x A. chinensis, and develops into a dense shrub following establishment in the landscape. This Abelia is a very heavy and very early bloomer. Flowering begins in early May and becomes very profuse by early June. ‘Raspberry Profusion’ boasts large showy, fragrant blooms of pink flowers or flamboyant raspberry-colored sepals (to which it owes its name). These large, showy panicles of pink flowers mingle with the vivid sepals and together cover the entire plant, practically obscuring the foliage which is a glossy and medium to dark green in color. After landscape establishment, a hard pruning is recommended in early spring to encourage compact growth and heavy blooming. During the winter months, ‘Raspberry Profusion’ is mostly deciduous.
Common Name: Abelia Hardiness Zone: 6 to 9Height: 57”Exposure: Full Sun to Partial Shade

Go to http://georgiagems.uga.edu/plants/shrubs/abelia.html for more information and photos.

Landscape - Problems with Leyland Cypress

2009-11-08T06:33:00.002-05:00

Leyland Cypress is a popular, fast growing hedge or border tree reaching heights of 50 to 100 feet and widths of 20 to 30 feet. Though Leyland cypress originally appeared pest resistant, as we have planted more of them - problems are becoming apparent. Over use of this plant and improper site selection and planting have led to disease problems with Leyland Cypress. The following is more on the issues with Leyland Cypress.

Certain fungi can cause canker diseases on Leyland Cypress. Cankers are infected wounds on limbs and branches that may ooze infectious sap. Leyland cypress can get two canker diseases. Bot canker kills individual branches in the tree. The foliage may turn grey-green before it dies. The dead branch will have darker bark and will have a sunken canker where the dead part of the branch begins. Limbs infected with Seiridium canker turn yellowish and then brown to grey when they die. Limbs often die back from the tips. The cankers on the main stem are sunken, reddish and ooze sap profusely. There can be many cankers on a limb. There is no spray to control these diseases. These diseases enter wounds and are worse during stressful conditions. The main control is to keep the plant in good health so it can resist these diseases.

Dry weather and improper watering can be big factors in the spread of these diseases. Plants with roots that get too wet or too dry are more likely to get these canker diseases. Prevent disease problems with proper site selection and care. Water plants deeply once every 7 – 14 days during drought. Wet soils to a depth of twelve to eighteen inches when watering. This will probably require one inch of water if you use sprinklers. Water this long each time. Soils must dry out between watering or roots may die. Avoid wetting the leaves and limbs when you water. Drip irrigation is better because they keep the foliage dry, which may reduce disease problems. Run systems once every 7 - 14 days in dry weather. Turn them on just long enough to wet the soil twelve to eighteen inches deep.

Leyland cypress planted near paved areas, walls or other heat reflecting surfaces may need special care in watering and planting to get established and to grow well. Plant Leyland cypress in well drained soils in sunny locations. Mulch them after planting but mulches should be no deeper than two to four inches. Apply mulch from the base of the tree out to several feet beyond the reach of the branches. Do not use landscape fabric unless the soil is very well drained. Do not pile mulch against the base of the plant.

Do not plant Leyland cypress in wet soils or poorly drained areas. They may respond to wet feet by getting sick or dying. Check soil drainage before you plant or if the tree has problems. Dig a hole about a foot deep and wide. Fill it with water. If it takes longer than three hours for the water to drain out, the soil is probably poorly drained.

Do not plant Leyland cypress closer than eight feet apart. As the plants get big enough for the limbs to touch, remove every other tree. As the limbs rub together they cause wounds that can be infected by disease.

If your Leyland Cypress already has canker diseases first cut out the dead limbs. Be very careful to cut way back into good live tissue. Cutting diseased limbs and then good limbs may spread the disease. While pruning you can periodically clean your shears with a towel dipped into rubbing alcohol. We generally do not cut the main stem on a Leyland cypress. If you have cankers on the main stem, remove the tree or treat the disease as per these directions and see if the tree recovers.

Finally, use the information mentioned earlier to find out what needs to change about the way we are growing the plant. The main problem is often improper watering. Solving tree problems often comes down to watering and root care since there is generally little else we can do for trees.

Other issues with Leyland cypress

Leyland cypress grow quickly but people plant them in areas too small for their mature size.

All Leylands are propagated by cuttings. Some cuttings do not root well and these trees are prone to be blown over in heavy winds.

Consider these issues when you plant

Avoid plants like Leyland cypress and Japanese cedar (Cryptomeria) if you cannot give them the care and conditions discussed today. Other plants may give you the same results without the potential problems. Consider selecting one of these alternatives. However remember that all plants have certain requirements. Match the plant to the site in terms of size, sunlight, soil type, irrigation and care required.

Possible alternatives to Leyland cypress

‘Green Giant’ Thuja
‘Foster’s’ holly
‘Little Gem’ magnolia
‘Bracken’s Brown Beauty’ magnolia
Lusterleaf holly
‘Nellie R. Stevens’ holly
Eastern red cedar (good option but growth rate can be slow)

Information from the Landscape Alert website from the University of Georgia Center for Urban Agriculture http://www.ugaurbanag.com/landscape-alert

Landscape - Seiridium Canker on Leyland Cypress

2009-11-08T05:48:00.000-05:00

The following are pictures of Seiridium canker on Leyland Cypress, one of the common causes for losses of this tree in Delaware.

Seiridium canker on Leyland Cypress. Note characteristic resin-flow on bark and dark fungal fruiting masses. Photo by Elizabeth Bush, Virginia Polytechnic Institute and State University, Bugwood.org.

Branch death on Leyland Cypress caused by Seiridium canker. Photo by Kevin Ong, Texas AgriLife Extension Service, Bugwood.org.

Landscape - Issues With Late Planted Evergreens

2009-11-07T07:56:00.003-05:00

Many homeowners are interested in buying live christmas trees to be planted out after Christmas and landscapers may want to do late fall plantings with evergreens. There can be significant winter injury to evergreens planted late and often they will not survive, especially if used as a live Christmas tree that is then planted out. The following is more information.

Newly planted trees and shrubs are not established and may suffer some winter injury if planted late. Avoid planting evergreen species after mid-October as the plants will not have sufficient time to establish new roots before the ground freezes. These species continue to lose water during winter and may suffer winter burn or even death the following early spring. All evergreen species are susceptible to winter burn, but these species are particularly susceptible, including evergreen rhododendrons and azaleas, boxwood, blue holly, groundcovers like wintercreeper and English ivy, and needle-leaved evergreens such as hemlock, yews, arborvitae, eastern white pine, and dwarf Alberta spruce. Even deciduous trees and shrubs need sufficient time after planting to acclimate to their new environment and begin to develop new roots before the ground freezes.

Information from "Winter Injury and Winter Protection of Woody Ornamental Plants" by Dr. Laura G. Jull, Department of Horticulture, University of Wisconsin–Madison http://www.waa-isa.org/pdf/NovDec2008/NovDec08-TreeLore.pdf

Landscape - Winter Leaf Burn

2009-11-07T07:41:00.002-05:00

With winter fast approaching, landscape plants can be exposed to winter injury. One such injury is foliage "burn". The following is more information.

Foliage on broad-leaved evergreen species, like rhododendrons and boxwood, as well as with narrowleaved evergreen species, like yews, arborvitae, and hemlock, may suffer desiccation during winter. Drying winds and bright sunlight may dry out the foliage. Even when the ground is frozen, plants, both deciduous and evergreen, require moisture during winter. When the ground is frozen and the root system is insufficient enough to supply water to the tops of the plants, the foliage will dry out resulting in brown, dry leaves that start at the edges or needle tips that later fall off in spring. Foliage on broadleaved evergreens can heat up to 50°F or more during sunny days in winter, causing tissue deacclimation. When the sun sets and temperatures drop sharply, the leaf tissue freezes rapidly causing death. The leaves on the outside of the plant and leaves facing the south, west, or southwest side of the plant will be most affected. The sun, as well as the harsh winter winds, causes the injury.

Information from "Winter Injury and Winter Protection of Woody Ornamental Plants" by Dr. Laura G. Jull, Department of Horticulture, University of Wisconsin–Madison
http://www.waa-isa.org/pdf/NovDec2008/NovDec08-TreeLore.pdf

Landscape - Mulching Basics

2009-11-06T05:38:00.006-05:00

The following is information on mulching for landscapers to consider.

After planting, mulch immediately with organic materials that slowly release nutrients and improve soil quality as they break down. Mulch moderates soil temperatures,reduces water needs and helps prevent weeds and erosion. Mulch also eliminates damage from string trimmers and lawn mowers.

• Apply mulch 2-4 inches deep and extend it past the drip line of plants. To prevent disease and insect damage, pull mulch away from the plant stem or trunk.

• Do not use plastic under mulch. Plastic film severely limits water and oxygen movement to plant roots. Landscape fabrics may be used, but weed and grass seeds that blow onto the fabric and root through it make removal difficult.

• Suitable mulches include softwood bark, pine straw, bark nuggets, bark mini-nuggets, shredded leaves, hardwood bark, and root mulch.

• Avoid heavy applications of grass clippings, which mat and repel water. Wood chips should be aged since fresh chips may release toxic substances into the soil and absorb nitrogen in the break-down process.

• Grouping plants together in a mulched bed instead of planting in individual holes keeps larger root areas cool and moist, providing better conditions for plant growth. It’s also easier to mow around large areas than small ones.

Information from "Environmentally Friendly Landscape Practices" By Robert R. Westerfield, Extension Horticulturist and Daryl Pulis, Master Gardener Advanced Training Coordinator, University of Georgia http://pubs.caes.uga.edu/caespubs/pubs/PDF/C967.pdf

Landscape - Planting Basics

2009-11-06T05:30:00.002-05:00

The following are some planting basics for landscapers to consider.

Proper planting is the key to healthy plants that can resist drought, insects and diseases. A well-prepared planting bed, dug to a depth of 12-15 inches and enriched with organic matter, encourages strong root development for shrub masses, islands and flower borders.

• Dig the bed and remove rocks and clods. Add lime, if indicated by a soil test. Incorporate approximately 2 inches of of fine organic material such as compost. Peat moss by itself is not recommended because it is devoid of nutrients and is difficult to rewet once it dries. Thoroughly
mix the organic matter with the native soil.

•When planting individual trees and shrubs, omit the organic matter and break up the native soil in a wide area around the planting hole. The panting hole should be at least twice the diameter of the root ball.

• Loosen and spread apart root balls to encourage roots to grow outward and to allow water to penetrate into the root mass.

• Before planting, check sub-surface drainage by filling the hole with water and allowing it to drain. If water stays in the planting hole for more than an hour, drainage is poor and needs to be corrected before planting. A slope is no guarantee of good sub-surface drainage. Raised beds or drainage tile may need to be incorporated to improve the site.

Information from "Environmentally Friendly Landscape Practices" By Robert R. Westerfield, Extension Horticulturist and Daryl Pulis, Master Gardener Advanced Training Coordinator, University of Georgia http://pubs.caes.uga.edu/caespubs/pubs/PDF/C967.pdf

Landscape - Tree Protection Zones During Construction

2009-11-04T06:02:00.005-05:00

The following is good information on setting up tree protection zones during construction activities to preserve desired trees.

Before construction or site work begins, tree protection zones must be established. A tree protection zone is a designated area around the trees to be saved in which no construction activity or traffic is allowed. Remember soil compaction begins with the first pass of a vehicle. To set up a tree protection zone: 1. Measure the diameter of the tree trunk in inches at 4.5 feet from the ground. This is called the diameter breast height or DBH. Multiply this value by 2.5. This result is the diameter of the root protection zone in feet. This is also considered the critical rooting distance. For example if an oak has a DBH of 20 inches the tree protection zone is 50 feet in diameter (20 x 2.5). Another way to think about it is to protect an area extending 25 feet in all directions from the trunk. Once the size of the area is determined, consider fencing materials. Orange tree save fencing or black silt fencing are commonly used. These materials are easy to install but they often get knocked down or removed when it is inconvenient to go around the tree save area. In some cases more permanent materials, such as chain link fencing, may be required. Whatever fencing material is used, it must be maintained throughout the construction process.

Tree protection zones are extremely important because they prevent harm from construction activities like soil cuts, soil fills, soil compaction, and the effects of chemicals from washing of equipment and disposal of wash waters. Most construction jobs start with rough grading of the property and removal of undesired vegetation. Keep in mind that trees grow in communities and often share rooting areas and wind loads, so grading and tree thinning may make the remaining trees prone to breakage from wind. The removal of soil is called a soil cut. The addition of soil is called a soil fill. The effects of soil cuts and soil fills are greatly influenced by soil texture. Simply adding one inch of clay soil over the root system will affect the health of a tree while three inches of clay will cause massive root damage. Likewise, sandy-textured soils used as fill initiate root damage at a depth of 8 inches, massive root damage at 24 inches. Soil texture influences soil porosity and structure. The finer the soil texture, the smaller the pore size. As pore size decreases, drainage and oxygen levels become more of a problem.

Information from "Tree Protection During Construction and Landscaping Activities" by Todd Hurt & Bob Westerfield, University of Georgia in the Georgia Certified Landscape Professional training materials http://apps.caes.uga.edu/urbanag/GCLP/Resources.cfm

Landscape - Tree Protection Zone

2009-11-04T05:16:00.001-05:00

The following is a picture of a well defined tree protection zone.

Photo from "Tree Protection During Construction and Landscaping Activities" by Todd Hurt & Bob Westerfield, University of Georgia in the Georgia Certified Landscape Professional training materials http://apps.caes.uga.edu/urbanag/GCLP/Resources.cfm

Landscape and Nursery - Long-stalked Phyllanthus Weed

2009-11-03T05:56:00.003-05:00

Long-stalked phyllanthus, Phyllanthus tenellus, is a perennial weed moving into our landscape and turf settings. The following is more information from the University of Maryland.

Long-stalked phyllanthus has been a weed found mostly in nurseries and greenhouses and has been spreading through movement of these ornamental plants. Mostly found to the south of Maryland, it is now appearing in many new areas as plant materials are shipped each year to meet the landscape market. Long-stalked phyllanthus is an erect perennial growing to eighteen inches in height. It germinates in the landscape as temperatures get warm and when the soil is moist. The leaves are alternately arranged on a central stem in two rows. Leaves are elliptical to oval in shape, having no petiole, and with a slight projecting tip at the apex. Stems are erect and both leaves and stems are without hairs. Flowers are small, white to green, and grow on a flower stalk that starts from the area between the leaflet and the central axis of the leaf. The fruit of this plant will be round, green, and may hang below the leaves.

Control of this weed starts with the removal of it from all containers prior to planting in the landscape. Evaluate the plants prior to placement. Once established it becomes harder to control. It is resistant to many of the commonly used pre emergent herbicides including Preen, Surflan and Barricade. The seeds of long-stalked phyllanthus are very small so the appropriate use of mulch will help prevent this from germinating. Large nugget mulch allows the seed to stay dry and not have the sunlight needed to germinate. Post emergent materials that are successful include diquat, glufosinate and glyphosate. Again consider cultural controls first.

Reprinted from and article by Chuck Schuster in the October 30, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Oct30L.pdf

Landscape and Nursery - Long-stalked Phyllanthus Weed Photo

2009-11-03T05:05:00.001-05:00

The following is a photo of Long-stalked Phyllanthus, a weed becoming more prominant in the region.

Photo from Wikipedia Commons http://commons.wikimedia.org/wiki/File:Starr_030418-0124_Phyllanthus_tenellus.jpg

Landscape - Winter Protection.

2009-11-02T05:52:00.005-05:00

Cold damage to ornamental plants can be a problem during the winter in the landscape. Recommended practices can maximize the chances that landscape plants will survive the winter. The following is an article on the subject from the University of Georgia.

During the summer months, ornamental plants are actively growing and would be severely injured by even the slightest frost. During the late summer and early fall, the plants must prepare themselves for winter through a process called cold acclimation. This process is initiated by the cooler temperatures and shorter daylengths that naturally occur at this time of the year.

Cold acclimation must occur in a timely fashion. If it occurs too early, the growing season of the plants will be shortened; if too late, they will be injured or killed by early frosts. Several factors including local weather conditions, plant selection, and maintenance practices during the growing season, can affect the timing and extent of cold acclimation of landscape plants.

Types of Damage and Conditions

Cold injury can occur on all parts of the plant including fruit, stems, leaves, trunk and roots. Typically, you will notice the cold damage first on the leaves and stems. Ice forms within the plant’s cells, the plant tissue dies, and leaves or stems become brownish-black and mushy. Cold acclimated plants can often withstand this type of ice formation. Plants that are not acclimated may sustain injury to the root system and may be severely damaged or killed. Sometimes this is not noticed until the plant fails to leaf out the following spring.

Windy conditions and accompanying cold also may cause plant damage through desiccation (evaporative water loss exceeds water absorption). This is the drying out of the plant. Marginal leaf scorching or leaf-tip burn is characteristic of this problem. Leaves may eventually turn completely brown and defoliate.

Damage to flower and leaf buds can occur during periods of low or fluctuating temperatures. This can lead to a reduction or total loss of blooms and damage of the foliage the following spring. Damage can be appraised by removing several buds and cutting them open to reveal their condition. If they appear green throughout, they are healthy; if they are partially brown or darkened, they have been injured.

One common problem that may occur during cold temperatures in woody plants is bark splitting. Bark splitting appears as loose bark in various areas on the trunk. As the bark exfoliates from dead tissue on the trunk, a frost canker can form. The canker may initially appear as a darkened, moist area. Bark splitting can cause structural damage and reduce the plant’s ability to transport nutrients and water. This can cause the death of the entire plant.

Frost cracks on the trunks of woody plants can occur when plants are exposed to extremely cold temperatures. A frost crack is a long, deep, narrow crevice running up and down the trunk of a tree. As temperatures cool down, the temperature of the trunk drops quickly and the trunk contracts and may split.

Preventive Measures

Plant and Site Selection

The best way to prevent cold damage is to select a plant that can tolerate cold temperatures in your area. It is important to select plants that meet the minimum cold hardy requirements for your area. When selecting cold-tolerant plants, be sure to consider whether they can survive the summer heat in your area as well.

In addition to plant selection, proper site selection is essential. Assess the property to determine the location of the coldest and the warmest spots. During the winter, the coldest spots are often found on the north and northwest part of the property and in low areas where cold air settles. The warmest spots are usually on the southern part of the property.

Assessing the microclimates of the property is also important. Elevation, land form, soil properties, canopy cover, and proximity of structures or other plants determine a microclimate. Microclimates can be used to help protect plants by placing cold-sensitive plants near the part of the house that receives southern exposure or near larger plants or other structures.

Plant Nutrition

Maintaining proper plant nutrition increases a plant’s tolerance to cold injury. A plant that has been given the appropriate nutrition is healthier and more capable of acclimating to cold temperatures. Fertilizing plants at the proper time of year is also vital. Fertilizing plants in the fall (after August or September) with a fertilizer high in nitrogen can cause a flush of new growth that is more susceptible to cold temperatures. Soil sampling is the best method to determine your plants’ nutritional needs. Contact your local county agent for testing procedures.

Pruning and Transplanting

Pruning in late summer or early fall can cause new growth that is more susceptible to cold injury. Prune plants just prior to the appearance of new growth in late winter or early spring. Plants transplanted in late fall or early winter are also more susceptible to cold injury. These plants may not acclimate properly when exposed to low temperatures. Transplant in the early fall.

Canopies and Shade

Radiational freezes occur on calm, clear nights when temperatures drop because of heat loss from the surfaces of objects. Canopies help reduce radiant heat loss from the plants and soil by preventing heat loss to the atmosphere. Plants that grow in shaded areas are less susceptible to winter desiccation, or drying out, than those grown in full sun. Plants that prefer full sun do not do well in the shade and will be unhealthy and less tolerant of cold temperatures if sited incorrectly.

Windbreaks

Windbreaks such as fences, buildings, evergreen plantings and temporary structures can help protect plants from cold injury. Windbreaks are most useful in reducing injury caused by cold winds and advective freezes (freezes that occur when temperatures drop because of the invasion of cold air masses into the area). They should generally be located anywhere cold winds are a problem; this is often on the northwest side of the planting.

Covering and Heating

Protect plants in containers either by placing them inside a protective structure (house, garage, greenhouse or shed) or by placing a protective covering over them. Container plants are especially susceptible to cold temperatures; their roots are more exposed because they are above ground. Plants with roots that are damaged by cold temperatures may not show immediate signs of damage; these plants will show signs of stress when temperatures rise and the demand for water from the roots is greater. Push together container plants that are left outside and mulch or cover them to decrease heat loss from the sides of the containers. Wrap the bases of the containers in plastic, burlap or blankets to reduce heat loss. Plants growing close to the ground are usually protected by heat radiating from the soil. Tall, more open plants do not receive as much radiating heat and are not as protected from the cold. Mulching helps reduce heat loss of the soil, thus minimizing temperature fluctuations.

Protecting the roots of tender perennials may also be beneficial for them to survive the cold and come back in the spring. Covering plants with insulating covers helps protect them from low temperature injury. Plastic sheeting is not recommended; the plant can heat up rapidly as temperatures rise be damaged). Remove the cover and provide ventilation during the day to allow the release of the heat that is trapped by solar radiation. You can build a frame from PVC or similar material to keep the cover from coming in contact with the plant and possibly breaking leaves and stems.

Water Needs Before a Freeze

Plants continue to have water requirements during the winter months. Therefore, following sound irrigation practices is essential for a healthy and cold hardy plant. Check the water needs of plants prior to a predicted cold snap and water if necessary. Moist soil absorbs more heat, helping to maintain an elevated temperature around the plants. Mulching the base of plants helps to retain moisture.

After a Freeze

Cold damage may not be apparent in the plant for several days or weeks. To determine if plants have been damaged by the cold, wait several days after a freeze and remove several buds, stems and leaves (if present) from the plant. Use a sharp knife or razor blade to cut a cross section of the bud’s top. If there is any discoloration in the bud, they have been damaged. To determine if stems have been injured by the cold, peel the bark back to reveal the cambium layer (layer directly under the bark). If there is any black or brown discoloration, damage has occurred. Leaf damage may appear as obvious black or burnt foliage, usually occurring at the tip of the branches. Damage on buds, stems and leaves may be localized and the entire plant may not be affected.

Waiting to prune after freezes have passed will guard against removing living wood. If localized damage has occurred to the foliage or stems, prune several inches below the injured tissue. Although injured buds may reduce or eliminate flowering or leaf emergence in the spring, no pruning is necessary.

Reprinted with minor edits from "Winter Protection of Ornamental Plants" by Robert Westerfield, Extension Horticulturist and Dr. Orville Lindstrom, Professor of Horticulture, University of Georgia http://pubs.caes.uga.edu/caespubs/pubcd/C872/C872.htm

Greenhouse and Nursery - Scout for Aphids

2009-11-02T05:47:00.002-05:00

Aphids are another pest that should be scouted for in fall greenhouse plantings. The following is an article on the subject from the University of Maryland.

Monitoring Aphids in the Fall

Throughout most of the year, aphids can reproduce parthenogenically (females do not mate and give live birth to more females). Aphids can give birth to females ready to give birth to more aphids which means aphid populations can build up very quickly. Winged forms can be produced when populations are high to help the aphids disperse to new plants or crops. In the fall, males are produced and they mate with the females. At this time, females lay eggs which overwinter. Aphids in the egg stage are not susceptible to insecticides.

Monitoring: Look for aphids feeding on growing tips, along stems and in flower heads. In heavy infestations, there will be many white cast skins and sooty mold on the plants. Aphids secrete honeydew as a waste product which is a food source for the sooty mold fungus.

Control: Insecticides for aphid control include neem products and horticultural oils. Most of the systemic insecticides labeled for ornamental crops give good control of aphids.

Biological Control: Predators and parasitoids can be ordered from biological control suppliers and released in the greenhouse to help control aphids before populations build to high numbers. The lady bird beetle, Hippodamia convergens, lacewings, parasitic wasps such as Aphidius colemani and the predatory midge, Aphidoletes aphidomyza, are readily available.

Reprinted from the October 30, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center. For the full article with pictures go to http://www.ipmnet.umd.edu/09Oct30G.pdf

Landscape - PLANET Sustainability Report

2009-11-01T06:44:00.002-05:00

Sustainable landscapes are the hot topic nowdays. The following is information on a recent report issued on the subject.

PLANET (Professional Landcare Network, aka ALCA) has just issued its annual “Crystal Ball Report” and the report declares that the green and sustainable landscapes trend is here to stay. The report characterizes the trend as “perhaps the biggest distinct business opportunity of the 21st century…” for the landscape and turf industry. In addition to exploring and defining sustainability for the landscape and turf industry, the report is chock full of ideas and specifics about how companies can implement sustainable practices in their work, both externally for customers and internally in their businesses. The report is a must-read for any landscape company owner who wants to learn how to profit from this growing trend.The report is available through the PLANET bookstore by clicking here . You may also want to download PLNA’s white paper on green infrastructure, download by clicking here .

Information from the Pennsylvania Nursery and Landscape Association website: http://www.plna.com/content/?/e-news/october-23-2009#planet

Landscape - Bilingual Bulletins

2009-10-31T06:52:00.000-04:00

The University of Georgia Center for Urban Agriculture has a number of english/spanish combination bulletins on its website. These would be very useful tools for training hispanic workers. The following are some links.

Bilingual Bulletins/Boletines bilingüe

Fireblight: Symptoms, Causes and Treatment / Quemazón de las Rosáceas: Síntomas, Causas y Tratamiento

Identifying and controlling most common Spring Plant Diseases in the Landscape / Identificando y controlando las enfermedades de plantas más comunes en la primavera en el paisaje

Nematodes in the Landscape: the Silent Threat to Plant Health / Los Nematodos en el Jardín Residencial: La Amenaza Silenciosaa la Sanidad de las Plantas

Powdery Mildew on Ornamental Plants: Facts and Controls / Cenicillas Polvorientas en Plantas Ornamentales:Hechos y Control

Promoting and Active Plant Disease Scouting in the Landscape / Promoviendo un Monitoreo Activo

Reminders for Improved Drop Spreader Performance / Recordatorios para Mejorar el Funcionamiento de las Aspersoras de productos químicos que funcionan por gravedad

Six Easy Steps for Success with Pre-emergence Herbicides / Seis Pasos Fáciles para tener éxito con Herbicidas Pre-emergentes

Sudden Oak Death / Muerte Repentina del Roble

Top Diseases and Plant Problems on Turf / Enfermedades y Problemas de Cespedes y Ornamentales mas Importantes

Greenhouse - Watch for Whitefly

2009-10-31T06:40:00.001-04:00

Watch for whitefly in fall greenhouse crops. The following is a short article on the subject.

Monitor poinsettia and other greenhouse crops closely for the different stages of whitefly. Avoid letting weeds grow under the benches which serve as epicenters for whitefly populations. If you treated poinsettias with imidacloprid (Marathon) or dinotefuran (Safari) as soil drenches after pinching then you should have pretty good control of whitefly on the foliage that expanded after the application. Be sure to continue closely monitoring lower leaves which would have expanded before the systemic was applied. Check pesticides labels to see whether they note “do not apply when bracts are in color”. In past years we have observed that Abamectin (Avid), pyridaben (Sanmite), chlorfenapyr (Pylon), acetamiprid (TriStar) and dinotefuran (Safari) applied as foliar sprays in bract stage without causing any noticeable damage on poinsettia varieties such as ‘Freedom’, ‘Prestige’ and ‘Monet’. When applying pesticides late in the season to poinsettias, it is best to try out a spray on a few plants before treating the whole crop. Other materials that work well include Azatin, Aria, Endeavor, Enstar, Flagship, Judo, Marathon, Pedestal, and Talus.

Reprinted from the October 30, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report University of Maryland Cooperative Extension Central Maryland Research and Education Center http://www.ipmnet.umd.edu/09Oct30G.pdf

Greenhouse - Whitefly Insectide Resistance

2009-10-30T06:25:00.004-04:00

Whiteflies can develop resistance to insecticides used for their control in the greenhouse. The following is more information.

Resistance Problems

Unquestionably, chemical controls such as Marathon, Safari, Distance and Avid are presently some of the premiere whitefly management materials with poinsettias. Typically they have shown to be outstanding insecticides and have enabled growers to reduce the number of treatments previously required when managing a poinsettia crop. Unfortunately, these control materials have become regional wide management approaches with their use commonly applied during all phases of the crop’s development stages.

It needs to be remembered that insecticide resistance is a reality in our industry. For example, during the past few years Marathon has experienced widespread resistance problems against silverleaf whiteflies (Q-Biotype strain). When the same insecticide is used extensively over an extended period of time, then resistance will inevitably begin to occur. There are at least 3-dozen insecticides which whiteflies in the Bemisia genus (silverleaf whitefly) are resistant to. Consequently, it is important to try to break the cycle of continual applications of insecticides that presently work best. For example, for the past 2-3 years Safari has become the material of choice for many poinsettia growers. Simply loading up on the latest and greatest insecticide presently available will produce problems. Hoping the pest control industry will continue to be able to produce new materials after others become resistant is an approach that will eventually lead to failures.

Information from "Some Thoughts on the Biointensive IPM Approach for the Management of Whitefly on Poinsettias" by Steven K. Rettke, Ornamental IPM Program Associate, Rutgers University in the October 15, 2009 edition of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition, A Rutgers Cooperative Extension Publication. http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln101509.pdf

Landscape - Smaller Trees for Delaware Landscapes

2009-10-30T06:13:00.003-04:00

The following are some smaller trees to consider for Delaware Landscapes

Amur maple (Acer tataricum ssp. ginnala). Hardy; multi-stemmed tree; 15-20’ tall; fragrant, inconspicuous, creamy-white flowers in spring; red fruit in summer that turns brown; bright orange to red fall color; can reseed in wild; tolerant to a wide range of soils and pH.

Japanese tree lilac (Syringa reticulata). Hardy; compact; upright; 15-25’ tall; reddish-brown, shiny bark; large, creamy-white, slightly fragrant, terminal flowers in June; yellow fall color; tolerant to a wide range of soils and pH; urban and salt tolerant.

American hornbeam, musclewood (Carpinus caroliniana). Hardy; wide-spreading; multi-stemmed tree with low branches; 20-30’ tall; fluted, muscle-like bark and branches; yellow to orange-red fall color; slow grower; prefers rich, moist, slightly-acid soil; salt intolerant; shade tolerant. Native tree.

Eastern redbud (Cercis canadensis). Hardy; spreading; vase-shaped tree; 20-30’ tall; reddish-purple new leaves that change to green; brownish-black bark with orange inner bark; reddish-purple flowers that fade to pink in early spring; yellow fall color; prefers a moist; welldrained soil; pH adaptable; partial shade tolerant; native tree.

Apple serviceberry (Amelanchier x grandiflora). Hardy; upright; multi-stemmed tree; 15-25’ tall; smooth gray bark; reddish-bronze new growth; white flowers in early spring; reddish-purple edible fruit in early summer; attracts birds; yellow-orange to red fall color; full sun to partial shade; prefers a moist, welldrained, slightly acid soil.

Landscape - Tree Planting Tips

2009-10-29T06:56:00.003-04:00

Early November is a good time to plant many deciduous tree species. The following are some tips on tree planting.

LOCATE LOGICALLY - Trees need room to develop root systems underground and branches above ground. Don't plant trees that will grow too large in small areas. Also avoid planting under power or telephone lines or too close to buildings. Site suitability will determine which, if any trees to plant. The designated site may be in the lawn, near a patio, along a street or sidewalk, in a garden, in sun or in a shaded spot. Soils may be clay, sandy, saline, compacted, wet or dry, gravelly or even full of old building rubble. Whatever the situation, you will need to determine if the site is suitable for growing a healthy tree. Consider planting for energy conservation. Deciduous trees will shade the west, south and east sides of the home in summer, and evergreen trees along the west and north edges of the lot will provide winter windbreaks.

CHOOSE CAREFULLY - For what reasons are you planting the tree? You may want privacy, increased property values, a windbreak, shade, fall color, flowers, fruit or a bird habitat. Perhaps you want to create a sound barrier. Combine this information with knowledge about the site.
This is a good time to visit your local Cooperative Extension agent. You'll want to consider that fast-growing trees often are weak and subject to storm damage. Think about the mature size and shape of trees and learn whether their roots might invade sewer lines, lift and crack sidewalks or make bumpy lawns. Learn which trees are likely to harbor insects or diseases.

DIG DILIGENTLY BUT CAUTIOUSLY - Before digging, contact your utility company to mark the location of any underground lines. You could be liable for damage done to such lines.
To prepare the site, mark a circle at least 3 times the diameter of the tree's rootball. Excavate the area with a pick and spade. In clay soil, dig to a depth 2-4 inches shallower than the height of the rootball. In sandy soil, dig to a depth equal to the rootball. Leave the bottom of the hole firm and undisturbed. Holes should be saucer shaped.

PLANT PROPERLY - Try to plant trees when the weather is cool, cloudy and humid, but not windy. If you can't plant right away, keep the tree in a cool, shady, protected spot and keep the roots moist. It helps to soak bare root trees and shrubs in a bucket of water overnight before planting. Remove any plastic or metal containers from the rootball. Place the tree upright in the center of the planting hole. If the tree is in a fiber pot, tear off the sides. If the roots of a containerized tree are potbound, "tease out" some of the roots. For balled and burlapped trees, cut any rope tied around the trunk and pull the burlap away. Cut any reinforcement wire, removing as much as possible, but be sure the rootball stays intact. Shovel backfill into the hole; continue until roots are covered and most of the backfill is used. Don't tamp the soil with your feet.

FERTILIZE FRUGALLY! - Don't put fertilizer into the planting hole; it may cause root injury. Next spring, fertilize young trees lightly. Root stimulator solutions have negligible value. You can use them, but they aren't necessary for transplant success.

WATER WELL - Water the soil at relatively low pressure, using the hose or a "bubbler." Let the water, not your foot, settle the soil. If the soil settles below grade, add more backfill. When done, the planting area should be well-soaked and moist backfill should barely cover the top of the rootball. Watering frequency depends on the soil, not the calendar. Dig with a trowel on the edge of the planting area. Soil that feels moist and holds together when squeezed doesn't need water. Overwatering drives air from the soil, causing root suffocation.

PRUNE PRUDENTLY - A newly planted tree needs only minimal pruning. Prune out only dead, diseased or injured branches. Research shows that transplanted trees establish quicker when as much foliage as possible remains. If you do prune, don't use pruning compounds on pruning cuts.

STAKE SENSIBLY - Trees can be staked too tightly or for too long. Don't stake small trees or those not in the wind's path. Large evergreen trees, planted in a windy site, will need staking. To stake,do not use garden hose and wire. Instead run wire through grommeted staking straps or use wide strips of carpeting. This way, the straps, not the wire, passes around the trunk. A year of staking usually is sufficient. Rigid staking of a tree is counterproductive; research shows trees don't develop normally if they're not allowed any sway.

MULCH MEANINGFULLY - A forest tree provides its own mulch with several inches of leaves on the ground. We can imitate this by mulching the planting area with 3 to 4 inches of wood chips, chunk bark, straw, pine needles or shredded leaves. Don't use plastic beneath the mulch; water or air can't penetrate it. Fabric-type weed-barriers are preferable. One thing you won't see in the forest is manicured lawns around a tree. Research shows that newly planted trees are at a disadvantage when they must compete with grass for water, air and nutrients. Keep grass from the planting area for at least one year. If you mulch around trees, instead of planting grass, you also prevent possible trunk damage by lawn mowers or string trimmers.

Adapted from "Ten Commandments of Tree Planting" By Robert Cox, Colorado State University Cooperative Extension agent, horticulture http://www.colostate.edu/Dept/CoopExt/4DMG/Trees/command.htm

Landscape - Highly Rated Trees for Delaware

2009-10-29T06:44:00.002-04:00

The following are some highly rated trees for planting in Delaware.

Paperbark Maple
Japanese Maple
Blue Atlas Cedar
Hinoki Falsecypress
Dawn Redwood
Sourwood
White Oak
Scarlet Oak
Shingle Oak
Bur Oak
Red oak
Japanese Stewartia
Baldcypress
Hedge Maple
Red Maple
Briotti Red Horsechestnut
Shadblow Serviceberry
Heritage River Birch
American Hornbeam
Shagbark Hickory
White Fringetree
American Yellowwood
Ginkgo
Kentucky Coffeetree
Common Witchhazel
American Holly
Golden Raintree
Sweetgum
Cucumbertree Magnolia
Saucer Magnolia
Star Magnolia
Sweetbay Magnolia
Blackgum
Norway Spruce
Sawtooth Oak
Willow Oak
Japanese Pagodatree
Japanese Snowball
Japanese Tree Lilac
Littleleaf Linden
Chinese Elm
Zelkova

Information from Pennsylvania and Delaware: Tree Species Rating and Valuation Guide; Penn-Del Chapter ISA

Landscape and Nursery - Black Root Rot of Holly

2009-10-28T06:23:00.002-04:00

The following is a good article on black root rot of Holly from the University of Kentucky.

Black root rot, caused by the fungus Thielaviopsis basicola can do significant damage to hollies in landscape beds. Black root rot is most frequently observed on Japanese holly, blue holly, and inkberry. Susceptible blue holly cultivars include: Blue Angel, Blue Maid, Blue Prince, Blue Princess, Blue Stallion, China Boy, China Girl and Dragon Lady. While English and Chinese hollies are reportedly resistant, American and Yaupon hollies are considered to be only moderately resistant. Other ornamentals known to be susceptible include begonia, cyclamen, geranium, gloxinia, oxalis, petunia, phlox, poinsettia, sweet pea, verbena, and viola (pansy). Black root rot may also affect alfalfa, cotton, cowpea, eggplant, peanut, snapbean, soybean, tobacco, and tomato.

Symptoms. The first symptoms of black root rot include yellowing and marginal scorch of the foliage and shoot dieback. Later, twigs or stems may die back and eventually the entire plant may die. The root system of the declining plant is stunted and decayed. These symptoms could be confused with Phytophthora root rot which was also widespread in landscapes this year. Unlike Phytophthora, black root rot causes black lesions on the infected roots which, in the early stages of disease, contrast sharply with the adjacent healthy white portions. Lesions may appear on the tips of feeder roots or elsewhere along the root. Diagnosis can be confirmed by microscopic analysis which reveals the characteristic chlamydospores of the fungus embedded in the root tissues.

Disease Management.

Landscapers and nursery growers need to be aware that the black root rot fungus can persist indefinitely in the soil or it can survive as a saprophyte on plant debris, so once a landscape or nursery bed is contaminated with the fungus, it is difficult to remove.

Plant only disease-free plants in the landscape. Sometimes diseased, but well-watered and fertilized, nursery-grown hollies or bedding plants will appear to be healthy but, after they are placed in the landscape, they may decline due to more stressful growing conditions. This means it is very important to examine root systems prior to planting. If blackened roots are evident, plants should be rejected.

Avoid planting susceptible plants in soils known to be infested with the fungus. While the fungus is widespread, it may be present in higher levels in soils where black root rot was previously a problem on other plants such as petunia or pansy. Occasionally, when old agricultural lands are developed for housing, homeowners may find they have also purchased a black root rot problem from a former tobacco or alfalfa field as well.

In the landscape, badly infected plants should be removed and the site replanted with a non-susceptible host.

There are no effective fungicide drenches available for controlling black root rot in the landscape. Steam pasteurization or chemical fumigation will eradicate the fungus from propagation and growing media in nurseries. The fungicide Medallion is registered for managing this disease in greenhouses.

Information from "Holly Black Root Rot is Active" By John Hartman in the current edition of the Kentucky Pest News http://www.uky.edu/Ag/kpn/kpn_09/pn_091027.html#Corn3

Landscape - Rose Mosaic Virus

2009-10-28T06:01:00.004-04:00

I recently was sent some rose pictures that looked like the plant had rose yellow mosaic virus. The following is more information.

Several viruses are associated with the range of symptoms of rose mosaic, including Prunus necrotic ringspot virus (PNRSV) and Apple mosaic virus (ApMV). The disease does not spread naturally, has no known insect vector, but grafting transfers it to healthy plants. Viruses can be in the rootstock or scion or both and may not show symptoms. 'Madame Butterfly', 'Ophelia', and 'Rapture' are highly susceptible. Some report the disease does not spread; others indicate it may spread very slowly over many years.

Symptoms may range widely depending on time of year, temperature, and type of virus(es) infecting the plant. Characteristic symptoms include chlorotic line patterns (zigzag pattern), ringspots, and mottles in leaves sometime in the growing season. There may also be yellow net and yellow mosaic symptoms. Symptoms often are evident in spring and early summer but may not be on leaves produced in summer. Vein-banding may be on leaves in long hot periods. Flower distortion, reduction in flower production, flower size, stem caliper at the graft union, winter survival, and early leaf drop, and increase susceptibility to cold injury have all been reported. Some infected cultivars may not show any symptoms at all.

Note the irregular pattern of yellow lines on leaves.

Sometimes the leaf veins are yellow in plants infected with this virus.

Cultural control:

Purchase clean and/or certified virus-tested (and found to be free of all known viruses) stock. Remove and destroy infected plants. However, the disease will not spread unless you propagate from or onto an infected bush. Heat-treat scion stock plants 4 weeks at 100oF before grafting.

Information and photos from the Online Guide to Plant Disease Control from Oregon State University http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=989

Landscape and Nursery - Some Cypress and Falsecypress Species for Delaware

2009-10-27T06:09:00.005-04:00

The following are some cypress and falsecypress species that are adapted to Delaware landscapes. Note that the genus Cupressus has been changed for some species to Callitropis. One particularly interesting species is Arizona cypress which deserves wider planting in Delaware as a substitute for Leyland cypress.

Nootka falsecypress (Callitropis nootkatensis) ‘Pendula’, ‘Green Arrow’, ‘Van der Acker’
Arizona cypress (Callitropis glabra) ‘Silver Smoke’
Arizona cypress (Callitropis glabra) ‘Blue Ice’
Japanese falsecypress (Chamaecyparis pisifera) ‘Boulevard’
Japanese falssecypress (Chamaecyparis pisifera) ‘Curly Tops’
Hinoki falsecypress (Chamaecyparis obtusa)

A high priority is to identify alternatives to the overused and problem-susceptible leyland cypress (X Cupressocyparis leylandii). One good example of an alternative to this screen plant is the Arizona cypress (Cupressus arizonica).

There is a debate on the proper nomenclature for this group of plants. This is a botanical lumper-splitter type of project. Some experts separate C. arizonica from C. glabra. Other experts lump them and place glabra as a variety of C. arizonica. The distinction is not as important, however, as the potential this group offers for Delaware gardens.

There are several reasons why this needle evergreen deserves more attention. First of all, the various cultivars all have an eye-catching silver-blue/powder blue color. The blue hue is even better than what you get with the blue atlas cedar (Cedrus atlantica ‘Glauca’). I love the cultivar names: ‘Blue Ice,’ ‘Blue Pyramid,’ ‘Carolina Sapphire,’ and ‘Silver Smoke.’

The second reason to admire this plant is for its rapid growth. For this reason it is grown frequently as a Christmas tree in the Southeast. So far the plant is also quite free of insect and disease problems. I have not observed bagworms, rust, or cankers like some other evergreen options.

The growth habit on young plants is very similar to our native Eastern red cedar (Juniperus virginiana). Because needles are not born in flat sprays like leyland cypress, the overall texture is very soft. Plants are pyramidal in shape and clearly taller than they are wide. As the plant matures it will open up. Very old specimens almost have a weeping, graceful appearance. ‘Blue Ice’ and ‘Blue Pyramid’ may have a much tighter pyramidal habit than ‘Carolina Sapphire.’

Arizona cypress thrives on full sun exposure. The fabulous blue needle color will probably be diminished in more shade. While constant moisture might promote growth, an established plant should tolerate fairly dry conditions.

Need a cute fact for the next garden party? Arizona cypress is closely related to the artistic and beautiful Monterey cypress (C. macrocarpa) found along the California coast. Unlike its cousin, the Monterey cypress does not seem to like the heat and humidity this area of the U.S. Another garden party trivia note: Monterey cypress is one of the parents of the intergeneric hybrid leyland cypress.

Common Name: Arizona Cypress
Varieties to look for: ‘Blue Ice,’ ‘Blue Pyramid,’ ‘Carolina Sapphire,’ ‘Silver Smoke’
Flower Color: none
Blooming period:
Perennial or annual: needle evergreen
Size: 45’ tall by 20’ wide
Exposure: sun to partial shade
Soil: tolerant
Watering: moist best
When to prune: not required
Suggested use: screen/hedge, specimen

Information on Arizona Cypress adapted for Delaware from "Arizona Cypress – Cupressus arizonica Shrub Profile" By: James Robbins, University of Arkansas. Photo also from that publication. http://www.aragriculture.org/horticulture/ornamentals/plant_database/shrubs/profiles/arizona_cypress.pdf

Landscape, Nursery, and Greenhouse - Mite Control

2009-10-26T05:37:00.003-04:00

The following is a good table on mite control options for horticultural use from North Carolina State University. Click on the table for a larger version in a new window.

Information from the 2007 Nursery Crops Short Course, Mountain Horticultural Crops Research and Extension Center, Fletcher, NC, North Carolina State University.

Landscape - Understanding Slugs

2009-10-26T05:27:00.003-04:00

We are certainly hearing about slug troubles this fall. With the cooler temperatures, slugs seem to be feeding incessantly. Slugs of course are most often problematic in mulched areas and thrive in high moisture parts of the landscape. The following is more information.

Most slugs have a single generation per year with overwintering eggs hatching in spring and slugs developing through spring, summer, and fall. As winter approaches, slugs lay eggs, which overwinter and hatch the next spring. Some adults can also survive over winter until next spring and resume feeding.

If slug problems are particularly bad, you might consider fall applications of metaldehyde baits. Such applications can be effective, but are not the most efficient use of these baits because some adult slugs may have already laid eggs and the chemical treatment might not contribute too much to reducing spring populations.

A final point worth mentioning in the struggle against slugs is that natural enemies have a lot of potential to contribute to slug suppression. Some ground beetle and harvestman (aka daddy long legs) species are voracious slug predators. Reduce insecticide use in landscapes to preserve these predators of slugs.

Adapted from an article in the Penn State Field Crop News.

Landscape and Nursery - Plants for Delaware Landscapes: Gaura lindheimeri

2009-10-25T06:50:00.003-04:00

The following is information on Gaura lindheimeri, a good herbaceous perennial for Delaware landscapes.

Gaura lindheimeri, whirling butterflies, is an herbaceous perennial native to Texas and Lousiana that comes into its own in the late summer and throughout the fall. It is very drought and heat tolerant and can stand up against high humidity without diseases slaying it. It grows in an upright bushy form to a height of 2 - 3 feet and will flower continuously from spring till the first hard frost. G. lindheimeri prefers a moist rich soil with a neutral to alkaline pH, but it grows very well in most soils regardless of moisture or pH. Despite its heat tolerance, G. lindheimeri can thrive from zone 5 - 10 as long as the roots are well mulched for the winter. The flowers are small and white or pink depending on the cultivar, but as the white flower matures it becomes a pale pink. They are arranged on the stem like a gladiola, with a few flowers blooming at a time and are held above the foliage. After flowering, the spent flowers fall cleanly without dead heading. The flower stalks are thin and wiry, often tinged with red or pink depending on the coolness of the night temperatures. G. lindheimeri can be used as a background plant or as a wild flower planting; it doesn’t conform to a formal planting. Some of the newer cultivars are more compact like ‘Swirling Butterflies’ or a darker pink like ‘Siskiyou Pink’, Pretty in Pink’ and ‘Crimson Butterflies’. Pests include aphids, leaf galls, leaf spots, root rot and rust.

Gaura lindheimeri

Information from Ginny Rosenkranz, University of Maryland in the October 23, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers, University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Oct23L.pdf

Landscape - Salt Tolerance of Landscape Plants

2009-10-25T06:02:00.000-04:00

Winter is not far around the corner and deicing salts will be used by road and parking lot maintenance personnel. Excess salts can damage landscape plants. The following are lists of salt tolerant and salt sensitive landscape plants. For areas that receive excess salts from deicing (such as parking lot islands), you should consider salt tolerant species.

Salt Tolerant Shrubs

bayberry
California privet
honeysuckle
Pfitzer juniper
rugosa rose
yucca

Salt Sensitive Shrubs

boxwood
spirea
viburnum

Salt Tolerant Deciduous Trees

boxelder
black cherry
black locust
bur oak
English oak
green ash
honeylocust
red oak
Russian olive
Siberian elm
weeping willow
white oak
white poplar

Salt Sensitive Deciduous Trees

American linden
beech
black walnut
flowering dogwood
ironwood
little-leaf linden
red maple
shagbark hickory
silver maple
sugar maple
sycamore

Salt Tolerant Evergreens

Austrian pine
Japanese black pine
pitch pine
red cedar
white spruce
yew

Salt Sensitive Evergreens

balsam fir
Canadian hemlock
Douglas-fir
eastern white pine
red pine

Information from "De-Icing Salts Can Injure Roadside Vegetation" by Ann B. Gould, Ph.D., Specialist in Plant Pathology in the Nov. 6, 2003 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2003/ln1106.pdf

Greenhouse - Whiteflies on Poinsettias

2009-10-24T06:47:00.003-04:00

The following is information on initial signs of whitefly damage on poinsettias.

Often a sign of a large whitefly population directly feeding on the poinsettia crop is chlorotic and bleached stems, leaves and bracts. In order to prevent this from occurring, growers should maintain good sanitation, install and monitor yellow sticky cards and routinely inspect the underside of leaves for the presence of whitefly eggs, nymph and adults. If whiteflies are found implement integrated pest management (IPM) practices to avoid the above problems and prevent whitefly pesticide resistance.

Chlorotic and bleached stems, leaves and bracts are often signs of heavy whitefly pressure on poinsettias.

Information from the Purdue Plant and Pest Diagnostic Laboratory Website http://www.ppdl.purdue.edu/PPDL/weeklypics/10-29-07.html

Landscape - Pear Blister Mite

2009-10-24T06:41:00.004-04:00

The following is an article on Pear Blister Mite, a pest to be watching for in the landscape

Over the last couple of years we have been seeing more pear blister mite damage on Asian pears, European pears and ornamental pears. These mites are very small and you will need at least a 15 to 20X hand lens to see them. They are white, long, slender, and striated. They also have a few long hairs. Eggs are spherical and pearly white.

Monitoring: Look under bud scales during winter where these mites feed. This feeding can cause buds to dry and fail to develop in spring. In the spring, pear blister mites feed on emerging leaves, flowers and developing fruit. Feeding results in blistered leaf spots that start red and eventually turn black. The spots on the fruit are usually depressed with a halo of clear tissue that tend to run together. Eggs are laid inside the blister which is where young mites start feeding so they are rarely seen.

Control: In late October the females will begin to seek out places on the branches to overwinter. They like to settle down into the bud scales and bark cracks. At this time of year they are moving about on the twigs and are susceptible to pesticide applications. You have a relatively small window in which to treat for this pest. A 2% rate horticultural oil can e applied in late October. The kill rate can be improved with addition of Abamectin (Avid) to the horticultural oil.

Pear blister mite damage.

Article and photo from the October 23, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Oct23L.pdf

Landscape and Nursery - Azalea Cultivars Resistant to Lace Bug

2009-10-23T05:37:00.001-04:00

The following are some azalea cultivars that are resistant to lace bug.

Lace bugs are a frequent pest on azalea, rhododendron, pyracantha and other hosts. These laceywinged insects feed on the undersides of leaves, suck leaf sap and leave a chlorotic dot on the upper leaf surface. They overwinter as eggs inserted into the leaves. Black varnish spots on the underside of leaves is diagnostic for this insect. Management techniques may involve malathion, insecticidal soap, pyrethroids, and resistant varieties.

The following azalea cultivars have resistance to azalea lace bug:

Dawn
Pink Star
Ereka
Cavalier
Pink Fancy
Dram
Seigei
Macrantha
Salmon Pink
Elsie Lee
Red Wing
Sunglow
Marilee

Information from the 2007 Nursery Crops Short Course, Mountain Horticultural Crops Research and Extension Center, Fletcher, NC, North Carolina State University.

Greenhouse and Landscape - Pansy Diseases

2009-10-23T05:23:00.000-04:00

Keep your eyes out for two diseases of pansy that have been increasing over the years.

Black root rot shows up just about anytime in the greenhouse and landscape. If plants are not establishing or declining without any obvious leaf spotting or other problems carefully dig the plants and check out the roots. If roots are black to very dark suspect black root rot and send in a sample.

Control: in the greenhouse keep medium pH between 5.5 and 6.0 do not reuse plug flats without sterilizing; control fungus gnats. Chemicals that work best as preventative treatment include thiophanate methyl (3336, Fungo) Medallion and Terraguard.

Cercospora leaf spot. Look for irregular spots with dark red- brown margins. This disease can be found in all stages of crop production as well as in the landscape. In the greenhouse try and keep the foliage dry, check frequently, rogue out badly spotted plants from the greenhouse. Fungicides for outside and inside use to control Cercospora leaf spot include Daconil, Compass, Heritage, Insignia, or SI’s such as Eagle (or Immunox for home use).

Information from Bob Mulrooney, Extension Plant Pathologist, UD

Landscape - Hardy Banana

2009-10-22T06:47:00.004-04:00

The following is information on hardy banana, a perennial plant to try in Delaware gardens for a "tropical" look along side of Cannas and similar plants.

A great tropical looking plant, native to Japan’s Ryukyu Islands and is hardy to zone 6 if mulched heavily with leaves in the autumn. Plants can reach 10’ in height, with foliage up to 6’ in length. Plants will produce new offsets each spring around the original plant, creating a great impact for the annual or mixed border!

Besides adding a tropical look to gardens, the hardy banana, Musa basjoo, is a fascinating plant. It, along with other species in the genus Musa are the world's largest herbaceous plants, mostly originating from tropical climates. Many species of Musa routinely grow more than twenty feet tall! The hardy banana grows to be anywhere from 12 to 18 feet tall, so it will probably attract some attention if planted in your garden.

While sometimes we talk about banana 'trees', in fact all parts of the plant are herbaceous–no parts are woody. What many of us mistake for the 'trunk' of the banana tree is in fact tightly wrapped leaves. Botanically speaking this is a pseudostem, meaning 'false' stem. Unlike a lot of plants, the growing point for a banana plant is not near the outside of the plant. It is deep within the pseudostem near the base, much like how German irises and canna lilies grow.

Each pseudostem on a banana plant has a limited lifespan. It only lives as long as it takes it to flower and produce fruit. For many species, this can take the better part of a year. In our climate it is unlikely that the hardy banana will grow long enough to produce fruit. If it does, unfortunately it is not edible.

Why would anyone grow a banana plant that produces inedible fruit? The answer lies in the other common name for Musa basjoo–Japanese fiber banana. Musa basjoo is actually from the Ryukyu Islands of Japan, and historic records indicate the Japanese have cultivated the banana for fiber since the 13th century.

The fibers are extracted from shoots by boiling the shoots in lye. Then the fibers are spun into yarn and used for garments. The fibers extracted from a shoot will vary in how coarse or soft they are. Those near the outside tend to be coarser, while those in the center are much softer. Other cultures also use banana fibers, but the extraction method differs. The end result is very similar. The softest fibers have been compared to silk in how they feel and look when used in textiles. Banana fiber can also be used to make paper.

Musa basjoo, hardy banana. Photo from the Miami of Ohio cold hardy tropical plant research group web site http://www.cas.muohio.edu/coldhardypalms/Lab%20Group/LabGroupMain.htm

Information from Rutgers University and an article by Jennifer Schultz Nelson, Unit Educator, Horticulture Macon County, University of Illinois.

Landscape - A Source Guide for Mid-Atlantic Wetland Plants

2009-10-22T06:39:00.002-04:00

The following is a good reference on where landscapers can buy wetland plants in the Mid-Atlantic area for doing wetland plantings.

A Source Guide for Mid-Atlantic Wetland Plants

83 Nursery Sources listed with name, address, phone, email, website

Includes:
Explanation of Terms
Indicator Categories
Characteristic or Form
Hardiness Zone
pH
Hydrology (Tidal/Non-Tidal)
Planting and Maintenance Information
54 pages – Softcover

Order Your Copy today for $17.95! (Virginia Nursery and Landscape Association Members)
Non-Members Add $5.00
(Includes Shipping & Sales Tax )
(credit cards accepted)

Click here for order form http://www.vnla.org/Forms/Wetlands_Order_Form.htm

Developed for the Virginia Nursery & Landscape Association By Cathy Palmintier, Pam Brown & Dr. Bonnie Lee Appleton, Hampton Roads Agricultural Research & Extension Center, Virginia Tech

Landscape - Some Trees to Avoid Fall Planting

2009-10-21T06:28:00.004-04:00

Early november is a good time to plant many tree species in Delaware. However, there are some species that are best planted in the spring. The following is more information.

Tree Transplanting (Fall vs. Spring)

Some trees are best planted in the spring, as opposed to the fall. Some tree species fail to adequately regenerate their root systems in the fall. They often have borderline hardiness and are best planted in spring so that they’ll have more time to become established before winter. The following is a list of plants that are not well suited for fall plantings and should be delayed until next spring: fir, birch, hornbeam, hickory, flowering dogwood, common persimmon, beech, ginko, American holly, walnut, golden raintree, golden chaintree, sweetgum, tulip tree, magnolia, blackgum, ironwood, sourwood, popular, Prunus species, golden larch, oak, willow, sassafras, cypress, and hemlock. If these species must be planted in the fall, be sure to allow for adequate water at the time of planting and until the ground freezes.

Adapted from an article by Steven K. Rettke in the October 10, 2002 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2002/ln1010.pdf

Landscape and Nursery - Watch For Root Rots

2009-10-20T06:53:00.003-04:00

Watch out for root rots in landscape plants this fall, over winter, and next spring. I have confirmed several instances of trees and shrubs dying from Phytophthora root rot this year already.

One of the potential impacts from the wetter than normal season will be increased chances of root rots or reduction of root systems, especially in areas with high water tables or poor drainage. If trees and shrubs begin to turn brown from the top down during the fall or next spring and no other reason can be found for the decline, check the root systems for rotted roots or lack of a good healthy root mass.

Information from Bob Mulrooney, Extension Plant Pathologist, UD

Landscape - Brown Marmorated Stink Bugs

2009-10-20T06:43:00.004-04:00

The brown marmorated stink bug, Halymorpha halys, [BMSB] has vastly expanded its impact as a nuisance pest in our area this year. Fortunately, it hasn't been a problem downstate. The following is more information.

First discovered in Allentown, PA in 1996, this insect has now spread its range to 25 States From the West Coast North to Wyoming, South to Mississippi and along the Eastern seaboard. It has a typical stink bug shape with a mottled brown color and does emit a pungent odor when crushed. Light brown-black nymphs hatch from light-green eggs and progress to the adult stage within several weeks. There was one generation per year reported in PA, but more are likely in areas with warmer weather. The ¾” long adult is generally the most visible life stage and it has been seemingly encountered everywhere this fall. Like other stink bugs, it feeds by inserting its sucking mouthparts into leaves and fruit of desired plants. Fruit distortion from stinkbug feeding can be referred to as “Cat-Facing”. Hundreds of hosts have been identified and there is concern that BMSB will become an agricultural pest of fruit trees and ornamentals where it becomes established. It feeds on Paulownia, apples, cherries, peaches, mulberry, soybeans, persimmons, etc. The good news is that BMSB does not appear to yet have damaging economic impact on ag crops and ornamentals. While abundant, its main impact is as a nuisance pest. Therefore, control methods should be primarily directed at monitoring for desired plants that are heavily damaged and refraining from treating unnecessarily. While an inconvenience, this pest does not yet warrant control in our area. For nuisance infestations indoors, one may choose to simply vacuum them up and or otherwise dispose of them. Restricting BMSB entry by caulking/sealing exterior gaps also helps to keep them out. Pesticide applications to exterior structural surfaces would only be warranted as a last resort in extreme circumstances. Educating others to do the same with this nuisance invader is also an important strategy.

Brown marmorated stink bug adult. Photo by Susan Ellis, Bugwood.org

Information from Casey Sclar, IPM Coordinator, Longwood Gardens

Landscape - Mulch and Termites

2009-10-19T06:34:00.003-04:00

In the past, it was thought that termite colonies could not establish in mulch. The following is a short article that shows that this might not be the case.

Termites in Mulch?

Termites have underground colonies and feed on wood, and may be found in mulch. In the past, most entomologists agreed that any termites brought into a site via mulch were workers and not reproductives (queens), and therefore there was little risk of a new colony developing. However, new research shows that if the mulch contains enough white worker termites, and they are given access to soil, these termites do have the ability to develop into secondary reproductives and establish a new colony! In light of this, bagged mulch should be stored on pallets off the ground, so termites cannot gain access to the mulch. Termites need ground to wood contact to easily gain access to the wood food source from their underground colony. Likewise, piles of mulch should not be stored directly on the ground. Keep bags of mulch in the sun as well, since termites should not survive high temperatures that build up during the day. Also beware of adding too much mulch to the landscape (2 to 3 inches is plenty).

Information from Steven K. Rettke in the October 10, 2002 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2002/ln1010.pdf

Landscape - International Society for Arboriculture Certification Program

2009-10-18T07:53:00.003-04:00

The International Society of Arboriculture is a worldwide professional organization dedicated to fostering a greater appreciation for trees and to promoting research, technology, and the professional practice of arboriculture. They have a certification program that landscape professionals working with trees should consider. Below is a snapshot from their certification web page and a link to the page.

The ISA's certification information web page can be found at http://www.isa-arbor.com/certification/certification.aspx

Landscape - Penn-Del Chapter of the International Society of Arboriculture

2009-10-18T07:44:00.004-04:00

The Pennsylvania-Delaware Chapter of the International Society of Arboriculture was founded in 1960. Their mission is to provide quality educational opportunities for its members. There are currently over eight hundred members in the chapter including commercial, consulting, municipal, and utility arborists, researchers and educators, horticulturists, and individuals interested in the care of trees and landscapes. Landscape professionals working with trees are encourages to become a certified arborist. A snapshot of their home web page is shown below with a link to take you to their page.

To go to their web page for more information the link is http://www.penndelisa.org/

Landscape - Avoid Tree Wrapping

2009-10-17T07:44:00.002-04:00

The following is a short article on why to avoid tree wrapping.

Tree wrapping, or wrapping the trunk of young trees after transplanting, is not recommended. In the past, wrapping was done on fall transplants in order to reduce sunscald and frost cracks. However, replicated studies have shown that wraps are not a deterrent to these problems. Wrapping can actually create problems by reducing photosynthesis (because young stems contain chlorophyll), and increasing potential pest attack from borers and certain diseases. The best benefit from wrapping is protection from chewing rodents. For this purpose, it should be in place only during the dormant season.

Information from Steven K. Rettke in the October 10, 2002 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2002/ln1010.pdf

Greenhouse - Cercospora Leaf Spot of Pansy

2009-10-17T07:34:00.004-04:00

A common disease of pansy is Cercospora leaf spot. The following is more information.

Greenhouse grown pansies may have problems with Cercospora leaf spot. Leaf spots tend to be on the older leaves or leaves that are close to the substrate surface. Initially leaf spots are 1- 3 mm in size with a sunken center. The leaf spots become dark gray or purplish in color, and have a feathery appearance. If left untreated the leaf spots will continue to expand, coalesce, and may cover the whole leaf. These leaves may turn yellow and drop off the affected plant. Sanitation is important in controlling Cercospora leaf spot – plants with severe symptoms should be discarded. Keep the leaves free of moisture as much as possible. Irrigating plants early in the morning will allow the leaves to dry off quickly and remain dry going into the coolness of the evening. There are a variety of fungicides that are labeled for this disease on pansy including mancozeb (Dithane T/O, Protect DF and others), thiophanate methyl (Cleary’s 3336), fludioxonil (Medallion), and chlorothalonil + thiophanate methyl (Spectro 90 WDG).

Note small spots on lower leaves of this pansy plant caused by the Cercospora fungus.

Information and photo from the October 16, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center http://www.ipmnet.umd.edu/09Oct16G.pdf

Turf and Landscape - Fall Fertilization

2009-10-16T06:21:00.000-04:00

Fall fertilization can be beneficial in the landscape if you follow some simple guidelines. The following is more information.

In turf, a second or third fall fertilizer application is often recommended with moderate amounts of Nitrogen (N), low phosphorus (P), and moderate to high rates of potassium (K), of course depending on soil test results for P and K. Timing of this application can affect turf performance. October applications can promote continued top growth and excess N at this time can reduce winter hardiness. If applying fertilizer in October, use modest N rates. A later fertilizer application at the end of November, can help root systems continue to grow and keep turf greener, longer into December. However, excess N at this time may be subject to leaching losses so limit soluble N fertilizers to modest rates that roots can utilize. Fertilizers with higher percentage of temperature dependent slow release N are very appropriate for fall applications. Potassium is important for improved wintering over and P is important for root growth so added P and K can be beneficial in the fall if soil levels are not high (based on a soil test).

Most other landscape plants require little or no fall fertilization if they are in the middle of fertilized lawns or in well maintained long-term established mulched beds with high organic matter. However, new landscapes, plantings in poor (low organic matter) soils, or landscapes that have been under stress may need additional fertilization. Woody landscape plants and some perennials continue root growth until soils are at freezing temperatures so fertilization using materials with low to moderate N, some P, and higher K levels can be beneficial to winter performance. Root growth will be improved and bud health can also be enhanced. However, excess N in the fall can promote bud break and new growth, or continued shoot growth in some plants, leading to increased winter damage.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Landscape - Pruning Deciduous Trees Workshop at the Morris Arboretum

2009-10-13T06:38:00.005-04:00

The following is information on an upcoming workshop at the Morris Arboretum of the University of Pennsylvania near Philadelphia.

Pruning Deciduous Trees

Date: Tuesday, October 20, 9 a.m. – 3 p.m. Rain date: Thursday, October 22
Fee: All day: $110 (including lunch) Fee: Morning only (9 a.m. – 12 noon) $60
Instructor: Iana Turner , Horticulturist, Morris Arboretum
Credits: This course carries 5.5 CEUs for ISA arborists and 1.0 PCH credit for the full day class.
Registration: To register call the Morris Arboretum at 215-247-5777, ext. 125 or 156.

Pruning young trees for healthy structural development is cost-effective care. This class will explain how recent research on pruning has changed both practice and understanding. Age-adjusted pruning strategies will be stressed to maximize tree longevity and structural health. In addition, techniques will be discussed to help tree managers evaluate the arboricultural work of others under their supervision. The morning session will consist of a lecture and a demonstration. The afternoon session will feature supervised, hands-on pruning. Participants may sign up to take the morning part only, or the entire daylong class. Please bring a hand pruner and a small orchard saw for the afternoon session.

Landscape - Sustainable Site Initiative

2009-10-13T06:31:00.002-04:00

The following is information on the sustainable sites initiative. This initiative seeks to increase sustainable landscaping throughout the US.

SUSTAINABLE SITES INITIATIVE

Three years of research and work culminates this November 5th, as the Sustainable Sites Initiative will release the first full national rating system for sustainable landscapes as part of the Guidelines and Performance Benchmarks 2009 report . This latest report takes into account feedback from hundreds of individuals and organizations across the country and around the world. In addition, the report release will include a supplemental educational report, titled Making the Case for Sustainable Landscapes , that provides scientific and economic arguments underlying the guidelines, and will highlight several case studies for sustainable practices.

Upon the release of the Guidelines and Performance Benchmarks 2009 , the Sustainable Sites Initiative will also formally open the Call for Pilot Projects. Projects selected for the Pilot Program will be the first to test the rating system and will be included in the Reference Guide, to be released in 2012. The Initiative will accept applications online starting November 5 through February 15, 2010. Any type of designed landscape is eligible to participate, ranging from academic and corporate campuses, parks and recreation areas, transportation corridors to single residences, with a minimum project size of 2,000 square feet. Fees for participating in the pilot project process will run between $500 to $5,000 depending on project budget (there may be limited scholarships available based on need).

For more information on the pilot projects, visit www.sustainablesites.org/pilot.You can learn more about the Sustainable Sites Initiative at these upcoming conferences. Check the Sustainable Sites website for the most current listings.

Greenhouse - Planning for Biological Controls

2009-10-11T07:31:00.002-04:00

The following is a good article from the New England Greenhouse Update website on preparing for using biological controls in greenhouses before the spring season.

If you are planning to use biocontrol for pest management in your greenhouse for spring crops, then it is time to prepare now. Management, growers and staff all need to be on-board and involved. A biological control program should never be started in the middle of a growing season. Begin a biocontrol program that will be at the start of a new crop cycle. Biocontrol prevents problems, it does not fix problems, which is why planning needs to be done now.

Begin by reviewing pest problems from this past year and VERY IMPORTANT, avoid pesticide use 3-4 months prior to using biological control. When crops are in the greenhouse, develop and start a consistent monitoring procedure. Set a start date for using biological control. Develop a strategy based on your production planning, that is right for your particular situation. Start using biological control agents in your propagation area, right from the start. If you are buy in rooted or unrooted cuttings ask your supplier/broker to supply specific information on what pesticides may have been using on the cuttings. Toxic pesticide residues either on in or around the greenhouse or on plant material is one of the main reasons for failure using biocontrol control agents. It is important to phase out the use of pest control materials in the organophosphate, carbamate, and pyrethroid chemical classes prior to releasing natural enemies since many materials in these chemical classes can persist for four months or longer in the greenhouse.

For more information on the compatibility of pest control materials with natural enemies refer to on-line databases under side effects, such as Koppert, Inc., or Biobest . Talk with your supplier of natural enemies, too. Research is continuing on the compatibility of pest control materials with natural enemies.

During the transition period, before using biocontrol, growers might use products that are not necessarily compatible with natural enemies, but have a short residual effect of less than 2 weeks. Examples of these pesticides are abamectin (Avid), imidacloprid (Marathon, Tristar), dinotefuran (Safari) and pyriproxyfen (Sanmite). Products that are compatible and have short residual include bifenazate(Floramite) and pymetrozine (Endeavor).

Article by Tina Smith, UMass Extension and Leanne Pundt, UConn in the New England Greenhouse Update http://www.negreenhouseupdate.info/index.php/updates

Landscape - Using Mulches in the Landscape

2009-10-11T07:30:00.000-04:00

The following is a good article from Rutgers University on how to use mulches in the landscape.

Although the mulching of trees and shrubs is an important plant health care practice, their effects can sometimes produce unexpected consequences. Different mulching materials should influence supplemental fertilizer practices. Nitrogen fertilizers can be applied to help reduce nitrogen immobilization where wood pallet or hardwood bark is found. Alternatively, where plants are growing in composted mulches, nitrogen application rates need to be adjusted to avoid over-stimulation. Over fertilization, especially with high nitrogen, may decrease mycorrhizae. It is most important to use these products when trees are first planted.

If raw or fresh mulches are used, they are best applied in the late fall or winter in order to reduce their initial negative effects on plant growth and health. As soon as the organic matter is partially decomposed and the competition for nutrients begins among soil microorganisms, then the beneficial effects can begin. Composted leaf and twig litter are best because they will support the growth of mycorrhizae. In natural forests where there is decaying leaf litter, the non-woody roots, and especially mycorrhizae, will be abundant in the highly organic top layer of soil. In cities, more composted wood and leaves should be added in correct quantities to soil about the base of trees.

Information from Steven K. Rettke, Ornamental IPM Program Associate in the September 17, 2009 edtion of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition, from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln091709.pdf

Landscape and Nursery - Fall Fertilization Pros and Cons

2009-10-10T07:34:00.003-04:00

The following is a good article on the pros and cons of fall fertilization from Andrew Ristvey from the University of Maryland.

Fall fertilization of landscape plants is truly a beneficial practice as long as certain guidelines are followed. This has been a contentious issue with experience on both sides challenging fall fertility. Physiologically speaking, even though the tops of plants have gone dormant or have slowed down, fall is an active period for roots. They are still growing and absorbing nutrients for next year’s spring flush until soil temperatures inhibit biological activity. All of next year’s spring buds will grow from stored nutrients attained this year. So the most effective application of fertilizers for next year’s growth is during late summer and fall of this year. However, because of dry and hot weather often experienced in Maryland towards the end of summer, optimal fertility times are towards the fall period.

Certainly, the most important growth factor for plants is water, and that was made evident this past mid-summer, when plant water stress was high. In the landscape, especially where plants do not have the luxury of irrigation, hot summer weather will inhibit plant growth. Fertilization should be minimized or stopped until better climactic conditions promote growth.

It is true that an over-application of nitrogen in fall can potentially awaken near dormant buds and expose plants to damage from frost which is just around the corner in our region. One relatively new study in the Journal of Arboriculture reviewed past research and looked at the effect of fall nitrogen fertility on cold hardiness of 5 landscape trees including Leyland cypress, crape myrtle and red maple in North Carolina. In most cases the researchers found no significant differences in hardiness of spring bud tissue with different nitrogen treatments for all the species. So there exists some evidence that fall fertilization does not reduce winter hardiness. But I have seen a heavy application of nitrogen in container grown plants increase vegetative growth in fall resulting in frost damage. However, those plants had not become completely dormant.

Most fall-based fertilizers are low in nitrogen and have higher ratios of phosphorus and potassium. Obviously, a serious fertilization program should rely upon a soil fertility test so that adequate amounts of nutrients are applied without risking toxicities or antagonisms (one nutrient overapplied can affect the availability of other nutrients). However, in general, a half rate of a low nitrogen or a 50% WIN combination in October should be considered as long as there is no longer any shoot activity. In container culture, a very low soluble nitrogen application (with excellent irrigation management to prevent nutrient runoff) may be acceptable periodically until temperatures fall below 55 °F, especially if your controlled release fertilizer prills no longer contain nutrients. Remember that fruit tree nutrition is based on leaf samples which should have been taken before the harvest. Fertilize according to those samples.

Information and photo from the October 9, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Oct09L.pdf

Landscape - Woolly Aphids

2009-10-10T07:26:00.003-04:00

You may see woolly aphids on many trees and shrubs in the landscape. The following is more information.

Woolly aphids (family Eriosomatidae) are found in the fall on many hardwood trees and shrub species including elm, silver maple, ash, alnus, alder, apple, pear, pine, spruce, hawthorn, and juneberry (Amelanchier). They are small (2-4 mm in length), pear shaped insects, and are often covered with white waxy strands. Woolly aphids generally have a primary host on which they overwinter, and a secondary host on which they spend much of the summer. They usually overwinter as eggs laid in bark of their primary host. The following spring, eggs hatch into females which give birth without mating. Each female can produce hundreds of offspring, so populations can grow rapidly. After one or two generations on the primary host, winged females are produced, and they fly to secondary hosts where they remain for the rest of the summer. Additional generations of aphids are produced until late summer or early fall when winged females fly to a primary host where they give birth to tiny male and female aphids that mate. Gravid females deposit a single large egg (or eggs) into protected locations in the bark and then die. While woolly aphids generally have two hosts, many species can sustain themselves on their secondary host alone. Woolly aphids feed on leaves, buds, twigs, and bark, but can also feed on the roots. Damage symptoms include twisted and curled leaves, yellowed foliage, poor plant growth, low plant vigor, and branch dieback. Natural enemies help keep these aphids from becoming a problem. In addition to the physical damage to the plant, accumulations of wax and shed skins can be very conspicuous on the leaves, twigs, and bark.

Woolly aphids.

Information and photo from the October 9, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Oct09L.pdf

Greenhouse and Nursery - Reusing Pots, Flats, Trays, and Other Containers

2009-10-09T06:53:00.003-04:00

The following is a short article on reusing containers in the greenhouse.

While some growers clean and re-use pots, trays and flats and it is important to do it properly. Plant pathogens such as Pythium, Rhizoctonia and Thielaviopsis can survive in root debris or soil particles on greenhouse surfaces. If the previous crop had a disease problem, then avoid re-using those containers. It is also a good idea to avoid planting crops that are prone to Thielaviopsis problems, like pansies, in containers that have been previously used.

All containers should be washed thoroughly to remove soil particles and plant debris before being treated with a greenhouse disinfectant, even if there was no evidence of disease in the crop. Debris and organic matter can protect pathogen spores from coming in contact with the disinfectant solution.

There are several products available for disinfecting surfaces including quaternary ammonium products (Greenshield®, Physan 20™, Triathlon®), and hydrogen dioxide (ZeroTol®, OxiDate®). Follow label directions for these products - labels indicate that pots must be soaked for at least 10 minutes in these products to be fully effective. A 10 percent solution of household chlorine bleach (one part bleach to 9 parts of water) may be used for pots and flats, but the solution has a shorter activity period than other disinfectants, losing half its strength in 2 hours. Chlorine bleach is also phytotoxic to some plants, and must be used in a well-ventilated area to protect workers

Information from the New England Greenhouse Update Website http://www.negreenhouseupdate.info/index.php/updates

Landscape - Adelgids

2009-10-09T06:45:00.003-04:00

The following is information on control of common adelgid insects in Delaware landscapes.

The Eastern Spruce Gall, Cooley Spruce Gall and Hemlock Woolly Adelgids all over-winter as immature females and are vulnerable to control treatments during the late months of the year. The product of choice with smaller plants is the use of horticultural oils or soaps when good coverage can be achieved. Remember to target sprays onto only the most recent growth or terminal twigs and buds where the adelgids are located. Heavy populations of HWA on large hemlocks are best controlled with an imidachloprid (Merit) treatment.

Hemlock woolly adelgid & treatment limitations:

The autumn season is an excellent time to control this hemlock pest, if no controls have been applied to date. The adelgid nymph is exposed on the underside of new growth, at the base of individual needles from May through early November. By November, it begins to cover itself with the white, wooly wax. Information from the US Forest Service indicates that hemlocks that have experienced over 50% needle loss from the adelgid will not recover in subsequent years (even if treated). Therefore, it is important that treatments be made when the needle loss is below 50% if hemlocks are to recover or survive. Fall treatments of insecticidal soaps, horticultural oils, or Merit are very effective. Excellent spray coverage is required with soaps or oils. When using Merit drenches, be certain adequate soil moisture exists.

Hemlock woolly adelgids. Photo by John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org

Information from Steven K. Rettke, Ornamental IPM Program Associate in the September 17, 2009 edtion of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition, from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln091709.pdf

Greenhouse - Cleaning The Greenhouse

2009-10-08T07:00:00.003-04:00

The following is a good article on cleaning the greenhouse prior to major production time. Information is from the New England Greenhouse Update http://www.negreenhouseupdate.info/index.php/updates

It is best to clean greenhouses as they become empty rather than to wait until just prior to the spring growing season. Cleaning early will eliminate over-wintering sites for pests and reduce populations for the next crop cycle. Greenhouse pests will overwinter in weeds and protected areas in unheated greenhouse, especially if the winter is unseasonably warm.

Remove leftover plants and debris and clean the floor of soil, organic matter and weeds. Clean areas around furnaces and along side walls where small weeds are usually found. Use weed barriers, repair tears in worn weed barriers and do not use stone on top. Stone will trap soil and moisture and create an ideal environment for weeds, diseases, insects and algae. It is also a good time to correct any drainage problems and low spots in greenhouses.

Next, disinfect the growing and plant handling areas, and irrigation system. There are several different types of disinfectants that are currently used in the greenhouse for plant pathogen and algae control including quaternary ammonium compounds (Green-Shield®, Physan 20®, and Triathlon®), hydrogen dioxide (ZeroTol®, Oxidate®), chlorine dioxide (Selectrocide), hydrogen peroxide plus peroxyacetic acid (ScaniDate) and sodium carbonate peroxydrate (Green Clean Pro®, TerraCyte®). All these products have different properties, so read and follow label directions. Chlorine bleach may be used for pots or flats, but is not approved for application to walls, benches or flooring. Alcohol is flammable and therefore not used as a general disinfectant. However, it is useful as a dip or swipe treatment to disinfect propagation tools. If possible, disinfectants should be used on a routine basis both as part of a pre-crop clean-up program and during the cropping cycle.

Organic growers have limited options for disinfectants. Oxidate® is the only material mentioned above that is currently listed by the Organic Material Review Institutes (OMRI), see www.omri.org. Ethyl or isopropyl alcohol is also allowed under the organic standards. Organic growers should always check with their certifying organization before using any material new in their farming practices.

Landscape - Leafminer Overwintering

2009-10-08T06:54:00.003-04:00

The following is information on leafminer overwintering in the landscape.

Arborvitae, Boxwood and Holly leafminers all over-winter as live larvae within foliage tissue. Pale colored lines or blotches indicate the leafminer presence in evergreen leaves. Inspect mines for live larvae and physically remove infested leaves when populations are small. Heavily infested plants can be noted in your records and scheduled for treatment next season. If soil moisture is adequate, then a soil systemic (e.g. Merit) can be applied during the fall months.

Holly leafminer mines on leaf. Photo by Daniel Herms, The Ohio State University, Bugwood.org

Information from Steven K. Rettke, Ornamental IPM Program Associate in the September 17, 2009 edtion of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition, from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln091709.pdf

Landscape - Bagworms in Fall

2009-10-07T06:42:00.002-04:00

The following is information on bagworms in the fall. They are now inside the bags and the only control is hand picking or waiting until they come out next year.

Obviously any type of spray applied in the fall or winter for bagworm control would be a waste of time and material. Over-wintering eggs are contained within the dead female bags. Most of the bags containing eggs are located on the upper portions of infested trees or shrubs. With this higher elevation, it is theorized that a certain percentage of a recently hatched population in late spring can more effectively be transported by the wind to new hosts. Remove individual bags by hand when populations are low and the upper portions of the plant can be reached. Otherwise, indicate in your records that sprays may be required during the late spring or early summer when the young larvae hatch and begin feeding.

Bagworms on conifers have pupated. During the fall mating and egg lying will occur within the female sack. Bagworms hatch out in mid-June from the over-wintering eggs within the dead female bag. Researchers in Kentucky have determined that most newly hatched bagworms disperse away from the ‘parental’ host plant. This may be because the offspring from only a few bags have the potential to defoliate a small plant. About 75% of immature bagworms disperse by ‘ballooning’ into the wind, and were observed traveling hundreds of feet. Failure to control populations upwind from a susceptible host may leave a potential reservoir of the pest in the future. (Reference: Cox and Potter, J. Arbor. 9/90) .

Information from Steven K. Rettke, Ornamental IPM Program Associate in the September 17, 2009 edtion of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition, from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln091709.pdf

Turf - Mulching Leaves in Lawns

2009-10-06T06:19:00.003-04:00

Mulching leaves in lawns has been shown to have no negative effects and is a practice you should consider for your clients because it will improve the soil and eliminate leaves going to landfills. However, this should be done several times during the fall to prevent leaf buildup that damages turfgrass. The following is more information.

Trees will be dropping their leaves soon and it is important to prevent a heavy layer of leaves from building-up on your turf before winter. Heavy layers of tree leaves will shade the grass can smother and kill grass yet this fall. Plus tree leaf cover favors a damaging winter turf disease called snow mold. The easiest way to dispose of leaves is to simply mow them into the turf. Regular mowing during the fall will chop the leaves into small pieces and allow them to filter into the turf. Research at many universities shows that tree leaves can be mulched without any detrimental effects on the soil or turf regardless of turf or tree species. Actually, just the opposite may be true where tree leaf mulching may help improve the soil. Mulching leaves with a mower is much easier than raking, blowing, and/or vacuuming the leaves like we have done in the past. Plus it disposes of the leaves without filling up our landfills and saves our cities thousands of dollars in disposal costs. Regular mowing over dry leaves is most effective for this, but deep layers of leaves or wet leaves may require raking. Heavily wooded lots may also require leaf disposal because of the sheer volume of tree leaves.

Information adapted from the 10/25/2007 edition of the Turf Tips newsletter from Purdue University.

Landscape - Fall Leaf Color 6

2009-10-06T06:15:00.002-04:00

The following is a continuation of the series on fall leaf color in deciduous plants. This post is a continuation on Anthocyanins that cause pink, red, and purple colors in fall leaves.

Anthocyanins (continued)

Kevin Gould of the University of Auckland in New Zealand is at the forefront of research on leaf anthocyanins. Senescing leaves seem to need special protection against bright light exposure because the metabolic pathways for the initial capture of energy don’t lose their efficiency as rapidly as the subsequent processes for processing that energy do. Bright light that reaches senescing tree leaves overloads light-gathering chlorophyll and slows it down (photoinhibition). Anthocyanins can offload some of that excess energy, decreasing photoinhibition, sustaining photosynthesis rates necessary to provide energy for nutrient resorption and other critical processes during senescence.

Anthocyanidins, formed from anthocyanins, are flavanoids: antioxidants that are beneficial to human health and possibly able to help prevent such diseases as cancer, Alzheimer’s disease, and cardiovascular disease. While reading an article on the human health benefits of consuming anthocyanin-rich blueberries, Gould decided to investigate the possibility that the antioxidizing powers of the leaf anthocyanins he was investigating also benefited their source plants. In test tube experiments he found anthocyanins purified from tree leaves were four times more effective at soaking up damaging free radicals than vitamins C and E. He and his colleagues devised a method to induce and observe an oxidative burst of hydrogen peroxide by using a needle to pierce the upper layers of a New Zealand shrub that produced red pimples when pierced by aphids. Gould and his coworkers were able to observe bursts of the powerful oxidant hydrogen peroxide one minute after stabbing leaves with a needle. In red leaf tissues the burst faded quickly, while in green tissues the hydrogen peroxide concentrations soared for at least ten minutes. These results suggest that anthocyanins function as protective antioxidants in plant leaves.

Anthocyanins may protect physiological processes in leaves from cold temperatures. Gould notes that a birch species he encountered in Finland held on to its red leaves year round, despite temperatures that plunged to -40 degrees C. William Hoch of the University of Wisconsin-Madison ranked the intensity of red coloration in autumn of species in nine genera of woody plants either from a cold zone in Canada and the northern U.S. or from a milder maritime climate in Europe. The species that produced the most intense red coloration came exclusively from the North American cold zone.

Linda Chalker-Scott of the University of Washington proposes that anthocyanins help leaves retain water. Anthocyanins dissolve in water, whereas chlorophyll and many other cell pigments do not. Water loaded with any dissolved substance has lower osmotic potential: a decreased tendency for water to flow away. Many plants produce soluble anthocyanins that may help leaves retain water when subjected to osmotic stresses from drought, salt buildup on leaf surfaces, and heat. Loading water with solutes also lowers its freezing point, possibly affording added frost protection to senescing leaves.

The evolutionary theorist W.D. Hamilton and Samuel P. Brown of the University of Montpelier speculated in a recent paper that the healthiest trees might put on the flashiest fall displays of (anthocyanin) red leaves. They further speculated that this leaf signal might give fall-feeding insects, such as aphids, a warning to avoid trees that are healthy and have the best defenses. This is an intriguing possibility for yet another role of anthocyanin in tree protection.

Information from "Why Tree Leaves Turn Color in Autumn" by Jeffrey O. Dawson, Professor of Tree Physiology, Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign. Go to http://web.extension.uiuc.edu/forestry/fall_colors.html for the full article.

Turf - Rust in the Fall

2009-10-05T06:40:00.006-04:00

Rust is a common problem on ryegrass and Kentucky blugrass in the fall. The following is more information.

Rust on perennial ryegrass and other turfgrasses is favored by the cool, moist weather of fall. Look for yellowing of turf. Close examination of the individual grass blades will reveal the reddishorange pustules of the rust fungus. It can cause some thinning of turf but the best treatment at this time of year is fertilizing the lawn. Lawns will outgrow the fungus in most cases. Rust is usually a low fertility, low vigor problem on turf.

A variety of related fungi cause rust. Ccommon names include leaf rust, crown rust, and stem rust, and the disease occurs almost exclusively on Kentucky bluegrass and perennial ryegrass. Rust is largely cosmetic, but the orange spores that dislodge easily from leaf surfaces can be a greater nuisance, covering shoes, pets, and lawnmowers with a rusty residue. Rust can severely damage new spring-seeded lawns that lose vigor during heat and drought conditions.

From a distance, rust-infected turf appears chlorotic. Symptoms occur in a diffuse pattern around the initial site of infection as disease increases. Outbreaks often first occur in shaded or protected areas, such as around the bases of evergreens or next to a structure’s foundation. Close inspection of rusted leaves reveals numerous yellow-orange pustules on leaf blades. Walking through grass with significant amounts of infection will disturb and release the spores within these pustules and leave a distinct orange color on shoes and pets. These spores, carried by the wind, spread the disease to other areas during the growing season. Rust outbreaks are most common in late summer and early fall, although sometimes the disease is active in the early spring, especially on poorly nourished turf. Rust is a disease of slow growing turf, so factors such as summer heat and drought stress, low nitrogen fertility, compaction, and shade contribute to poor growth tend to favor rust development. Rust outbreaks require moderate temperatures (50°-60°F) and long evening dew periods (more than 10 hours). The pathogen survives as resilient spores over the winter or as inactive mycelium in dormant turf.

Rust Control

Maintaining a healthy and vigorous turf stand is the most effective and efficient method of rust control. Since slow growing turf in late summer is most vulnerable to outbreaks, small amounts of nitrogen fertilizer (0.25-0.5 pound of N per 1,000 square feet) in chronic trouble spots—shaded and possibly compacted areas—will help control the disease. The nitrogen will promote leaf growth and allow for regular mowing, which helps the turf outgrow rust’s relatively slow infection cycle. Avoiding irrigation during the early evening also will help limit disease spread by lessening the chance of extended dew periods.

DMI and QoI (strobilurin) fungicides are very effective against rust, but on well-established turf, should be considered only as a remedial treatment when cultural practices fail to prevent an outbreak. On newly seeded stands, fungicides should be appliedat the first sign of disease. In most cases, a single application of an effective fungicide, combined with efforts to encourage turf growth, will quell outbreaks.

Rust on perennial ryegrass. Photo from the August 10, 2009 edition of Turf Tips from Purdue University

Information from Bob Mulrooney, Extension Plant Pathologist, UD in the Current Ornamentals Hotline from UD Extension and Rick Latin, Turfgrass pathologist in the August 10, 2009 edition of Turf Tips from Purdue University

Landscape and Nursery - White Prunicola Scale

2009-10-05T06:31:00.002-04:00

The following is information on white prunicola scale. This scale pest has active crawlers this time of year.

White prunicola scale crawlers are active. This armored scale feeds on a number of hosts including: Acer, Alunus, Aucuba, Buxus, Forsythia, Ilex, Ligustrum, Malus, Prunus, Rhododendron, Syringa, and others. Crawlers of the second generation are active at 2314 - 3586 [3010 peak] GDD. Male scales are elongate, felted, white and light yellow at one end; whereas females are round with light yellow covers slightly off center. Male scales are inconspicuous white masses on the undersides of branches. Chemical control includes horticultural oil, insecticidal soap, dinotefuran (Safari), pyriproxyfen (Distance) or one of the pyrethroids.

White prunicola scale. Photo from the June 3, 2005 edition of the Branching Out newsletter from Cornell Cooperative Extension

Information from Brian Kunkel, Ornamental IPM Specialist, UD

Greenhouse - Alert on Salvia Divinorum

2009-10-03T19:04:00.004-04:00

Greenhouse growers should be aware that there is concern about the use of Salvia divinorum as a drug by young people. The following is more information.

Salvia - A Hallucinogenic?

An article in The Washington Post mentioned that Salvia divinorum has attracted the attention of young people across the United States. Salvia divinorum is not the same as the salvia that greenhouse growers have been selling as a flowering bedding plant or herb. S. divinorum is creating a stir because the foliage contains salvinorin that can be dried and smoked to provide a short-lived hallucinogenic trip. The U.S. Drug Enforcement Administration has labeled salvia a drug of concern. You may find that young customers are suddenly interested in salvia this spring, even though the salvia that greenhouses are growing is the not the salvia that they are really interested in.

Photo from http://www.flickr.com/photos/ericinsf/ / CC BY-NC-ND 2.0

Information from October 2, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center.

Landscape - Fall Leaf Color 5

2009-10-02T07:00:00.000-04:00

The following is a continuation of the series on fall leaf color in deciduous plants. This post is on Anthocyanins that cause pink, red, and purple colors in fall leaves.

Anthocyanins

Anthocyanin pigments are responsible for the pink, red, and purple leaves of sugar and red maple, sassafras, sumac, white and scarlet oak, and many other woody plants. They are formed in sap inside the vacuole, a storage compartment within plant cells, when sugars accumulate and combine with complex compounds called anthocyanidins. Anthocyanidins are a subclass of flavanoids, a group of antioxidant compounds found in plants including fruits and vegetables. The variety of pink to purple colors in leaves is due to many, slightly different compounds that can be formed. Their color is also influenced by cell pH. These pigments usually are red in tree species with acidic sap, and are purplish to blue in alkaline cell solution. Anthocyanins are not commonly present in leaves until they are produced during autumn coloration. A few trees, however, such as 'Crimson King' Norway maple produce reddish leaves throughout the growing season due to anthocyanins. Trees lacking the genes for production of anthocyanin develop yellow and brown shades of autumn color.

With the formation of the abscission layer and with higher viscosity of cell sap under cold conditions, the phloem tissues of a tree’s vascular system, the pathway for conduction of sugars out of leaves, become less efficient and are eventually severed where the leaf petiole joins the tree branch. However, the nonliving xylem vessels that transport water and nutrients from the roots upward, remain intact. This allows them to continue to carry water to the senescing leaves while sugars derived from continued photosynthesis and the conversion of stored starch to soluble sugars are trapped by the impaired phloem of the abscission layer and are available for anthocyanin production. Trees of the same species growing together often differ in color because of differences in amounts of soluble sugars in the leaves for anthocyanin production. These differences are caused by genetic and environmental factors. Leaves exposed to the sun, such as those on the outside branches of the tree crown, may continue photosynthesis and turn red while others in the shade may be yellow. A single tree may even have branches with different colored leaves due to differences in leaf shading. It is common to see sugar maples with reddish leaves only on exposed outer branches of the upper crown.

Fall weather conditions favoring formation of bright red autumn leaf color are warm sunny days followed by cool, but not freezing, nights. Rainy or cloudy days with their reduced sunlight near the time of peak coloration decrease the intensity of reddish autumn colors by limiting photosynthesis and the sugars available for anthocyanin production. There is an old wives' tale that claims rain washes the color out of leaves. It is not true, but the overcast conditions do reduce light intensity, and heavy rains and high winds can sweep the leaves off trees prematurely.

Information from "Why Tree Leaves Turn Color in Autumn" by Jeffrey O. Dawson, Professor of Tree Physiology, Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign. Go to http://web.extension.uiuc.edu/forestry/fall_colors.html for the full article.

Landscape - Fall Leaf Color 4

2009-10-01T06:47:00.003-04:00

The following is a continuation of the series on fall leaf color in deciduous plants. This post is on tannins that cause brown and bronze colors in fall leaves.

Tannins cause the brown hues in leaves of some oaks and other trees in the autumn. The golden yellow or copper colors produced in some leaves, such as those of beech, result from the presence of tannins along with the yellow carotenoid pigments. Like the carotenoids, these compounds are always present, but only become visible as chlorophyll and carotenoids both disappear from leaves. They are common products of metabolism in trees, deposited in the cell sap inside the vacuole as well as in cell walls, and often accumulate in dead tissue. Considered waste products, tannins actually act as a defense mechanism in plants against pathogens, herbivores and hostile environmental conditions. Consumed in sufficient quantities, bitter-tasting tannins are toxic to susceptible herbivores. Oaks defoliated by gypsy moths often produce a secondary flush of leaves higher in protective tannins than the first set of leaves. Tannins discourage insect feeding on leaves and bark, and, in the case of the lip-puckering, unripe persimmon fruits, discourage fruit and seed consumption by animals until both the fruit and seed are ripe. Once ripened, fruits are sweet, attracting seed dispersing animals, and seeds have a fully developed seed coat to prevent seed destruction in passage through the digestive tracts of animals.

The leaves of green tea, a woody plant, are a source of beneficial human dietary tannins. Monomeric flavanols, the major components in green tea, are precursors of condensed tannins. Tannins from grapes and oak barrels used for aging play an important role in preventing oxidation in wine. Tannins in fruit juices, such as those found in pomegranate juice, provide antioxidant and other health benefits to humans. Perhaps research will also find evidence for a similar function in senescing leaves.

Information from "Why Tree Leaves Turn Color in Autumn" by Jeffrey O. Dawson, Professor of Tree Physiology, Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign. Go to http://web.extension.uiuc.edu/forestry/fall_colors.html for the full article.

Landscape - Bad Year for Crabapple Scab

2009-10-01T06:39:00.004-04:00

This year was a bad one for crabapple scab. Crabapple scab normally does not kill crabapples, but annual defoliation could weaken the trees, making them susceptible to other problems. Landscape managers can help improve the health of their flowering crabapples by doing the following:

1) While trees are dormant, rake up and destroy or chop up old, infected, fallen leaves where the fungus overwinters.

2) On mature landscape trees, thin out crabapple foliage by pruning selected branches to allow improved ventilation and sunlight penetration.

3) Professionals may want to consider application of fungicides in spring. To prevent primary infections, apply fungicides when the first green shoot tips are showing in early spring before flowers open and repeat 3 or 4 times at two-week intervals. Fungicide choices include protectants containing ingredients such as mancozeb or chlorothalonil. Eradicant fungicides containing thiophanate-methyl, or myclobutanil are also available.

4) Any new crabapple plantings should be done with disease-resistant cultivars.

Adapted from an article by John Hartman in the current edition of the Kentucky Pest News
http://www.uky.edu/Ag/kpn/kpn_09/pn_090929.html

Landscape - Fall Leaf Color 2

2009-09-30T07:32:00.002-04:00

The following is the second post in a series on fall leaf color in deciduous plants.

Leaf Senescence

There are popular and scientific myths about the causes of fall color in temperate deciduous forests. Jack Frost is alleged to paint tree leaves with his chilling touch, bringing on color change along with a frosty coating. Another twist on this myth is that Jack Frost brings reds and purples to autumn trees by pinching the leaves with his icy fingers. A less poetic explanation of fall color, favored by scientists for decades, is that the autumnal coloring of leaves was caused by waste products accumulated in the leaves and revealed to us with the fading of green chlorophyll pigments. As it turns out, the waste product theory now seems to be considered a bunch of, well, crud. The fall color pigments are produced, or revealed, only in living leaf cells of deciduous trees during the critical, seasonal process of leaf senescence. In fact, if Jack Frost did his thing too early, or, in other words, if there was an early killing frost, the leaf color display would be dulled, if not stopped altogether.

What triggers these fall changes if not Jack Frost? A specific combination of shortening day length and cooling temperatures in autumn at a given locale is typically “sensed” by plant receptors resulting in the production of plant hormones that initiate leaf senescence. The initiation and timing of the various processes of leaf senescence are genetically controlled for tree populations of a rather narrow climatic zone. How narrow is it? Seedlings originating from a local population in Illinois are usually planted within northern, central and southern seed zones each about 130 miles from south to north. This precise genetic programming, evolving through the impetus of natural selection, allows leaves to escape autumn frost damage in a specific climatic region during senescence. In the western mountains, it is possible to observe the wave of aspen coloration beginning at higher mountain elevations and progressing downwards to milder climates at lower altitudes.

In the living cells of senescing leaves, complex molecules, such as starch and proteins, are broken down into smaller, soluble ones, such as sugars and amino acids, and then exported to storage cells (resorbed). Living storage cells are found in the inner bark of twigs, the outer sapwood of the main stem (in and near wood rays) and in corresponding root tissues. Resorbing and storing these compounds permits the tree to shed its leaves while avoiding loss of the large percentage of their nutrients in leaves. This, in turn, allows the tree to avoid having to compete with other plants and soil microbes for the resorbed nutrients that would otherwise be cycled back into the soil system through leaf litter decomposition. Resorbed nutrients including nitrogen, phosphorus, potassium, sulfur, and carbohydrates. are mobilized from cells and stored within the tree. The following spring the stored nutrients are remobilized and used to support the intense flush of new leaves and spring growth burst in other tissues.

More energy is required for the biochemical breakdown of leaf substances by enzymes, and for loading the soluble products into the leaf-veins for transport out of the leaves, than that which is available as reserves in leaves. Hence it is necessary to protect chlorophyll, at least during the earlier phases of senescence, in order to prolong production of energy rich compounds that initiate the enzymatic reactions necessary for leaf senescence. Additional important biochemical processes supported by photosynthesis in senescing leaves include the production of enzymes and their products that allow leaf cells to better tolerate freezing and drying, that absorb energy from light bursts damaging to the photosynthetic apparatus, that deter leaf predators, that prevent oxidative damage to cell constituents, including membranes, proteins and DNA, caused by free radicals produced during senescence, and that protect and transform the cells of leaf tissue that form the abscission layer at the base of the leaf petiole. The abscission layer allows the leaf to break away cleanly from its branch without forming an opening from which sap could leak and through which disease organisms could enter the tree.

Information from "Why Tree Leaves Turn Color in Autumn" by Jeffrey O. Dawson, Professor of Tree Physiology, Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign. Go to http://web.extension.uiuc.edu/forestry/fall_colors.html for the full article.

Landscape - Fall Leaf Color 3

2009-09-30T07:12:00.000-04:00

The following is the third in a series on fall leaf color in deciduous plants.

Carotenoid compounds

Carotenoid pigments are found abundantly in such vegetables as carrots and tomatoes. The carotenoids include lycopene and beta-carotene, known to be powerful antioxidants and cancer-fighting substances in humans. Another form of carotenoid found in senescing tree leaves is xanthophyll. Carotenoids are responsible for the yellow and orange colors of autumn leaves. The unmasking of the carotenoids accounts for the yellow fall leaf color of Ohio buckeye, yellow-poplar, sycamore, birches, hickories, ashes, and many other tree species.

Carotenoid pigments and chlorophyll are attached to membranes in intricate structures (organelles) called chloroplasts. Chloroplasts give leaves their green color. Carotenoid pigments assist chlorophyll in the capture of sunlight for photosynthesis. The light energy is converted to a form that charges energy-rich compounds needed to activate enzymatic reactions. These yellowish pigments are always present in leaves, but are not visible for most of the year because they are masked by larger amounts of green chlorophyll. As chlorophyll degrades in the fall, the carotenoid pigments degrade more slowly and persist, revealing their yellowish colors.

In pistachio trees undergoing summer leaf senescence in the Mediterranean, S. Munne-Bosch and J. Penuelas of the Science Faculty of the Autonomous University of Barcelona found that carotenoid substances actually increase during the early stages of senescence. Carotenoids are thought to provide both photo-protection and antioxidative protection to the photosynthetic apparatus. Carotenoids dampen damage, caused by high light intensity, to the susceptible photosynthetic apparatus of senescing leaves.

Information from "Why Tree Leaves Turn Color in Autumn" by Jeffrey O. Dawson, Professor of Tree Physiology, Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign. Go to http://web.extension.uiuc.edu/forestry/fall_colors.html for the full article.

Landscape - Fall Leaf Color 1

2009-09-29T06:56:00.002-04:00

The following is the first in a series on fall leaf color changes.

During summer, the leaves of trees are factories producing sugar from carbon dioxide and water by the action of light on chlorophyll. Chlorophyll causes the leaves to appear green. (The leaves of some trees, such as birches and cottonwoods, also contain carotene; these leaves appear brighter green, because carotene absorbs blue-green light.) Water and nutrients flow from the roots, through the branches, and into the leaves. The sugars produced by photosynthesis flow from the leaves to other parts of the tree, where some of the chemical energy is used for growth and some is stored. The shortening days and cool nights of autumn trigger changes in the tree. One of these changes is the growth of a corky membrane between the branch and the leaf stem. This membrane interferes with the flow of nutrients into the leaf. Because the nutrient flow is interrupted, the production of chlorophyll in the leaf declines, and the green color of the leaf fades. If the leaf contains carotene, as do the leaves of birch and hickory, it will change from green to bright yellow as the chlorophyll disappears. In some trees, as the concentration of sugar in the leaf increases, the sugar reacts to form anthocyanins. These pigments cause the yellowing leaves to turn red. Red maples, red oaks, and sumac produce anthocyanins in abundance and display the brightest reds and purples in the autumn landscape.

Information from the following website http://scifun.chem.wisc.edu/CHEMWEEK/fallcolr/fallcolr.html

Greehouse and Nursery - Iron Chelates

2009-09-29T06:08:00.004-04:00

The following is a good article on using iron chelates to correct iron deficiencies in greenhouses and nurseries.

Plants take up nutrients only when they are in solution, which can be a problem with iron.At pHs above 6.5, interactions with calcium and other ions in the media solution cause iron to precipitate out of solution and become unavailable to plants.Using iron chelates can keep plants green and growing until you can drop the pH to proper levels.

Chelates can best be visualized as a lobster’s claw (appropriate since the word chelate comes from a Greek word meaning claw) made of carbon and hydrogen atoms holding an iron ion. The more bonds, called ligands, that form between the iron ion and the carbon atoms, the stronger the iron ion is held within the chelate.The strength of the chelate’s hold on the iron ion determines, as pH increases, how long the iron ion will continue to be in solution and therefore available to plants.

There are four commonly used chelates: citric acid, EDTA (Ethylenediaminetetraacetic acid), DTPA (Diethylenetriaminepentaacetic acid) and EDDHA (Ethylenediamine di(o-hydroxyphenylacetic acid)). According to data presented by Norvel (Equilibria of Metal Chelates in Soil Solution, in Micronutrients in Agriculture, Soil Science of America, 1972) citric acid does not strongly bond with iron and is not effective at pHs above 6.0. EDTA strongly holds iron in solution up to pH 6.0, but by pH 6.5, almost one-half the iron is precipitated, and by pH 7.0, almost none of the iron is available to plants.DTPA is an excellent iron source up to media pH 7.0; however, 60 percent of the iron is precipitated and unavailable by pH 8.0. EDDHA is the strongest chelate of any of the commonly used materials and maintains iron availability to plants past pH 9.0. These chelates are ranked in the same order of effectiveness by Drs. Bill Argo and Paul Fisher in Understanding pH Management, Meister Publications.

Chelates prove the maxim “You get what you pay for.” The cheaper the chelate, the less useful it is.You may have to sit down when you write the check for iron-EDDHA, but remember you use very little per plant and you are assured that iron is available to your crop no matter the pH.

Sometimes growers are puzzled by plants showing iron deficiency symptoms when the media pH is only slightly higher than desired.Phosphorus ties up iron and the combination of a weak chelate, slightly high pH and high phosphorus levels can cause iron to be unavailable.Another reason not to over apply phosphorus.

Reprinted from "Selecting which iron chelate to use" by Dean Krauskopf, MSU Extension, Southeast Michigan in the May 10, 2007 Greenhouse Alert newsletter from Michigan State University.

Greenhouse and Nursery - Fall Aster Diseases

2009-09-28T06:23:00.004-04:00

Fall asters are being produced and sold along side of mums in many Delaware greenhouses and nurseries. The following are some diseases common on fall asters that you may have to manage.

Aster Diseases
- Leaf spots (Alternaria sp., Ascochyta compositarum, Cercospora asterata, Cercosporella cana, Ramularia asteris, Septoria asteris, and S. astericola). Control watering to avoid prolonged
wetness
- Downy mildew (Basidiophora entospora). Control as soon as problem arises with fungicides specific for downy mildew.
- Powdery mildew (Erysiphe cichoraceurum). Mildew that is comonly found on the lower
half of asters. Start control as soon as mildew is apparent using fungicides specific for powdery mildew
- Rusts (Coleosporium soldaginis, Puccinia asteris, P. extensicola, P. grindeliae, P. stipae, Uromyces compactus, and U. junci). Avoid alternate hosts; pines, grasses, and sedges

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Landscape - Deer Resistant Shrubs

2009-09-28T05:35:00.000-04:00

Deer damage is more and more common in Delaware landscapes, especially in newer developments in rural areas. The following is a list of shrubs and climing plants rarely damaged by deer.

Shrubs and Climbers Rarely Damaged by Deer

Buddleia spp. Butterfly Bush
Calycanthus occidentalis California Sweetshrub
Ceanothus spp. Cheonothus
Choisya ternata Mexican Orange
Cistus spp. Rock Rose
Cornus sanguinea Bloodtwig Dogwood
Daphne spp. Daphne
Enkianthus campanulatus Redvein Enkianthus
Forsythia spp. Forsythia
Hippophae rhamnoides Sea Buckthorn
Ilex glabra Inkberry
Jasminum nudiflorum Winter Jasmine
Juniperus chinensis Chinese Juniper
Kerria japonica Japanese Kerria
Kolwitzia amabilis Beauty Bush
Laurus nobilis Laurel
Lonicera spp. Honeysuckle
Mahonia spp. Grape Holly
Myrica pensylvanica Bayberry
Nandina spp. Heavenly bamboo
Osmanthus heterophyllus Holly Osmanthus
Philadelphus spp. Mock Orange
Prunus laurocerasus Cherry Laurel
Ribes spp. Currant
Spirea spp. Spirea
Syringa villosa Late Lilac
Syringa vulgaris Common Lilac
Viburnum juddii Judd Viburnum
Viburnum rhytidophyllum Leatherleaf Viburnum
Viburnum carlesii Koreanspice Viburnum
Viburnum plicatum Doublefile Viburnum
Weigela florida Old Fashion Weigela

Information from the University of Maryland go to http://www.agnr.umd.edu/ces/pubs/pdf/FS655.pdf for the full fact sheet.

Nursery - Fall Acclimation for Wintering Over Plants

2009-09-27T07:45:00.004-04:00

It is important to acclimatize plants for overwintering in nurseries during the fall months. The following is an article on the subject.

Hardening plants or providing dormancy requires many conditions to occur all at the same time within the plant. Nursery practices like fertilizer applications, irrigation, pruning and light levels all contribute to how successful plants will overwinter and avoid winter injury.

Plants that have a balanced nutrient content overwinter better. Avoid fertilizing plants about six weeks before the average first frost date for your area. Be sure you choose the correct controlled release fertilizer so your plants have lower nutrient levels in the pots over the winter. Research has shown plants prefer higher potassium (K) levels going into the winter. High K promotes cell permeability that is important in avoiding cellular freeze injury. A foliar level of 50 to 75 ppm K is generally sufficient. Field grown plants having soil test levels above 50 lbs./A. is adequate.

Overwintered plants require moisture so be sure to provide enough water to allows some moisture to reach the bottom of the container. Check field stock for moisture availability because a dry September can cause fertilizer that was applied earlier to release when rains do occur causing a flush of new growth. Overwintered nursery stock survival is directly correlated with reduced energy storage due to dry root balls. Dry plants in the fall may not have enough root reserve to break bud and shoot expansion in the spring.

Avoid late season pruning, which may stimulate bud break that ends up causing new growth that is not hardened off. Pruning like fertilization should stop six weeks before the first frost date.

When temperatures begin to drop, most plants slow their growth and begin the winter hardening process which ends up as dormancy. Figure 1 shows this process.

Light levels decrease in the fall, and shorter day lengths signal to the plants that dormancy is starting to occur. Shaded plants acclimate more slowly than those in the sun do. That is another reason for removing shade cloth in the fall.

Be sure to apply protective fungicides to plants being protected for overwintering. A fungicide drench for Pythium or Phytopthora is suggested. Also, a foliar fungicide application is suggested to protect any cut stems, branches or wounds during the hardening off process. If herbicides are used, be sure a safe amount of time has elapsed between application and the covering of poly houses to avoid crop injury.

Information from "Points to ponder as you prepare nursery plants for winter protection" from Thomas Dudek, MSU Extension West Central Region in the September 18, 2009 posting on the Michigan State University Landscape Crop Advisory Team Alert website http://ipmnews.msu.edu/landscape/

Greenhouse and Nursery - Evaluating Alternative Fuels

2009-09-27T07:38:00.003-04:00

Many greenhouse and nursery growers are interested in exploring alternative fuel sources and alternative heating systems. Although propane prices are reasonable now, the price spike in 2008 showed what could happen if world demand for natural gas increases again as we come out of recession. It is often challenging to evaluate alternative heating systems. Below are some tables comparing fuel sources and efficiencies from Auburn University. While the information came from the poultry industry, it is very applicable to greenhouse heating.

Tables from the Auburn poultry newsletter. See the link below.

Greenhouse growers can learn a lot from the poultry industry and visa versa. The following are two good articles on evaluating alternative heating systems for poultry houses that can also be used by greenhouse growers.
Newsletter 61 - Alternate Fuel Systems Simple Economics from Auburn University
http://www.aces.edu/poultryventilation/documents/Nwsltr-61AlternativeFuels.pdf

Biomass Heating Systems...Do They Make Economic Sense? from the University of Georgia
http://poultryventilation.engr.uga.edu/tips/2009/vol21n11.pdf

Landscape and Turf - Fall Soil Sampling

2009-09-26T07:42:00.007-04:00

Fall is the time of year that most soil samples are taken by landscapers and turf managers. This is a good service to provide to clients and can help you to explain fertilization and liming programs to clients. The following are some guidelines for taking soil samples.

Take soil samples from a uniform depth. Soil tests have been calibrated at the depth of the cultivated layer (6-8 inches) for all but extablished turf. A 7 inch depth should be targeted. This would include areas where new lawns are to be established, flower beds, landscape beds, and areas with trees and shrubs.
Established turf should be sampled at a depth of 4 inches.
Use a soil coring tool (soil sampling tool).
Ideally, a minimum of 20 cores should be taken and composited for a sample. When you mix the cores to form the samples, make sure that you have mixed them well before you take the subsample to send to the lab. All clods or core pieces need to be broken up. The most common mistake in soil sampling is not mixing cores adequately.
Take cores in a random pattern in the areas sampled.
Divide landscapes up into sampling areas. Beds, turf areas, and garden areas should be sampled separately.
If fertilizer has been spot applied to an area (such as fertilizer stakes), samples should stay off of the spots if at all possible. If the spots are not known, then plan to take extra cores.
Different soil types within a landscape or turf area should be sampled separately.
Avoid any features in a landscape that might skew the test results. Examples would be disturbed areas (such as where pipes were trenched in), wet pockets, or areas right next to pavement or cement walkways. Do not take cores from these areas for the composite. If you are interested in the fertility of these areas, take separate samples.
Take samples at least once every 3 years.
Target soil sampling at the same time of year each time you take the sample. Time of year is not as important as being consistant in when you take the sample. However, fall sampling gives the most consistant results.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Landscape - Azalea Lace Bug

2009-09-26T07:25:00.004-04:00

The last generation of Azalea lace bug is now active in Delaware. The following is more information.

Last Generation of Azalea Lace Bug Active

Azalea lace bug (Stephanitis pyriodes), nymphs and some adults are present in Delaware. The adults will be laying eggs in October and the insects overwinter in the egg stage. The eggs are inserted into foliage, usually along the midvein area. We usually see nymphs in May in Delaware and can see at least 2 to 3 generations per year. In southern Delaware where the growing season is a little longer the 3rd generation is more likely. Azalea lace bug populations tend to be highest when plants are grown in full sun and the damage can be the most severe at these sites.

Cultural control: The best thing you can advise your clientele to do is to stop growing rhododendrons and azaleas in full sun and move them into areas of filtered shade or landscapes with shade part of the day. Also, keep pH low with acidic mulch (pine needles, pine bark) and soil moisture even. A stressed plant is more likely to show heavier injury.

Chemical Control: Imidacloprid has been used by most landscape managers for the last decade. Some are starting to use some of the newer neonicotinoids such as Flagship and Safari for lace bug control. The imidacloprid has controlled both species of lace bug for at least a full growing season. We have had several landscape mangers report that they continue to see control carry into a second season.

Photo of azalea lace bug damage by Whitney Cranshaw, Colorado State University, Bugwood.org

Adapted for Delaware from an article in the September 25, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Sep25L.pdf

Landscape - Oak Lace Bug

2009-09-25T06:48:00.005-04:00

I recently got a call from a landscaper describing damage from the oak lace bug. The following is more information.

I recently have seen damage from the oak lace bug in DE landscapes. Oak lace bug adults overwinter under the bark or in leaf litter near the base of the tree. Next spring, look for black eggs and nymphs on the undersides of foliage. At this time of year control is not necessary.

This insect is very similar to lace bugs found on azaleas, hawthorns, and sycamores. Their fall peak of activity is between 1613 3384 [2300 peak] GDD. Stipled leaves have black 'tar spots' on the underside of the leaf. There are two generations per year in our area. Natural enemies often keep this insect controlled, however when treatments are necessary options include acephate, carbaryl, pyrethroids, or imidacloprid. Horticultural oil or insecticidal soap are options when temperature and humidity permit.

Oak lace bug adults and lymphs feeding on underside of white oak. Photo from Michael Masuik, Penn State University.

Lacebug damage on white oak, Quercus alba. Photo from Michael Masuik, Penn State University.

Information from multiple sources: Brian Kunkel, UD; University of Maryland, and Penn State University.

Landscape, Greenhouse, and Nursery - UDBG Landscape Color Trial Garden

2009-09-25T06:36:00.004-04:00

The UDBG had an All-American Selections color trial garden again in 2009. Watch for ratings as data from this year is analyzed. The following is more information.

Landscape Color Trial Garden

Located adjacent to the Herbaceous Garden, the Color Trial/All-American Selections Garden features bold sweeps of annual color, combining the newest cultivars with a display of All-American Selections winners that have proven outstanding in national evaluations. The garden offers both home gardeners and industry professionals a chance to observe how up-and-coming plant selections can enliven the landscape with minimal maintenance. For plant suppliers, the garden provides information about how their new selections fare in the mid-Atlantic climate.

UDBG staff conducts bi-weekly evaluations throughout the summer to rate each plant on its performance. Click on the link below to access results and other information for each year.

Coleus varieties in the 2009 color trial garden at UDBG. Photo by Gordon Johnson, UD.

To view 2007 and 2008 ratings go to http://ag.udel.edu/udbg/gardens/trial.html. 2009 ratings will be posted later this year at the same site.

Information from the UDBG website.

Landscape - Fall Needle Drop in Pines

2009-09-24T06:54:00.003-04:00

Inner needle drop is a natural occurance in pines and other evergreens in the fall. The following is more information.

White pines with inner needles turning yellow are not dying, they are just experiencing normal fall yellowing and leaf drop. While evergreens do not loose all their leaves in the fall, individual leaves/needles do not last on the tree forever. If trees are small, you can shake them and loosen the needles. You will end up with a nice pine straw mulch below the trees.

In some years, the natural needle drop will occur in a relatively short period of time, with rapid and noticeable browning of the older needles, which leads to fears the tree is dying. In other years, people don't even notice it happening, because the browning is spread over a long period of time.

The symptoms are normal for the fall. Pines and arborvitaes normally shed their oldest needles in the Fall. White pines usually retain their needles for one to two years. The older needles, those towards the center of the tree, turn yellow before dropping. Older arborvitae leaves turn a reddish brown. Natural needle discoloration may be more noticeable on trees that have experienced root stress due to less than optimal growing conditions. Extended dry periods during the summer months, as well as sites with poorly drained, heavy clay soils may accentuate root stress to pines. Since the newest growth (this year's needles) are still green and healthy in appearance, you can be assured that this yellowing phenomenon is a natural one.

Fall needle drop in pine. Photo from the Plant & Pest Digital Library at Purdue University.

Information from the Ornamentals Hotline Newsletter from UD Cooperative Extension and Gail Ruhl and Jeff Burbrink, Purdue University.

Landscape - Bulb Plant Growth in Fall

2009-09-24T06:40:00.004-04:00

It is common for certain spring flowering bulbs to have some foliage growth in the fall. The following is more information.

Some bulbs tend to come up in the fall -- grape hyacinths are a good example. Customers may become concerned that there is something wrong and that the bulbs won’t bloom in the spring. Spring-flowering bulbs have hardy foliage and will not suffer much foliage damage by coming up in the fall. Their flowers won’t come up until spring and will bloom normally. It might be a good idea to cover emerged foliage with a light layer of leaf mulch.

Grape hyacinth foliage dies back following flowering in the early summer, but grows actively again starting in mid-fall. The foliage will persist through the winter. Depending on how severe the winter conditions are and how much protection it receives from snow cover, it may be an attractive element in the winter landscape right up to the time that new growth begins in spring.

Grape Hyacinth in late November. Photo from the Plant & Pest Digital Library at Purdue University.

Information from the Ornamentals Hotline Newsletter from UD Cooperative Extension and Mike Dana, Department of Horticulture and Landscape Architecture, Purdue University.

Landscape - Witches' Brooms

2009-09-23T06:28:00.004-04:00

Witches" Broom is a term to describe a certain growth abnormality in plants and can have a number of causes. The following is more information.

The development of witches’brooms on woody plants and the resulting formation of abnormal growth can cause curiosity and concern to your clients. Typically, the new growth is distorted and a proliferation of leaves or fruit/cones closely clumped together appears when apical dominance is lost. Witches’ Brooms are created on plants when the transfer of growth hormones is disrupted (perhaps caused from the introduction of a foreign substance). Insects (e.g., aphids), fungi, bacteria, phytoplasmas, and herbicides have all been implicated in causing the formation of witches’ brooms in a large number of plant species. It is interesting to note that sub-lethal doses of glyphosate (Round-Up) when applied late in the season can cause witches’ brooms on new plant growth the following spring.

Witches' broom. Photo from University of Georgia Plant Pathology Archive, University of Georgia, Bugwood.org

Information from the September 3, 2009 edition of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln090309.pdf

Landscape - Boxelder Bugs

2009-09-23T06:18:00.004-04:00

Boxelder bugs are nuisance pests that can enter houses in the fall. The following is more information.

The boxelder bug overwinters as an adult in protected places such as houses and other buildings, in cracks or crevices in walls, doors, under windows and around foundations, particularly on south and west exposures. In the spring when tree buds open, females lay small, red eggs on leaves and stones and in cracks and crevices in the bark of female boxelder trees. The eggs later hatch into young nymphs that are wingless and bright red with some black markings. These young bugs usually are found on low vegetation near boxelder trees until seeds are formed on the tree, on which they start to feed.

Boxelder bugs are primarily a nuisance pest, annoying residents by crawling on exteriors and inside dwellings on warm fall and winter days. They also may stain draperies and other light-colored surfaces and produce an unpleasant odor when crushed, but these are not major problems. They do not reproduce during this period. They may attempt to feed on house plants but do not cause any damage. On rare occasions, they have been reported to bite humans.

Types of Control

The most permanent solution to the boxelder bug problem is the removal of female boxelder trees from a neighborhood, although this may not be practical or desirable. Because boxelder bugs usually overwinter near the trees that they feed on, the removal of one or two problem trees may help. Screening or sealing cracks or other entrances into the dwelling is important. Once boxelder bugs have entered the home, control becomes more difficult.

When the bugs begin to congregate on building exteriors, these areas (including all resting and hiding places) may be sprayed with residual insecticides. However, most insecticides registered for treatment of building exteriors are not that effective against boxelder bugs. Laundry detergent and water mixes are cheap, safe and effective when applied directly to boxelder bugs. Drawbacks of detergent sprays are that they will kill only if they contact the insect directly, and they may damage vegetation.

Use a vacuum cleaner to control bugs that have entered the house. Household insecticidal aerosols and many household spray cleaners also are effective when applied directly to individual Insects. These measures provide temporary relief only. Bugs may continue to enter the home as they move about on warmer days throughout the fall, winter and early spring. Nuisance infestations should be finished by late May, as the boxelder bugs have either died or moved back to the host trees.

Boxelder bug adult. Photo by William M. Ciesla, Forest Health Management International, Bugwood.org

Information from a fact sheet on Boxelder Bugs by F.B. Peairs from Colorado State University http://www.ext.colostate.edu/pubs/insect/05522.pdf

Turf and Landscape - Do Not Let Weeds Go to Seed

2009-09-22T06:39:00.004-04:00

I see many lawns with crabgrass and other weeds in seed now. These seeds will be problems for years to come. The following is more information.

Farmers say, “One years’ seeding means 7 years weeding.” This adage indicates how long weed seeds remain viable in the soil. For example, if a soil contains 10,000,000 (ten million) weed seeds per acre, 50% will typically decay per year. Assuming no replenishment through reseeding, at the end of 7 years the population will be reduced to approximately 100,000. This is a lower number, but still significant. Also realize that the weeds that emerge each year often account for less than 5% of the soil’s weed seed population.

Information from the September 3, 2009 edition of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln090309.pdf

Landscape - Avoid Tree Staking if Possible

2009-09-22T06:25:00.003-04:00

There is considerable controversy over whether or not to stake trees. Certainly, top heavy trees, trees with limited root balls, or trees in heavily exposed or windy areas may need to be staked. However, many trees are staked that do not need to be. The following are some facts about staked versus unstaked trees.

No staking is necessary for newly transplanted trees that can stand by themselves or have branches to the ground. Compared to rigidly staked trees, unstaked trees will: develop a 33% greater basal trunk area; grow 19% less in height; develop a 30% greater trunk taper; develop a stronger, larger root system; develop more uniform xylem to support itself upright; have few or no rubbing or girdling injuries.

Guy wires with rubber hose protectors. Left on more than one growing season. Partial stem girdling. Photo by Andrew Koeser, International Society of Arboriculture, Bugwood.org

Information from the September 3, 2009 edition of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln090309.pdf