Landscape - Moisture Extremes and Tree Decline

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

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

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

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