Saturday, November 28, 2009

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

Friday, November 27, 2009

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

Thursday, November 26, 2009

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

Wednesday, November 25, 2009

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

Tuesday, November 24, 2009

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

Monday, November 23, 2009

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

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

Sunday, November 22, 2009

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

Saturday, November 21, 2009

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

Friday, November 20, 2009

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

Wednesday, November 18, 2009

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

Tuesday, November 17, 2009

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

Monday, November 16, 2009

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

Sunday, November 15, 2009

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.

Saturday, November 14, 2009

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

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

Thursday, November 12, 2009

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

Wednesday, November 11, 2009

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

Monday, November 9, 2009

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

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


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

‘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

‘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

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Sunday, November 8, 2009

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

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,

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

Saturday, November 7, 2009

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

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

Friday, November 6, 2009

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

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

Wednesday, November 4, 2009

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

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