Monday, March 31, 2008

Greenhouse - More on New Guinea Impatiens: Pest Issues

The following is additional information on New Guinea Impatiens insect and disease control from the University of Maryland.

Diseases to watch for:

- Pythium- root and stem rot. Symptoms include stunting, yellowing, wilting, and soft brown roots. Development promoted by over-irrigation and over-fertilization.
- Botrytis- look for the fuzzy gray spores on senescing flowers and dead plant material. Requires film of water on plant surfaces for several hours to germinate.
- Rhizoctonia- can cause root rot and stem cankers. It is called “web blight” when the mycelium grows on aboveground plant parts causing them to “melt down”

Foliar Leaf Spots

- Alternaria- fungal disease which requires a film of water and moist conditions for infection and sporulation.
- Myrothecium- attacks injured or stressed plant tissues and causes necrotic lesions with dark rings, often on the leaf margin. Green/black spores on white sporodochia are characteristic of this disease.

Virus – Tospovirus

- INSV (impatiens necrotic spot virus) some leaves show dark spots and rings, while others can have mosaic symptoms. If virus transmission is going on in the greenhouse, the tolerance level for thrips drops to almost zero. Monitor for thrips using sticky cards.

Thrips control: rotate between materials. Pedestal controls larvae of thrips. Pylon at the high rate of 10-15 oz/100 gallons works. Conserve can be one of the choices, but don’t just rely on this chemical for solving all of your thrips problems. Fortunately the suppliers are doing a better job of cleaning up tospovirus and we are seeing less and less of it. Still stay alert and look for the symptoms on plants. If you see it show up in your greenhouse immediately rogue out the infested plants.


Examine the undersides of foliage for mites. We usually see mites injuring New Guineas grown in the hottest parts of the greenhouse, especially hanging baskets and plants on south walls. Control: Akari, Avid, Floramite, Pylon, Judo, horticultural oil.

Information from the March 28, 2008 edition of the Greenhouse TPM/IPM Weekly Report
from the University of Maryland Cooperative Extension

Sunday, March 30, 2008

Nursery and Landscape - Plants to Consider for Delaware Landscapes Featured at the Upcoming UDBG Plant Sale

This is the fourth in a series of plants to consider for Delaware Landscapes featuring those plants that are being offered at the UDBG Spring Plant Sale.

Cercis canadensis ‘Appalachian Red’. Eastern Redbud 20-25'. Red – almost! Truly distinctive from other selections, this cultivar offers the deepest colored flower buds to date — a deep purple-red that opens to brilliant pink flowers. Size and habit are similar to the species.

Liquidambar acalycina ‘Burgundy Flush’. Chinese Sweetgum 30-50'. The new foliage emerges with an extraordinary burgundy flush in the spring that rivals fall color. The flush of color continue throughout the summer with each new growth spurt before the entire tree turns a deep red in the fall.

Ilex glabra ‘Nova Scotia’. Inkberry 2-4'. One of the best inkberries as it maintains a compact, dense habit without pruning. It is a female although the small black fruit are hidden by the evergreen foliage. Valuable for foundations, hedges, and in sweeps.

Panicum amarum ‘Dewey Blue’. Coastal Panicgrass. A new selection with waxy, silver blue leaves; found growing wild along the southern Delaware coast. Blooms in mid-summer with arching, dense plumes. Heat and drought tolerant; poor soil; deer resistant. A fabulous low-maintenance, fine-textured addition to the garden.

For more information go to the online UDBC Spring Plant Sale catalog at

Greenhouse - New Guinea Impatiens Culture

The following are some tips on growing good New Guinea Impatiens for greenhouse growers. Information is from the University of Maryland.

New Guinea Impatiens

We have moved into New Guinea season, and here are a few reminders. First off, do not fertilize New Guinea impatiens until the roots hit the bottom or sides of the pot. Then start feeding at 100 ppm. Grow them on the dry side and do not pinch the plants.

Fertilization in April and May:

• Adjust for pot size and space plans
• Bench Crops – do not want tall, lush plants, bypassing buds. 100-150 ppm N, rotating with clear water, EC .85-1.1 microsemens
• Bench Crops (after spaced) – can tweak feed up slightly 100-150 ppm N, clear water leach after 2-3 feeds, EC 1.0 – 1.25 microsemens
• Baskets/Containers – 150-250 ppm N, clear water leach after 3-4 feeds, EC 1.0-1.5
• At these rates, New Guineas can handle the NH4 from a typical 20-10-20 with positive results.
• Clear water in rotation to avoid build-up of salts

Light is Critical for good Quality:

• 3,500 – 5,500 foot candles is ideal
• If you have less than 3,000 foot candles, you’ll end up with poor-flowering, leggy plants
• If light is greater than 6,000 f.c., you will end up with reduced flower size and the potential for scorching
• If you have a heavy canopy of baskets in the greenhouse and try to grow New Guineas on the bench below, it may hinder flowering. Keep basket canopies somewhat open by alternating the heights of the baskets so it does not block light to plants below.

Spacing of New Guineas:

• Start out growing New Guineas next to each other with 4.5” space within the flat. Take out every other plant as they mature to increase the spacing to 7- 8”.
• If using a 6-6 ½” pot, move the spacing to 10-12” as the plants fill in.
• Hanging baskets may start on the bench, but move them to a 21-24” spacing to develop the fullest plants.

Reprinted in part from the March 28, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension. Go to for the full issue.

Saturday, March 29, 2008

Nursery and Landscape - Plants to Consider for Delaware Landscapes Featured at the Upcoming UDBG Plant Sale

This is the third in a series of plants to consider for Delaware Landscapes featuring those plants that are being offered at the UDBG Spring Plant Sale.

Cercis canadensis ‘Silver Cloud’. Eastern Redbud 15-25'. Everything in moderation is the motto of this plant. Although variegated, the indiscriminate white splashes in the dark green leaves are display that contrast with the solid green of other plants in the summer garden. Flowers are rosy pink.

Solidago rugosa ‘Fireworks’. Goldenrod 3-4'. Dense plumes erupt in a dazzling show of tiny, bright yellow blooms in late summer/fall. Not to be confused with ragweed—goldenrod does not cause seasonal allergies. Attracts butterflies and bees; perfect for meadow plantings or mixed borders. Delaware Nursery and Landscape Association Plant of the Year Award Winner.

Carex dolichostachya ‘Kaga-nishiki’. Gold Fountain Sedge 10-14'. The fountain-like, fine-textured, narrow green leaves of this sedge are edged in golden-yellow. This low-maintenance clump-forming plant provides a marvelous foliage color for the garden.

Viburnum nudum "Brandywine™". Viburnum 6-8'. This cultivar has fabulous fall foliage and abundant fruit. A compact plant that produces white flowers in the late spring nicely displayed against glossy foliage. In fall, the foliage turns a glowing merlot, the perfect foil for the plentiful fruit that turns first pink, then blue, and finally dark purple, persisting into the winter where they provide food for birds.

For more information go to the online UDBC Spring Plant Sale catalog at

Landscape and Nursery - Mites Present Now

The following are two mite pests to look for in the landscape and nurseries now and in the next 2 weeks. Information is from the University of Maryland.

Spruce Spider Mite, Oligonychus ununguis

Spruce Spider Mite. Photo by Petr Kapitola, State Phytosanitary Administration,

Spruce spider mite hatches at about 30 - 50 degree days. We have reached this point in most of Delaware at this time.

Host: Look for spruce spider mites on junipers, spruce, arborvitae, cryptomeria, dawn redwood, hemlock, and pine.

Monitoring: Examine twigs for red eggs, usually near the base of the needles. The nymphs that are hatching are light colored. You can place a clipboard with white paper under the tree branches, rap the branches several times, and examine what’s crawling on the paper using a 10 -15 X magnification lens.

Control: Horticultural oil works very well on this mite. The mite growth regulators Hexygon and TetraSan work well when applied to young populations of mites. Avid, Floramite and Acari are some other options.

Boxwood Spider Mite, Eurytetranychus buxi

Boxwood Spider Mite. Photo from Rayanne Lehman, Pennsylvania Department of Agriculture,

Boxwood spider mite overwinters as eggs and should be hatching in early April in most of Delaware. They have multiple generations per year but they become less active as we move into the hot part of the summer.

Hosts: English and European boxwood

Host resistance: Japanese and Korean boxwood tend to be less susceptible to boxwood mite

Monitoring: Use the clipboard/rap test for this mite. The mites will be tan colored with relatively long legs.

Control: Avid, Hexygon, horticultural oil, insecticidal soap

Information modified from the March 28 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers, University of Maryland Cooperative Extension.

Friday, March 28, 2008

Nursery and Landscape - Plants to Consider for Delaware Landscapes Featured at the Upcoming UDBG Plant Sale

This is the second in a series of plants to consider for Delaware Landscapes featuring those plants that are being offered at the UDBG Spring Plant Sale.

Cercis canadensis ‘Hearts of Gold’ Eastern Redbud 15-25'. The heart-shaped foliage is brilliantly gold, fading to chartreuse — exquisite throughout the summer. Thankfully the purple-pink flowers appear before the gold foliage as the mix might be considered garish to some.

Cladrastis kentukea ‘Perkins Pink’. American Yellowwood 30-50'. A true star in the garden but this one is pink with a heavenly fragrance. The nearly 12-in. long terminal clusters provide quite a display in mid to late May. A great small- to medium-sized tree for residential landscapes. Clear yellow leaves develop in the fall. Tolerant of wet soil conditions.

Thuja orientalis ‘Beverly Hills’. Oriental Arborvitae 8-10' . More heat tolerant than our eastern arborvitae, the bright yellow green winter color foliage is a sure eye catcher. Plants stay relatively small with a consistent, conical habit.

Clethra alnifolia ‘Ruby Spice’. Summersweet 4-6'. Arguably one of the best of the pink flowered cultivars prized for its fragrant, non-fading, ruby-red flowers that bloom in late summer. Plants may also be more compact than other pink cultivars.

For more information go to the online UDBC Spring Plant Sale catalog at

Landscape - Plants to Cut Back Now

Now is the time to cut back ornamental grasses and other perennials to get rid of the dead tissue and provide space for this year’s foliage to emerge. If you wait too long, you will have to cut back newly emerging plant tips--not much of a problem with grasses but more problematic with some perennials. Liriope can be mowed to remove winter damaged tissue.

Cut back shrubs grown for their winter foliage now. Red twig dogwood can be cut back to the ground completely or you can remove two/thirds of the old canes back to the ground. Do not cut redtwig dogwood back uniformly to 1-2 feet in height (as I have seen in a number of places). That will result in heavy branches at the base of the plant that won’t exhibit good red coloration next winter. Only young stems color well and you want the coloration to extend all the way to the base of the plant.

Thursday, March 27, 2008

Greenhouse - Thielaviopsis Root Rot

Black root rot (Thielaviopsis) is a common problem in greenhouses and nurseries. The following are some control recommendations.

Photo from the Pennsylvania Department of Agriculture

Thielaviopsis root rot, or black root rot, is common on fuchsia and snapdragon and can be found on many greenhouse and nursery plants. To manage Thielaviopsis, treat with fungicides such as thiophanate-methyl materials (e.g., Banrot, Cleary’s 3336, Fungo Flo, OHP 6672). Other options that help suppress symptoms include triflumizole (in Terraguard). Also, if possible keep the growing media pH low (~5.5 to 5.8) as a lower pH inhibits Thielaviopsis. To prevent future problems, thoroughly disinfest benches, floors and all areas where Thielaviopsis-infected crops were located, and avoid planting susceptible plants in these areas – pansy, petunia, calibrachoa and catharanthus are common hosts.

Control recommendations from the Northeast Floriculture IPM Notes from Rutgers University.

Landscape - Plant Disease Free Material

One of the basic rules of disease control in the landscape is to plant disease free material. The following is an article on the subject.

This is the time of year when Delaware landscapers will be planting trees, shrubs, perennials, and annuals for color. Landscape introductions carry the risk of introducing new disease-causing pathogens. Landscapers, knowing that plant disease will not occur if the plant and the pathogen can be kept apart will want to consider using the principle of exclusion for disease control.

Normally, when exclusion for plant disease control is considered, we think of quarantines and inspections to keep new diseases from entering a state or nation. Currently, Delaware and other states in the eastern U.S. are excluding Phytophthora ramorum, cause of sudden oak death, by inspections of nursery plants moving from the West Coast where the disease occurs, to the East. Similarly, through exclusion, Ralstonia solanacearum race 3 biovar 2, a devastating disease of potato and other crops, is prevented from entering the U.S. on geraniums or other transplants. We can only imagine what our Eastern U.S. forests or urban streets would look like if chestnut blight or Dutch elm disease had been excluded.

On a much smaller scale, although a landscape disease may be widespread in Delaware, it doesn't mean that every site harbors the pathogen. In order to keep the site free of some plant pathogens, it becomes the responsibility of the landscaper to exclude diseases that might be damaging to plants. This means landscapers need to undertake careful inspections of incoming plants and reject those that don't meet good health standards.

Some examples might include:

Black root rot, caused by the fungus Thielaviopsis basicola, may be present on roots of holly, petunia, pansy, impatiens, geranium and other transplants. The fungus is not already present in most soils, but once introduced, will persist in the soil for many years. The tops of the plants may not show symptoms in the nursery or garden center so in order to find the disease, the plants must be knocked out of the pots and the roots examined. Inspect plants carefully and reject those with dark root lesions or blackened root tips. Once planted in the garden, these plants will decline and grow poorly.

Geranium bacterial blight, caused by the bacterium Xanthomonas campestris pv. pelargonii can devaste geraniums grown in outdoor beds. This disease is sometimes introduced into the landscape via infected transplants. On leaves, look for brown spots, often with yellow margins or check for sunken cankers on the stems. If these symptoms are observed, reject the plants because once the pathogen is introduced into the landscape, that bed can become contaminated and provide a source of infection for future geranium plants grown in the same bed. Examine geranium plants carefully and exclude any that have symptoms of leaf spot or stem cankers.

Viruses such as Impatiens Necrotic Spot Virus and many others can be carried on transplants. Most commercial transplants are free of this disease, however, we do see it from time to time on greenhouse and nursery grown annuals and perennials. Virus symptoms on transplants include deformed leaves, spotting, and yellow mosaic patterns on the leaves. Be wary of transplants with virus symptoms; exclude them from the landscape.

For a healthier landscape, remember to use the principle of exclusion to reduce the chances of introducing a pathogen that causes a plant disease that will be regretted later in the season or in the coming years.

Modified from AN EXCLUSIONARY PRINCIPLE FOR THE GARDEN By John Hartman in the March 24, 2008 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.

Wednesday, March 26, 2008

Landscape and Nursery - Pine Bark Adelgid

The following is an article on Pine Bark Adelgid, a pest of white pine that you should start scouting for this time of year.

Photo by Petr Kapitola, State Phytosanitary Administration,

Pine Bark Adelgid, Pineus strobi, is a common pest on eastern white pine. This insect is found throughout the native range of eastern white pine and sometimes on Austrian and Scots pines. The species is native to Europe, and was unintentionally introduced into the United States on nursery stock in the early 1900s.

The overwintering life stage is the mature female, who begin to lay eggs in early spring. Winged and wingless females develop from these eggs. This species reproduces by parthenogenesis (without the need of males for fertilization). The winged forms fly to spruce where they lay eggs, but nymphs from these eggs do not complete their development, and eventually die. The wingless forms continue to develop on white pine, feeding on bark. If abundant, the pine bark adelgid may decrease the health of a small eastern white pine. Five generations are produced each year in the Mid-Atlantic States.

From a distance, the trunks of heavily infested white pines often appear to be whitewashed. When the white "wool" is pulled away from a mature pine bark adelgid, a black teardrop-shaped insect with short legs may be revealed. Examine the bases of eastern white pine buds on small plants from late March through April for the presence of this insect. Apply horticultural oil as a dormant treatment. Formulations of acetamiprid, bifenthrin (Bifenthrin Pro Multi-Insecticide, Talstar F, Talstar Lawn & Tree Flowable, and TalstarOne Multi-Insecticide only), chlorpyrifos (Dursban 50W only), cyfluthrin and imidacloprid, deltamethrin, horticultural oil, imidacloprid, insecticidal soap, oxydemetonmethyl, and tau-fluvalinate are labeled for management of this pest. Apply according to label directions from late April through May when these insects are active, if indicated. Use a high-pressure spray of water to wash infestations off the trunks and branches of large eastern white pines.

Written by Gregory Hoover in April 16, 2004 edition of Ornamentals Hotline from the University of Delaware Cooperative Extension. Recommendations were added from the Penn State Woody Ornamental Insect, Mite, and Disease Management Website.

Greenhouse - Pest Control Recommendations and Botrytis Control

The following is some information from Bob Mulrooney, UD Extension Plant Pathologist.

The following is a good source of pest management recommendations for Greenhouse crops.

This is a great publication with good information on control of diseases. At this time of year Botrytis blight can be a real problem. They address this in this publication. Remember to alternate fungicides with different mode of action. Be sure to check labels for crops that can be sprayed with the different products. Decree, Medallion, Chipco 26019, Daconil are all good products and could be rotated.

Bob Mulrooney, Extension Plant Pathologist, University of Delaware

Tuesday, March 25, 2008

Nursery and Landscape - Kabatina Tip Blight on Junipers

Picture from the University of Missouri Extension Plant Diagnostic Clinic

Kabatina blight will be beginning to show up on infected junipers in the next month. Tips of branches will turn light brown and usually a small gray canker can be found between the healthy and diseased tissue. They will shed by themselves eventually. Prune to remove cankers and the spores that cause them when the plants are dry. Do not confuse this with scale insects, webworm damage or old spider mite damage, which can be present at this time as well.

Greenhouse and Nursery - Pricing

The following are some considerations on pricing greenhouse or nursery products from Ginger Myers at the University of Maryland.

1. Develop a pricing strategy- consider:

a. Utilizing odd-evening pricing ($3.99 instead of $4.00), standard mark-up pricing (typically a manufacturer marks his price up 15% over his total cost per unit, a wholesaler 20% over his costs, and a retailer 40% over his costs.), or customary pricing ( when the product “traditionally” sells for a certain price, such as a pack of gum).).
b. Targeting “quality” customers versus “quantity” customers
c. Offering volume discounts or add-on products
d. Offering two layer pricing- one price for premium service and a lower price
for an economy service
e. Matching competitor’s pricing
f. Always using the same price to establish consistency

2. Develop a goal for your pricing strategy.

“What’s the goal for your business?” Pricing is part of your marketing strategy and reflects how you position your product. If you want to be the go-to-guy for a certain product or service, then you need to always sell only top quality product and offer great service. You may have to extend operating hours for customer convenience or perhaps offer a money-back, no- questions- asked
return policy. If you’re positioning your enterprise as a family activity, then you need to have activities and operational hours geared towards the weekends with familyfriendly packaging, activities and prices.

3. Study the competition.

The Internet can give you an abundance of information about your customer, the marketplace and the profit potential - all at a very low cost. You can even interview some potential customers. You might tell them you’re thinking about selling a certain product and ask them what they are currently paying for similar products.

4. Calculate your total costs of producing a product or offering a service by adding together your fixed costs + variable costs.

Once you have your total costs, you can calculate the break-even price for a product or service. Of course you’re not in business to just break even.

5. Identify your added value.

“What’s your unique selling point? Is it quality, different varieties, free delivery, convenient location, or locally grown? What can you offer that customers are willing to pay more to obtain?”

Remember this golden rule when setting prices: perception is everything. How customers view your product or service and what they are willing to pay for it is based upon perceptions. In the end, customers will tell you loud and clear through their purchasing behavior whether or not your prices are too high, too low, or right on the money.

Reprinted in part from "Master Marketing Highlight - Is the Price Right?" by Ginger S Myers, Regional Extension Specialist, Marketing, Univeristy of Maryland Cooperative Extension in the March 21, 2008 edition of the Greenhouse TPM/IPM Weekly Report, University of Maryland Cooperative Extension.

Monday, March 24, 2008

Greenhouse and Nursery - Web Blight

The following is an article on web blight, a Rhizoctonia disease of ornamental plants, from the Univeristy of Maryland.

Rhizoctonia Web Blight

This fungus has a very wide host range, causing disease on many crops, vegetables, ornamentals and even on turf-grasses. Moist conditions favor this disease- try to space susceptible crops so that the foliage dries after rains or irrigation. When the weather is hot and humid and night temperatures do not fall below 68° F, Rhizoctonia is happy and most vigorous. Rhizoctonia can cause root rot and stem cankers, but when it is growing on the aerial plant parts, and causing extensive aerial blight, it is called “web blight”. To diagnose, we examine the tissues and find the distinctive mycelium of Rhizoctonia. Look for fine, wispy, tan mycelium (especially in early morning before dew has dried) that is causing above ground plant parts to “melt down” and that sticks the dying plant parts together.

Management: Many fungicides are registered to control Rhizoctonia. These include (but are not limited to) Banrot, Chipco 26 GT, Cleary’s 3336, Compass, Heritage, Junction, Medallion, Protect T/O, Terraguard, and Terraclor.

Extracted from the March 21, 2008 edition of the "Greenhouse TPM/IPM Weekly Report" from the University of Maryland Cooperative Extension

Sunday, March 23, 2008

Landscape and Nursery - Plants to Consider From the Upcoming UDBG Plant Sale

This is the first in a series of plants to consider for Delaware Landscapes featuring those plants that are being offered at the UDBG Spring Plant Sale.

Cupressus arizonica ‘Blue Ice’. Arizona Cypress. 20-30' Steely, ice-blue foliage with mahogany stems make this one of the most sought after of conifers. The narrow (1/3 as wide as tall) habit makes these plants great for grouping in larger landscape or ideal specimens in smaller settings.

Nyssa sylvatica ‘Hayman’s Red’. Red Rage™ Black Tupelo 30-50' Red Rage™ is an appropriate name as the intensity of the emotion is equal to the intensity of the fall color. Truly a vibrant scarlet unmatched by any other plant's fall foliage display.

Abeliophyllum distichum ‘Roseum’. White Forsythia 3-5'. The “white forsythia” with pale pink flowers! Flowering early in the spring, Abeliophyllum is not a forsythia, but a close relative with exceptionally fragrant flowers. Flowers outside in March to April; however, bring spring inside by cutting branches to force.

Cercis racemosa. Chain-flowered Redbud 15-25' Many references refer to this as the most attractive redbud. Flowers are borne on 2 to 4 in. long, dangling racemes, providing a spectacular spring display. The late J. C. Raulston described it as the “most beautiful redbud in existence,” while John Frett is “amazed and enamored with the novelty of the flowers.”

Saturday, March 22, 2008

Greenhouse - Thrips Resistance to Insecticides

Insecticide resistance is a very common problem for thrips and thrips management in greenhouses. The following is an article on the subject from the New England Greenhouse Update.

Thrips populations are increasing as the weather is getting warmer. Some growers have reported that Conserve (spinosad) is not controlling thrips as well as in past years. This may be due to pesticide resistance, inadequate pesticide coverage or other factors.

Pesticide resistance is genetic. An insect cannot become or acquire resistance during its life (within one generation). Resistance tends to occur when there is widespread application of an insecticide with some individuals surviving and passing on genetic factors. The surviving pests can transfer the resistance factors throughout the population allowing the population to become resistant over time. Repeat applications with the same type of pesticide will eventually leave only those with the resistant gene. One way to delay resistance is to rotate pesticides with different modes of action (MoA) every two to three weeks or after up to three successive applications of insecticides with the same mode of activity. Mode of action is how a pesticide affects the insect. Most pesticide labels now have a number on the label that correlates with their mode of action group to make it easier to recognize the MoA for rotation. Or you can look up the information on a chart in the Greenhouse Recommendation Guide.

To manage thrips, shorten spray intervals to 4-5 days and rotate pesticides with different modes of action using suggestions above for delaying resistance. A rotation program for thrips might include Conserve (spinosad-group 5), Avid (abamectin-group 6), Mesurol (methiocarb-group 1A), Pedestal (novaluron-group 15), Azatin (azadirachtin-group 18B). Note that Mesurol has a 48 hour REI and Pedestal is for immature stages. Other pesticides labeled for thrips that growers are using include Pylon (chlorfenapyr-group 13), Tristar (acetamiprid-group 4A) and BotaniGard (Beauveria bassiana). A couple of growers reported good control with Pylon. For a complete list of insecticides labeled for use against thrips, see the New England Greenhouse Floriculture Guide.

In addition to injury caused by their feeding, western flower thrips vectors impatiens necrotic spot virus (INSV) a serious disease of greenhouse crops. To confirm that plants are infected with INSV, plants can be submitted to a diagnostic laboratory or growers can purchase easy to use test kits that are available from Agdia. If plants are infected with INSV, there is no cure. Infected plants should be removed from the greenhouse. Some growers keep a few test kits on-hand in their refrigerator to test suspicious plants. It only takes a few minutes to do the test and it can provide peace of mind and early detection.

Reprinted from "Thrips and Pesticide Resistance" in the March 20 edition of the New England Greenhouse Update

Landscape - Forsythia is in Bloom, That Means Tent Caterpillars are Hatching

The following is a short article on tent caterpillar hatching from the University of Maryland

Forsythia blooming… Eastern Tent Caterpillar hatching

Newly hatched eastern tent caterpillars (ETC) eggs are being found hatching on cherry. Interestingly, the plants haven’t started to leave out yet. The tiny caterpillars seemed to be “hanging out” at the buds just waiting for food.

Monitoring: The beginning of bloom on forsythia is a plant phenological indicator that the overwintering eggs of ETC will start hatching.

Control: It is still a little early to apply control measures for two reasons. Most controls for caterpillars have to be ingested. Therefore, you should wait until the host plants (many Rosaceous plants) have leaved out. Second, not all caterpillars have hatched out yet.

Eastern Tent Caterpillar Egg Masses. Photo by A. Steven Munson, USDA Forest Service,

Friday, March 21, 2008

Landscape - Maintenance to Reduce Disease in Yellow and Red Twigged Dogwood

Now is time to perform maintenance on yellow and red twigged dogwood to remove diseases. The following is a short article on the subject.

If Botryosphaeria canker has been a problem on red or yellow twigged dogwood, rejuvenation pruning now can remove most of the old cankered wood and allow new vigorous stems to develop that are resistant to infection. Now is a good time to inspect the shrubs and look for the girdling stem cankers that kill the stems. If stem cankers are found, remove that old wood.

Landscape, Turf, and Nursery - Planning for Pest Management

It is critical to develop plans for managing pests in the landscapes, nurseries, or turf areas that you manage. The following is an article on the subject.

Spring is here and that means that the potential for pest problems in landscapes, nurseries, and turfgrass could be just around the corner. Be prepared and have a plan in place to deal with problems as they arise.

Some areas to consider as we enter the season:

Cultural Practices – Often the first thought that comes to mind for any pest problem is, "What pesticide can I use for control?" However, the incorporation of cultural practices into your pest management strategy can dramatically reduce the chances for development of problems. Use cultural practices that will aid in the reduction of inocula or the improvement of spray coverage. Practices such as proper pruning, sanitation, renovation, mulching, cultivation, etc. should be an integral part of any pest management strategy where appropriate.

Sprayer and applicator maintenance – Now is the time to check the pump, hoses, filters, nozzles, etc. to be sure that everything is in good working order before your first pesticide application. Also practice routine sprayer maintenance during the season such as lubrication of bearings and cleaning and flushing of sprayer after each use. Check drop spreaders and spinner spreaders for gate slide function.

Sprayer and granular applicator calibration – Pesticides are expensive. Improper calibration can cost you money by either using an excess of material or through lack of control due to inadequate amount of pesticides applied. Calibrate your sprayers and granular applicators at the beginning of the season and at least once during the season. The sprayer or applicator should be calibrated in the landscape or field under conditions in which they will be operated.
A useful site for pesticide applicator technology with many links is at

Review your records – Depending on your crop and problem, a dormant oil spray (for management of scale, or mites) or early lime sulfur spray may be needed (e.g., for phomopsis). Hopefully you have been keeping records of pest problems during the past season(s). This is the first step in developing a management plan for the upcoming season. Review pest problems and outline IPM strategies to address these problems early. If you have not kept records concerning pest problems in your plantings then start this year.

Pest Identification – Before you can properly manage a pest situation you must correctly identify the problem. Know how to identify pests, insect injury and disease symptoms or seek assistance in identification (e.g., Cooperative Extension).

Scouting – Routine scouting should begin at bud swell and continue throughout the season on at least a weekly basis. Early detection and correction of problems is key to avoiding major losses. Subscribe to the Ornamentals Hotline to receive the most recent updates on current pests and control measures.

Pesticide Usage - Consult guides published by University extension programs in the region to determine the most effective pesticides and spray timings for your problem. Use an adequate amount of water for good coverage during spraying and adjust pH of water according to the pesticide label.

Pesticide Resistance Management – To minimize the possibility for development of pesticide resistance do not exclusively use the same pesticides or class of pesticides throughout the season. Mix up the use of chemicals for any particular problem by alternating materials and /or tank mixing.

Throughout the season continue to re-examine your IPM practices and adjust where needed. If you are not accomplishing adequate management results for a particular problem then ask yourself, Why not? A few questions to keep in mind: - Are cultural practices being used? - Is the choice of pesticides correct or the best? - Was spray coverage poor? - Was spray timing(s) incorrect? - Were spray intervals too long? - Were pesticide rates too low? - Were too few applications used?

Adapted and modified from "Plan for Successful Pest Management" by Andy Muza, Penn State Cooperative Extension, Erie County

Thursday, March 20, 2008

Landscape - Anthracnose in Liriope

Many landscape maintenance firms will be cutting back liriope in the near future. The following is a short article on anthracnose in liriope.

When cutting back old liriope leaves, look for the diagnostic red spots of anthracnose. This disease, caused by the fungus Colletotrichum, can disfigure current season's leaves from about midsummer on. The first signs of infection are small red spots that enlarge into large spots with tan canters and red borders. Anthracnose is favored by either stress conditions during the growing season or above average rainfall. The fungus overwinters on the old infected leaves, so removing the old leaves before the new ones emerge usually keeps it under control. Fungicides are generally not needed.

Landscape - Tent Caterpillar Season Coming Up

Tent caterpillar season is fast approaching. The following is some information on this pest from the Kentucky Pest News.

Eastern tent caterpillar (ETC) egg hatch should be complete by early April. Small ETCs move to feed on expanding leaves and build tents at branch and limb forks. Initial growth of the caterpillars will be slow but during the latter part of April caterpillars in limb nests will begin to move to main trunk branch angles and join in a smaller number of larger tents on individual trees. This aggregation behavior can be used to advantage in managing the insect by physically destroying or treating accessible aggregations. Caterpillars will leave defoliated trees in search of food on which to complete development. When full grown, they will wander to find a pupation site. In either case, successful control of dispersing caterpillars is difficult.

Foliar sprays for caterpillar control can be made during this time period, as well. Spray residues of products based on Bacillus thuringiensis (Bt) must be eaten by small caterpillars to be effective; there is no contact effect. Consequently, applications should be made to as much of the canopy as is feasible, especially the foliage around active nests. Direct application to nests will not provide any control. Bt residues on foliage can be broken down by sunlight in 3 to 4 days so it is important to assess control and re-treat if necessary. Effectiveness of Bt decreases as caterpillar size increases.

Foliar sprays with products such as bifenthrin (Talstar) or carbaryl (Sevin) have both stomach and contact activity so they can be effective when sprayed on to foliage or tents. The residual life of carbaryl is about a week; that of bifenthrin is at least 2 to 3 weeks. Another option is to inject trees with either bidrin (Inject-A-Cide "B" or 2% Abacide. Regardless of the treatment used, it is important to re-visit the sites in about 5 days to assess caterpillar activity.

Adapted from an article by Lee Townsend in the April 2, 2007 edition of the Kentucky Pest News from the University of Kentucky, College of Agriculture.

Wednesday, March 19, 2008

Greenhouse - Growth Regulator Use During Grow-out

Controlling growth in greenhouse plants is essential to produce high quality plants in the greenhouse. Using growth regulators during the grow-out stage where plants are grown to their finished size can help greatly. The following is an article on the subject from the New England Greenhouse Update.

During the spring crop production season growers often need to use plant growth regulators (PGRs) for a variety of reasons. Most often the purpose to control plant vigor is during the grow-out stage.

During the grow-out stage the objective it to slow stem stretch while allowing the plant to grow. Low rates of PGRs are recommended for this purpose. With low rate applications, the PGRs can be reapplied as needed to control growth. Any of the commercial PGR products can be used at this stage but of course not all species respond the same to any one material. Therefore, growers are advised to have several different classes of compounds on hand. For instance, make sure you have a triazol class chemical (Bonzi, Sumagic or Topflor) plus either Cycocel or B-Nine. Between the two, you will be able to control most of the plant species you grow.

For growers starting with plugs or rooted cuttings, growth regulation should start at or soon after transplant. If you are starting your own seed, treatments can start within 24-hours of germination.

With transplants in small containers (flats & 4" pots) materials such as B-Nine and Cycocel can be sprayed at weekly intervals. Apply the first spray as soon as new growth is evident. Use a rate at the low end of the recommended range for that species. Repeat at 7-14 day intervals as needed. Note: if you are using Florel to prevent flowering and to stimulate branching, then a growth retardant will not be needed during the early stage of development.

Triazol-class materials (Bonzi, Sumagic etc) offer more options during this stage. These materials can be applied as a soil surface spray prior to transplant (Pre-plant Soil-surface Spray or PSS), or as a Media Spray (MS) applied immediately after transplant. Note that MS applications treat both the soil surface and the plant. Triazol-class materials can also be used as traditional drenches or spray applications once the plants are established and the leaves expand to fill in the allotted space in the pot or flat.

With both PSS & MS applications, the concentration or rate applied is higher than for a drench but less than for a typical spray. For example, the spray recommendation for Sumagic on petunia is 25-50 ppm and the drench rate is 1-2 ppm but the PSS rate is 5-7.5 ppm.
In both PSS & MS, a spray volume of 2-quarts per 100 square feet is used but because the soil surface is exposed and the chemicals are highly root-active, these applications have a mild drench-effect. This spray coverage (2-qt/100 sq ft), typically referred to as spray to glisten, is not enough to soak deep into the soil so the total dosage delivered to the root zone is less then with a traditional drench even though the concentration used is relatively high.

Reprinted from "Controlling Plant Growth During the Grow-out Stage" by Richard McAvoy, University of Connecticut, in the March, 2007 edition of the New England Greenhouse Update

Landscape and Nursery - Japanese Maple Scale

Japanese maple scale is a common pest problem in nurseries and landscapes and can overwhelm plants when in high numbers. The following is an article on the subject.

Photo From the United States National Collection of Scale Insects Photographs Archive, USDA Agricultural Research Service,

Japanese maple scale is a common problem in nurseries and landscapes. Many trees can be attacked including Zelkova, American holly, Redbud, Stewartia pseudocamellia, Euonumus alatus, Cornus species, Prunus species, Japanese maple, and American red maple. To control Japanese maple scale, Apply 3 % oil to the trunk and branches now. The next opportunity for applying control measures will be when crawlers are active. Last year it was in mid June when Hawthorn ‘Winter King’ was inbloom and when the buds of Asclepias tuberosa and A. syriaca were showing color. The Insect Growth Regulator "Distance" can be applied when the crawlers are active. If high populations have resulted in dead branches on trees prune these out before crawler hatch to reduce the number of scales potentially moving onto other branches and trees.

Modified from an article in the March 30, 2007 edition on the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension

Tuesday, March 18, 2008

Turf - Wild Garlic Control

Wild garlic is showing up in lawns and turf areas across the state. The following is an article on this weed and its control.

Wild garlic is one of the most problematic early season perennial broadleaf weeds in turfgrass. Wild Garlic began rapid vegetative growth as air temperatures rose in late March. Generally we recommend herbicides be applied in May/early June for optimum control of broadleaf weeds such as dandelion and plantains. However, if the infestation level of wild garlic is substantial, an early season herbicide application may be warranted to reduce competition with the desired turfgrass.

Wild Garlic is a perennial that germinates from underground bulbs in the fall and grows vigorously in April and early May. Wild Garlic will generally complete it's reproductive growth phase by early June and dissipate from the turf until the following fall. Intensive mowing will speed up this process but may also be detrimental to the desired turf. Herbicide combinations that contain a high concentration of the ester formulation of 2,4-D in combination with dicamba are very effective in providing long-term control. For optimum wild garlic contro,l leave the turf unmowed for several days prior to herbicide application and then do not mow for at least 24 hours following application. Try to time the herbicide application when air temperatures are 60 F or above in the day and above 40 F at night. Due to the orientation of the leaves of wild garlic, the addition of a surfactant (non-ionic or spreader sticker) may increase the retention of the spray solution on the leaves and improve control.

Written by Dr. Steve Hart in the April 2, 2004 edition of the Ornamental Hotline from the University of Delaware Cooperative Extension.

Landscape - Diseases and Disease Control

The following is an article on diseases and disease control in the landscape by Bob Mulrooney, UD Extension Plant Pathologist.

Under Delaware conditions foliage diseases of trees and shrubs rarely threaten plant health but are unsightly and reduce the aesthetic value of our ornamentals. Repeated defoliation or high levels of infected foliage can reduce growth and weaken plants. This stress can make them more susceptible to insect pests or adverse weather such as drought. So disease control may be needed even if the plant is not in immediate danger. Each disease situation should be evaluated for the importance of the host plant in the landscape, the threat to plant health that it poses, and the acceptable level of plant damage or infection. Keep records of disease outbreaks. Record keeping allows the plant owner to establish a history, which indicates patterns and establishes priorities in making disease control decisions. If foliage disease control is warranted, consider replacing the plant with a resistant cultivar if available, e.g. crabapples resistant to scab; or apply a fungicide. Sometimes replacing the plant with one that has fewer pest problems is the best solution. When fungicides are needed, apply before disease symptoms appear. Prevention is the key to control with fungicides and bactericides. For trees and shrubs, most infections occur during wet, warm spring weather so the first fungicide control spray is generally aimed at bud-break and repeated 10-14 days later. Be sure to check the product label for timing and rates. Often when I report that a certain disease has been found in the landscape, the opportunity for chemical control is past. Remember three factors must be present in order to have a disease 1) a susceptible host plant 2) a disease causing organism (pathogen) and 3) suitable weather conditions for infection. If you can affect one or more of the legs of this disease triangle you can eliminate or reduce diseases in the landscape.

Written by Bob Mulrooney, Extension Plant Pathologist in a past issue of the Ornamentals Hotline.

Monday, March 17, 2008

Turf - Crabgrass Germination and Preemergence Programs

It is critical to know when the first crabgrass germination will occur so that preemergence herbicides can be applied just prior to crabgrass germination. The following is an article on the subject from Virginia Tech.

It is likely that higher than average winter temperatures will move our PRE herbicide application dates up a week or two as compared to average years, but the only way to really know this is by charting growing degree days. Growing degree days are calculated as the average of the maximum and minimum temperature for a given day minus the base temperature for crabgrass germination (50 F). Thus, a maximum of 75 and minimum of 27 gives us one growing degree day. If the value is negative, zero growing degree days are added to the running total. Crabgrass starts emerging when the running total reaches 70 to 140 units. You can also keep an eye on soil temperatures and expect emergence after 4 to 5 days of temps reaching 55 to 58 F at the 4" depth. Forsythia bloom is usually a good indicator in northern climates with crabgrass emergence occurring at 50% bloom drop but plants like Forsythia, dogwood, and daffodil will probably be less useful this year due to the sporadic warming trends in January and February.

Extracted and modified for 2008 from "Whacky Winter Weather Worries" in the Crop and Soil Environmental News, January 2007, by Mike Goatley, Shawn Askew, Brandon Horvath, Rod Youngman, and Erik Ervin

Landscape and Nursery - Phenological Indicators

The following is a short article on phenological indicators and how they are used.

Landscape managers in Delaware contend with a wide variety of plants and associated pest problems. In any given landscape, there may be hundreds of species and cultivars of native and exotic trees, shrubs, and garden plants. Throughout the growing season, these plants may be attacked by a similarly diverse assortment of insects, including wood borers, leafminers, scale insects, plant bugs, and leaf-feeding caterpillars.

Timing is everything when managing landscape pests. To be effective, insecticides or biological controls must be applied when pests are present and at their most vulnerable life stage. For example, scale insects are best controlled after the eggs have hatched but before the crawlers have formed a protective cover. Controlling wood borers requires treating host trees with insecticides to intercept the newly hatched larvae before they have penetrated the bark. Leaf-feeding caterpillars such as bagworms and tent caterpillars are easiest to control when the larvae are small. Timing is especially important when using short-lived materials such as summer oils, soaps, and Bacillus thuringiensis (BT).

Frequent in-field inspection is the most reliable means to detect insect problems and time control efforts. Unfortunately, regular monitoring is too time-consuming for many landscape managers. Field workers may not know when or where to look for vulnerable life stages or may not recognize them when encountered. Pests such as the holly leafminer, honeylocust plant bug, and potato leafhopper feed in advance of any recognizable damage. Pheromone traps are available for monitoring certain insects (e.g., clearwing borers) but require time and expertise to use effectively.

Forecasting Using Plant Phenology

Phenology is the science dealing with the effects of climate on seasonal biological events, including plant flowering and insect emergence. Insects are cold-blooded, and like plants, their development will be earlier or later depending on spring temperatures. Since both plant and insect development are temperature-dependent, seasonal appearance of particular insect pests should follow a predictable sequence correlated with the flowering of particular landscape plants.

In our Ornamentals Hotline Publication, phenological indicator plants for Delaware are commonly given. Knowing what is in bloom can help you greatly in insect management decisions.

Adapted and modified from "Timing Control Actions for Landscape Insect Pests Using Flowering Plants as Indicators" by G.J. Mussey, D.A. Potter, and M.F. Potter: Department of Entomology, University of Kentucky.

Sunday, March 16, 2008

Landscape and Nursery - Some New and Different Landscape Plants to Consider

The following are some new and different landscape plants to consider. Information is from Andrew Bunting, Scott Arboretum, Swarthmore College.

Paeonia rockii. Tree peony. Large, deciduous shrub with dark green green leaves in groups of nine. Semi-double flowers that are white with some red and yellow stamens are produced in late spring and early summer.

Poliothyrsis sinensis. Chinese Pearlbloom Tree. This is a shrub-like deciduous tree that can reach up to 25 feet. It likes full sun and blooms during the summer with white, fragrant flowers. In the fall, the leaves turn a burgundy color.

Prunus mume ‘Kobai’ Japanese Flowering Apricot. Deciduous tree with red semi-double flowers in late winter.

Rhododendron ‘Solidarity’. A pink flowered Rhododendron blooming midseason.

Information from Andrew Bunting, Scott Arboretum, Swarthmore College,

Saturday, March 15, 2008

Turfgrass - Recommended Kentucky Bluegrass

The following are recommended Kentucky Bluegrass varieties from the Virgina and Maryland turfgrass variety trials. Kentucky bluegrass best used as a mixture with turf-type tall fescues and not as a stand alone lawn in southern Delaware. In northern Delaware, they can be used more extensively.

Kentucky Bluegrass – Individual varieties selected must make up not less than 10%, nor more than 35% of the total mixture on a weight basis. All varieties must be certified. Selections can be made from Category I alone or various combinations of Categories I, II, and III as noted. Kentucky bluegrasses listed as “Promising” (Category III below) can account for no more than 35% of the blend by weight).

Category I – Recommended Kentucky Bluegrass Varieties (65–100% of blend by weight).

Apollo, Award, Awesome, Beyond, Blackstone(1), Bordeaux, Brilliant, Cabernet, Champlain, Courtyard, Dynamo, Everest, Everglade, Excursion, Glenmont, Impact, Liberator, Limousine, Midnight, Moonlight, NuDestiny, NuGlade, Perfection, Princeton 105, Quantum Leap, Rambo, Raven, Skye, Total Eclipse, and Tsunami.

Category II – Special use varieties (10–35% on a weight basis) – These varieties have been noted for specific enhancement of Kentucky bluegrass performance as related to shade tolerance and reduced maintenance requirements.

Shade Tolerant: Ascot, Brilliant, Liberator, Moonlight, NuGlade, Princeton 105, and Quantum Leap.

Low Maintenance Tolerant: Baron, and Midnight.

Category III – Promising Kentucky Bluegrasses (10–35% on a weight basis) – These grasses have performed in the top statistical quality category for a minimum of 2 consecutive years in Virginia and Maryland trials. Seed may be difficult to locate for some cultivars. Note: Durablue, ThermalBlue, and ThermalBlue Blaze are commonly referred to as Hybrid Bluegrasses, but they are classified by USDA as Kentucky bluegrasses. To date they have had better performance in traditionally warmer areas of Virginia.

Barrister, Bluestone, Diva, Durablue, NuDestiny. ThermalBlue, ThermalBlue Blaze

Reprinted from the 2007-2008 Virginia Turfgrass Variety Recommendations, Mike Goatley, Turfgrass Specialist, Virginia Tech

Turf - Hybrid Bluegrasses

Dr. Mike Goatley, turf specialist at Virginia Tech spoke at a turf session held at the University of Delaware Carvel Research and Education Center on 3/14. In his first talk, he gave information on new turfgrasses that are coming on the market. One group are the hybrid bluegrasses which have some desirable traits that warrant consideration in Delaware. The following is some information from Dr. Goatley from the Virginia Tech Turf and Garden Tips website.

There are some new grasses on the market that warrant attention in Virginia (and Delaware). One of those grasses is hybrid bluegrass, a cross between our long-time standard Kentucky bluegrass with Texas bluegrass. The result of this cross is touted to be a seeded turf with the great looks and recuperative potential of Kentucky bluegrass and the added heat and drought tolerance of Texas bluegrass. So what is the take of Virginia Tech’s Turfgrass Team on hybrid bluegrass to date? We believe this grass certainly has merit, but most cultivars still have not been around long enough in our field research trials to be added to our “promising” or “recommended” cultivar list.

Some early observations of hybrid bluegrass.

1) Hybrid bluegrasses germinate from seed slightly faster than Kentucky bluegrass, but the differences in overall establishment rate have not been significant. Hybrid bluegrass germinates and establishes slower than tall fescue.

2) These grasses survive prolonged heat and drought periods, but their performance has not been significantly different from most Kentucky bluegrasses or turf-type tall fescues to date. Hybrid bluegrasses enter dormancy in these stressful periods, a survival feature already well documented for Kentucky bluegrass. Don’t interpret hybrid bluegrass’ claims as being heat and drought tolerant to mean it maintains a lush green color throughout a prolonged dry period.

3) Perhaps the most promising characteristics of hybrid bluegrass to date is its tolerance to one of the major summer diseases in Virginia’s lawns: Rhizoctonia blight (often referred to as “brown patch”). Research by Dr. Jeff Derr and Dr. Brandon Horvath at the Hampton Roads AREC is indicating hybrid blue has much lower brown patch pressure than tall fescue in the Tidewater climate.

4) The other characteristic noted in our trials is that hybrid bluegrass really responds to nitrogen fertilization, similar to Kentucky bluegrass. Under low N fertility programs (say 0.5 to 1 lb N/1000 sq ft/yr), this grass has a tendency to develop diseases noted for their occurrence in low fertility situations: leaf rust, dollar spot, pink patch, and red thread. It appears that in order to maintain the best quality hybrid bluegrass turf possible, it is going to require 3-4 lbs N/1000 sq ft/yr, with 75% of the seasonal N being applied in the recommended September to November period.

5) Spring greening and regrowth is still very slow (similar to Kentucky bluegrass) as compared to tall fescue and perennial ryegrass.

What about the commercially available mixtures of hybrid bluegrasses and tall fescues? Tall fescue continues to be the best adapted cool-season turfgrass for most of Virginia (and Delaware) because of its tolerance to heat and drought stress primarily because of its deep root system. It is only logical that two grasses touting heat and drought tolerance would be combined as a seed mixture for Virginia’s (and Delaware's) lawns. However, there are not a lot of university research trials to date to document the success and/or failure of these mixtures. The best we can do is to hypothesize what these combinations might provide if the mixtures perform up to expectations:

1) Hybrid blue/tall fescue combinations seem reasonable based on expectations in turf quality. Most hybrid bluegrasses currently on the market have a slightly wider leaf blade than Kentucky bluegrass and are very similar in appearance to the turf-type tall fescues. The clumping problems associated with mixtures of Kentucky bluegrass and older, forage-variety tall fescues in years past are not likely an issue with this new combination.

2) Hybrid bluegrasses possess a strong creeping growth habit due to rhizomes (underground stems). This creeping growth potential is something that most tall fescues do not possess. This should further improve turf density and provide for recuperative potential if a turf stand is damaged.

3) The brown patch tolerance will likely improve turf quality during periods when disease pressure is high, possibly reducing the need for fungicide applications.

4) The tall fescue component in the mix will enhance spring greening and regrowth.

At this time, it seems probable that the hybrid bluegrasses are viable alternatives and/or partners to turf-type tall fescue for much of the Tidewater and Piedmont regions (and for Delaware). The ideal time to establish any cool-season turf (including hybrid bluegrass) continues to be in late summer and early fall. Though most hybrid bluegrass seed is sold in the busy spring planting season, successful establishments are much harder to achieve from spring plantings. Virginia Tech researchers will continue to evaluate the latest offerings in turfgrasses to hit the store shelves and keep you abreast of our findings as the data become available.

Reprinted from "Can You Cure Your Lawn Woes by Singin’ the Hybrid Blues?" by Mike Goatley, Extension Turf Specialist, Virginia Tech in Turf and Garden Tips from Virgina Cooperative Extension

Friday, March 14, 2008

Landscape and Nursery - Compaction Tolerant Trees

The following is a good list of trees that are better able to stand compacted soil conditions as are often found in new developments. The list is from the University of Georgia.

Click on tables to bring up a large image in a new window

Information taken from "Compaction Tolerant Plants" by Dr. Kim D. Coder, University of Georgia.

Greenhouse and Landscape - Springtails

Photo from the North Carolina State University

The following is an article on springtails, a nuisance insect often found in greenhouses and landscapes from the New England Greenhouse Update.

Springtails are very small, wingless arthropods about 1/16 to 1/8 inch (1 to 2 mm) long. Some springtails are known as “snow fleas,” because they appear outdoors on the top of snow during late winter and early spring. They occasionally are observed in greenhouse growing media, especially if plants have been over-watered. Springtails do not bite humans, or spread disease.


Springtails may be white, gray, yellow, orange, metallic green, lavender or red; some are patterned or mottled. They get their name from the ability to catapult themselves (leap) through the air three to four inches by means of a tail-like mechanism (furcula) tucked under the abdomen. When disturbed, this appendage functions as a spring, propelling them into the air away from the danger source. Young springtails resemble adults except for size and color. Eggs are spherical. Growers may occasionally mistake some types of springtails for thrips, however, thrips do not have the characteristic furcula tucked under their abdomen.


Springtails occur in nearly every climatic condition throughout the world–in high mountain regions, pools, streams, snow-covered fields, forest floors, etc. They live in the soil, leaf mold, decaying logs, organic mulches, termite nests, snow, greenhouses, and on the surface of freshwater pools and under bark. Populations are often high, up to 100,000 per cubic meter of surface soil–many millions per acre. Springtails feed on algae, fungi, and decaying organic matter, and they are abundant only in damp, moist or very humid locations.


Springtails have chewing mouthparts, but they rarely damage the roots or leaves of ornamental plants in the greenhouse. Since springtails feed on fungi and decaying organic matter, they sometimes are blamed for causing the decay, if they are present. Over-watering is usually the cause of unhealthy decayed roots and springtails are a secondary organism.

A few species feed on living plants and are occasionally regarded as pests: In gardens or the field, Bourletiella hortensis (the garden springtail) may damage seedlings in early spring. As they feed, small holes and surface scarring develops that resembles flea beetle injury. Roots are also fed on by some species. Most types of springtails are beneficial as they reduce decayed vegetation to soil (functioning as recyclers).

Management: Springtails are commonly found where there are sources of moisture. Avoid over-watering and allow the growing media to dry between waterings.

Information was adapted from the Virginia Cooperative Extension, the Ohio State University Extension and Rhode Island Cooperative Extension.

By Tina Smith in the February 2008 edition of the New England Greenhouse Growers Update

Thursday, March 13, 2008

Turfgrass - Tenacity Herbicide (mesotrione) Now Available

Mesotrione, the active ingredient in the new turf herbicide, Tenacity, has a wide range of activity on turf weeds and will give us a tool to control some of our difficult weeds. It received registration over the winter and is now available but only for use in golf courses and turf farms. A residential turf label is expected later in 2008. The following is some information on this herbicide.

Mesotrione the active ingredient in a new herbicide that is registered now for use in turf. Syngenta has named the herbicide Tenacity. Mesotrione is a pigment inhibitor type herbicide (turning weeds white) that will have many uses for weed control in cool season turf. It has excellent safety on tall fescue, perennial ryegrass, and Kentucky bluegrass.

With annual grass weeds, mesotrione is highly active against crabgrass both pre and post emergence, has shown the ability to control goosegrass at higher rates, and is active on annual bluegrass as a fall treatment pre and post emergence.

What is noteworthy is that mesotrione can suppress or control certain weedy perennial grass species including nimblewill, and creeping bentgrass in cool season turf. Another problem weed controlled by mesotrione is yellow nutsedge.

Mesotrione has activity against many broadleaf weeds such as chickweed, henbit, plantain, and oxalis. It has good activity on dandelion and fair activity on clover. However, when combined with triclopyr (Turflon), clover control is excellent.

Another feature of mesotrione is its safety on new turfgrass seedings. Research in New Jersey has shown that it can be used safely as a preemergence herbicide on new seedings. There is some risk of injury with early postemergence applications in the first 3 weeks of seedling growth, especially at higher rates so it is best used preemergence (after seeding but before emergence).

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Landscape and Nursery - Alternatives for Leyland Cypress

The following is a good article on substitutes for Leyland Cypress from the Clemson University Home and Garden Information Center

Because of all its problems, it is necessary to consider substitutes (not just a single substitute) for Leyland cypress in the landscape. The idea is to choose plants for a particular site based upon cultural conditions and aesthetic considerations. It is best to have diversity in the landscape. The use of a variety of well-adapted species, whose requirements match the site conditions, results in more healthy plants.

When choosing screening substitutes for Leyland cypress, consider the actual needs – both of site conditions, and of screening purpose. How high does the screen really need to be for privacy? Few home sites actually require the height that Leyland cypress can ultimately reach. What is the purpose of the screen? Is full year privacy needed, or is screening needed only in certain seasons and for parts of the property? If instant privacy is needed, a fence fronted by shrubs and trees for interest may be more suitable than overcrowding plants. Alternatively, two staggered rows will create a screen more quickly with less chance of crowding. Also consider the contribution to the overall landscape that screening plants will provide. The best screening solutions should be a part of the total design for the property.

Recommended Screening Plants

For those who desire a tall narrow conifer similar in form to Leyland cypress, consider Arizona cypress (Cupressus arizonica) for dry sites in full sun or ‘Green Giant’ arborvitae (Thuja plicata ‘Green Giant’) for moist, but well drained, fertile sites in full sun. Japanese cedar (Cryptomeria japonica) makes a fine tall screen in partly shady areas.

Many broadleaved evergreens make excellent dense screens and also provide flowers or berries for seasonal interest. Tall, narrower cultivars of Southern magnolia (Magnolia grandiflora) such as ‘Alta’, ‘Bracken’s Brown Beauty’and ‘Edith Bogue’ are ideal for screening. In areas where not quite as high or wide a screen is needed, ‘Little Gem’ is very compact and upright in growth. Sweetbay magnolias (M. virginiana) will tolerate moister soil than most. The cultivars ‘Henry Hicks’ and ‘Santa Rosa’ are reliably evergreen.

Hollies provide a multitude of choices for tall screening plants. ‘Foster’s’ holly, the closely related ‘Savannah’ holly (both Ilex x attenuata), and the Aquipernyi hollies (I. x aquipernyi) ‘Dragon Lady’ and ‘Carolina Sentinal’ are all tall, narrow hollies suitable for areas where plant width is a consideration. In less restricted areas, broader hollies such as lusterleaf holly (Ilex latifolia), ‘Nellie R. Stevens’ holly, and many others can be considered. Most hollies grow well in either sun or part shade.

In many cases screens that range between 6 and 15 feet tall will be sufficient to provide privacy. For these areas, numerous choices are available. Northern Bayberry (Myrica pensylvanica) is excellent for many difficult sites with it’s tolerance of sand, wind, salt, and poor soil. It does require full sun. Taller varieties of yaupon holly (Ilex vomitoria) will give a fine texture and will tolerate a variety of difficult growing conditions from wet to dry soil, and even salt spray in sun or light shade. There are viburnums available for virtually any situation, and they will add to the landscape with flowers and berries. Many other species should be considered when looking for appropriate screening for a site.

Adapted for Delaware from "Leyland Cypress Alternatives" from the Clemson University Home and Garden Information Center written by Karen Russ, HGIC Horticulture Specialist, Clemson University.

Wednesday, March 12, 2008

Turf and Landscape: Star-of-Bethlehem

The following are pictures of Star-of-Bethlehem, a problem weed in turf and landscapes. Note the leaf shape, vein color, bulbs, and flowers which will differentiate it from wild garlic or wild onion.

Star of Bethlehem. Photos from the March 14, 2008 edition of the Missouri Integrated Crop and Pest Management Newsletter. Article by Kevin Bradley.

Tuesday, March 11, 2008

Landscape, Turf, and Nursery - Winter Annual Weeds: Bittercress

Bittercress is a common winter annual weed that can proliferate in landscapes, turf areas, and nurseries. Below is a picture of this common weed that is now in flower in Delaware.

Picture from the Woody Ornamental Pest Scouting Report from Penn State University

Greenhouse - Iron Deficiency

Iron deficiency is a common problem in greenhouse plants if the pH drifts too high. The following is an article on the subject from the New England Greenhouse Update site.

Iron deficiency symptoms generally show up as an interveinal chlorosis, normally starting at the shoot tips, but often they occur throughout the entire plant. Sometimes the leaves of iron deficient plants turn almost white. Bacopa, calibrachoa, scaevola, snapdragons, and petunia are crops susceptible to iron deficiency. Preventing iron deficiency can be accomplished by controlling pH and using an iron chelate fertilizer.

Acid pH favors the availability of iron to plants, therefore the target pH range for crops susceptible to iron deficiency is fairly low, 5.5 to 5.8. Most commercial soilless media have pHs in this range to start and the use of an acid-forming fertilizer (e.g., 20-10-20, 15-16-17, 15-15-15) may be enough to keep the pH in this range. 21-7-7 Acid Special fertilizer is effective at quickly lowering pH, but it should not be used more than once or twice to fertilize bedding plants and other annuals. If plants are irrigated with high alkalinity water then iron chelate fertilizer or acid injection should be considered. If a grower mixes his/her own sphagnum peat-based growth medium dolomitic limestone should be added at a rate of no more than 5lbs./yd. Too much limestone is an aggravating factor contributing to iron deficiency.

Fertilizing sensitive crops with iron chelate fertilizer from time to time is probably the least complicated way of preventing iron deficiency. Most greenhouse supply companies carry Sprint 330 (10% iron), Sprint 138 (6% iron), or similar iron chelate products. Sprint 138, however, is the preferred chelate because it maintains iron availability over the widest pH range. Sprint is generally applied as a soil drench at the rate of 8 oz./100 gal.(½-¾ tsp. per gallon). At this rate, iron chelate can be applied every 3 or 4 weeks if desired. Iron chelate can also be mixed as a concentrated solution for injection or low rates can be mixed and injected with other fertilizers.

By Douglas Cox in the March, 2006 edition of the New England Greenhouse Update

Monday, March 10, 2008

Ornamentals Hotline - A Great Resource to Subscribe To

Click on the form above for a larger image in a new window to print out for subscription.
All those involved in landscape maintenance, turfgrass maintenance, and ornamental pest management should subscribe to the Ornamentals Hotline from the University of Delaware Cooperative Extension. The following is information on this publication.
It is time once again to subscribe or resubscribe to Ornamentals Hotline. This one-page seasonal newsletter is designed to tell you what you need to know about pests, diseases, weeds and cultural problems in the landscape. Ornamentals Hotline is published weekly during the growing season.

Contributing authors scout the landscape and monitor Cooperative Extension calls to determine current problems. Reading Ornamentals Hotline will keep you in tune with your customers and their landscape problems. We will tell you when to scout for common (and sometimes not so common) landscape pests and diseases.

Thirty dollars provides you with a subscription of “Ornamentals Hotline” for 2008 (26 issues). To subscribe, fill out the application at the top of the page and send with a check payable to “University of Delaware” to:

Susan Barton
Dept. of Plant & Soil Sciences
Townsend Hall
Newark, DE 19717-1303

Sunday, March 9, 2008

Landscape - Leyland Cypress Problems

Leyland Cypress trees were planted extensively in Delaware as windbreaks and screens over the last 15 years. It is a quick growing and attractive evergreen. Unfortunately, many of them are dying now and replacements must be sought. Some information on the problems with Leyland Cypress follows

Leyland Cypress Problems

Problems with established trees began cropping up several years ago, and the incidence of damage from disease and insect pests has increased every year. Seiridium canker, Botryosphaeria dieback and Cercosporidium needle blight are becoming increasingly common in landscapes as are infestations of bagworms and spider mites. Because of the height of the plants, treatment is difficult or impossible for most homeowners.

Other problems occur simply because Leyland cypress are often seen as the one solution for all screening needs and are planted in situations inappropriate for them. Planting in poorly drained or wet soils, or where excessive overwatering occurs often leads to fungal root rots. Leyland cypress requires full sun to grow well, and when planted in shade, rapidly thins and sheds lower branches. Failure to realize how very tall the plants become (60 to 70 feet tall) leads to trees being planted in improper places, such as under overhead utility lines where a shorter screen would be quite adequate. The desire for instant screening often leads to trees being planted too closely, which results in overcrowding at maturity. Overcrowding leads to problems with poor air circulation, increasing the possibility of disease occurrence and shading out of lower branches.

In addition, Leyland cypress is rather shallow rooted and is susceptible to storm damage (trees topping over in storms). The shallow rooting also means that Leyland Cypress are very susceptible to drought. Many trees were lost last year due to the dry weather.

Information on good alternatives to Leyland cypress will be posted in the future.

Information taken in part from "Leyland Cypress Alternatives" a factsheet from the Clemson University Home and Garden Information Center

Landscape and Nursery: Some New and Different Landscape Plants to Consider

The following are some new and different landscape plants to consider. Information is from Andrew Bunting, Scott Arboretum, Swarthmore College.

Magnolia virginiana ‘Santa Rosa’ Sweet Bay Magnolia. Santa Rosa is a good evergreen form of sweet bay magnolia with lemon scented flowers.

Magnolia ‘Judy Zuk’. This is a Magnolia x brooklynensis hybrid with yellow flowers with a slight purple blush at the base. It has a very attractive fruity fragrance.
Gelsemium sempervirens ‘Margarita’. Carolina Jessamine. This is a vine that produces profuse quantities of trumpet shaped yellow flowers in late spring and early summer. It has a sweet Jasmine scent.

Emmenopterys henryi. Chinese emmenopterys. This is a rare blooming tree with white, wing-like bracts surrounding white to pale yellow, fragrant flowers in clusters in mid summer. It is a beautiful tree with dark green leaves.

Information from Andrew Bunting, Scott Arboretum, Swarthmore College,

Saturday, March 8, 2008

Buffalograss - Not Well Adapted to Delaware

I was recently asked about buffalograss as a low maintenance turfgrass for Delaware. This is a Great Plains native warm season grass species that is being used in states such as Kansas for lawns. However, native buffalograss is not found in Delaware and therefore may not be adapted to the Delaware climate. In states where it is adapted it makes a very nice lawn that needs little or no mowing and has low water needs. New varieties are being released each year and we do not know if they will be better adapted than the common species for our eastern conditions. The following is some information on this grass.

Buffalograss, Buchloe dactyloides, is a perennial grass native to the Great Plains from Montana to Mexico. Buffalograss is, perhaps, our only truly native turfgrass. Its tolerance to prolonged droughts and to extreme temperatures together with its seed producing characteristics enables buffalograss to survive extreme environmental conditions. That being said, it favors heavy clay soils in moderate to low rainfall areas and suprisingly does not do well in sandy soils, even though it is drought tolerant. It also does not do well in higher rainfall or humid areas. When buffalograss is planted in these higher rainfall areas or when it is irrigated and fertilized, bermudagrass and other weedy grasses can invade a stand of buffalograss. Buffalograss is best adapted to low rainfall areas (15 to 30 inches annually) commonly found in the Great Plains of the US. Being a warm season grass, it will green up late in the spring and go dormant in the winter. This means you will have that brown look for an extended period of time.

In my opinion, until we have research information that shows that buffalograss can persist in Mid-Atlantic conditions, a better choice would be the turf-type bermudagrasses if a warm season grass is desired.

Information take from multiple extension sources (largely from Texas A&M) and compiled by Gordon Johnson, Extension Horticulture Agent, UD, Kent County.

Turf - Slower Growing Turf Species

Fine leaf fescues are useful for low maintenance areas to reduce the need for mowing. The following is some information.

Turf grasses with the lowest maintenance requirements are the fine leaf fescues. They are recognized for being survivors in adverse conditions, including our infertile, acidic soils. They also have excellent tolerance to shade, drought, most pests, and cold temperatures. The three most commonly used fine leaf fescues are the chewings, hard, and creeping types.

Traditional sites for growing low-maintenance grasses have included roadsides and highway medians, cemeteries, and large grassy areas in parks and military installations. Low maintenance grasses that retain density and some aesthetic qualities also would be suitable for golf course roughs and some lawn situations. The use of fine leaf fescues should not be considered for athletic fields, intermediate roughs or other sites that will receive large amounts of traffic from people or vehicles.

Noted below are some mixtures that have performed well under low maintenance in Maryland.

1) Hard fescue (1 or a blend of 2 cultivars) @ 90% by weight + 10% sheep fescue, creeping red fescue, or chewing fescue
2) Bighorn sheep fescue @ 90% by weight + 10% hard fescue, creeping red fescue, or chewing fescue
3) Hard fescue @40% by weight + 40% Bighorn sheep fescue + 20% creeping red fescue
4) High Traffic Area Mix: Tall fescue (1 or a blend of 2 to 3 cultivars) @ 90% by weight + 10% creeping red fescue or hard fescue.

Chewings fescues normally out-perform creeping red fescue in full sun, but creeping red fescue has better recuperative potential due to its rhizomatous growth habit. Both chewing and creeping red fescues generally provide inferior quality under low maintenance in full sun when compared to recommended cultivars of tall fescue, hard fescue and Bighorn sheep fescue. Bighorn appears to have better disease resistance than other sheep fescue cultivars that are currently available.

To retain turf density and to retard annual grass weed invasion, the fescues should be mowed no lower than 2.5 inches in height. For best aesthetic quality, fescues should be mowed two to three times monthly during spring and fall of the first year, and less frequently during the summer. In subsequent years, mowing frequency will decline, assuming weeds do not become excessive.

Never mow fine leaf fescues (i.e., hard, sheep, creeping red or chewing) in summer during conditions of heat or drought stress. For stands dominated by the fine leaf fescues, a minimum cutting height of 2.5 inches is recommended, but a 3.5 inch or higher height of cut is preferred and mowing may be as infrequent as once or twice per month during the spring and fall, and once monthly in summer. Mow to ensure that the fine leaf fescues do not produce mature seedheads. Mowing following mature seedhead formation weakens and thins-out stands of fine leaf fescues. Regardless of cutting height, always wait until it rains before mowing fine leaf fescues in the summertime. Mowing fine leaf fescues when it is hot or when soils are dry will cause extensive injury or death of plants, and therefore a marked reduction in turf density. This injury will occur when soils are dry, despite no visual signs of wilt or drought stress in the fine leaf fescues. Tall fescue is not as severely injured by mowing under these summer conditions, but even tall fescue should not be mowed when stressed by heat and/or drought. Mowing high and infrequently in summer is the key cultural consideration for maintaining good quality fine leaf fescue stands under low maintenance. Furthermore, mowing in a 3.5 to 5.0 height of cut range will retard annual grass weed (i.e., crabgrass, foxtail, goosegrass) encroachment for many years.