Landscape Message - Landscape Nursey and Urban Forestry

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The LANDSCAPE MESSAGE is an educational newsletter intended to guide landscape, nursery and urban forestry professionals in identifying pests in the landscape, monitoring their development, planning management strategies and creating site-specific records for future management reference.

UMass Extension has updated this issue to provide timely pest management information and the latest regional news and environmental data throughout Massachusetts. Through the months of July, August, and September this newsletter will be published bi-weekly. The next update will be available on or about July 17, 2009.

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Interested in additional turf-oriented content? UMass Extension Turf Program Management Updates

2009 GROWING DEGREE DAYS

Soil Temp
(°F at 4" depth)

Precipitation
(1-Week Gain)

Total accumulation for 2009

n/a = information not available

* = no activity to report/information not available

Euonymus caterpillar - the crisp white moths with black spots have begun to emerge. Another generation of caterpillars will be produced soon. However, they will remain small for the remainder of this growing season and cause virtually no damage. They will overwinter and be capable of defoliating plants next spring.

Imported Pine Sawfly caterpillars will be appearing soon and may be found on the same plants that acted as previous hosts for the European Pine sawfly.

Hemlock Woolly Adelgid (HWA) remains active but will enter into summer dormancy within the next 2-3 weeks. It will remain on the twigs as an immature but will not be feeding or developing. Activity will resume in October, and this pest will then be active throughout the winter. HWA can still be managed with oil sprays at the summer rate if the weather conditions are conducive for its application without harming plants. Systemic (soil or trunk) applications of imidacloprid can be applied starting in mid August, as long as sufficient water is available for several weeks after application to allow for plant-uptake of the product.

Viburnum Leaf Beetle adult beetles will appear within the next 1-2 weeks and will remain active until the first frost. This pest has made tremendous inroads into Massachusetts within the past two years; and in some regions, defoliation of viburnum is severe. For more details and preferred viburnum host species, visit: http://www.hort.cornell.edu/vlb Spinosad products work well for the larvae.

Lily Leaf Beetle - the second generation adults are starting to appear in warmer regions. Lily leaf beetle has now been reported as being prevalent in Berkshire County (MA).

Asian Longhorned Beetle (ALB) was found in Worcester, MA last August. The Regulated Area is now at 64 square miles. Approximately 22,000 trees have been removed and rendered into wood chips since January 2009. It is estimated that this population may have been in Worcester for at least 15 years. Survey work has renewed within the Regulated Area, and it is already known that many more trees are infested. Everyone must be on the lookout for this pest and should report any potential finds immediately if eradication efforts are to be successful. Also, take great care when moving firewood to avoid transporting this very serious killer of forest and landscape hardwood trees.

To report a potential ALB find: http://massnrc.org/pests/alb
To see “How to Recognize ALB” slide presentation: recognize_alb_ppt.pdf

White-spotted Pine Sawyer beetle (WSPS) beetle adults remain very active. This longhorned beetle is native and not considered to be a pest as it attacks only already weak and dying pine trees. However, it strongly resembles the Asian Longhorned Beetle (ALB). The WSPS does not have a shiny jet-black color with crisp white spots as does the ALB. The WSPS also has one obvious and very distinctive white spot directly behind the head between where the wing covers (elytra) attach to the body. To view comparisons between the two species, see our “How to Recognize ALB” slide presentation: recognize_alb_ppt.pdf

Bronze Birch Borer adults are active and seeking stressed host trees. Keeping trees healthy is the key to prevention. Some choose not to prune susceptible birches from June into September in order to minimize the amount of plant volatiles in the air that might attract this pest. This insect can only survive in a previously weakened tree. Avoid drought stress for susceptible species.

Asiatic Garden Beetle are becoming more prevalent. These beetles are a rust color and only appear at night to feed. Often they are attracted to lights. This beetle feeds on a variety of garden plants including, basil, peppers, and others as well as attacking landscape plants such as rhododendron. Inspect with a flashlight between 9:30 PM and midnight for their activity. If found in large numbers, treat with an insecticide that contains one of the registered pyrethroids.

Spider Mites are active. Cool-season mite species, such as spruce spider mite will build up in numbers on such hosts as spruce, fir, arborvitae, and others and then go dormant when the hot weather arrives around July. They will then return to feed and multiply by late August and continue into the fall. Inspect the two- and three-year-old growth for their activity. Treat when numbers become large. Warm-season species, such as the two-spotted spider mite, are also active and have a wide range of host plants. Populations of these remain active and thrive during the hottest times of the summer. Inspect weekly for increases in numbers and treat when necessary.

Fiorinia Scale (a.k.a. Elongate Hemlock Scale) has become more prevalent in MA in recent years. Inspect the undersides of hemlock needles for the tiny, yet, often numerous scales. Stressed trees (those affected by compacted soil, drought, hardscape, etc.) tend to succumb sooner to this pest. Fiorinia scale produces crawlers throughout much of the growing season and is, therefore, difficult to manage. Oil sprays may help but usually require follow-up treatments. Systemic dinotefuran (Safari™) has been showing much promise for armored (hard) scales recently. However, it is a restricted use compound in MA.

Lecanium Scales on oaks (often the European Fruit Lecanium Scale) are in the egg stage now, but these eggs will hatch into crawlers very soon. Horticultural oil sprays (summer rate) can be quite effective for the eggs as well as the new crawlers when good coverage is achieved. These scales produce much honeydew, which leads to problems with sooty mold. Look for the dark-brown, gumdrop-shaped remains of the female scale lined up along the stems. Inspect closely with a good hand lens for the presence of numerous pale-pink eggs under each scale.

Dogwood Borer adult moths remain active. Pheromone traps are available to monitor for the emergence of this moth. The primary host is flowering dogwood. Inspect the trunks of trees for oozing sap and wet sawdust at the site of entry. Avoid injuring the bark of dogwoods with mowers and line trimmers; wounds attract this pest and allow for ease of entry into the plant. Plants that become infested this year can be treated with a coarse spray of beneficial nematodes in August.

Lacebugs on shrubs remain very active. Inspect the undersides of certain shrubs such as Japanese pieris/andromeda, rhododendron, evergreen azaleas, cotoneaster, and others for their activity. Plants in sunny growing sites have the potential to be severely injured by these insects over the course of the summer. Soil applied imidacloprid works very well in managing these pests. Horticultural oil sprays and insecticidal soap sprays also work for the immature stages, but the spray must be concentrated to the undersides of the foliage in order to cover the pest at the time of application.

Reported by Robert Childs, Entomologist, Plant, Soil and Insect Sciences Department, UMass Extension, Amherst.

See our disease fact sheets section for many helpful fact sheets on disease problems of trees and shrubs.

Gymnosporangium rust infections are visible as orange-yellow spots on susceptible hawthorn, apple, and crab apple leaves. In addition, there are tiny yellow-white tube-like fruiting structures beginning to extend from the underside of infected leaves. From mid summer to autumn, spores are wind-carried from the broadleaf host’s leaves and, when conditions are wet, they infect green shoots and needles of junipers. Pea-sized to 2 inches diameter round, brown galls develop on susceptible juniper needles and twigs between 12 and 20 months after infection. The best long-term approach to manage this disease is to grow Gymnosporangium rust resistant hawthorn, apple, and crab apple as well as juniper varieties. In addition to gall formation on junipers, Gymnosporangium rust infections may cause twig and branch dieback. If desired, apply fungicides to protect high value eastern red cedar and other susceptible junipers from mid July through early September.

The yellowing and spotting of leaves is highly visible, but the best time to apply fungicides to protect emerging crabapple leaves from apple scab has passed for this season. It is still helpful to prune densely branched trees to increase air circulation and sunlight penetration that speeds drying of foliage. There are numerous resistant varieties of apple, crabapple, and mountain ash to grow and simplify disease management.

Continue to apply fungicide treatments to manage black spot on high value roses and repeat the applications per label directions into the fall. Provide good air circulation and irrigate early in the day to minimize the period of plant wetness to further suppress the disease. If the problem persists, gradually replace susceptible varieties of roses with those resistant to black spot to reduce buildup of inoculum and the need for fungicide treatment.

Mushrooms in lawns often develop from thatch, buried logs, dead roots, stumps, or even construction debris. They have many different sizes, colors, shapes, and habits of growth and develop fruiting structures or mushrooms in lawns after prolonged wet weather. The fungi that produce these mushrooms are beneficial because they decompose organic matter in the soil, making nutrients available to other plants. These mushrooms usually are harmless to grasses, but some people consider them unsightly or want to get rid of them because young children play in the area. Neither spray applications nor drenches of fungicides are effective in controlling these mushrooms. A simple way to remove mushrooms is to mow the lawn while collecting the clippings or by raking them up. Elimination of excess thatch and aerating the soil to improve water penetration also helps in some cases. In addition, the mushrooms gradually disappear without interventions if the weather becomes drier.

Powdery mildew fungi are visible as a dusty, gray to white spots on a number of host plants including red horsechestnut, dogwood, sycamore, phlox, and rose. Once established on plants, powdery mildews grow superficially on both upper and lower leaf surfaces as well as green shoots and flower buds. They are obligate parasites and derive sustenance only from living host plants. They do this by using minute, tube-like structures (haustoria) that penetrate the epidermal cells and draw out material they need to survive. Later this summer spherical, black fruiting structures are visible with a hand lens on the underside of leaves in the dusty, gray mycelia. Generally, the damage caused by powdery mildew is of minor consequence to healthy plants and does not warrant chemical control if unsightliness is not a critical concern. If considering chemical control, there are a number of unconventional applied materials labeled to protect susceptible plants. They include summer horticultural oil, commercial baking soda preparations (sodium bicarbonate and potassium bicarbonate), anti‑transpirants, as well as a number of conventional fungicides. Chemical spray programs are most effective when begun just as symptoms of powdery mildew begin to show. Once powdery mildew is extensive on the plant, there is little benefit from chemical control that season. Applications need to coat both surfaces of all susceptible plant parts to prevent infection. Spray on a regular schedule, and repeat more often during warm, humid weather.

Status of Phytophthora ramorum in 2009:

Note: There were no updates for 2009 reported by USDA-APHIS-PPQ at this time. See earlier 2009 editions of the Landscape Message for a summary of the 2008 program.

Reported by Dan Gillman, Plant Pathologist, UMass Extension Plant Diagnostic Lab, Amherst.

For a complete listing of upcoming events, see our Conferences and Workshops page.

Don't forget to visit the UMass Extension Online Weed Herbarium!

2008-2009 Professional Management Guide for Insects, Diseases and Weeds of Trees and Shrubs in New England - Pesticide label registration changes every year in all states and you can only legally apply pesticides according to the current year's label. This updated 2008-09 guide tells you what is current and legal for use in all the New England states and is the way for you to stay current with pesticide information. If you already have the 2003 version, this is the updated supplement for pesticide information. Remember, if you're a pesticide applicator, it's the law! Created by UMass Extension professionals, this manual offers the latest on virtually all the insects, diseases, and weeds of woody plants in New England; current and legal listings of chemical compounds labeled for the management of these pests; Integrated Pest Management (IPM) considerations for most of these pests; environmentally friendly alternatives in pest management such as horticultural oils, soaps, biologicals, etc.; and Growing Degree Day (GDD) information for most of the insect pests of woody plants. Click here to order online from the UMass Extension Bookstore or contact (413) 545-0895; eweeks@umext.umass.edu for information.

Planting and Maintaining Sustainable Landscapes: A Guide for Public Officials and the Green Industry - An updated and reprinted collection of fact sheets, including Trees and Shrubs for Low Maintenance Landscapes; Recommendations for Planting and Maintaining Trees and Shrubs; Integrated Pest Management and Plant Health Care; Streetscape Design and Planting; Selecting Turfgrasses for Low Maintenance Sites; Turf Pesticides and the Environment; Children's Protection Act and School IPM Plans; and Guidelines for Planting within the 100 Foot Wetland Buffer. Click here to order online from the UMass Extension Bookstore or contact (413) 545-0895; eweeks@umext.umass.edu for information.

UMass Extension's Landscape, Nursery, and Urban Forestry Program
UPCOMING EVENTS

Visit our Conferences & Workshops page for details & registration

7/22	Great Ideas! Summer Conference Dartmouth, MA
7/29 8/6 8/26	Weed Identification Workshops
8/5	Turf Summer Stress Seminar South Deerfield, MA
8/12	Turf ID & Selection Workshop Amherst, MA

UMass Extension Landscape Message #18
July 3, 2009

DIAGNOSTIC SERVICES

UMass Extension Landscape Message #18 July 3, 2009

DIAGNOSTIC SERVICES

UMass Extension Landscape Message #18
July 3, 2009