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. During the months of April through June, this newsletter will be published weekly. The next update will be available on or about May 8, 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

Winter Moth eggs have all hatched and, hopefully, the caterpillars did not have much time to spend within swelling buds to cause significant damage. Winter moth caterpillars are now feeding freely on expanding foliage and can be managed with Bacillus thuringiensis Kurstaki (B.t.K.), while they are still small, or with a product that contains spinosad, or with a registered pyrethroid product.

NOTE: when spraying B.t. soon after budbreak, it will only cover the exposed foliage. As these new leaves expand and create new surface area, B.t. will not be on this new growth thus allowing the caterpillars to consume more foliage before it ingests the portions of the leaf covered with the product.

Eastern Tent Caterpillar is now active, primarily on Malus (apple) and Prunus (cherry) species. The very small larvae are constructing silken webs in the crotches of branches and move out of the web on warm days to forage on newly emerging foliage. Webs can be removed by pruning out and destroying or larger populations can be treated with Bacillus thuringiensis Kurstaki or a product that contains spinosad.

Gypsy Moth will be active very soon in the warmer regions of the state. Egg hatch can be expected once 90–100 GDDs have been accumulated. The blooming of shadbush (Amelanchier) is a good phenological indicator for gypsy moth egg hatching. This genus of plants began blooming in the Amherst area within the past 4 days.

Hemlock Woolly Adelgid (HWA) is rebounding from the significant winter mortality it experienced in 2005 in Massachusetts. HWA can be managed with oil sprays at the summer rate if the weather conditions are conducive for its application without harming plants (avoid tender new growth or conditions that delay drying time) or with systemic applications of imidacloprid.

Viburnum Leaf Beetle was found in MA during the 2008 growing season in several different counties. It was known to be established in Berkshire county for the past 3 years but has now been identified in Franklin, Bristol, and northern Worcester county. Many of the finds suggest strongly that this serious pest is being moved on nursery plants throughout the Northeast. Inspect now for the eggs, which were deposited on the terminal twigs last season. When found, such twigs should be removed and destroyed prior to the eggs hatching in late April–early May. Larvae will appear soon after the leaves emerge and feed until approximately mid-June whereupon they will pupate. Adult beetles appear about 2-3 weeks later and feed until the first frost. Much damage can occur, especially from the larvae. For more details and preferred viburnum host species, visit: http://www.hort.cornell.edu/vlb Spinosad products work well for the larvae. Inspect viburnum twigs now for any signs of eggs; prune out and destroy if found.

Lily Leaf Beetle adults are very active, feeding on foliage of Asiatic lilies, and mating in the warmer regions of the state (e.g., Amherst area). Eggs will appear soon on the undersides of lily foliage. Monitor for the bright red beetles and also for the eggs on the undersides of the foliage. Inspect the leaves for fine tan-colored, irregular-shaped lines about one inch long. On closer examination, these tan lines will be a row of eggs. When eggs are found, they can be removed and destroyed. Use pyrethroids for the adult beetles. After, when the nymphs appear, a product containing spinosad works very well.

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 moving 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

Balsam Twig Aphid is now active. The ‘stem mothers’ can be seen with a hand lens. These pale green aphids will feed on true firs, in particular, and then produce many offspring that will feed on the new needles as they emerge from the buds causing them to twist and curl. This insect also produces much honeydew, which causes new (twisted) needles to stick together. This pest is of most concern in Christmas tree plantations but can be problematic in the landscape. If found in significant number, treat with a registered pyrethroid or with a horticultural oil if weather and plant phenology allows.

Mining Bees and Ground Bees: Many reports have been received within the past two weeks concerning the activity in large numbers where the soil is suitable for them to build tunnels for offspring. Dozens or more at a time can be seen flying above the ground and entering into anthill-like holes in the ground. There are numerous species, but virtually all are quite docile and rarely, if ever, sting. However, their presence usually creates alarm for some people. Their busiest time is now and will continue for the next several weeks. After that, they usually become unnoticeable. Treatments are generally not applied given that these insects are important pollinators.

Hemlock Eriophyid Mites are now active. These tiny, yet just visible, peg-shaped and 4-legged mites feed openly on the needle surfaces of hemlock. Inspect carefully for their presence. Affected trees often appear slightly chlorotic. These mites can cause harm if appearing in large numbers. They remain active until early to mid June. When found to be numerous on any particular hemlock, treat with an oil spray (weather permitting) or with one of the registered pyrethroid insecticides.

Winterkill: Many evergreen plants, especially rhododendrons, experienced winterkill this past winter. The drooping and browning foliage now was actually affected last January or February. On cold but sunny days, the foliage of rhododendrons may actually perform some photosynthesis, but when the sun sets and the night becomes very cold, the foliage cannot replace the water lost from transpiration due to the plant’s roots being in frozen ground. The result is the death of foliage. This is often seen randomly within one plant and throughout plantings due to the exact micro-climate that forms around each shoot under such conditions. Some shoots will be killed while others just escape injury. Wait a couple more weeks to see exactly which shoots are dead and then prune out these killed branches.

Inkberry Leafminer: This pest overwinters as a larva within the foliage of inkberry. The characteristic brown leaf tips usually do not appear until January and thus get missed by many. Hold browned leaves up to the light to see if the leaf has been mined or cut into the browned area in search of the larva. If numerous mines are found, wait until mid to late May to hang yellow sticky cards on the affected plants. Once the adult flies appear, treat with a pyrethroid insecticide to kill the adults and to limit the incidence of re-infestation of the same plants. Foliage without mines but possessing browned tips may have experienced some winter injury.

Birch Leafminer: This once prevalent pest has been diminishing in numbers for over a decade now in Massachusetts. However, it does appear sporadically and has the potential to damage virtually every new leaf on native white-barked birches. The adult sawfly wasps will appear around the time that the host plant leaves are about half-emerged from the buds, and the females will lay their eggs within the tender new foliage. If a large population is expected in a given area, hang a yellow sticky card from a host tree branch just as budbreak starts. Then monitor these cards every day for the emergence of the birch leafminer adults. Then treat with a pyrethroid insecticide to prevent egg-laying, if necessary.

Cottony Taxus Scale (a.k.a. Cottony Camellia Scale): Inspect for sooty mold and white cottony egg sacs on the undersides of foliage. Host plants include certain hollies, Taxus, and others. Treat with a horticultural oil spray if proper plant phenology and weather conditions prevail.

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.

When irrigation/rainfall wets developing leaves for 6-10 or more hours, that makes them vulnerable to disease infections, especially when accompanied by temperatures of 50-70° F. This is the time to begin applications of protective fungicides to nursery and specimen woody landscape plants known to be susceptible to diseases such as, apple scab on flowering crabapple, dogwood anthracnose on flowering dogwood, fire blight on mountainash, crabapple and Callery pear, Entomosporium leaf spot on English hawthorn, Phomopsis tip blight on juniper, and black spot on rose. Reduce inoculum on the plants by collecting last year’s leaves, and when this year’s foliage is dry, removing dead shoots and branches. Provide irrigation during extended dry periods. Apply a balanced fertilizer per soil test results. If severe leaf spot and shoot blight occur regularly due to these diseases, consider gradually replacing the high maintenance plants with disease resistant ones well adapted to the site.

Ramorum blight, also known as sudden oak death (SOD) and ramorum dieback: The Phytophthora ramorum detection, quarantine, and eradication survey completed its seventh year as a United States Department of Agriculture-Animal and Plant Health Inspection Service-Plant Protection and Quarantine (USDA-APHIS-PPQ) regulatory program in 2008. The program began by monitoring nine counties in California along with part of Curry County in Oregon. It focused on regulating movement of risk articles such as wood, soil, foliage, and nursery stock. Infested areas grew to 14 California counties and the larger part of Curry County in Oregon, which Oregon aggressively surveyed and treated since 2001. Discovery of a shipment of P. ramorum-infected Camellia plants from a large production nursery to many garden centers and retail nurseries nationwide resulted in the USDA-APHIS-PPQ regulatory program receiving a great deal of scrutiny and policy revision in 2004. As a result, in January 2005 USDA-APHIS-PPQ extended the regulation of nursery stock to the entire states of California, Oregon, and Washington. Through ongoing surveys of nurseries, USDA-APHIS-PPQ continues to define the extent of the pathogen’s distribution in the U. S. and limit its artificial spread beyond infected areas through quarantine and a public education program.

Status of Phytophthora ramorum in 2009:

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

Federal Regulation, State Inspection, Nursery Survey, and Other Finds. There was no report this month.

Forest Detection Survey. There was no report this month.

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

Mouse-ear Cress (Arabidopsis thaliana)

Thymeleaf Sandwort (Arenaria serpyllifolia)

Downy Brome (Bromus tectorum)

Shepherd's-Purse (Capsella bursa-pastoris)

Bittercress (Cardamine hirsute)

Sticky Chickweed (Cerastium viscosum)

Horseweed (Conyza canadensis)

Spring Whitlowgrass (Draba verna)

Henbit (Lamium amplexicaule)

Red Deadnettle (Lamium purpureum)

Field Pepperweed (Lepidium campestre)

Virginia Pepperweed (Lepidium virginicum)

Pineappleweed (Matricaria matricariodes)

Annual Bluegrass (Poa annua)

Knawel (Scleranthus annuus)

Common Chickweed (Stellaria media)

Field Pennycress (Thlaspi arvense)

Corn Speedwell (Veronica arvensis)

Purslane Speedwell (Veronica peregrine)

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 Landscape Message #9
May 1, 2009

DIAGNOSTIC SERVICES

UMass Extension Landscape Message #9 May 1, 2009

DIAGNOSTIC SERVICES

UMass Extension Landscape Message #9
May 1, 2009