UMass Extension Landscape Message #6
April 7, 2006

Quick Info Menu ------------------------------- ENVIRONMENTAL DATA REGIONAL NOTES - Cape Cod - Southeast - East - Central - Pioneer Valley - Berkshire PHENOLOGY WOODY ORNAMENTALS - Insects - Diseases - Lab Report - Weeds TURFGRASS - Insects - Diseases - Weeds INFO RESOURCES DIAGNOSTIC SERVICES Use this menu to instantly jump to any portion of the message!

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. The next update will be available on Friday, April 14, 2006. Missed a previous message? Visit the Landscape Message Archive. Interested in additional turf-oriented content? UMass Extension Turf Program Management Updates

ENVIRONMENTAL DATA

The following growing-degree-day (GDD) and precipitation data was collected for a two-week period, March 30, 2006 through April 5, 2006. Soil temperature and phenological indicators were observed on April 5, 2006. Accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments since the beginning of the current growing season. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

REGIONAL NOTES

Cape Cod Region (Barnstable) - General Conditions: March was warm and very dry this year, and the first week of April has continued the trend. We received some much needed precipitation on the 4 th of April, with colder temperatures also making a return. Plant development is really ahead of the typical Cape spring, with forsythia already beginning to bloom. As of this message, we have not yet observed hatching winter moth larvae in the buds we are monitoring. Pests/Problems: Crows, starlings, and skunks are digging up lawns in search of white grubs. Western conifer seed bug is being found indoors.

Southeast Region (Hanson) - General Conditions: Nice spring-like weather continued this past week, with temperatures in the low 70's over the weekend. Cooler temperature and light rain today (April 5) followed by snow! Some much needed rain fell (0.49 of an inch early this week), but much more is needed. Soils are dry. Cornus mas, Pieris japonica spp., pussy willow, Abeliophyllum distichum (white forsythia), Omphalodes, crocus, Helleborus niger, H. foetidus, H. x hybridus, scilla, Iris reticulata, and Corydalis solida are in full bloom. Early daffodils, Vinca minor, Pieris floribunda, Pieris 'Brouwer's Beauty', Pulmonaria sp., and Magnolia 'Leonard Messel' are just starting to bloom. Snowdrops and Hamamelis x intermedia 'Pallida' are past bloom. Pests/Problems: Chickweed is in bloom. Solitary bees are active. Ticks are active; conduct tick checks frequently, especially after yard cleanups. In Hanson, winter moth caterpillar eggs have not started to hatch. Skunks are digging up lawns.

East Region (Boston) - General Conditions: No report.

Central Region (Boylston) - General Conditions: Cooler temperatures have returned and brought much needed moisture to the area. The landscape is beginning to color up with the bloom of early daffodils, dwarf iris (I. reticulata), crocus, hellebores, Siberian squill (Scilla sibirica), and glory-of-the-snow (Chionodoxa spp.). White forsythia (Abeliophyllum distichum) is in full bloom, as is spicebush (Lindera benzoin) in wet areas. Spring peepers and wood frogs became active during the warm weather.

Pioneer Valley Region (Amherst) - General Conditions: Hyacinth, crocus, and now a few scattered daffodils are in bloom. The lawns continue to turn greener by the day. The Pioneer Valley received a several hour-long, steady rainfall in the early part of this week, along with a little snow, so soil moisture conditions improved. Pests/Problems:Black knot is quite visible now as fruiting structures erupt through the bark of infected branches of cherry and plum trees. Deicing salt damage is especially visible along highways as needle browning on white pine.

Berkshire Region (Great Barrington) - General Conditions: Snow on the ground this morning (4/4). The brief warmth of last week has been replaced by a cool and wet period, yet this is very typical of spring in the Berkshires. Despite making outdoor landscaping work messy, the precipitation is much needed as soils were getting very dry. Bans on open-burning were in effect throughout the county but will probably be rescinded, allowing for burning of brush. Pests/Problems: Other than the ubiquitous deer tick, no other pest of note have yet to be reported.

PHENOLOGY

The phenological indicators are a visual tool for correlating plant development with pest development. The following are the indicator plants and the stages of bloom observed for this period:

CAPE COD REGION - Roberta Clark, Horticulturist for Barnstable County, Barnstable.

SOUTHEAST REGION - Deborah Swanson, Horticulturist for UMass Extension in Plymouth County, Hanson.

EAST REGION - James R. Allen, Horticulturist and Greenhouse Manager for UMass Biology Department, Boston.

CENTRAL REGION - Joann Vieira, Superintendent of Horticulture, Tower Hill Botanic Garden, Boylston.

PIONEER VALLEY - Dan Gillman, Plant Pathologist, Urban Forestry Diagnostic Lab, UMass, Amherst.

BERKSHIRES - Ron Kujawski, Specialist, UMass Extension Landscape, Nursery & Urban Forestry Program, Amherst.

WOODY ORNAMENTALS

INSECTS

The atypically warm weather during the last week in March accelerated insect activity but then the significantly cooler temperatures of this week have slowed that pace somewhat. However, the early season pests, such as winter moth, eastern tent caterpillar, and forest tent caterpillar are on the very edge of becoming active. Now that foliage is beginning to emerge, these pests will be hatching and feeding very soon

Winter moth - The eggs are still orange but will start to turn a deep dark blue/black color very soon, which indicates their imminent hatching. This exotic pest has been recently shown to be far more prevalent than previously understood. Most of eastern MA, all of RI, some spots in southeastern NH, southeastern CT, southern NH, and certain areas along the Maine coast have this pest. The highest population numbers, by far, are in MA and RI. Once the tiny caterpillars emerge from the eggs, they will seek buds that are just beginning to swell. Winter moth caterpillars wriggle into buds and feed on both foliage and flower parts within the buds.

Gypsy moth is expected to be in high numbers in MA and other northeastern states. The fungus, Entomophaga maimaiga, that controls gypsy moth naturally has not performed well during the past two springs. This is primarily a function of spring weather conditions; rainy periods at critical times during the caterpillar stage are essential for the spread of this pathogen to gypsy moth caterpillars. There has been some anecdotal evidence provided recently that E. maimaiga may have been more active and successful in the westernmost part of MA last year (Berkshires) than it was in the rest of southern New England.

Eastern tent caterpillar is once again expected to be in large numbers and attacking their favored host plants of apple and cherry. Egg hatch will occur once the leaves are half to fully emerged from the buds.

Forest tent caterpillar is also expected to be in large population numbers once again in MA and other surrounding states. Last year, this pest caused more than 200,000 acres of defoliation in MA. Forest tent caterpillar has been a problem in eastern MA for several years, primarily on oaks, but it is now building in serious numbers statewide, as well as in VT, on sugar maple as well.

Fall cankerworm is expected to be in large numbers in eastern MA and on parts of Long Island, NY in 2006. Parts of RI may also experience some of this pest’s activity. Egg hatch will occur about early to mid May.

Hemlock woolly adelgid has been actively feeding since last October and has now produced the next generation. This will be the time when the cottony masses that surround the eggs will be most visible, especially from the undersides of the branches. Make note of those plants that will require treatment with oil sprays once the correct weather conditions prevail.

Spruce spider mite from last fall has not yet shown up yet. It will “suddenly” become apparent on those affected plants, but no mites will be seen at that time. However, make note of those plants that were injured from last fall’s feeding and expect to have more mites on those plants this spring. Once the correct weather conditions prevail, treat with an oil spray or, if eggs are present, they can be treated with one of the mite growth regulator products that has ovicidal activity.

White pine weevil has been active. This species overwinters as an adult in sheltered places and will break its dormancy once we have achieved seven growing degree days (7 GDD), which has already occurred. Female weevils seek the base of terminal buds on white pine and spruce to chew small holes and lay their eggs. Larvae then tunnel downward through 2-3 years of growth and eventually cause the terminal to wilt and die. If treatments are deemed necessary, they should be applied while the adults are active to prevent (reduce) egg-laying.

Inkberry leafminer mines have now become obvious. Despite the larvae being in the mines since early last summer, the browning of these mines has only just occurred within the past month or two. Make note of plants with noticeable infestations and prepare to place yellow sticky cards out around early May to monitor for the emergence of the adult flies, which will indicate the time to apply controls to break the cycle of re-infestation.

Birch leafminer - Purchase yellow sticky cards now to place out on susceptible birches at bud break. Adult sawflies should appear around the time that the leaves are half-emerged from the buds. Treat when the adults appear.

European pine sawfly will not become active for at least several more weeks. However, take inventory now of those plants that were attacked last year by this pest. Mugo pine is the most common host here, but other pines are also attacked. Treat the young larvae with insecticidal soap or a spinosad product.

If leaf spots and blights were serious problems last year, infected parts of trees and shrubs from last year may produce fungal fruiting structures this spring that release an abundance of spores. During wet springs, these spores infect young leaves and shoots. For high value plants where appearance is important, consider several applications of fungicides beginning as buds open if conditions are wet this spring. Alternatively, consider replacing plants with recurring leaf spots and blights with resistant varieties or other plant materials better adapted to the site.

In addition, scout rosaceous plants commonly infected with the fire blight bacterium, such as crabapple, apple, pear, firethorn, hawthorn, and cotoneaster. Remove dead branches and dispose of them away from the plants to reduce sources inoculum. Lilacs with dead shoots from bacterial blight also benefit from their removal. Disinfect pruning tools between each cut with 70% ethyl alcohol, a 10% bleach solution, or a comparable bacterial disinfectant.

On plum and cherry trees that are infected with black knot canker look for swollen branches (~twice the normal diameter). Prune to remove infected branches, but also to improve the branch structure within the tree crown. Removal of inoculum before the fruiting structures erupt through the bark helps reduce inoculum that could cause new infections in the spring and is a key factor in managing this disease.

Finally, collect and dispose of fallen leaves around crab apple (apple scab) and horsechestnut (Guignardia leaf blotch) , as well as leaves and twigs from around flowering dogwood (dogwood anthracnose ) to reduce overwintering inoculum available to initiate new infections this spring.

Ramorum Blight, also known as Sudden Oak Death (SOD) - Since the early 1990’s, oaks and tanoaks were dying in the coastal counties of California. Since then, other types of plants have been found to be infected or associated with this disease, referred to as Sudden Oak Death, ramorum leaf blight or ramorum dieback, or by regulation as Phytophthora ramorum. The first positive identification of the disease was in 1995 on tanoak in Mill Valley (Marin County), California. Since that time, surveys confirmed Phytophthora ramorum on various native hosts and nursery plants in several locations in California, Oregon, Washington, and British Columbia. When nursery surveys find infected plants prompt quarantine and/or eradication activities ensue. Research conducted by the Agriculture Research Service, US Forest Service, universities, and others is under way to better identify hosts, improve methods of detection, and develop effective treatments. Currently, 84 plants are regulated, two of which at the genus level (Camellia and Rhododendron). There are no chemical treatments currently available to eliminate Phytophthora ramorum from infected plants.

Status of Phytophthora ramorum Monitoring Surveys - The 2005 National Nursery Survey involved 49 states and Puerto Rico. The survey visited 3,790 nurseries and collected 68,275 samples. Overall, the survey reported 99 positive sites in 2005. The breakdown by state was: CA (55), GA (4), LA (2), OR (20), TN (1), SC (1), and WA (16).

New Hosts Added - USDA APHIS issued a Federal Order on November 15 adding Abies concolor (white fir) and Viburnum opulus (= V. trilobum) (American cranberry viburnum) to the official list of host and associated host plants. In addition, USDA APHIS issued a Federal Domestic Quarantine Order on February 10 adding Frangula purshiana (formerly listed as Rhamnus purshiana), Adiantum aleuticum, and Adiantum jordanii to the official list of P. ramorum hosts. They also identified 13 new plants as associated hosts. One of the plants, found in an infested area of California and identified by Washington State, was Abies magnifica. The other 12 new species were reported from Canada, and include: Acer davidii, Ardisia japonica, Euonymus kiautschovicus, Gaultheria shallon, Hamamelis x intermedia (H. mollis and H. japonica), Leucothoe axillaris, Magnolia grandiflora, Michelia maudiae, Michelia wilsonii, Osmanthus decorus (=Phillyrea decora; =P. vilmoriniana), Prunus lusitanica, and Rosa rugosa. The Koch’s postulate process for these plants (the process involves isolating the pathogen from the infected plant, reinfecting a healthy plant, and then reisolating the pathogen from the second plant to confirm infectivity) is not complete. Until USDA completes the Koch’s postulate process, due to uncertainty about the pathogenicity of P. ramorum on these plants, these 13 new species are on the associated host list.

Dan Gillman, Plant Pathologist, based in the UMass Extension Plant Diagnostic Lab at UMass, Amherst.

WEEDS

No report this week. Visit the Landscape Message Archive for previous messages.

Reported by Randall Prostak, Weed Specialist, UMass Extension Landscape, Nursery and Urban Forestry Program, Amherst.

TURFGRASS

Insects:

White Grubs. They're back! It will come as no surprise to many of you that white grubs are returning to the root zones in New England. We found oriental beetle grubs and European chafer grubs feeding on the UMass Amherst campus last week, and with the recent warm temperatures, grubs are becoming active throughout southern New England. Just a quick refresher—European chafers are spreading throughout New England and can be found in many parts of Massachusetts now. They are the most damaging species of annual white grubs (species that have one generation per year), in part because they are the largest species and because they are least sensitive to cold. In many areas the chafers have been feeding for a couple weeks already. (And, of course, the European chafers tend to be the most difficult species to control.) Regardless of species, any of the annual white grubs you notice this spring will feed until late May or early June before they pupate. Adult beetles will emerge in mid June (European chafers) to early July (Japanese beetles, oriental beetles, Asiatic garden beetles).

Grubs that are active in spring are difficult to control because they are quite large and their physiology is changing. Nevertheless, a quick acting insecticide such as trichlorfon (Dylox™) can provide some relief in some cases. While we do not have data on soil temperatures, we believe that spring insecticides should not be applied until soil temperatures (at two inches) have reached at least 50 degrees. So there is a very short window of opportunity between the time when soils are warm enough and the grubs stop feeding. If you do treat for spring grubs, remember to water in the application with at least 0.1 to 0.2 inches of irrigation (or rainfall).

Note that imidacloprid (Merit™) applied in the spring does not work on the grubs that are present in the spring. So do not be misled by the "season-long control" claim that can be found on some of the homeowner formulations of imidacloprid. Also, in New England, applications of imidacloprid made as early as May might or might not still be active in July and August when our more challenging grub species are present. So unless you have a really good reason (and assuming that white grubs are your primary concern), delay imidacloprid applications until mid June to early August. Finally, note that the two "curative" insecticides normally used against white grubs in the spring trichlorfon (Dylox™) and carbaryl (Sevin™) are both on the list of pesticides that cannot be used on school grounds that come under the auspices of the "Act Protecting Children and Families from Harmful Pesticides" in Massachusetts. For more information, go to the Massachusetts Department of Agricultural Resources website for the act: http://www.massnrc.org/ipm

This means that turf managers who are managing athletic fields on school grounds in Massachusetts have no insecticide options for controlling white grubs that damaged fields last fall or are damaging fields this spring. Insect-attacking nematodes might be considered by some to be an alternative, but research out of Rutgers University indicates that Heterorhabditis bacteriophora (a nematode that is commercially available and has some activity on grubs) is only effective against Japanese beetle grubs. In many areas of Massachusetts, the Japanese beetle has become secondary to European chafers and oriental beetles. And there is very little information on how effective nematodes are when applied in the spring, or what the soil temperature must be at the time of application. Thus, the primary "option" for turf managers without access to Dylox™ or Sevin™ will be to manage the damage as much as possible. This may mean rolling fields before games to try and reduce slippage. And if your grub activity is significant this spring, make a note to apply imidacloprid during July to forestall similar problems this coming fall.

Pat Vittum, Professor and Extension Turf Entomologist, UMass Amherst Department of Plant, Soil and Insect Sciences

Weeds: No report: Visit the Landscape Message Archive for previous messages.

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

UMass Extension’s Turf Management Guide and IPM Facts: For more information about the pests mentioned in this message, you will need to refer to the following publications: the Professional Guide for IPM in Turf for Massachusetts, 2003-2004 edition and Turf IPM Facts . Call (413) 545-2717 to order these publications from the UMASS Outreach Bookstore

DIAGNOSTIC SERVICES

UMass Laboratory Diagnoses for Turf and Landscape Problems - Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Send specimens and payment (payable to the University of Massachusetts) to UMass Extension Plant Diagnostic Lab, Holdsworth Natural Resources Center, 160 Holdsworth Way, UMass, Amherst, MA 01003. The fee for a woody plant disease analysis is $50; the fee for turf disease analysis or nematode assay is $75. All insect, weed and turfgrass identification samples are $25 each. For more detailed submission instructions see http://www.umass.edu/agland/diagnostics

NEXT UPDATE: The next issue will be available on Friday, April 14, 2006.

This message is produced by the UMASS Extension, Landscape, Nursery and Urban Forestry Program. The copy is prepared by Anna Greene from data and reports provided by the staff and faculty of the UMass Landscape, Nursery and Urban Forestry Program and the UMASS Extension Turf Program as well as cooperating horticulturists and Green Industry professionals. The text is adapted for access via the internet by Jason Lanier and made available to subscribers via electronic transmittal by Ellen Weeks.

DISCLAIMER. This message is intended for commercial use. UMASS Extension assumes no liability for recommendations. The use of trade names does not imply endorsement. Similarly, there may be other products you prefer to use.

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