UMass Extension Landscape Message #8
April 23, 2010

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SCOUTING INFORMATION BY REGION

REGIONAL NOTES -

Metro West (Waltham) – General Conditions: The past week’s cool temperatures have been more “spring-like” and have slowed things down a bit.  There was only a 3 degree gain in growing degree days, compared to the previous week’s “summer-like” temperatures with a gain of 24.5 GDD.  The cool temperatures and the multiple days of precipitation make for excellent planting and transplanting weather as long as your soil isn’t too wet.  Much that was in bloom last week has continued to stay in flower this week, although new to bloom this week in the woody plant category are: Magnolia ‘Elizabeth’, M. ‘Daybreak’, Lindera angustifolia (Oriental Spice Bush), Rhododendron ‘Black Satin’ and Vaccinium angustifolium (Lowbush Blueberry).  Herbaceous plant material new to bloom includes:  Aurinia saxatilis (Basket of Gold), Caltha palustris (Marsh Marigold), Darmera peltata (Umbrella Plant), Phlox stolonifera (Creeping Phlox), Primula spp. (Primroses),  Pulsatilla vulgaris (Common Pasque Flower), and Veronica umbrosa ‘Georgia Blue’ (Speedwell). Pests/Problems:  Winter moth caterpillar remains active.  Many weeds are in flower including Glechoma hederacea (Ground Ivy), Lamium purpureum (Purple Dead Nettle), Nasturtium officinale (Watercress), Ranunculus ficaria (Fig Buttercup), Senecio vulgaris (Common Groundsel), Stellaria media (Common Chickweed) and Taraxacum sp. (Dandelion).   Alliaria petiolata (Garlic Mustard) is ready to flower.

Central Region (Boylston) – General Conditions: The weather seems to have been pretty typical for April in the past week – sleet and hail one day, sunny and 70 degrees two days later.  Many early perennials, spring bulbs and flowering woody plants overlapping in bloom. Daffodils are at their peak. Pests/Problems:  Mosquitoes, black flies  and ticks are active.

Pioneer Valley Region (Amherst) - General Conditions: Mild daytime temperatures and adequate soil moisture from spring rainstorms continue to spur plant development.  Lawns keep on greening as young leaves emerge on many trees and shrubs. Pests/Problems: If rainy weather continues and mild temperatures warm, that favors leaf spot and blight disease infections.  When shopping for garden vegetables, flowers, herbs, and new woody landscape plants, select disease resistant varieties if possible.

ENVIRONMENTAL DATA -

The following growing-degree-day (GDD) and precipitation data was collected for a one-week period, April 15, 2010 through April 21, 2010.  Soil temperature and phenological indicators were observed on or about April 21, 2010.  Accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments from the beginning of the current calendar year.  This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

PHENOLOGY

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

CAPE

METRO WEST REGION – Julie Coop, Horticulturist, reporting from the UMass Extension Center, Waltham.

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

PIONEER VALLEY REGION - Dan Gillman, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass, Amherst.

WOODY ORNAMENTALS

INSECTS -

Winter Moth - Growing conditions for host plants along with development of winter moth (WM) caterpillars remains about 2 weeks ahead of last year.  Population numbers of WM are significantly increased over last year as well.  The cool weather of the last week has slowed bud expansion but WM caterpillars have continued to feed at a moderately slowed pace. Defoliation damage of untreated trees should start to appear soon.  It is too late now for horticultural oil sprays for this pest.  Spinosad products, Bacillus thuringiensis (Kurstaki), and certain pyrethroids are labeled as sprays for winter moth caterpillars

Eastern Tent Caterpillar - This insect is active and small silken webs are starting to appear in the crotches of branches in apples and cherry.  Population numbers for this pest statewide appear to be quite low this year.  Individual webs can be collected with the larvae on cool evenings and destroyed. Spinosad products, Bacillus thuringiensis (Kurstaki), and certain pyrethroids are labeled.

Fall Cankerworm caterpillars will become active soon.  Numbers are very low statewide but a few pockets exist that may require attention.  Small egg clusters can be found wrapped around twigs or deposited directly onto trunks and larger branches.  Treat the same as winter moth once they hatch and settle to feed.  This pest shares many of the same hosts as winter moth, including oak. Spinosad products, Bacillus thuringiensis (Kurstaki), and certain pyrethroids are labeled.

Gypsy Moth caterpillar has hatched but numbers statewide are very low.  Treat the free-feeding caterpillars now that they have settled. Spinosad products, Bacillus thuringiensis (Kurstaki), and certain pyrethroids are labeled.

Forest Tent Caterpillar will be active soon but numbers of this pest now are greatly reduced from past years.  Oaks and maples are primary hosts but it does have a rather wide deciduous host tree range. Spinosad products, Bacillus thuringiensis (Kurstaki), and certain pyrethroids are labeled.

Euonymus Caterpillar should be active in most parts of the state now.  This small yellow caterpillar with black spots can be found feeding throughout infested euonymus plants.  This caterpillar produces much silk and may entirely cover shrubs with it by late June.  When occurring in large numbers, this pest can completely defoliate its host. Spinosad products, Bacillus thuringiensis (Kurstaki), and certain pyrethroids are labeled.

European Pine Sawfly is active on a variety of pines, especially mugo.  In cooler regions, inspect for the yellow blocky patches along needles, which are the embedded eggs.  If occurring in small numbers, remove and destroy needles that contain eggs.  In warmer regions where the caterpillars are now active, inspect for clusters of tiny caterpillars at needle tips on the terminal ends of branches. Treat the young larvae with an insecticidal soap spray or a product that contains Spinosad.

Azalea Sawfly Caterpillar will be active soon, if not already.  Inspect the leaf margins of deciduous azaleas, especially Exbury types, for beginning defoliation.  The larvae are almost the same color as the leaf and tend to ‘hug’ the leaf margin, thus rendering them very difficult to observe even for the trained eye. This pest consumes all but the mid-vein of foliage and is capable of complete defoliation of the host plant. Treat with a product that contains Spinosad.

Viburnum leaf beetle - No reports have yet been received for the activity of the larvae but it will most likely occur any day now, usually right after leaves begin to appear on host plants.  Treat the young larvae with a product that contains Spinosad.

Lily Leaf Beetle - These bright red adult beetles should be very active now and seeking newly emerging (Asiatic) lily foliage.  Neem products may work to repel adult beetles and possibly to sterilize the adult female.  Neem products need to be applied every 10-14 days while the pest is active.  Spinosad products work well to kill the larvae once they appear in another 3-4 weeks.

Hemlock Woolly Adelgid (HWA) remains very active. There are over-lapping generations active right now, including eggs.  Horticultural oil sprays work very well on all life stages of this pest. Systemic imidacloprid is effective as well, but soil applications may take 2-3 months before they are fully systemic within a large tree.  Heavy populations of HWA may need to be reduced first with a chemical insecticide or oil spray before the systemic can begin to perform.

Snowball Aphid is active on certain viburnum.  Curled, distorted foliage is already apparent.  The dark-colored stem mothers can be found in the leaf curls feeding.  Offspring will appear soon, if not already, in the warmer regions.  It is too late now to prevent damage (curled foliage). 

Balsam Twig Aphid has been active for a couple of weeks and beginning to produce offspring.  Inspect firs for honeydew and new foliage that is distorted (curled).  Treat if necessary.  

Eastern Spruce Gall Adelgid is active and stimulating gall formation as the buds of the host plant begin to swell and open.  In areas where buds have not yet opened, treat with a horticultural oil spray to kill the exposed nymphs. Common host plants in Massachusetts are Norway and white spruces.

Boxwood Psyllid is active and feeding.  Look closely within expanding buds or last year’s cupped foliage for the white (wax-covered) nymphs.  This insect only causes cupping of the foliage and does not create yellow stippling.  However, in certain cases, this damage may be unacceptable.  Systemic imidacloprid can be effective but given the time delay for it to become systemic within the plant, it is most likely too late in much of the state to apply it for this year.  Certain pyrethroid sprays can be effective.

Honeylocust Plantbug is active.  Monitor for this pest at bud-break and soon thereafter by gently jarring branches over a sheet of paper, then inspecting for the tiny, light-green nymphs.  If many are found, treatments may be necessary.  Numerous nymphs coupled with slow bud opening can result in much distorted foliage and occasionally loss of foliage.  Treat with insecticidal soap sprays or with one of the registered pyrethoids. 

Inkberry Leafminer adult flies appear between 100 and 150 GDD.  Yellow sticky cards can be used to time the emergence and then apply a cover spray if necessary.  Damage appears now as large brown spots on the foliage, especially near the margins of the leaf.  When opened, they are hollow and contain a pupa.

Hemlock Eriophyid Mite is active but no reports have been received thus far this spring.  This pale-yellow, tiny mite with a tapered body is just visible to the naked eye and can be found feeding on the needle surfaces.  Affected foliage becomes dull and chlorotic.  Treat with an oil spray (summer rate now but be careful of tender new emerging foliage).

Spruce Spider Mite is active on spruce and hemlock primarily.  Inspect carefully with magnification for these two-tone colored mites.  They tend to be more prevalent on the 2-3 year old foliage.  If large numbers begin to become evident or if the plant experienced damage last year, then treatments may be necessary. 

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

DISEASES -

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 50o-70o 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 mountain ash, 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.

Note: There were no updates for 2010 reported by USDA-APHIS-PPQ at this time.

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.

LANDSCAPE TURF

INSECTS

Invasive crane flies were confirmed from Edgartown (Martha's Vineyard) and Falmouth last September. Both populations were identified as "marsh crane flies" (sometimes called "common crane flies"). This species usually has two generations per year and we are approaching the time when adults may be emerging from the overwintering generation.

So for those of you in the southeastern part of Massachusetts (or coastal Rhode Island or Connecticut, for that matter), you should be watching for flights of insects that look like giant mosquitoes. The adults have very long slender legs, and the "leg span" (length of the insect from tip of mouthparts to tip of hind leg) can be nearly 1.5 inches. Just before the adults emerge, the pupae wriggle toward the surface of the turf and stick straight up into the air. So if you see some strange looking torpedo-shaped creatures sticking up out of the turf, get some pictures and send them to us! And then start watching for adults.

If you do catch some likely suspects, please let Dr. Vittum know and she will give you instructions on sending them to Dr. Dan Peck, who is the entomologist on the East Coast with the most experience with these insects. He confirmed the first two populations, and has offered to continue to identify crane flies from the area.

If you do confirm the presence of crane fly adults, there are some insecticide options that can minimize damage from the larvae of the next generation. (The larvae of the next generation will be active through the summer months and adults of the second generation should emerge in late August or early September.)

Reported by Pat Vittum, Extension Entomologist, UMass Department of Plant, Soil and Insect Sciences, Amherst

IMPORTANT INFORMATIONAL RESOURCES

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

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

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.

DIAGNOSTIC SERVICES

A UMass Laboratory Diagnoses 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. 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 detailed submission instructions see http://www.umass.edu/agland/diagnostics

Soil and Plant Tissue Testing - The University of Massachusetts Soil and Plant Tissue Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The function of the Soil and Plant Tissue Testing Laboratory is to provide test results and recommendations that lead to the wise and economical use of soils and soil amendments. For complete information, visit the UMass Soil and Plant tissue Testing Laboratory web site at: http://www.umass.edu/soiltest Alternatively, call the lab at (413) 545-2311.

NEXT UPDATE: The next issue will be available on or about April 30, 2010.

This message is produced by the UMass Extension, Landscape, Nursery and Urban Forestry Program. The copy is prepared by 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 compiled and adapted for access via the internet by Jason Lanier.

DISCLAIMER. This message is intended for commercial use. UMass Extension assumes no liability for recommendations. It is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The use of trade names (™) does not imply endorsement. Similarly, there may be other products you prefer to use.

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