UMass Extension Landscape Message #8
April 21, 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 28, 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, April 13, 2006 through April 19, 2006. Soil temperature and phenological indicators were observed on April 19, 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: Alternating cool and warm temperatures, with occasional dampness are typical of spring on Cape Cod. Plant development is moving along at a good pace. Daffodils, periwinkle, and grape muscari brighten up the ground, while many spring flowering shrubs are providing color to the landscape. Soils tend to be on the dry side. Pests/Problems:Winter moth caterpillars have begun to hatch. Termites are swarming. Dandelions are beginning to bloom in lawns while many winter annuals, such as chickweed and bittercress, are blooming as well. Adult deer ticks are active.

Southeast Region (Hanson) - General Conditions: Hanson received little rain this past week, and soils are dry. Norway maple, sugar maple, Pieris japonica, Pieris floribunda (Mountain Pieris), Pieris 'Brouwer's Beauty, Pyrus calleryana ‘Bradford’ (Bradford pear), Lindera benzoin, Cherry 'Holly Jolivette', Chaenomeles speciosa (common floweringquince), Leonard Messel Magnolia, Pieris floribunda (mountain pieris),  Forsythia x intermedia (border forsythia),  Helleborus orientalis, Helleborus foetidus, Corydalis solida, Omphalodes, Dutchman's breeches, bloodroot, vinca, daffodils, Pulmonaria, Epimedium, early tulips, and violets, are in full bloom.  Phlox stolonifera, trillium, and anemones are beginning bloom.  Red maple, Cornus mas , and Helleborus niger are ending bloom. Turfgrass has started to green-up. Pests/Problems: Winter moth caterpillars are active and were found inside developing buds of many plants including:  sugar maple, lilac, apple, and crabapple.  Larch casebearer, carpenter bees, mosquitoes, mayflies, ticks, forest tent and eastern tent caterpillars are all active. The small webs of eastern tent caterpillar were observed in the branch crotches of wild cherry, apple, and crabapple. Violets and dandelions are in full bloom. Skunks are digging up lawns.

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

Central Region (Boylston) - General Conditions: Dry - intermittent streams and vernal pools that are normally full this time of year are dry. Early perennials, daffodils, and minor bulbs are glorious.

Pioneer Valley Region (Amherst) - General Conditions: The days have been generally pleasant, and highs on three dates since the last report reached into the 70’s. Breezy conditions have prevailed, however. Plant development continues at a steady rate. Several earlier flowering trees and shrubs are just beginning to push out foliage, and many lawn areas are about ready for a first mowing. Possible rain in the forecast for the coming weekend should help things along. Pests/Problems: Although about an inch and a quarter of rain has fallen this month in Amherst, less than one tenth of an inch has fallen since April 7. Consistent wind and low relative humidity have kept ground surfaces very dry. As a result, fire danger warnings are in effect for much of central and western Massachusetts as of this writing (April 19). In other news, healthy dandelions have been spotted in turf and black flies are active. Moles are active.

Berkshire Region (Great Barrington) - General Conditions: No report.

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, UMass Extension Plant Diagnostic Lab, UMass, Amherst.

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

WOODY ORNAMENTALS

INSECTS

Despite the previous week’s weather having been slightly cooler than normal for this time of year, the early season insects have continued to develop and become active. Bud expansion and opening, for most trees and shrubs, is now occurring statewide. The early-season insects are now very active.

Winter moth - Although staggered throughout the past 7-10 days, it appears that all of the winter moth eggs have now hatched. Reports have been received from Cape Cod (fewest GDD where winter moth is known to occur in New England) that this pest is now active. Spot inspections of expanding buds have revealed many winter moth caterpillars per bud on favored host plants. Fortunately, leaf expansion appears to be quick this year, which will reduce the incidence of severe damage to foliage and flowers while in the bud stage. However, winter moth caterpillars will feed on expanded foliage and are capable of creating total defoliation. Recent DNA analysis of male winter moths that were captured in pheromone traps this last winter indicated that this species was established in a much greater range than just eastern MA. The DNA also indicated that winter moth was hybridizing with our native moth, the Bruce Spanworm. Early tests suggested that winter moth had been found in one part of Long Island, NY, but now it is thought that only a hybridized moth was captured there and not a true winter moth. What this means, exactly, is still being investigated but, to date, it can not be said that a true winter moth (Operophtera brumata) has been found on Long Island.

Gypsy moth is expected to be in high numbers in MA and other northeastern states. The fungus, Entomophaga maimaiga, which 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 beneficial pathogen for control of 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 has now hatched from the buds, and their small silken webs are becoming obvious in the crotches of branches of apples, crabapples, and cherries. So far, many webs per tree have been noted, which indicates another big defoliation year for this pest.

Forest tent caterpillar eggs hatch soon after the appearance of eastern tent caterpillar (ETC), which means that we’ll be seeing this caterpillar very soon. Its host plant range is greater than that of ETC; so along with it being capable of attacking Malus and Prunus species, we mostly see this species on oaks (more in eastern MA) and on sugar maples in western MA and VT. Forest Tent Caterpillar does not make a noticeable silken web, but it is a very serious defoliator.

Fall cankerworm is expected to be in large numbersin 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. However, be aware of tender new foliage that will soon be emerging, and delay spraying oils (at the summer rate) until after this new foliage is fully expanded and “hardened.”

Spruce spider mite from last fall is just now starting to appear. It will “suddenly” become apparent on those affected plants, but no mites will be seen at first. 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 Regulators that has ovicidal activity. However, we are quickly approaching the time of year where the application of dormant oil sprays needs to be carefully considered. As plants break dormancy, they become very susceptible to the potential phytotoxic effects of dormant oils, especially the conifers.

White pine weevil has mostly finished its egg-laying activity for this spring, and it is now too late to treat in most regions of southern New England.

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 - Yellow sticky cards should be placed out now in susceptible birches where leaf expansion has begun. Adult sawflies should appear around the time that the leaves are half-emerged from the buds. Treat when the adults appear.

European pine sawfly eggs are showing up as yellow patches along the length of needles. In the warmest regions of the state, some of these eggs are becoming large and protruding through the needle surface. A few have actually hatched. Inspect now for the eggs and treat once they have all hatched.

Snowball aphid will be active very soon. Its preferred hosts are certain viburnum species, such as Korean spicebush, cranberry viburnum, mapleleaf viburnum as well as others. Once the aphids hatch they begin to feed with their piercing-sucking mouths on newly expanding foliage, which causes severe leaf curling and distortion. The aphids continue to feed through the rest of April until about the end of May within the confines of the curled leaves. Their feeding does not kill the foliage nor does it create yellow-stippling injury that is so typical to other piercing-sucking insects. However, it can create so much leaf distortion that it de-values the aesthetics of affected plant material. Imidacloprid that is already systemic within the plant from last summer works very well. Treating with a contact insecticide offers little management given that these aphids are so well hidden within the curled foliage.

Balsam twig aphid is active. The “stem mothers” have been feeding but are now about to produce many offspring capable of creating much feeding injury in the form of needle distortion and much sticky honeydew. True firs, such as Balsam and Frasier, are most susceptible. High numbers of this pest can render Christmas trees unfit for sale.

The rainfall has given plants a good watering, but with leaves developing, they are vulnerable to leaf spot and shoot blight infections, especially when accompanied by temperatures of 50-70 degrees F. This is the time to apply 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.

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.

Rhabdocline needle cast fruiting structures will soon be visible on infected Douglasfir needles. Symptoms of Rhabdocline infection appear as elongated red-brown spots and bands on infected needles. Spots often coalesce and most of the needle turns color except for the base, which remains green. Infection tends to occur on the bottom of the tree first. Infected needles drop prematurely from now into the summer. Spores released from these fruiting bodies during cool, wet weather infect new needles that will soon start developing. Avoid overhead watering of Douglasfir at this time of the year. Provide adequate spacing and limit weed growth around young trees. Consider fungicide applications to susceptible, high-value trees if this spring is wet. Maintain protection during the vulnerable period when the needles are first emerging from buds until they expand to full size.

Sphaeropsis (Diplodia) shoot blight on pine can cause significant damage to stressed red, pitch, Japanese black and, especially, Austrian pine in our area. If wet weather continues, new shoots developing on these trees are vulnerable to infection. Consider applying fungicides to protect susceptible trees as soon as buds swell significantly. Reapply sprays at labeled intervals until the new growth fully expands, if wet conditions persist. The Sphaeropsis fungus produces significant amount of inoculum on the outer scales of second-year cones, as well as infected shoots and needles. Prune affected shoots when plants are dry to improve appearance, but this will make little difference in reducing inoculum for new infections without cone removal, too. If replacement of severely affected pines is an option, plant trees resistant to Sphaeropsis shoot blight as well as better adapted to grow on the site.

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 & 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

Continue the treatment of winter annuals and perennials in ornamental beds with glyphosate or glufosinate. Non-herbicide material containing clove oil, citric acid, or acetic acid can be used on small winter annuals but not on perennials. With the warm weather most winter annuals are now too large to be mulched over, consider an herbicide application. Perennials will need to be treated before mulching. Preemergence herbicides should be applied to ornamental beds now.

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

TURFGRASS

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

Weeds:

Forsythia is in full bloom, and applications of preemergence herbicides should be in full swing. Many perennial weeds are appearing in turf but should not be treated now as control will be poor. Broadleaf herbicide applications for winter annual weeds can be done now. Prostrate knotweed can be seen in compacted and heavy traffic areas, broadleaf herbicide can be applied. but the underlying compaction problem should be addressed.

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

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 28, 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.

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