UMass Extension Landscape Message #9
April 28, 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, May 5, 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 one-week period, April 20, 2006 through April 26, 2006. Soil temperature and phenological indicators were observed on April 26, 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: Cool, wet weather over the weekend gave way to warm, spring conditions at the beginning of the week. Soils are damp, but we still haven’t had any soaking rainfall, and newly planted material should be watered regularly. Dandelion, chickweed and bittercress are all in bloom in the lawn and garden. Pests/Problems: Crabapple leaves are emerging with small holes due to winter moth caterpillar feeding. Tent caterpillar has hatched. Lily leaf beetle adults are now active. White grubs are up in the turf root zone. Dog tick adults are active, along with adult deer ticks. Termites are still swarming.

Southeast Region (Hanson) - General Conditions: Hanson received approximately 1 inch of much needed rain this past week. Magnolia 'Elizabeth', Norway maple, sugar maple, Pieris japonica, P. floribunda  (Mountain Pieris), P. 'Brouwer's Beauty, Mayflower viburnum, Pyrus calleryana ‘Bradford’ (Bradford pear), Lindera benzoin, Cherry 'Holly Jolivette', Chaenomeles speciosa  (Common Flowering Quince), Forsythia x intermedia  (border forsythia), Helleborus orientalis, H. foetidus, Corydalis solida, Omphalodes, Dutchman's breeches, bloodroot, vinca, daffodils, Pulmonaria, Epimedium, Pachysandra procumbans, tulips, Trillium, anemones, Phlox subulata, and violets are in full bloom. Phlox stolonifera, bleeding heart and Phlox divaricata, are beginning bloom. The bracts on pink flowering dogwood are expanding and starting to show color. Leonard Messel Magnolia and Star Magnolia are ending bloom. Pests/Problems: Gypsy moth, eastern tent, forest tent and winter moth caterpillars, larch casebearer, carpenter bees, mosquitoes, mayflies, ticks, are all active. Severe damage, browning and dieback, to two areas of established microbiota has been reported. Chickweed, violets and dandelions are in full bloom. Japanese knotweed has emerged. Skunks are digging up lawns.

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

Central Region (Boylston) - General Conditions: No report.

Pioneer Valley Region (Amherst) - General Conditions: Rainfall in Amherst was sparse until the past weekend when over an inch fell. Tulip, daffodil, pansy, and grape hyacinth are a few of the plants blooming in gardens, while a number of woody and herbaceous perennials are leafing out and/or flowering, too. Pests/Problems: With extended periods of wet weather, fungal and bacterial diseases may well infect tender flowers and foliage of susceptible plants. Dandelions are evident in many lawns. Ticks are active.

Berkshire Region (Great Barrington) - General Conditions: Rain over the weekend and some mild temperatures have spurred a flush of growth and flowering in landscapes. Soil moisture is very good at this time. Pests/Problems: Deer ticks, carpenter bees, various wasps, and mosquitoes are active. Tents of eastern tent caterpillars are quite visible, but damage to expanding tree foliage is minimal as of April 26. Deer and rabbits are browsing on daylilies and other emerging herbaceous plants.

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

Most of the early-season caterpillar species are now active, in fact, some like forest tent caterpillar, hatched before their host plants had begun to produce foliage from the buds. This phenomenon is not all that unexpected, however. Such early-season feeders tend to be more successful when they appear early, which allows them to start feeding before the host plants develop their full compliment of defensive compounds that helps them to deter herbivores. Caterpillars that appear a couple of weeks after bud break may not fare as well.

• Winter moth - This pest has been active for more than a week, and despite their small size, are feeding actively on emerged foliage. They will continue to cause injury until approximately the third week in May. Monitor for their presence, and treat if found. 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 numbersin MA, and other northeastern states. Shadbush (Amelanchier, spp.) is now in bloom in warmer regions of the state. This is a phenological indicator for gypsy moth egg hatch (GDD 90-100). Once hatched, the tiny caterpillars will climb high into trees, spin down on long silken threads and will be wind-blown to new hosts where they will settle and feed until about the third week in June. Oaks are the preferred hosts, but they can feed on dozens of different species. 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 - silken webs are now 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. Defoliation is becoming noticeable.
  
• Forest tent caterpillar eggs have all hatched. Its host plant range is greater than that of ETC. Along with it being capable of attacking Malus and Prunus species, we also 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. Numbers of this pest are very high in southern New England right now.
  
• 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. In warmer regions of the state (e.g. Amherst area) the crawlers are becoming active. This is a very dangerous time for the movement of this pest by birds and humans. Carefully inspect hemlocks before moving them to other areas. Do not place bird feeders in or near hemlocks. Make note of those infested plants that will require treatment with oil sprays (at the summer rate) once the new foliage has expanded fully and hardened off. Systemic applications of imidacloprid are also effective, but translocation time can vary from weeks to months.

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. If eggs are present, they can be treated with one of the mite growth regulators that has ovicidal activity

White pine weevil has 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 now be placed out 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. In the Amherst area, eggs are hatching. Inspect now for the eggs, and treat once the caterpillars are all active. Mugo pine is one of the common hosts for this pest.

Snowball aphid is active. Its preferred hosts are certain viburnum species, such as Korean spicebush, cranberry viburnum, maple-leaf viburnum as well as others. When 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 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. In the Amherst area, new leaves have already been affected.

Balsam twig aphid is active. The “Stem Mothers” have been feeding but are now about to produce many offspring which are 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.

Larch casebearer caterpillars have resumed activity and are now causing brown tips to occur on susceptible hosts. In large numbers, they can be complete defoliators. Monitor for this caterpillar, which is in a cigar-shaped case made from a needle tip, and treat if necessary.

Larch adelgid is active and can be seen as white cottony masses scattered throughout the needles of its host. When in large and very noticeable numbers, it should probably be managed.

Pine bark adelgid is active again, and large populations can appear like wind-driven snow on trunks and undersides of scaffold branches of white pine. Although very showy, it rarely requires treatment.

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. USDA APHIS currently regulates 84 plants, two of which are 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 2006 National Nursery Survey is likely just getting underway. In past years the survey visited nurseries and collected samples from host plants exhibiting leaf spot, blight, and canker symptoms associated with Phytophthora ramorum infections.

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

WEEDS

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

TURFGRASS

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

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 freshly revised Professional Guide for IPM in Turf for Massachusetts, 2006-2007 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, May 5, 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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