UMass Extension Landscape Message #8 - 2005

Scouting Information by Region

Environmental Data

The following growing degree day (GDD) and precipitation data was collected for the one-week period from April 13 through April 20, 2005. Soil temperature and phenological indicators were observed on April 20, 2005. Accumulated GDDs represent the heating units above the 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: This reporting period has seen some glorious spring weather with warm, sunny days and cool nights. However, we have not had any precipitation and the upper surface of sandy soils is already quite dry. Buttercup Winterhazel (Corylopsis paucifolia), hyacinths and early tulips provide color in the garden. Lawns are greening up nicely and the mowing season has begun. Pests/Problems: The first, eyelash-sized winter moth caterpillar was observed in Marstons Mills on the 16 th of April. We expect most of Cape Cod to be inundated with this pest this year. Eastern tent caterpillars have hatched. Adult lily leaf beetles are active. Adult deer and dog ticks are active.

Southeast Region (Hanson) - General Conditions: Most of the accumulation of GDD for this week occurred on Wednesday when the temperatures were in the 80's. Hanson received very little rain this week and soils are drying out. Abeliophyllum distichum (White Forsythia), Pieris japonica, Pieris 'Brouwer's Beauty, Leonard Messel Magnolia, Cornus mas (Corneliancherry Dogwood), Helleborus orientalis, Helleborus foetidus, Corydalis solida, Omphalodes, Dutchman's breeches, bloodroot, Vinca, daffodils, Pulmonaria, early tulips, Primula sp. and Scilla sp. are in full bloom.. Epimedium sp. and Pieris floribunda (Mountain Pieris) are starting to bloom. Red maple, pussy willows, Helleborus niger are past bloom. Pests/Problems: Winter moth caterpillars have hatched and have been found inside developing Norway maple buds. Larch casebearer, carpenter bees, ticks and eastern tent caterpillars are all active. Violets and dandelions are in full bloom .

East Region (Boston) - General Conditions: Threats of dry mulch igniting with cigarette butts. Brush fires are making the news in several of the areas outlying Boston.

Central Region (Boylston) - General Conditions: Exposed soils are very dry. The warm weather has pushed many plants into full bloom - narcissus and minor bulbs, tulips and early perennials are making a fine show. Prunus subhirtella var. pendula (Weeping Higan Cherry), Abeliophyllum distichum (White Forsythia) and Vinca minor (Common Periwinkle) are in full bloom.

Pioneer Valley Region (Amherst) - General Conditions: After a very wet period, things have certainly dried out and temperatures are soaring into the 80's as of this writing (Wednesday, April 20). Nights have been cool, however. The last measurable precipitation in Amherst fell on April 8. Weather reports for later in the week indicate that relief is on the way in the form of cooler temperatures and rainfall. Despite the variable weather, shrubs and trees in the landscape are more or less on schedule in terms of development. Turf areas are growing and green and will soon be ready for a first mowing. Pests/Problems. 'Fire Danger' warnings have been issued for most of the state due to the recent lack of precipitation and very low relative humidity. Scattered winter/salt damage is still evident on many woody plants. Healthy, blooming dandelions have been noted in many lawn areas.

Berkshire Region (Great Barrington) - General Conditions: Very warm, very dry conditions have occurred over the past week. Soils are dry and deficient in moisture, especially on well-drained sites. Plant development is occurring rapidly. Daffodils are at their peak and tulips are just beginning to bloom (mostly species tulips at this time). Lindera benzoin (Spicebush) is in full bloom. Pests/Problems: Eastern tent caterpillars have hatched. Mosquitoes and ticks are common.

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

Lepidopteran caterpillars:

• Gypsy Moth - Monitor now for the tawny colored egg masses that can be found on tree trunks, rock walls and elsewhere. Use the numbers as an indicator of population size. This pest increased in numbers statewide last year and is expected to be problematic in some areas this year, especially Southeastern MA. Eggs will hatch at 90-100 GDD, which is typically the first week in May in much of MA. There are no control measures for the egg stage. The blooming of Amelanchier sp. (Juneberry, Serviceberry, Shadbush, etc) is a good phenological indicator that gypsy moth eggs are hatching. The larvae will climb to tree tops and spin down on long silken threads to be carried off by the wind (ballooning). Wait until the caterpillars are finally settled and feeding to apply Bacillus thuringiensis ssp. kurstaki (B.t.k.) or a product containing spinosad.
• Winter Moth - Most coastal towns as well as some inland towns in MA will experience large numbers of this introduced pest this spring. Much damage is expected. Eggs have been hatching for over a week now on the trunks and major branches of oaks, maples, fruit trees, blueberry plants and many other deciduous hosts. New tiny larvae will crawl into buds and feed but being a warm spring, many buds are now opening rapidly. It is now too late in the season for dormant oil sprays. Once they become free-feeders, after bud break, they can be managed with Bacillus thuringiensis kurstaki or a spinosad product (e.g., Conserve SC™) or a tebufenozide product (e.g., Confirm ™).
• Forest Tent Caterpillar - Also on the rise as a serious defoliator, this caterpillar mostly prefers oaks in MA but can be a pest on maples, crabapples and other deciduous hosts. They will appear after the buds open and will be free-feeders. Treat the same way as winter moth.
• Eastern Tent Caterpillar - Common to Malus and Prunus species, this native defoliator was present in high numbers last year across much of the Northeast. Eggs hatched over a week ago and the small silken webs are now appearing in the crotches of small branches. Once they become free-feeders, treat with B.t.k. or a spinosad product or a tebufenozide product. Single webs can physically removed by hand on cooler nights when all of the larvae are within it.
• Fall Cankerworm - This native pest is still in high numbers, especially in towns north of Boston. It can be found primarily on oaks but it has a rather wide deciduous host range. Eggs hatch around 50 GDD (soon after bud break) so this pest is now active in some areas of MA. Treat with a B.t.k. product or spinosad or tebufenozide.
• Fruitworms - This complex of caterpillars will become active between 50 and 100 GDD. They initially look like winter moth but most have 5 pairs of prolegs and not two. They are free-feeders and have been increasing in numbers over the past 2-3 years. Oaks, maples and many other deciduous hosts are attacked. Treat the same way as the other Lepidoptera.
• Larch Casebearer caterpillars have been active for about a week. Right now they appear like little cigar-shaped pieces of needles on the trunks and branches. They are migrating to the buds where they will sit and wait for buds to open. They will then feed on the new foliage. Once feeding begins, treat with Bacillus thuringiensis ssp. kurstaki (B.t.k.) or a spinosad product or a tebufenozide product.
• European Pine Sawfly - Inspect the foliage of such host plants as mugo pine for small, yellow and block-shaped patches. These will be the eggs that have been laid within the needles. When found in small numbers, remove by hand. When found in large numbers, wait until they hatch and begin to feed on the needles; then treat with an insecticidal soap or spray with a product containing spinosad.

Beetles:

• Viburnum Leaf Beetle - Inspect all viburnum plants (those that are established in the landscape and nursery, as well as those that are newly arriving) for the presence of this unwanted pest. The indicator of its presence at this time of the year will be bare twigs that have a 'sandpaper' texture, which is a sign of the over-wintering eggs. Report any new findings in MA to Robert Childs, rchilds@psis.umass.edu, 413-545-1053.
• Lily Leaf Beetle - The bright red adults have been seen for the past week in warmer parts of the state. They are foraging for food and eventually a mate. This is a pest of all true lilies (not daylilies), fritillaria, Solomons-seal and others. It is a devastating pest to true lilies. Eggs won't appear until mid/late May, which are laid in irregular lines on leaf undersides. Neem-based products, when applied every 10-14 days, can be effective against the larvae when they begin to appear. Other than that, certain pyrethroid insecticides may be necessary.

Piercing-Sucking Pests:

• Spider Mites - Inspect the needles and stems of conifers now for the over-wintering eggs of such pests as spruce spider mite. It is too late for a dormant oil spray. One of the growth regulator products that affects developing mite eggs may be useful.
• Hemlock Eriophyid Mite - This tiny "peg-shaped" mite is just visible to the naked eye. When found in large numbers, they cause the foliage of hemlocks to turn an unhealthy olive green color. Treat when found in sufficient numbers. Inspect the upper needle surfaces, in particular, for this pest. It will remain active until approximately early June.
• Hemlock Woolly Adelgid (HWA) - This pest experienced a phenomenal reduction in population numbers during the winter of 2003/2004. However, by being milder, this past winter did not have the regulating effect on HWA as did the previous one. New eggs are now noticeable. Monitor for increasing numbers and treat with a horticultural oil spray (when plant phenology allows) and/or whenever the correct weather conditions prevail. Systemic imidacloprid products can also be of benefit.
• Mealybugs - Begin to inspect the inner branches for taxus mealybug. Treat when found.
• Balsam Twig Aphid - Stem mothers are active. Inspect host plants (mostly balsam and Fraser firs) and treat before they produce copious amounts of offspring. This pest causes new needles to be twisted and they will also be stuck together with large amounts of sticky honeydew.

Scale Insects:

• Armored Scales - A group of scale insects characterized by a hard, convex covering over their bodies, such as pine needle scale, euonymus scale, juniper scale and white prunicola scale can be monitored now. Treat with a horticultural oil spray when plant phenology and correct weather conditions prevail.
• Soft Scales - Tuliptree scale and azalea bark scale can be monitored now. Look for sooty mold on the host plants. In the case of tuliptree scale (found on tuliptree and magnolia), one can also find the large, dark brown coverings on the stems. Azalea bark scale will appear white and cottony and will mostly be found in branch axils along the main trunk. Treat with a horticultural oil spray or systemic imidacloprid. These can be difficult to manage and may require future monitoring and treatments.

Gall Formers:

• Eastern Spruce Gall Adelgid - Nymphs are active at the base of buds and will soon stimulate the new shoots to become galls. Treat before gall formation occurs.

Leaf Miners:

• Start thinking now about Birch Leaf Miner (BLM). Purchase yellow sticky cards to monitor for the adult emergence and treat at that time with a "knockdown" type spray, such as a pyrethroid, to prevent egg-laying within the foliage. Adult BLM appear when the newly emerging foliage of the host plant is about the size of a dime.
• Inkberry Leafminer - Inspect foliage of inkberry now for brown patches. These are most likely the mines of this pest. Mines do not show up until some time in the winter, so any late-season monitoring last fall would not have detected their presence. Use yellow sticky cards to monitor for the emergence of the adults in mid-late May and treat at that time if necessary.

Reported by Robert Childs, Entomologist, UMass Extension Landscape, Nursery and Urban Forestry Program, Amherst

Diseases

Sudden Oak Death (SOD), also known as Ramorum blight - Since 1995 oaks and tanoaks have been 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 (SOD), ramorum leaf blight or ramorum dieback, or by regulation as Phytophthora ramorum. P. ramorum was first seen in 1995 in Mill Valley (Marin County) on tanoak. Since that time the disease has been confirmed on various native hosts in fourteen coastal California counties (Marin, Santa Cruz, Sonoma, Napa, San Mateo, Monterey, Santa Clara, Mendocino, Solano, Alameda, Contra Costa, Humboldt, Lake, and San Francisco) and in Curry County, Oregon. Molecular tests detected evidence of P. ramorum on a single tree in Nassau County, NY but the organism could not be isolated.

Current Status of Sudden Oak Death. Regulations were published February 14, 2002, to control the movement of sudden oak death from twelve infested counties in California and an area under eradication in Oregon. A national survey is underway. Research being conducted by the Agriculture Research Service, US Forest Service, Universities and others is under way to better identify hosts, methods of detection and effective treatments. Currently, 64 plants are regulated, two of which at the genus level (Camellia and Rhododendron). There are no chemical treatments currently available to eliminate the disease in nursery stock. In April 2004 a Federal order (as amended) was issued to address a concern of P. ramorum moving via nursery stock from California.

Reported by Dan Gillman, Plant Pathologist, based in the Urban Forestry Diagnostic Lab at UMass, Amherst, Mass

Landscape Turf

Insects

White grubs - Most grubs should be back in the root zones feeding at this point. Now would be a good time to monitor your areas to see which species are active. Keep in mind that European chafers and oriental beetles have been expanding steadily, so many turf managers are now dealing with two, three, or even four pest species in a given location. Get out, take a look and figure out which species you have. It will have a direct bearing on your options later in the season.

Pat Vittum, Professor, Turf Entomology, Department of Plant, Soil & Insect Sciences, UMass, Amherst.

Weeds

Forsythia is currently in full bloom in most parts of the state. Preemergence crabgrass and annual weed control products for turf should be applied before forsythia flowers drop. Products should be watered in. Apply products before a light to moderate rainfall is expected. If rainfall does not occur within a few days, use an irrigation event of at least 1/4 inch to water in product. Preemergence products that do not receive rainfall or irrigation may not work effectively. Remove winter debris from turf to insure application uniformity. Siduron™ should be used if a spring renovation or overseeding is being considered.

Apply preemergence herbicides to ornamental beds. Rework the mulch prior to application.

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