UMass Extension Landscape Message #20
July 30, 2004

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ENVIRONMENTAL DATA

The following growing degree day (GDD) and precipitation data was collected from July 15 through July 28, 2004 . Soil temperature and phenological indicators were observed on July 28, 2004. Accumulated GDDs represent the heating units above the 50° F. baseline temperature collected via our mini-computers since the beginning of the current growing season. Please note that this data is particularly useful for pinpointing pest development at any time during the season.

Southeast - General conditions: Pleasant summer weather for the past two weeks, some humidity. Sunny days and cool nights but with very little rain. Soils are very dry. Hydrangea paniculata (early cultivars), Hydrangea quercifolia (Oakleaf hydrangea), Hydrangea macrophylla 'Blue Billows', hollyhocks, Joe-pye-weed, Rudbeckia 'Goldsturm', Echinops ritro, Echinacea purpurea, Corydalis lutea, Nepeta, Heliopsis 'Summer Sun', Monarda didyma, Dicentra 'King of Hearts, Campanula sp., Lysimachia clethroides, Phlox paniculata and daylilies are in full bloom. Pests/Problems: Chipmunks are everywhere and we've received many calls regarding them. Oriental, Asiatic, and Japanese beetles remain active. Earwigs, tarnished plant bug, four-lined plant bug, spider mites, slugs, snails, ticks, and mosquitoes, are all active. Old-fashioned potato beetle adults and larvae are feeding on Datura, Brugmansia, and Nicotiana. Lots of leaf blight on plants, especially powdery mildew on garden phlox. Anthracnose is evident on sycamore, dogwood, maple and others.

East - General Conditions: No report.

Central - General Conditions: No report.

West - General Conditions: The conditions in the Pioneer Valley have been mostly cool with a mix of several days of warm, humid weather. Lawns continue to be green and newly seeded areas have filled in well. Gardens, trees and shrubs are also thriving. Pests/Problems: Powdery mildew is visible on herbaceous and woody ornamentals such as phlox, zinnia, flowering dogwood, sycamore and lilac. Botrytis blight is also evident in sheltered areas, especially where susceptible plantings are growing in dense groups.

Berkshire - General Conditions: Soil moisture is good. Landscapes and gardens are in very good shape for mid-summer. Pests/Problems: High mosquito populations are a nuisance to all who work outdoors. Slugs are devastating the foliage on susceptible plants. Bristly roseslug has just completed a generation after skeletonizing roses.

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.

WESTERN REGION - Dan Gillman, Plant Pathologist, Urban Forestry Diagnostic Lab, UMass, Amherst.

BERKSHIRE REGION - Ronald Kujawski, Nursery Specialist, UMass Extension Agriculture & Landscape Program, Amherst.

WOODY ORNAMENTALS

INSECTS

Caterpillars

In general, products containing Bacillus thuringiensis (B.t. kurstaki) are very effective against the younger free-feeding caterpillars in the Lepidoptera only. Products that contain spinosad are generally very effective against caterpillars in the Lepidoptera and the Hymenoptera (wasp-like as adults). There are also many chemical insecticides that are labeled for caterpillars, which are pyrethroids, organo-phosphates, carbamates, and other classes.

Lepidoptera (moths):

• Gypsy Moth adults are still active but nearing the end of their mating cycle. The brown male moths with black spots on their wings and feathery antennae are still flying. Females are white with black spots and very small and threadlike antennae; they do not fly. New eggs masses are tawny-colored and about 1" to 1 1/2" in length with each containing upwards to 800 eggs.
  
• Mimosa Webworm caterpillars remain very active. The larvae tie foliage together in clumps and then skeletonizing the leaflets from within these 'pads' of leaves. Look for clumps of browned leaves. Treat with a spinosad product or one of the registered chemical insecticides. In some cases, this pest can affect every leaf on honeylocust and by late summer, the trees become very unattractive.
  
• Juniper Webworm caterpillars are active again. They will tie foliage with silk and cause browning of the foliage. They will be active until the fall and then again next spring until they pupate. It is the second generation that is active now. Treat with a Bacillus thuringiensis, subsp. kurstaki product or a product that contains spinosad. Chemical insecticides are also labeled for this pest. Upright junipers are often times more susceptible to this pest but they will be found attacking other junipers as well.
  
• Fall Webworm tents are beginning to appear, mostly out near the tips of branches. This pest has dozens of deciduous host species. The larvae feed from within the silken webs and expand the size of the tents, down the branch towards the trunk, as they feed. Injured foliage remains intact but is skeletonized and brown. This pest is mostly aesthetic and unsightly webs may remain through the winter. Individual webs can be pruned away now and destroyed. Never burn webs while still on the tree! Treat with one of the many registered chemical insecticides or a spinosad product.
  
• Silverspotted Skipper caterpillar is active now on black locust, rose acacia, and wisteria. Inspect for foliage that is tied together with silk and that has been feed upon. Caterpillars are quite spectacular in appearance by having a large dark head with two large yellow eye spots. The first thoracic segment is small and red. The rest of the body is a pale greenish-yellow with faint stripes going around the body. Controls are not necessary unless they appear in large numbers.

Hymenoptera (sawflies):

• Introduced Pine Sawfly remains active and may be found on the same host plants as the European pine sawfly. Last year, this pest was quite prevalent in the eastern part of MA and caused much defoliation. Treat the young caterpillars with insecticidal soap or one of the products that contains spinosad. Chemical insecticides are also labeled for this pest.
  
• Birch Sawfly species remain active. They will appear in clusters on foliage of many species of birch. Treat with a spinosad product when found. Small individual clusters can be pruned away and destroyed by hand.

Beetles

In general, products containing spinosad are effective against the larvae (at least) of many free-feeding beetle, especially the Chrysomelids (leaf beetles) species. However, there are also many chemical insecticides that are labeled for beetles, which are pyrethroids, organo-phosphates, carbamates, and other classes.

Leaf Beetles:

• Lily Leaf Beetle - Adults of this bright red beetle are out again. However, some larvae are quite large and still feeding. As larvae feed, they pile their own excrement on their backs thus giving them a very unattractive appearance. Monitor for their appearance on true lilies, fritillaria, and Solomon seal. Recent feedback from pest control practitioners suggests that NEEM products may not achieve the desired results for management of this pest. Spinosad products and many different chemical insecticides are labeled for this pest.
  
• Viburnum Leaf Beetle - has finally been found in MA in the town of Great Barrington (Berkshire County) not far from the NY border. Adult beetles have emerged, mated and the females have laid eggs. No more activity will occur this year with this pest. On viburnums that have chewed foliage, inspect for terminal twigs that are bare of foliage and that have a sandpaper feel. This is a good indicator of eggs, which will hatch next year. Visit the following Cornell web site to become more familiar with this pest: http://www.hort.cornell.edu/vlb
  
• Imported Willow Leaf Beetle remains active. The small, round blue-black adults will chew ragged notches in the margins of foliage but it is the larvae that create the bulk of the injury. These small, black, elongate larvae are now active. They line up on the leaf surface and skeletonize. There are multiple generations per year and they will remain active until September. By August, entire trees can appear to have been swept by fire; all of the leaves will be intact but dead and brown from total skeletonizing. Treat with a spinosad product or with one of the many registered chemical insecticides.

Scarab Beetles:

• Asiatic Garden Beetle adults are now quite prevalent. These rust-colored beetles will be active for a month, or so. The grubs of this pest cause minimal injury to turf (usually found in poorly maintained lawns) but the adults can appear in great numbers and feed at night between first dark (approx 9:00 PM) until about midnight. Adults feed on many hosts including garden plants, annuals, perennials and others. Their feeding can range from notched foliage to heavy defoliation. Inspect at the feeding time with a flashlight; treat if necessary.
  
• Japanese Beetle adults are very active and prevalent now. The number of new adults emerging per day is still increasing. They are strong fliers and individual beetles may live for 2-3 weeks. Very soon, there will be large numbers of this pest actively feeding. They have a very wide host range. Refer to the Turf Section below for more details.

Weevils (Snout Beetles):

• Polydrusus Weevil - These small and often bright green weevils are active on a variety of deciduous host plants. They will remain active well into July. They mostly create injury by notching the margins of the foliage, often to an extreme. Treat with a chemical insecticide when found in abundance. Spinosad products might be effective.
  
• Black Vine Weevil adults are beginning to appear. Adult weevils feed at night and notch the margins of foliage, mostly low on the plant. Placing loosely crumpled burlap around the base of plants can also be used as a monitoring tool. Weevils will utilize the burlap as if it were leaf litter and will hide there during daylight hours. Inspect and destroy adult beetles. Treat with a chemical insecticide when found in large numbers.

Piercing-Sucking

In general, imidacloprid applied systemically is very effective on most, with the exception of spider mites. Horticultural oil or insecticidal soap, especially against the immature stages, is usually very effective.

Lacebugs:

• Andromeda Lacebug is very active throughout MA. Inspect the undersides of foliage for their presence. Systemic imidacloprid products work well. If contact (mechanical mode of action) pesticides, such as summer oil sprays or insecticidal soap are utilized, they need to be targeted to the foliage undersides. Japanese andromeda in sunnier growing sites will experience greater problems with this pest.
  
• Azalea Lacebug remains active. Like Andromeda Lacebug, this pest is active all summer and capable of creating much stippling (chlorosis) of the foliage. Drought conditions and sunnier growing sites tend to favor this pest.
  
• Sycamore Lacebug remains active. Although common to Sycamore, it can be especially destructive to English White Oak. Active all summer, it can lead to serious chlorosis of the host plant.

Plantbugs:

• Tarnished Plantbug is very active. This small, brown insect with pale yellow markings has a wide host plant range that includes shrubs and annuals. Its feeding can cause brown spots to appear on foliage and may even kill flower buds. It has been reported to be a problem on daylily flower buds (destroying them prior to opening). Many different chemical insecticides are labeled for the management of this sometimes destructive pest.
  
• Four-lined Plantbug remains active. Its feeding causes brown dead patches to appear on foliage that resemble disease caused by pathogens. If much spotting occurs, controls may be necessary. This insect is active for much of the summer. At first appearance, it almost looks beetle-like with its dark body and yellow stripes.

Aphids:

• Assorted Aphid Species are active on many different hosts. Inspect plants carefully for building populations. Catalpa, rose, lindens, and many others are common hosts for aphids. Severe sooty mold problems are beginning to appear from the copious amounts of honeydew that these insects produce. Treat with insecticidal soap sprays, an imidacloprid product, a summer oil spray, or with one of the many registered chemical insecticides.

Adelgids:

• Hemlock Woolly Adelgid can still be treated with horticultural oil even though this pest is now dormant. The young instar nymphs have settled on the stems at the base of the needles and will not move or feed again until about mid-October. However, they can still be managed with horticultural oil sprays. To know if they are alive or not, inspect them under magnification (a microscope, if possible) and gently poke them with a sharp needle. If they are dried and brittle, then they are already dead. If they exude a small amount of liquid, then they are most likely alive and dormant. If the use of systemic imidacloprid is desired, wait until the third or fourth week in August or once regular rain or irrigation is available along with cooler temperatures, for application.

Other Piercing-Sucking Insects:

• Spider Mites - Several growth regulator products are available that offer high levels of control; mostly for population numbers that are low to moderate in size. Most are so specific that they kill spider mites but not the beneficial predatory mites. Some even posses ovicidal (egg-killing) qualities. Horticultural oil sprays can also be very effective. Many insecticides and miticides are specifically labeled for spider mites as well.
  
• Two-spotted Spider Mite remains very active. This species has a wide host range. It is also a 'warm-season' spider mite, which means that it will remain active all season long and be very prolific once the very hot and dry season approaches. Begin to monitor now and continue monitoring throughout the growing season for increasing population numbers. Treat if numbers become too high and (especially) if predator mite population numbers are too low. Horticultural oil sprays (summer rate) can be very effective as well as the other labeled pesticides for mites. Treat only if necessary. Deciduous plants, such as winged euonymus (E. alatus), will develop very chlorotic foliage and may even drop its leaves when high populations occur.
  
• Spruce Spider Mite is dormant but will return in about another month.

Leafminers

• Arborvitae Leafminer are mining foliage. Browning of mined foliage will not appear until January or February.
  
• Locust Leafminer on Black Locust continues to be very active and its injury is now noticeable. Adults skeletonize the foliage while the larvae mine the inside leaf tissue. The next generation of adult beetles are active and mating now. Treat with a spinosad product or with one of the registered chemical insecticides to break the cycle of re-infestation. In many cases, untreated trees will appear to be fire-swept by August as all of the foliage is killed.

Scale Insects

In general, horticultural oil sprays work well against most armored scale species, especially when they are in the crawler stage. Imidacloprid™ does not work well on armored scales but is much more effective against many soft scales.

Armored (hard) Scales:

• Monitor for Pine Needle Scale on mugo and Scots pines, in particular.
  
• Monitor junipers for Juniper Scale.
  
• Monitor different euonymus for the Euonymus Scale.

Continue to monitor scale species at the appropriate time of the season for crawlers and treat again at that time, if necessary.

Soft Scales:

• Monitor yews and certain hollies for the Cottony Camellia Scale (aka: Cottony Taxus Scale). Treat the active nymphs with a summer oil spray. This pest creates much honeydew that generates much sooty mold. We have received many reports about this pest, this year, from central and southern CT especially. Coastal areas of MA are also experiencing injury from this pest.
  
• Monitor azaleas for the Azalea Bark Scale. Inspect inner branches for nymphs and sooty mold. Treat with a summer oil spray if necessary.
  
• Taxus Mealybug (technically not a scale but a close relative) can be found actively feeding on the inner branches of Taxus. This pest also is responsible for much sooty mold. In high numbers, it can seriously stunt plant growth. Move foliage aside to inspect the inner branches.

Gall Formers

• Maple Gouty Vein Gall has been rather widely reported this year. Sugar and red maples (mostly sugar) are the primary hosts. This tiny fly (a midge) attacks foliage as it is emerging and stimulates gall formation along the main veins of the leaf, usually on the undersides. These galls are initially green but may turn red as they mature. In some cases, there are so many galls per leaf that foliage becomes stunted and distorted. However, the injury is aesthetic. There are now controls nor are they necessary.

Wood Attackers

• White-Spotted Pine Sawyer adult beetles remain active. This species is only attracted to previously weakened pines and is not considered to be a pest. However, it looks very much like the Asian Long-Horned Beetle (ALB), which is not yet known to exist in MA. The adults of ALB are a very shiny black with crisp white spots. Their antennal segments alternate between white and black segments. The WSPS also has the same type of antennae, but its body coloration is more of a dull grey and has a varying number of dull white spots. Visit the web site listed here for more details: http://www.na.fs.fed.us/spfo/alb (the main Forest Service page for ALB). Under the heading for Information, select publications; then open the link to the fact sheet titled "Asian Longhorned Beetle vs. Whitespotted Sawyer."
  
• Monitor previously stressed plants (drought, soil compaction, etc.) for signs of invasion of wood borers. Bronze Birch Borer is one such invader. Water infested trees during drought periods. Insecticide injections may be effective in some cases. The adults of BBB are seeking new host plants for egg-laying. Even though they only emerge over a few weeks time, the adults can remain active through August. It is recommended that susceptible birches not be pruned during this time, especially if they have been previously weakened. Pruning (wounding) releases plant chemicals that attract BBB females. The Two-lined Chestnut Borer, which is a close relative of the BBB is also very active in previously stressed oaks and birches. Inspect for declining health and 'D'-shaped exit holes.
  
• Conifer Bark Beetles, such as the Black Turpentine Beetle invade stressed trees. Inspect for pitch tubes and streaks of pitch on the bark. These are signs of an already weak tree. Water during times of drought.
  
• Dogwood Borer - Continue to monitor for new infestations (adults are active) and continue to avoid any wounding of the tree trunks with mowing equipment and string trimmers, which encourages infestations of this pest. If necessary, monitor for adult emergence with pheromone traps.
  
• Rhododendron Borer - Tunneling larvae will expel sawdust but this is often hidden due to dense foliage. Often, infestation is not noticed until much later in the summer when individual shoots wilt and suddenly die. Adults can be treated with a chemical insecticide. New tunnels, if possible to find, can be treated with beneficial nematode sprays.

Nuisance Pests

• Many wasp, bee and hornet species [Hymenoptera] are increasing in numbers. Be aware of their potential presence, especially when around plant material, in order to avoid their stings.
  
• Western Conifer Seedbug populations are building and can be found on the seeds (cones) of conifers. These do not create harm for conifers in the Northeast. However, as populations build, the adults become a nuisance in late autumn as they seek shelter in homes. Inspect all screening on windows, doors and attic vents now; repair, if necessary. Also, inspect and repair caulking around the same areas.

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

DISEASES

Horsechestnut (Guignardia) leaf blotch - scattered, irregular-shaped orange-brown blotches are visible on infected leaves. They are primarily affecting lower and inside leaves. As the summer progresses, the impact of the disease is becoming more noticeable; but chemical intervention for this season is of little benefit.

Powdery mildews - These fungi are now visible as a dusty, gray-to-white coating on phlox, dogwood, sycamore and rose leaves, to name a few. In addition to having this dusty coating, infected immature leaves become yellowed, puckered and stunted. Powdery mildews grow superficially over both leaf surfaces as well as green shoots. They are obligate parasites and derive sustenance only from living host plants. They do this using minute, tube-like structures (haustoria) that penetrate the epidermal cells and draw out material they need to survive. Later this summer spherical, black fruiting structures (cleistothecia) will be visible with a hand lens on the underside of leaves in the dusty, gray mycelia. If control is desired, apply fungicide sprays at intervals specified on the label. Fungicides labeled to protect foliage on susceptible plants are listed in the UMass Extension Management Guide for Woody Ornamentals.

Black spot on rose - Black spot can be ugly and destructive to highly susceptible roses. Black, rounded spots are developing on infected leaves and rose hips. Infected first year canes have lesions that are reddish colored initially and then turn black. Black, pin?head sized fruiting structures develop in the center of the spots. Repeated black spot infection cycles will occur during wet periods throughout the remainder of the growing season. Eventually, spotted leaves turn yellow and drop off prematurely. Plants that sustain considerable leaf loss fail to thrive and are more prone to winter damage. Prune and destroy all infected leaves and canes. Avoid wetting foliage during irrigation. If overhead irrigation cannot be avoided, water before mid day to reduce period of time leaves are wet. Many beautiful, resistant varieties are available. Apply fungicide sprays at intervals specified on the label. Fungicides labeled to protect foliage on susceptible plants are listed in the UMass Extension Management Guide for Woody Ornamentals.

Gymnosporangium (several different species of the fungus) rust is visible as red-orange-yellow blister-like spots on susceptible hawthorn, apple and crab apple leaves. By mid-summer tiny yellow-white tubes will extend from the underside of infected leaves. From mid-summer to autumn, spores are wind-carried from the broadleaf host leaves and, when conditions are wet, they infect green shoots and needles of junipers. Pea-sized to two-inches diameter brown galls, as well as fissures in the bark, develop on susceptible juniper needles and twigs between 12 and 20 months after infection. The best long-term approach to manage this disease is to grow Gymnosporangium rust resistant apple, hawthorn and juniper cultivars. Also, prune dormant galls on junipers infected with the cedar-apple form of Gymnosporangium rust during the summer, fall, winter and early spring (before orange jelly-like horns form). The time to apply fungicides to protect high value apples from cedar-apple rust has passed for this season. Fungicide protection of susceptible junipers is seldom performed; but if it were desired, it would be from mid-August through September.

The minute red-purple spots of hawthorn (Entomosporium) leaf spot are visible on leaves and causing some yellowing and defoliation of susceptible hawthorn. Now that the fungus is established, it regularly produces spores; and with recurring wet periods the disease spreads via these secondary infection cycles. A long-term management strategy to consider is replacement of susceptible hawthorns with resistant trees. Otherwise, preventative fungicides must be applied as buds open or when the first rains begin after the leaves start to develop in the spring; these should be repeated at labeled intervals several times until early summer. There is little benefit from chemical controls of this disease when they are started this late in the season.

Apple scab lesions are visible on susceptible crab apple leaves. Many leaves are curling or cupping where lesions developed before the leaves were mature, and the dead leaf tissue constricted leaf expansion. Within weeks after infection the olive green fruiting bodies produce new spores. New infections can occur essentially the entire growing season during wet and mild conditions. Fungicide protection at this point in the season is of little benefit. Prune to increase sunlight penetration and air circulation, which promotes rapid drying of wet foliage. If apple scab is a chronic problem and replacement is an option, consider planting a resistant variety of crabapple near the susceptible one. Once it is well established the susceptible tree can be removed, and management of this disease is much easier.

Dogwood anthracnose infections are evident on susceptible flowering dogwood (and even some resistant Kousa dogwood). Infected trees have scattered leaves exhibiting irregularly shaped gray-brown areas with purplish-brown margins. This can be a difficult disease to control due to the abundance of inoculum that over-winters on twigs and fallen leaves. In addition, heat and water stressed dogwood sustain more extensive branch dieback than those trees that have more vigor. If this is a recurring problem, consider replacing the tree with a resistant tree. On susceptible specimen trees consider a late summer fungicide application to protect the new flower buds from infection if the weather is cool and wet.

Sudden Oak Death (SOD) - The fungus Phytophthora ramorum causes SOD. It is a severe disease of oak and tanoak in certain Pacific Northwest fog forest areas. In March 2004 Phytophthora ramorum was found in two large ornamental nurseries in southern California. This detection demonstrates that the pathogen is not necessarily limited to the moist coastal regions of northern California and southern Oregon. At least one of the two nurseries distributes nursery stock nationwide, including Massachusetts.

There were recent discoveries of P. ramorum in commercial nurseries not associated with plants shipped from the initially positive Los Angles County wholesalers in the states of Oregon and Washington. More than 950 facilities received 844,000 plants.

Canada has identified three infested nurseries in British Columbia; one of which is a production nursery that shipped potentially infected plants to 19 nurseries in CA, OR and WA. Program staff has sent a list of nurseries that received plants from the British Columbia nursery to the affected States.

This pathogen has a wide range of host plants, including rhododendron, viburnum and camellia, which are potential 'carriers' of the fungus when plants are transported. The damage on non-oak hosts involves minor leaf spotting and twig dieback. However, infections on these non-oak hosts may contribute to a rapid build-up of the fungus in an area, serving therefore as a reservoir of inoculum. All of the details of how the fungus spreads have not been worked out, but these reservoir plants may play an important role.

SOD (Phytophthora ramorum) surveys in nurseries and forest areas around the state are well underway. Agencies involved include the Massachusetts Department of Agricultural Resources (MDAR), Massachusetts Department of Conservation and Recreation (MDCR), and USDA Animal and Plant Health Inspection Service (APHIS) with UMass Amherst providing the lab and staff to perform the assays. To date, Phytophthora ramorum has not been found in Massachusetts, but nearby states in which it has been positively identified include Pennsylvania (indoors), New York and New Jersey.

Trace forward and national surveys continue as APHIS PPQ determines the distribution of P. ramorum. The total number of confirmed positive locales from the trace forward, national, and other survey finds is 148 in 21 States. The breakdown per State is: AL (3), AR (1), AZ (1), CA (53), CO (1), FL (6), GA (13), LA (5), MD (2), NC (9), NJ (1), NM (1), NY (1), OK (1), OR (10), PA (indoor), SC (3), TN (2), TX (10), VA (2) and WA (22). It is important to note that only three are from landscape/environment situations.

As of July 23, 2004, the participating States have surveyed 1,118 sites and have collected 29,729 samples; 18 sites are confirmed positives. The US Forest Service P. ramorum nursery perimeter and general forest surveys continue; all sampling results are negative to date. As of July 22, the US Forest Service has conducted 26 nursery perimeter and 13 general forest surveys.

On July 2 APHIS Plant Protection and Quarantine (PPQ) confirmed the presence of Phytophthora ramorum in Nassau County, NY. A joint PPQ, US Forest Service, NY Department of Agriculture team collected sample in the county after PPQ received information from a member of the public. The team collected the positive sample from a mature red oak tree located in a 192 acre forested county park. Further surveys are underway to identify other possible infected plants and infested sites. PPQ is currently working on determining the most appropriate regulatory response to the find.

Special note: As in any widespread survey such as this one, sometimes there are differences of opinion about the results. An example in our area is the possible find of Phytophthora ramorum in Nassau County, NY on July 2. This was discussed in Cornell Extension's Branching Out Newsletter from July 16, 2004.

Sudden Oak Death in New York? - News of discovery of the sudden oak death pathogen, Phytophthora ramorum, in Nassau County spread quickly last week and with every ounce of fact, there seemed to be a pound of fiction to accompany it. Here's what we know. Three of 44 bark samples submitted to the Cornell Plant Disease Diagnostic Laboratory in May by a private citizen were tentatively identified as P. ramorum. An intensive survey of the suspect areas by state and federal officials failed to confirm presence of the pathogen except at a site on Long Island in Nassau County where another positive sample was taken. The second sample was from red oak whereas the first one from the same site was from black birch, and the original black birch tested negative when resampled during the follow-up surveys. All diagnoses have been based solely on analysis of fungus DNA extracted from the bark of the trees; no one has successfully cultured the pathogen from samples in New York despite numerous attempts.

The technology on which the diagnoses are based is relatively new, and it is so sensitive that even the smallest bit of contamination can lead to a false reading. Furthermore, some healthy plant species and some other species of Phytophthora seem to react with a weakly positive reading in the test. This suggests that there are other chemicals in natural systems that are close enough in structure to the P. ramorum extracts to cause some organisms to test positive for the pathogen when it really isn't there. Thus, there is some justifiable skepticism about the New York discoveries, and work continues in an effort to clarify what is now a confusing picture.

For more information about SOD and Phytophthora ramorum check out the Massachusetts Introduced Pests Outreach Project web site at www.massnrc.org/pests/ . From the home page, hit the Search for Pest Info button; then enter the keywords 'sudden oak death' in the search box. Follow the link to the fact sheet.

Landscape, Nursery, and Urban Forestry Diagnostic Lab Report

The following are some of the interesting disease/abiotic disorder samples received at the UMass Extension Landscape, Nursery, and Urban Forestry Diagnostic Lab in Amherst during the period July 12 through July 23, 2004:

• Syringa 'James McFarlane' - there was fairly uniform reddish-brown discoloration of the leaves of only this cultivar of lilac growing in a nursery field; this cultivar is particularly sensitive to ozone damage during previous week's air inversion episode.
• Green ash - initially foliage shriveled up followed by leaf loss and affected branches are now dead; Verticillium wilt.
• English oak - 80-year-old tree regularly loses several small to medium sized branches every few years; shading/natural senescence/Botryosphaeria canker.
• Ulmus 'Accolade' - extensive lesions developed on stems and branches of scattered 10-year-old trees planted last spring in nursery field; Botryodiplodia canker.
• American elm - mature trees in Falmouth developed several yellow-brown branches high in their crowns; Dutch elm disease.
• English yew - well-established plant with a large amount of needle discoloration + loss, as well as scattered dieback of twigs and small branches; winter damage/marginally hardy and secondary Botryosphaeria dieback.

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

TURFGRASS

Diseases: No report. Visit the Landscape Message archive for previous messages.

Insects:

Making Sense of Consumer Insecticide Products - As I mentioned in an earlier posting, there can be considerable confusion when a homeowner tries to find an insecticide to use against lawn insects. Many of these products have colorful sketches of insects on them and useful names like Bug-B-Gone™ or Home Defense™. In some cases, the pictures on the bag do not match the insects for which the product can be effective. Following is a short list of products I found in a brief foray into two retail settings - a local Wal-Mart and a local garden store. In each case I give the trade name (sometimes lengthy) followed by the common (generic) name. Note that some of these are lawn products and others are not.

• Bayer Advanced Season Long Grub Control™ (imidacloprid)
• Bayer Advanced Power Force Multi-Insect Killer™ (cyfluthrin)
• Bayer Advanced Lawn and Garden™ (cyfluthrin)
• Bonide Eight Insect Control™ (permethrin)
• Ortho Home Defense™ (bifenthrin)
• Ortho Bug-B-Gon Max™ (esfenvalerate)
• Ortho Bug-B-Gon Granules™ (bifenthrin)
• Ortho-Klur for termites and ants™ (bifenthrin)
• Ortho Orthenex Garden™ (acephate, triforime, and fenbutatin-oxide)
• Eliminator Sevin Dust™ (carbaryl)
• Eliminator Flower and Garden™ (permethrin)
• Eliminator Soil and Turf Insect Killer™ (deltamethrin)
• Eliminator Lawn Insect with Sevin™ (carbaryl)
• Garden Tech Sevin™ (carbaryl)
• Garden Tech Sevin Ready-to-Use™ (carbaryl)
• Garden Tech Lawn Insect Granules™ (carbaryl)
• Jonathan Green Pest Kill Turf Insecticide™ (trichlorfon, referred to as Dylox™)
• Monterey Garden Insect Spray™ (spinosad)
• Spectracide Triazide Concentrate™ (lambda-cyhalothrin)

In the greater scheme of things, this is a very short list of the materials that are available to homeowners. There are a few points to make here. Several of the products listed above are pyrethroids, synthetic products based on the structure of pyrethrin (the active ingredient in pyrethrum, a natural product). They include bifenthrin, cyfluthrin, deltamethrin, esfenvalerate, lambda-cyhalothrin, and permethrin.

In general the pyrethroids are good substitutes for diazinon and chlorpyrifos (Dursban™), both of which are being phased out of the home market. The pyrethroids can be very effective against a variety of surface insects, such as chinchbugs and caterpillars. However, pyrethroids are not effective against white grubs (no matter what the label claims or the picture might imply). This is primarily because pyrethroids are very insoluble in water and do not penetrate the thatch and reach the grubs in the soil.

Carbaryl has been around for over forty years and is a broad spectrum insecticide. It can be quite effective against caterpillars, in particular, but has been very inconsistent when used against white grubs. Nevertheless, it is about the only curative option available for grubs for those people who cannot use trichlorfon, Dylox™. (Dylox™ is not available for school grounds in Massachusetts or for any turf applications in Maine.) Carbaryl is very toxic to honeybees, among other things. There are often restrictive statements on the label to help protect foraging honeybees.

Spinosad is a biorational product derived from a naturally occurring soil actinomycete. It has been shown to be effective against a variety of caterpillars and does not appear to harm most beneficial insects.

Imidacloprid is the active ingredient in the product often referred to as Merit™. (Note that while the Bayer bags claim "season long control", spring applications of Merit™ will not reduce populations of the grubs already present in the spring. In addition, spring applications of Merit™ may not remain active enough to control European chafers and Oriental beetles in New England.

While our limited look did not uncover any bags of halofenozide (often sold as Mach 2™), it should be mentioned here. This product is a molt accelerating compound and induces white grubs to molt before they have stored enough energy to complete the process. It is very effective against Japanese beetle grubs but is somewhat less effective against other species of grubs.

Sometimes academics fall into the "trap" of recommending chemicals based on the most common trade names. While these names sometimes are mentioned on the homeowner products, other times the names are hard to find on the bag. So, as I said earlier, you simply have to read the small print and find the common name of the active ingredient (which, by law, must be on the main section of the label).

Good luck! The chemical section of a garden supply area can be quite a challenge to negotiate.

Pat Vittum, Professor and Extension Entomologist, UMass, Amherst, Mass.

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IMPORTANT INFORMATIONAL RESOURCES

Two UMass Extension Web Sites are specially designed to provide Green Industry professionals with resources, upcoming educational programs and events, and other relevant information. The Internet address for the Landscape, Nursery, and Urban Forestry Program is http://www.umassgreeninfo.org. The Turf Program address is http://www.umassturf.org .

UMass Extension’s Management Guide for Woody Ornamentals is NOW available! Remember to use the Professional Management Guide for Insects, Diseases and Weeds of Trees and Shrubs in New England 2003-2004 as a reference tool along with this message. The guide is a 130-page guide to provide arborists, tree wardens, and green industry professionals with current information on the materials and products available to manage pests of woody plants in New England, updated every two years by the University of Massachusetts Extension's Landscape, Nursery and Urban Forestry Program. Send orders (checks payable to UMass) to UMass Extension Bookstore, Draper Hall, 40 Campus Center Way, Amherst, MA 01003. You can also order with a credit card by calling the Extension Bookstore at 413-545-2717. The cost is $26 (plus $5 shipping) for Part I: Professional Management Guide for Insects, Diseases, and Weeds of Trees and Shrubs in New England; $12 (plus $5 shipping)for Part II: Strategies for Plant Health Management of Woody Ornamentals; or $40 (plus $5 shipping) for both Parts I and II and the inscribed 3-ring binder to hold them. For more details or to order online, go to the Publications Section of this web site.

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 Extension 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 Urban Forestry Diagnostic Laboratory is available to serve commercial landscape contractors, turf managers, arborists, nurseries, and other green industry professionals. It provides woody plant disease analysis, woody plant and turf insect identification, turfgrass identification, landscape and turf 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 made payable to the University of Massachusetts to Urban Forestry Diagnostic Lab, 160 Holdsworth Way, Holdsworth Natural Resources Center, UMass, Amherst, MA 01003. The fee for a woody plant disease analysis is $50.00. All insect, weed, and turfgrass identification samples are $25.00 each. For complete information and instructions on how to send specimens, visit the Urban Forestry Diagnostic Lab page.

Turfgrass disease samples should be directed to the UMass Turf Disease Diagnostic Lab . This service is available ONLY to green industry professionals such as landscapers, lawn care companies, and golf course managers. For more info specifically on turf disease diagnostics, visit the Disease Diagnostics page at www.umassturf.org .

NEXT UPDATE: The next issue will be available on Friday August 13, 2004.

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 Turfgrass Program as well as cooperating horticultural, green industry, and other professionals from the field. 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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