UMass Extension Landscape Message #19
July 22, 2005

Quick Info Menu ------------------------------- ENVIRONMENTAL DATA REGIONAL NOTES - Cape Cod - Southeast - East - Central - Pioneer Valley - Berkshire PHENOLOGY WOODY ORNAMENTALS - Insects - Diseases - Lab Report 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. This issue has been updated to provide timely pest management information and the latest regional news and environmental data throughout Massachusetts. During the months of July, August and September, the LANDSCAPE MESSAGE will be updated on a bi-weekly basis. The next update will be available in two weeks on Friday, August 5, 2005. Missed a previous message? Visit the Landscape Message Archive.

ENVIRONMENTAL DATA

The following growing degree day (GDD) and precipitation data was collected for the two-week period from July 6, 2005 through July 20, 2005. Soil temperature and phenological indicators were observed on July 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.

The statewide GDD averages for this period are as follows: Total = 1158.7; 2-week gain= 128.6; GDD/day = 18.4

REGIONAL NOTES

Cape Cod Region (Barnstable) - General Conditions:Hot humid weather continues to be the norm. While other areas of the state have received rainfall, only widely scattered showers have happened on the Cape. Some plants are showing marginal scorching symptomatic of dry soil. Pests/Problems: Gypsy moth caterpillar defoliated fairly large areas of the Cape this year, along with Forest tent and winter moth caterpillars. Some defoliated trees have still not re-leafed. Currently, those plants favored by Japanese beetles are looking skeletonized. Oriental and Asiatic garden beetles are also active. Brown, wilted leaders on white pine and spruce are characteristic of white pine weevil infestation. Cottony taxus scale eggs have hatched, and the crawlers have dispersed. Deer tick nymphs are still quite active, as are mosquitoes.

Southeast Region (Hanson) - General Conditions: Hot, hot, hot and humid. Soils are very dry in this part of the state. The Hanson /Halifax areas have only received approximately 3.7 inches of rain since the first of June. Remind clients to water drought stressed trees and, especially, those that were defoliated.Early blooming panicle hydrangeas like, Hydrangea paniculata ‘Praecox,’ are blooming. Albizia julibrissin (Mimosa), Hydrangea quercifolia (Oakleaf hydrangea), Hydrangea macrophylla ‘Blue Billows,’ hollyhocks, Yucca filamentosa, daylilies, Corydalis lutea, Nepeta, Heliopsis ‘Summer Sun,’ Monarda didyma, Filipendula venusta, Dicentra ‘King of Hearts’ and Campanula sp., Astilbe and hosta are in full bloom. Lysimachia clethroides and Phlox paniculata are beginning to bloom. Pests/Problems. The Hanson Extension office has received calls and office visits regarding numerous brown moths flying around. Those are the male gypsy moths. The females are a whitish buff and don't fly. The males and females are mating, and the females are laying eggs. Judging from the amount of moths we are seeing, it just might be a big gypsy moth problem next year. Japanese, Oriental, Asiatic, and lily leaf beetles are active. Four-lined plant bug, slugs, snails, and ticks are all active. Mosquitoes are plentiful. Anthracnose is showing up on a number of plants including dogwood. Powdery mildew is showing up on garden phlox.

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

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

Pioneer Valley Region (Amherst) - General Conditions: The past week has been oppressively humid with a lot of cloudiness and scattered, episodic downpours. Generally, lawns, gardens, trees and shrubs look green and robust. Pests/Problems. Powdery mildew is evident as curling, gray-colored leaves on dogwood, sycamore, oak, lilac, and a number of herbaceous plants. In addition some of the leaf spot diseases are causing some premature yellowing and defoliation on crabapple, hawthorn, cherry, and dogwood to name a few.

Berkshire Region (Great Barrington) - General Conditions: Conditions are ideal for landscapes and gardens with plenty of soil moisture. Many plants, especially daylilies, are outstanding. Lawns continue to grow rapidly, and few show any summer dormancy despite the hot weather. Pests/Problems: Japanese beetles, Asiatic garden beetles, leaf hoppers on birch, two-spotted spider mites, slugs, and deer ticks are common. Powdery mildew is just beginning on phlox and beebalm. Anthracnose is common on sycamore and ash. Horsechestnut leaf blotch and oak leaf blister were observed this week.

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 Agroecology Program, Great Barrington.

WOODY ORNAMENTALS

INSECTS

Now that the peak season for heat and humidity has arrived , and doesn’t appear to be abating, we are seeing a major increase in the pests that perform well under those conditions; namely warm-season spider mites and lacebugs. Natural control factors, such as predators and certain parasitoids, often greatly diminish their activities or cease all together during such conditions. In addition, spider mites and lacebugs will go through their generational times at an accelerated pace, therefore, leading to sudden outbreaks of these pests. Monitor infested plants closely for increasing population numbers.

Gypsy Moth - Defoliation from this pest has been much greater than anticipated in many parts of the state and is at its highest level in more than two decades. Moths began to appear within the last two weeks and now they are quite prevalent in much of the state. Adult gypsy moths do not feed. They are mating and laying eggs. Adult activity will continue for about two more weeks.

Forest Tent Caterpillar (FTC) - Flight for this pest is now virtually over for this year, and egg masses have been deposited around small branches of host plants.

Fall Cankerworm - This pest is finished feeding for this year and is pupating. Adult moths will emerge around Thanksgiving time.

Fall webworm moths have been active for at least a couple of weeks. These pure white moths are often attracted to lights at night and usually go unnoticed. The females are now laying eggs on foliage, and the new caterpillars will begin to form unsightly silken webs around the foliage. As they feed, they will expand the web down towards the trunk of the tree. By mid-August, these webs can become quite large. Treat with Bacillus thuringiensis Kurstaki or with a spinosad product. Note. Fall webworm caterpillars feed within the silken web and can be somewhat protected from sprays. Make sure the spray penetrates the silken webs and gets to the foliage where this pest is feeding.

Hymenopteran Caterpillars (Sawflies):

Introduced pine sawfly remains active and may be found on many of the same host plants as European pine sawfly (e.g., mugo, scots and other pines). Inspect and treat when found. While insecticidal soap works well on the younger caterpillars, a product that contains spinosad works on caterpillar stages.

Mountain ash sawfly caterpillars have ceased their feeding activity and are now pupating.

Beetles:

Viburnum Leaf Beetle - Adult beetles are active. Once mated, the females will deposit eggs along the bare twigs and cover them with excrement, giving the twigs a sandpaper feel. Very little damage will be incurred for the remainder of this year. Visit the Cornell web site, http://www.hort.cornell.edu/vlb/index.html , for current information on this pest. Report any new findings in MA to Robert Childs, rchilds@psis.umass.edu, 413-545-1053.

Lily Leaf Beetle - This pest remains very active and is well into the next generation. Monitor for its presence and treat when found. Spinosad products work well against the larvae.

Asiatic garden beetle adults remain very active. These night feeders are most active between the hours of 9 PM and midnight. They are attracted to a wide range of host plants from the landscape to the garden. Their feeding can cause much defoliation. Inspect plants at night with a light, and treat if necessary.

Black Vine Weevil - Continue to monitor foliage of taxus and rhododendron in the landscape and nursery for notched foliage, especially on the lower part of host plants. The adult weevils will become active soon and begin to feed on foliage. This insect does not fly and must walk up the host plant each night to feed. Place loosely folded burlap strips on the ground around plants and inspect during the day. Adult weevils will use the burlap as a hiding place during daylight hours; collect and destroy beetles. If found in large numbers, treat with a product that contains lambda-cyhalothrin.

Piercing-Sucking Pests:

Spider Mites:

• Inspect the needles and stems of conifers now for injury from spruce spider mite. Now that the hot and humid weather has been here for a while, this pest remains in its summer dormancy but will return by the end of August and can be active well into the fall. Horticultural oil sprays (at the summer rate) can be effective once they return to feed on the plant.
  
• Two-spotted spider mite (one of the warm-season mites) is becoming noticeable on a wide range of host plants. Warm season mites prefer, and thrive, during hot weather. Their rate of development is greatly accelerated by the heat; and at the same time, predatory mites often leave the host plant and go into a summer dormancy in the leaf litter or mulch. This gives spider mite populations the potential to explode in numbers and to create much plant injury in a short amount of time. Continue to monitor on a regular basis, and treat increasing populations before they become too large. Horticultural oil sprays at the summer rate can be quite effective, as are the new mite growth regulator products. Avoid the overuse of chemical pesticides; spider mites are quite adept at developing pesticide resistance.

Hemlock Woolly Adelgid (HWA) - This pest is now in its summer dormancy, and the tiny nymphs are settled along the stems at the base of the needles. Feeding will cease until mid-October. Horticultural oils can still be applied at the summer rate when the correct weather conditions prevail; avoid very hot and humid days for oil applications.

Mealybugs - are quite active now. Inspect the undersides of inner branches for taxus mealybug. Treat when found. This pest can greatly reduce plant growth, and it also produces much honeydew, which leads to problems with sooty molds.

Andromeda lacebug is extremely active. Inspect leaf undersides of Japanese andromeda for the activity of this pest. Treat the plant with a soil-applied systemic treatment of imidacloprid or spray the leaf undersides with an insecticidal soap. Pyrethroid insecticides are also labeled for this pest.

Potato Leafhopper - This leafhopper cannot survive a Massachusetts winter, yet it is a problem here every summer. It arrives about this time from more southern states and can be a problem on maples, especially in the nursery. They feed by sucking plant juices from the foliage, and heavy populations will create a bleached appearance on the foliage. Inspect for new piercing-sucking injury that is very fine and expanding. Also look for the pale-colored leafhoppers on the foliage undersides. Treat with a pyrethroid insecticide when found in unacceptable numbers.

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 (summer rate) when plant phenology and correct weather conditions prevail. Pine needle scale has a new batch of crawlers that are settling now to feed.

Euonymus scale crawlers have been active. Treatments now are most effective against this pest. Use a horticultural oil at the summer rate. Monitor for scale crawlers with a piece of black electrical tape that has been repeatedly daubed on the stems; the tiny euonymus scale crawlers will appear as orange spots on the tape.

Soft Scales - Tuliptree scale and azalea bark scalecan 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.

• Azalea bark scale is active. Inspect the intersections of branches with the main stems for the cottony, white females with egg-sacs. Wait for the crawlers to emerge (soon) and treat with a horticultural oil spray at the summer rate or a spinosad product or with a cyfluthrin product.

• European fruit lecanium scale has many hosts. Inspect for the large, dark brown female scale coverings from last year that will appear lined-up on the stems. This is another soft scale that is problematic to control. Wait for the crawlers to emerge (late June into early July) ,and treat with a horticultural oil spray at the summer rate or a spinosad product or with a cyfluthrin product.
  
• Cottony Camellia Scale (a.k.a. Cottony Taxus Scale) remains active. Inspect leaf undersides for the nymphs. Females, when present, are tan-colored and round with an elongate and whie egg-sac attached to their covering. When in large numbers, this pest can greatly diminish plant growth and also be responsible for much unwanted sooty mold.

Leaf Miners:

Arborvitae Leafminer adults are active. This leafminer (a moth as an adult) is not attracted to yellow sticky cards. Inspect foliage for browned tips and exit holes. Gently shake branches to dislodge the tiny, off-white moths. Treat with a pyrethroid insecticide or a spinosad product to kill the newly hatching caterpillars. Eggs are laid on the foliage and the larvae must chew their way into the leaf, which usually occurs on the leaf underside.

Wood Borers:

Dogwood Borer - The adult moths remain active. Pheromone traps are available for this pest. Keep flowering dogwood free of wounds from mowers and line trimmers, which encourage invasion by this insect. Treat infested trees in August with a trunk/branch spray of entomopathogenic (beneficial) nematodes.

Rhododendron Borer - This is another clear-winged moth caterpillar that is a wood borer and a close relative to the dogwood borer (family: Sesiidae). Inspect around the base of rhododendrons, on the ground, for coarse sawdust that has been expelled by the caterpillar boring in the shoot. Physically prune out and destroy infested shoots or use a coarse spray of entomopathogenic nematodes.

Bronze Birch Borer - This wood boring beetle requires a previously weakened tree for successful colonization. Keep birches healthy by watering during drought, mulching and avoiding soil compaction. Some advise that birches not be pruned from June into September to avoid releasing plant volatiles that may attack female beetles. However, healthy trees should be able to withstand pruning at this time and still naturally defend itself against this pest.

White-spotted pine sawyer (WSPS) adult beetles have been active for at least a couple of weeks. This native longhorned beetle bears a strong resemblance to the Asian longhorned beetle (ALB). However, WSPS is not a pest. It only attacks pines that are previously very weakened already. Extension receives many calls every year about WSPS due to its resemblance to ALB. White-spotted pine sawyer is a grayish/ black color with diffuse white spot(s) while ALB has a black body that looks like shiny black patent leather. The white spots on its body are crisp and obvious.

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

DISEASES

Black spot on rose can be ugly and destructive to highly susceptible plants. Black, rounded spots develop on infected leaves and rose hips. In addition, infected first year canes exhibit lesions that are reddish colored initially, which later turn black. Black, pinhead-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. Roses that sustain considerable leaf loss fail to thrive and are more prone to winter damage. Prune and destroy all infected leaves and canes. Minimize the duration of foliage wettings after irrigation. If overhead irrigation cannot be avoided, water before midday to reduce period of time leaves are wet. The longer leaves and canes are wet the more time the black spot fungus spores have to infect the rose. Many beautiful, black spot resistant rose varieties are available. To protect susceptible roses, apply fungicide sprays at intervals specified on the label. The numerous fungicides labeled to protect foliage on susceptible plants are listed in the UMass Extension Management Guide for Woody Ornamentals.

Mushrooms in lawns often develop from thatch, buried logs, dead roots, stumps, or even construction debris. They have many different sizes, colors, shapes, and habits of growth and invade lawns after prolonged wet weather. The fungi that produce these mushrooms are beneficial because they decompose organic matter in the soil, making nutrients available to other plants. These mushrooms usually are harmless to grasses, but some people consider them unsightly or want to get rid of them because young children play in the area. Neither spray applications nor drenches of fungicides are effective in controlling these mushrooms. Remove mushrooms growing from buried wood or roots by picking them as they appear or by digging out the wood. Elimination of excess thatch and aerating the soil to improve water penetration also helps in some cases. In addition, if the mushrooms are left to themselves, they just disappear when the weather becomes dry.

Cedar-apple rust is visible as orange-yellow spots on susceptible hawthorn, apple and crab apple leaves. Many of the undersides of the yellow-orange spots have tiny tube-like fruiting structures extending from infected leaves. From now to leaf fall, spores are wind-carried from the apple leaves and, when conditions are wet for several hours duration, they infect green shoots and needles of junipers. Pea-sized to 2” diameter round, brown galls 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 cedar-apple rust resistant apple and juniper varieties. Also, prune dormant galls on juniper during the summer, fall, winter and early spring (before jelly-like horns form). Avoid growing susceptible junipers close to apples. The time to apply fungicides to protect high value apples from cedar-apple rust has passed for this spring. Fungicide protection of eastern red cedar and Rocky mountain junipers is seldom performed; but if it were desired, it would be from now through September when there are extended wet periods.

Horsechestnut (Guignardia) leaf blotch is evident as scattered, irregularly shaped orange-brown blotches on infected leaves. As the summer progresses, the impact of the disease is often more noticeable; but chemical intervention at this time for this season is of little benefit. Likewise, it has been noted that horsechestnut that suffer repeated severe infections continue to grow vigorously in spite of Guignardia leaf blotch.

Powdery mildew fungi are now visible as a dusty, gray to white spots/blotches on horsechestnut, phlox, dogwood, sycamore and rose leaves in the Amherst area. Once established on plants, powdery mildews grow superficially on both upper and lower leaf surfaces as well as green shoots and flower buds. 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. Generally, the damage caused by powdery mildew is of minor consequence to healthy plants and does not warrant chemical control if unsightliness is not a critical concern. If chemical control is desired, there are a number of unconventional applied materials that are labeled to protect susceptible plants. They include summer horticultural oil, commercial baking soda preparations (sodium bicarbonate and potassium bicarbonate), anti_transpirants, as well as a number of conventional fungicides. Chemical spray programs are most effective when begun just as symptoms of powdery mildew begin to show. Once powdery mildew is extensive on the plant, there is little benefit from chemical control that season. Applications need to coat both surfaces of all susceptible plant parts to prevent infection. Spray on a regular schedule, and repeat more often during warm, humid weather.

Oak leaf blister is showing up on red and pin oak leaves as tan to brown blister-like spots. Puckering is minimal but noticeable, if you look closely. This is a not a serious fungal disease problem in Massachusetts. If a severe outbreak is occurring on specimen trees, note that for future reference. Chemical control activities on specimen or nursery trees should be started just as buds open next spring.

Apple scab is visible on susceptible crab apple leaves. Some 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. If infection has just begun now is a favorable time to maintain scab_susceptible crabapples in the landscape with fungicides. These fungicides act primarily to prevent new infections, especially those infections that would develop on newly emerging leaves. Systemic fungicides can reduce the incidence of apple scab as the season goes on if they are applied soon, before the extent of infection is too severe, and protection is maintained at labeled intervals. Alternate every second or third systemic fungicide spray with a broad-spectrum fungicide to reduce problems with the development of fungicide resistance by the apple scab fungus. Prune to increase sunlight penetration and air circulation to promote rapid drying of wet foliage. If apple scab is a chronic problem, consider planting resistant varieties of crabapple if replacement is an option. This fall remove and destroy fallen leaves in the vicinity of the tree to reduce primary inoculum available for initial infections next spring.

Sycamore, maple, oak and ash anthracnose. Crowns on sycamore, maple, ash, and oak trees are filling in as these trees recover from spring anthracnose infections. Anthracnose causes some premature leaf loss, but that is not going to seriously affect an otherwise healthy tree. In the fall fine prune infected twigs and collect and dispose of fallen leaves to reduce over-wintering inoculum. Promote drying of foliage by pruning and spacing plants to increase the penetration of sunlight and air circulation in and around plants.

Dogwood anthracnose is visible as brown-tan spots/blotches as well as some shoot blighting. Remove and dispose of dead leaves, twigs and branches to reduce anthracnose inoculum in infected trees. Dogwoods receiving good cultural care are better able to limit the extent of dogwood anthracnose damage. Water during dry periods and maintain 2-4 inches of composted bark mulch over as much of the root area as possible. It is too late this spring to protect new shoots and leaves with fungicide applications. Next spring begin as buds break open, when bracts have fallen, and four weeks later. Later this summer, after flower buds form, if there is wet weather a fungicide application may protect the flower buds from infection. If dogwood anthracnose is a persistent problem consider planting one of the many resistant cultivars of Cornus florida and C. kousa now commercially available.

Ramorum Blight, also known as Sudden Oak Death (SOD). 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, ramorum leaf blight or ramorum dieback, or by regulation as Phytophthora ramorum. SOD 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. 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.

Status of Phytophthora ramorum Monitoring Surveys. The 2005 National Nursery Survey is underway. As of July 13, 40 states have reported National survey results: 2,155 nurseries have been visited, 35,397 samples collected. Thirty-six positives sites in six states have been identified through national survey or Federal order and annual cleanliness compliance surveys. Outside of the three regulated west coast states, seven national survey positives have been confirmed. Georgia reports four positive nurseries, Louisiana reports two positives nurseries, and Tennessee reports one positive nursery. In the regulated states, California has found 23 positive nurseries during their Federal Order compliance surveys and annual cleanliness surveys, Oregon has identified five positive nurseries during their Federal Order compliance surveys and Washington has reported one National Survey positive

The US Forest Service and states are conducting nursery perimeter and general forest detection surveys in 38 states during 2005. As of June 15, USFS reports 205 nursery perimeter surveys in 19 states. USFS has collected 488 samples; results are available for 62 samples and all are negative. USFA reports 127 general forest surveys have been conducted in four states; 306 samples have been collected. There are no confirmed positives based on 28 results.

UMass Extension’s Landscape, Nursery & Urban Forestry Diagnostic Lab Report. The following are some of the interesting disease/abiotic disorder samples received at the diagnostic lab in Amherst during the period June 27 through July 8, 2005:

• Crab apple – 20-year-old tree has scattered browning of current season and a bit of the contiguous older parts of the branches; fire blight bacterium (Erwinia amylovora)
   
• Basswood – 30-year-old tree with dark brown to black fruiting structures erupting through the bark in the root flares and at the base of the stem; carbon cushion fungus (Hypoxylon deustum).
   
• Red maple – 50-year-old tree with scattered dark, irregularly shaped spots on many of the leaves, especially on the lower par of the tree; Venturia leaf blight (Venturia acerina).
   
• Austrian pine – 15-year-old trees with thinning crowns and premature needle loss especially in lower parts of the tree hedge, with some trees heavily infected while others have no evidence of disease; Ploioderma needle cast. 

Insects:

If the weather patterns we have seen so far continue this summer, you might find that beetles choose to lay eggs in places that are a little higher and drier than you usually see them. In many areas heavy rains have left soils moist, and females will try to avoid laying eggs in saturated soils. Of course, the weather might change and things might start to dry out . In the meantime, keep an eye on the higher and usually drier sites as potential places for grub activity.

I have had several reports from people throughout New England reporting plenty of adults flying— Japanese beetles, Oriental beetles, Asiatic garden beetles, European chafers. You name it; they are out and about. One intrepid reporter told me his swimming pool (in Granby, Massachusetts, just south of Amherst) was loaded with oriental beetles and asiatic garden beetles the last couple nights. As he skimmed the pool, more beetles piled in.

When soils are very dry in the summer, beetles often delay their egg-laying activity until soils get wetter. This year there will be no delay! Soils are plenty moist, and egg laying is already underway. Grubs seem to be surprisingly resilient in wet soils. Last year we sampled an area just a few days after it had been flooded for three days, and the grubs (European chafers) were just fine, as healthy as could be. So, the wet soils many of us currently have will probably not discourage grub activity at all.

Keep in mind, however, not everyone in New England is wet as we are here in western Massachusetts. (I measured 7.25 inches of rain in a six-day period at my house just north of Amherst. It fell as 2.35, 0.9, and 4.0 inches, at two-day intervals, with the last "dump" on Monday afternoon, July 18.) Needless to say, our soils in many places are still rather wet.

Conditions are variable, and there are places in southeastern Massachusetts, among others, that are very dry. If soils are very dry, beetles may delay their egg-laying for one to three weeks. This means that grubs are delayed in their development and damage is masked until well into September. By then it sometimes is too late to do anything. So, monitoring is even more important this summer. Look for the pearly white eggs in the soil (one to three inches below the surface), and look for tiny grubs in the upper part of the root zone or lower thatch.

Several people have asked me about imidacloprid (Merit™) applications for grubs. Normally we recommend that the applications be made by the end of July, if possible; but this year the wet soils are having an impact. Do not apply Merit™ (or any other grub material) when soils are saturated. It is better to wait until soils dry out a bit. In most cases, applications that are in place by the 10 th of August or so should work fine. The exception would be south-facing slopes in areas where European chafers are the primary grub species. In those situations, try to get the material down by the end of July if at all possible. Dave Shetlar, my colleague at Ohio State University, says that his studies have indicated that Merit™ can be used even later in the summer, if necessary. The main "rule" this summer is to avoid treating when soils are saturated.

If soils are so dry (coupled with high temperatures) that the turf goes dormant, it is even more important to water in the insecticide. Keep in mind that imidacloprid (Merit™) has systemic qualities and is absorbed by the roots. It can be harder to get it to the right target when turf is dormant because roots are not actively taking up water.

If water is available and soils are very dry, studies indicate you will benefit by irrigating the area about 24 to 36 hours before you treat (with at least 0.2 inches of water), and then following the application with at least 0.1 inch of irrigation. The reason this seems to help is that grubs naturally migrate down in the soil profile when soils are hot or dry. The pre-treatment irrigation tricks the grubs into thinking conditions are improving in the root zone and they migrate upward, where they get an unpleasant surprise.

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

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

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 .

New England Guide to Weed Control in Turfgrass - The updated 2005 New England Guide to Weed Control in Turfgrass is now available. It contains extensive information about currently registered turf herbicide products, including specifics on application, timing and environmentally responsible use. The guide is available as a free, downloadable PDF file in the Online Publications section of http://www.umassturf.org

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 in Friday, August 5, 2005.

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.

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.

Comments or suggestions in regard to the Landscape Message? Please e-mail the webmaster.

Missed a previous message? Visit the Landscape Message Archive.