UMass Extension Landscape Message #23
September 16, 2005

Quick Info Menu ------------------------------- ENVIRONMENTAL DATA REGIONAL NOTES - Cape Cod - Southeast - East - Central - Pioneer Valley - Berkshire PHENOLOGY WOODY ORNAMENTALS - Insects - Diseases - Lab Report - Weeds TURFGRASS - Insects - Diseases - Weeds INFO RESOURCES DIAGNOSTIC SERVICES Use this menu to instantly jump to any portion of the message!

The LANDSCAPE MESSAGE is an educational newsletter intended to guide landscape, nursery and urban forestry professionals in identifying pests in the landscape, monitoring their development, planning management strategies and creating site-specific records for future management reference. This issue has been updated to provide timely pest management information and the latest regional news and environmental data throughout Massachusetts. During the month of September, the LANDSCAPE MESSAGE will be updated on a bi-weekly basis. The next update will be available in two weeks on Friday, September 30, 2005. Missed a previous message? Visit the Landscape Message Archive. Interested in additional turf-oriented content? UMass Extension Turf Program Management Updates

ENVIRONMENTAL DATA

The following growing degree day (GDD) and precipitation data was collected for the two-week period from September 1 through September 12, 2005 . Soil temperature and phenological indicators were observed on September 12. 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: Once again we are back to extremely dry weather. There has been no rainfall in the past two weeks, and we can only hope that the remnants of Ophelia give the Cape some much-needed wet weather. Drought stressed trees are showing premature fall color. Pests/Problems. Some maples, including Norway, sycamore and red, are turning crispy brown and dropping leaves. Mites are present in high numbers on herbaceous plants. Locust leaf miner has turned many black locust brown. Lacebugs are still active on azalea, sycamore and pieris. Red headed pine sawfly has been reported on Austrian pine.

Southeast Region (Hanson) - General Conditions: Fall blooming clematis, Joe-Pye weed, Rudbeckia trilobum, Rudbeckia 'Goldsturm', Echinacea purpurea, Corydalis lutea, Lobelia syphilitica, Lobelia hybrids, Sedum sp., Phlox divaricata, many ornamental grasses and Phlox paniculata are in full bloom. Goldenrod and ragweed are in full bloom. Pollen from ragweed may cause allergies in some people, but goldenrod is often mistakenly blamed. Kousa dogwood fruit (red) and Viburnum trilobum fruit (orange/red) are starting to turn color; staghorn sumac fruit is red. Pests/Problems: Pieris lacebug, earwigs, ticks, spider mites, slugs, aphids, snails and mosquitoes are all active. Mosquitoes carrying EEE (Eastern Equine Encephalitis) are active in Plymouth County. Black sooty mold is evident on many catalpa and oak trees. Powdery mildew is prevalent on a wide range of plant material such as sycamore, garden phlox, lilac, dogwood, and others. Anthracnose is still evident on sycamore, dogwood, maple and other shade trees.

East Region (Boston) - General Conditions: Dry. Pests/Problems: Drought.

Central Region (Boylston) - General Conditions: Soils continue to be dry in un-irrigated areas.

Pioneer Valley Region (Amherst) - General Conditions: The last couple of weeks have been dry and, in recent days, warm in the Pioneer Valley. Fall color is beginning to show on green ash, poison ivy and sumac, to name a few, but most of the landscape remains green. Diseases/Problems. Tarspot on Norway maple and powdery mildew on a number of plants continue to develop on affected foliage. (See Disease Report below) The early loss of spotted leaves also continues on a number of plants due to early season fungal leaf spot infections. Even though this is unsightly, it is not harmful to otherwise healthy trees and shrubs.

Berkshire Region (Great Barrington) - General Conditions: Soils have become very dry. Even lawns that remained green in summer are now browning. Newly set plants will need to be watered if they are to become well established before winter. Foliage on many herbaceous plants are showing typical late season yellowing and browning. Temperatures at this time of year can vary considerably from day to day as witnessed this week with a low of 41° F on 9/11 and a high of 89° F on 9/12. Pests/Problems. Slug activity remains high despite dry conditions. Cool nights of late are beginning to drive certain insects indoors.

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

The warm and sunny days continues to drive lacebugs and warm-season spider mite populations. Infested plants in sunnier locations are experiencing greater injury, overall. A few late season caterpillars remain active on fairly specific host plants while the handful of nuisance household invaders are about to become obvious.

Fall webworm - The webs are now fully formed, and only a few stragglers remain in the webs. Chances are that these are parasitized individuals and will linger in the webs but no longer feed on foliage. Unsightly webs may be pruned out, but treatments are no longer feasible.

Hymenopteran Caterpillars (Sawflies):

Redheaded Pine Sawfly - This yellow caterpillar with black spots and a rust-colored head capsule is now active. Treat young larvae with an insecticidal soap spray or treat caterpillars of all ages with a product that contains spinosad. This pest can be active into October and is capable of creating much late-season defoliation on pines, especially mugo.

Dogwood Sawfly - This yellow caterpillar with black spots is usually covered with a dense white pubescence that gives it the appearance of a bird dropping. Larger populations that go untreated can cause much defoliation. When found in considerable numbers, treat with a spinosad product.

Hibiscus sawfly remains very active and is causing much skeletonizing of host plant foliage. Inspect for “lacey” foliage, and then look more closely for the rather small and pale green caterpillars. Treat with a product that contains spinosad.

Beetles:

Viburnum Leaf Beetle - Adult beetles are no longer active. Look for eggs along the bare twigs which results in a ‘sandpaper’ texture. 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.

Adult Japanese beetle activity is virtually over for this year .

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 now very active 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 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 used 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 remains 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.

Andromeda lacebug remains 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.

Azalea Lacebug remains extremely active. Plants that are in sunnier locations can be severely damaged by this pest. (See Andromeda Lacebug above for recommendations.) Untreated plants in sunny locations can have foliage with a bleached appearance by mid to late August.

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 using 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. Treat with a horticultural oil spray (summer rate) when plant phenology and correct weather conditions prevail.

Soft Scales:

• 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 white egg sac attached to their covering. When they are present in large numbers, this pest can greatly diminish plant growth and also be responsible for much unwanted sooty mold.

Leaf Miners:

Locust leafminer remains extremely active. Black locusts in most locations now appear as if swept by fire from this pest’s feeding. Nothing can be done now.

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 and early September 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 (Sesiidae Family). 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.

Nuisance Pests:

Boxelder bug will soon be leaving its preferred host, female boxelder, where it feeds primarily on the seeds, and will seek shelter in protected areas, such as your house. When infested trees grow within close proximity to homes, thousands of these black bugs with red markings will cluster on the sides of homes.

Birch catkin bug is still active and feeding on seeds of birch. These very small and tan-colored bugs also can be a nuisance when infested plants are close to homes or other often utilized buildings.

Western conifer seedbug, which has been feeding mostly on seeds of conifers all summer, will soon seek shelter, often in homes. These bugs are rather large (approx. 3/4"), dark in color and rather slow movers. They emit a foul-smelling odor when handled.

Asian ladybird beetle (ladybugs) will seek winter shelter within the next month, depending on the weather. These dull-orange-colored beetles have between zero and 19 black spots and can invade by the thousands. Although very beneficial through much of the growing season by feeding on scale insects and aphids, they become a horrific nuisance when they invade houses. When handled, this insect exudes an orange colored liquid that is not only noxious, it can stain fabrics and other surfaces.

Management of House Invaders:

• inspect and fix all caulking around windows, doors and attic vents.
• repair all screening.
• repair loose siding that may act as entry points.
• once they are inside, vacuum up the invaders and then remove the bag from the cleaner and place outside. Otherwise, they will crawl out of the vacuum and re-invade the house.
• “bug bomb” type treatments can be utilized; but if the above precautions are utilized, these pests will be prevented from invading in the first place.

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

DISEASES

Powdery mildew fungi continue visible as dusty, gray to white spots/blotches on horsechestnut, phlox, dogwood, lilac, sycamore leaves, as well as rose leaves and flower buds. Once established on plants, powdery mildews grow superficially on both upper and lower leaf surfaces as well as green shoots and flower buds. Spherical, black fruiting structures (cleistothecia) are becoming visible with a hand lens on the underside of infected 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. Once powdery mildew is extensive on the plant, there is little benefit from chemical control that season.

Cedar-apple rust is visible as reddish-yellow spots on susceptible hawthorn, apple and crab apple leaves. Many of the undersides of the reddish-yellow 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. The best long-term approach to manage this disease is to grow cedar-apple rust resistant apple and juniper varieties. Prune dormant galls on juniper during the summer, fall, winter and very early spring (before jelly-like horns form). Avoid growing susceptible junipers close to apples. The time to apply fungicides to protect high value apples and junipers from cedar-apple rust has passed for this season.

Horsechestnut (Guignardia) leaf blotch is evident as irregularly shaped orange-brown blotches on infected leaves. As the summer progresses, the impact of the disease has become 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.

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 2-3 inches of composted bark mulch over as much of the root area as possible. If dogwood anthracnose is a persistent problem, consider planting one of the many resistant cultivars of Cornus florida and C. kousa now commercially available. At this time, a fungicide application may be beneficial to protect the flower buds from infection during cool wet weather in the fall.

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 August 24, forty-eight states have reported compliance or national survey results; 4,226 nurseries have been reported visited and 106,118 samples collected. Fifty-one positives sites in seven states have been identified through national survey or Federal order and annual cleanliness compliance surveys. Outside of the three regulated west coast states, eight national survey positives have been confirmed. Georgia reports four positive nurseries; Louisiana reports two positives nurseries; and Tennessee reports one positive nursery and, as of this week, South Carolina 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 11 positive nurseries during their Federal Order and compliance surveys. Washington has reported nine national survey positive sites.

The US Forest Service and states are conducting nursery perimeter and general forest detection surveys in 38 states during 2005. As of August 3, USFS reports 390 nursery perimeter surveys in 28 states with 932 samples collected; results are available for 246 samples and all are negative. USFS reports 303 general forest surveys have been conducted in 27 states; 661 samples have been collected. There are no confirmed positives based on 128 results.

There was one new positive in the Eastern Region in the last three weeks. APHIS confirmed that a Camellia located at a wholesale nursery/broker in Jasper County, South Carolina was positive for P. ramorum. This is the first report of a positive nursery in South Carolina in 2005. The nursery is part of a chain of nursery dealers. Another chain location, in Norcross, Georgia, tested positive earlier this year. In the Western Region during the last three weeks, three nurseries were confirmed as infested with Phytophthora ramorum—one in Oregon and two in Washington State. The Oregon nursery is located in Washington County, and the pathogen was found on a Rhododendron. It is a retail nursery/landscape company. In Washington, P. ramorum was identified at a Pierce County nursery on a Rhododendron as well as at a retail nursery in Skagit County also on a Rhododendron.

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

WEEDS

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

TURFGRASS

Insects:

Several of our faithful readers have reported an unusual situation - they are seeing wireworms in turf settings and seeing damage as a result of these insects. Wireworms normally are not a major problem in turf but apparently something about this summer has been to their liking.

Wireworms are the larvae of click beetles. Wireworms are quite slender, often yellow to brown, and relatively hard-bodied and somewhat flattened. They range in size from 0.25 to 1.5 inches. They can be found in many different kinds of soil, and may be present at any time of year. We often see a few wireworms when we are digging for grubs but have never associated them with damage. The adults are "click beetles" - somewhat elongated beetles that have a special structure on the underside that enables the beetle to flip up in the air, ostensibly away from harm. The beetle makes a clicking noise when engaging this "spring". Most click beetles are about 0.5 inch long.

Wireworms/click beetles have a long life cycle. The larvae (wireworms) may be present for two to six years at a given location. When they complete their development, they pupate (also in the soil) for about two weeks in late summer before the new adults emerge. The insects overwinter as adults, which then lay eggs the following spring. Most wireworms feed on seeds or occasionally on roots of grasses or grassy crops. They also will bore into fleshy underground stems.

The bad news is that the agricultural producers who deal with wireworms report them as being very difficult to manage. The wireworms are in the soil and have a very heavily sclerotized exoskeleton, which gives them an extra level of protection against insecticides. Most of the soil insecticides that might have been effective have been removed from the turf market. (As an aside, there are those who think the old organochlorines, like DDT, chlordane, and dieldrin, provided years of protection and we didn't even know it.) Vegetable producers recommended planting a different crop the following year, one that the wireworms won't like. Obviously we can't do that in turf!

So for now we have no tangible suggestions. Manage the damage as much as possible - raise the mowing height if possible to give the roots a chance to develop more deeply and withstand attack. The rains passing through today may provide some relief. I am not aware of any turf insecticides that are currently available and labeled for wireworm, but will look into it.

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

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

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

Don't forget to visit the UMass Extension Online Weed Herbarium!

UMass Extension’s Turf Management Guide and IPM Facts: For more information about the pests mentioned in this message, you will need to refer to the following publications: the Professional Guide for IPM in Turf for Massachusetts, 2003-2004 edition and Turf IPM Facts . Call (413) 545-2717 to order these publications from the UMASS 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, September 30, 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.

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