UMass Extension Landscape Message #24
September 30, 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. From October 2005 through February 2006, the LANDSCAPE MESSAGE will be updated on a monthly basis. The next update will be issued early November 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 13 through September 27, 2005. Soil temperature and phenological indicators were observed on September 27. 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: The weather pattern has begun to change into fall conditions. The cape received heavy downpours from the remnants of Ophelia and Rita; dormant lawns have greened up, dead lawns are still brown. Cool night temperatures and bright sunny days should bring us some good fall color. Pests/Problems. Fall house invaders are beginning to appear. Western conifer seed bugs and the Asian ladybird beetle are making their way indoors. Yellow jackets are somewhat aggressive.

Southeast Region (Hanson) - General Conditions: Thanks to the remnants of hurricane Ophelia, Hanson received 2.75 inches of rain. Other parts of the county received over 4 inches. Thanks also to the remnants of hurricane Rita, Hanson received 1.75 inches of rain. Beautiful fall weather has returned. Fall color is starting to show up on red maples, catalpa, burning bush, bittersweet, and flowering dogwoods. Fall blooming clematis, the flowers of Hydrangea paniculata 'Tardiva', Sedum 'Autumn Joy', Rudbeckia 'Herbstonne', Eupatorium rugosum, landscape roses, Heptacodium miconioides, Chelone, fall blooming anenomes, Cimicifuga simplex, Trycertis sp., many ornamental grasses, Phlox paniculata, fall asters, goldenrod, Kousa dogwood fruit, holly fruit, the aging flowers of Hydrangea paniculata and Viburnum trilobum fruit, are all providing late season color to the landscape. Pests/Problems: Insect and disease activity has slowed down. However, earwigs, ticks, slugs, snails and mosquitoes are all active. Powdery mildew is evident on many plants as is tar spot on maples.

East Region (Boston) - General Conditions: Dryer than expected judging from the cloud cover and passing weather fronts.

Central Region (Boylston) - General Conditions: Soils are still dry in spite of the modest rains in the last two weeks. Trees are beginning to color up, as are the fruits of winterberries and viburnums.

Pioneer Valley Region (Amherst) - General Conditions: The asters, roses and mums are coming on as the goldenrods fade. Fall colors are becoming more visible on some woody plants such as dogwood, ash, katsuratree, sumac and poison ivy. Moreover, as Randy Prostak put it, “all the weeds and perennials have that, I’m tired look.” Established turf continues to look green, and newly seeded lawns are greening up well. Pests/Problems: One of the reasons so many herbaceous and some woody plants look “tired” is because it was another banner year for leaf spots and shoot blights as well as powdery mildew. Sugar maples were turning color early, and now many are defoliated. In many cases these trees are growing where compacted soil, deicing salt, as well as, water shortage and heat stress have been weakening them for years. Compacted soil damages roots and impairs water absorption when it does fall. Deicing salt damages roots and changes soil structure and chemistry unfavorably. Water shortage and heat stress during the growing season shuts down photosynthesis during the periods conditions are dry. The cumulative effect of all this is beginning to show up as more sugar maples continue to decline.

Berkshire Region (Great Barrington) - General Conditions: Night time temperatures have cooled considerably in the past 10 days with several lows in the upper 30s being recorded. Color change has begun for certain species. Many trees, i.e. birch, ash, have already lost most of their leaves, probably as a result of drought stress. Despite a few rainfalls, soil moisture is low. Watering trees and shrubs now, while root activity is at its peak, is essential to the survival of stressed plants. Pests/Problems. Slugs, ticks, and wasps are prominent pests while foliar diseases, especially powdery mildew remain the most widely occurring diseases.

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 that result 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 bugis 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 - The following are guidelines for managing insects that seek shelter indoors for the winter:

• 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 a 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 visible with a hand lens on the underside of many 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 brown-blotched leaves. The impact of the disease is quite noticeable. However, it has been noted that horsechestnut that suffer repeated severe infections continue to grow vigorously in spite of Guignardia leaf blotch.

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, U. S. 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.

The U. S. 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

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

WEEDS

Japanese knotweed or Polygonum cuspidatum is approaching the end of its flowering period in most parts of New England. Herbicide applications to control Japanese knotweed should be made now and can continue as long as plants are not showing fall color. Products containing glyphosate will provide good control; however, retreatment next year will probably be needed.

Prepare ornamental beds for the onslaught of winter annual weeds, especially if the mild weather of last winter resulted in beds becoming overrun with weeds. Add a fresh layer of mulch if mulch has not been added since late spring and early summer after last year’s crop of winter annuals set seed. Mulch can be used in conjunction with an application of a preemergence herbicide. Control existing weeds by hand-pulling or a non-selective herbicide before applying the preemergence herbicide. A non-selective and a sprayable preemergence herbicide can be tank-mixed and applied at the same time. Tank-mixes, depending on situation and type of plant material present, may limit the amount of area that you are able to effectively treat. Allow weeds to show herbicide symptoms, and then mulch. Monitor for escapes, and treat when they are small. 

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 are normally not a major problem in turf, but apparently something about this summer has been to their liking. Wireworms are the larvae of click beetles. They 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 adult click beetle is somewhat elongated and has 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 of an 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 lately may have provided 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:

Broadleaf herbicide applications made in late summer and early fall are generally more effective than those made at other times of the year. Fall applications can continue through the month of October. Applications made later during this period will result in slower but still effective weed control.

Crabgrass and other annual grassy weeds continue to decline with the arrival of cooler weather and shorter days. Areas of turf that have thinned as a result of moderate or heavy crabgrass pressure should be fertilized in order to regain density. 

Randall Prostak, Weed Specialist, UMass Extension, Plant, Insect & Soil Sciences Dept., Amherst

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 early November , 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.

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