UMass Extension Landscape Message #24
September 24, 2004

Quick Info Menu ------------------------------- ENVIRONMENTAL DATA REGIONAL NOTES - Cape Cod - Southeast - East - Central - West - 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!

ENVIRONMENTAL DATA

The following growing degree day (GDD) and precipitation data was collected from September 9 through September 22, 2004. Soil temperature and phenological indicators were observed on September 22, 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: Beautiful fall weather. Thanks to the remnants of hurricane Ivan, Hanson received 2.75 inches of rain. Fall color is starting to show up on red maples, Catalpa, burning bush, bittersweet and flowering dogwood. The aging flowers (pink) of Pee Gee hydrangea (Hydrangea paniculata 'Grandiflora'), fall blooming clematis, Corydalis lutea, Lobelia syphilitica, Sedum 'Autumn Joy', many ornamental grasses, Phlox paniculata, fall asters, goldenrod, Kousa dogwood fruit, 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. There has been three confirmed human cases (two deaths) of eastern equine encephalitis, a mosquito borne illness, in the Brockton/Holbrook area. Wasps and hornets are plentiful.

East - General Conditions: No report.

Central - General Conditions: No report.

West - 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. And, as Randy Prostak put it, "all the weeds and perennials have that 'I'm tired' look". Established turf continues to look green and plush, 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. There are some sad looking sugar maples around that were turning color early and now are defoliated. In many cases these are trees growing along roadways where compacted soil, deicing salt, as well as, water shortage and heat stress from years ago, are beginning to send the trees into decline.

Berkshire - General Conditions: It was a wet two weeks due to two major rain events. The latest was fallout from Hurricane Ivan, depositing 3.80 inches of rain in about 24 hours creating some flooding. As expected, soil moisture levels are high. The moisture is good for trees and shrubs and enhances their chances of winter survival. Pests/Problems: The usual array of foliar diseases that have plagued perennial plants and certain woody species continue to be noticeable. Early color change is evident on stressed trees in home landscapes and along roadways.

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):

• Mimosa Webworm are slowing down and, in most cases, there is no need for management. Occasionally, in the fall they do become a temporary problem when seeking shelter, often on houses.
  
• Fall Webworm are very noticeable now; however, this pest has finished feeding for this year.
  
• Oak Skeletonizer become especially noticeable at this time of year. The tiny, yellow caterpillars can be seen hanging from long threads from oak leaves. Larvae form cocoons that appear as small grains of rice. In larger populations, oak leaves will have numerous individual skeletonized 'windows' on the foliage and leaves. This pest usually does not require control.

Hymenoptera (sawflies):

• Red-headed Pine Sawfly remains very active. Mugo pine is a common host but other pines are susceptible. Spinosad products work well. Small infestations can be pruned away. This pest will feed well into the fall, usually up until the first hard frost. It has the potential to be a very serious defoliator.

Beetles

In general, products containing spinosad are effective against the larvae (at least) of many free-feeding beetle, especially the Chrysomelid (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:

• Imported Willow Leaf Beetle is quite noticeable; however, feeding has ceased for this year.

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 remains active throughout MA. Inspect the undersides of foliage for their presence. Summer oil sprays or insecticidal soap are the best options now.
  
• 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.

Aphids:

• Assorted Aphid Species remain active on many different hosts but they are becoming less common. Inspect plants carefully for building populations. Catalpa, rose, lindens and many others are common hosts for aphids. Sooty mold problems are now at peak levels from the copious amounts of honeydew that these insects produce. Treatments now are most likely not necessary. Ladybugs are prevalent on plants that were infested with aphids.

Adelgids:

• Hemlock Woolly Adelgid (HWA) can still be treated with horticultural oil even though this pest is still 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 to make the application until regular rain or irrigation is available along with cooler temperatures.

Other Piercing-Sucking Insects:

• Sharpshooter Leafhopper (aka Red-banded Leafhopper) remains active. Although found on various host plants, they cause their injury particularly to rhododendrons. By feeding on the newest foliage, they cause stunting and curling of the foliage. These will be active until the first good frost. Although they don't kill host plants, their feeding can reduce the aesthetic value of plants, especially those in nurseries. Treatments now are not necessary.
  
• 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 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 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 active once again on spruces and hemlock. Being a cool-season mite, it will remain active through October and possibly into November. Monitor for building population numbers and treat if needed.

Leafminers

• Arborvitae Leafminer are mining foliage. Browning of mined foliage will not appear until January or February.
  
• Locust Leafminer on Black Locust has ended its activity and its damage is now very apparent.

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:

• The Tuliptree Scale is very noticeable now. The large, brown 'gumdrop-shaped' coverings of the dead females may harbor up to 3000 eggs each. This pest produces huge amounts of honeydew and now sooty mold problems will be quite obvious. Treatments at this time are challenging.
  
• Taxus Mealybug (technically not a scale but a close relative) has finished feeding for this year.

Wood Attackers

• Asian Long-Horned Beetle (ALB), which is not yet known to exist in MA, remains very active in New York City and New Jersey. The adults of ALB are a very shiny black with crisp white spots. Their antennal segments alternate between white and black segments. Visit the web site listed here for more details: http://www.na.fs.fed.us/spfo/alb
  
• Monitor previously stressed plants (drought, soil compaction, etc.) for signs of invasion of wood borers. Bronze Birch Borer is one such invader.
  
• The Two-Lined Chestnut Borer, which is a close relative of the BBB, is usually found in previously stressed oaks and birches. Inspect for declining health and 'D-shaped' exit holes.
  
• Tunneling larvae of Rhododendron Borer will expel sawdust but this early signal can be hidden by dense foliage. Often, an 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. Yellow jacket populations are now at peak levels and often come into contact with humans at this time of the year.
  
• Western Conifer Seedbug populations are building and can be found on the seeds (cones) of conifers. These do not harm 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 now on windows, doors and attic vents; and repair, if necessary. Also, inspect and repair caulking around the same areas.
  
• Squirrels are now chewing shoots from many different trees, such as oaks, in order to obtain the seeds. Dozens of live shoots with green leaves can be seen littering the ground. However, this usually does not hurt the tree.

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

DISEASES

Horsechestnut (Guignardia) leaf blotch - As summer progresses the scattered, irregular-shaped orange-brown blotches are becoming larger, but it is too late for chemical intervention this season. Collect and dispose of leaves as they fall.

Powdery mildews - These fungi are visible as a dusty, gray to white coating on phlox, lilac, dogwood, and sycamore leaves, as well as rose leaves and flower buds. 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. On some leaves spherical, black fruiting structures (cleistothecia) are 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 when the white dusty spots first appear in late spring next year. 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 develop 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 midday to reduce period of time leaves are wet. If replacement is an option, many beautiful, resistant varieties are available. Apply fungicide sprays at intervals specified on the label to protect healthy foliage. Nothing can be done to disinfect spotted leaves. 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. 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 2" diameter brown galls, as well as fissures in the bark are visible 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 of little benefit; but if it were desired, it would be from mid-August through September.

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 flowering 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 2004 Phytophthora ramorum has been found in nurseries in California, Oregon and Washington. These detections demonstrate that the pathogen is not necessarily limited to the moist coastal regions of northern California and southern Oregon. All of these nurseries distribute nursery stock nationwide, including Massachusetts. 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.

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 (see below -- there is some doubt about this situation) 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 157 in 21 States. The breakdown per State is: AL (3), AR (1), AZ (1), CA (53), CO (1), FL (6), GA (18), LA (5), MD (2), NC (9), NJ (1), NM (1), NY (1), OK (1), OR (10), PA (indoor), SC (3), TN (2), TX (11), VA (2) and WA (25). It is important to note that only three are from residential landscape situations, two in Georgia and one in South Carolina, as well as one environs find on Long Island, NY.

As of September 2, 2004, the participating States have surveyed 2,166 sites and have collected 39,406 samples; 15 sites are confirmed positives. The number of positive finds has been adjusted down due to re-categorization of 4 finds in Washington State. On a similar note, there are colleagues in New York that still question the find in a natural area of Long Island (see paragraph below). Tests are still pending to resolve this question. The US Forest Service P. ramorum nursery perimeter and general forest surveys continue; all sampling results are negative or still pending to date, with the exception of 2 positives Coast Live oak in Golden Gate Park in San Francisco, and 11 positives in the regulated area of Curry County, CA. As of September 3, the US Forest Service has conducted 610 nursery perimeter surveys in 32 states and 399 general forest surveys in 18 states.

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.

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 September 6 through September 17, 2004:

• Arborvitae - there was scattered dieback of twigs and some branches; winter freeze + drying damage/worsened by Pestalotiopsis blight.
• Austrian pine - several newly transplanted 8-year-old trees in south shore area with fairly uniform branch tip browning and stunted growth this year; no disease/transplant stress/water shortage.
• Sugar maple - ~20-year-old street tree with many branches in the crown yellowing and dying; several years of drought stress/soil compaction/deicing salt damage/opportunistic Phomopsis (Diaporthe) canker.
• American elm - 75 year old specimen tree with wilted and brown leaves on 50% of crown; phytotoxic reaction to improper fungicide injection.
• Mugo pine - 25 year-old tree with scattered brown, stunted new shoots and needles; Sphaeropsis (Diplodia) shoot blight/windy site/root damage.

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

WEEDS

Japanese knotweed or Polygonum cuspidatum is now in flower or just past flowering in New England. Herbicide applications to control Japanese knotweed should be made now. Applications can be made through the month of September as long as plants are not showing fall color and/or dropping leaves. Products containing glyphosate will provide good control; however, re-treatment next year may be needed.

Prepare ornamental beds for the onslaught of winter annual 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 applied during the month of September and early October. Control existing weeds by hand-pulling or applying 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. Allow weeds to show herbicide symptoms and then mulch. Monitor for escapes and treat when they are small.

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.

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

TURFGRASS

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

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

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

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 . NOTE: Dr. Schumann's lab at Marquette University is permanently closed as of August 31, 2004. All samples for turf disease diagnosis must now be directed to UMass Amherst.

NEXT UPDATE: The next issue will be available on Friday, October 8, 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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