UMass Extension Landscape Message #25
October 8, 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 22 through October 6, 2004. Soil temperature and phenological indicators were observed on October 6, 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 continues although nights are getting chilly. Hanson had a light frost the 5th of October, but impatiens, coleus and other annuals survived. Hanson received 3.0 inches of rain. Fall color is starting to show up. However many of the trees still have tattered leaves from the caterpillar damage last fall and good colorful foliage is sparse. The aging flowers (pink) of Pee Gee hydrangea (Hydrangea paniculata 'Grandiflora'), Corydalis lutea, Sedum 'Autumn Joy,' many ornamental grasses, Phlox paniculata, fall asters, goldenrod, Kousa dogwood fruit, and Viburnum trilobum fruit, continue to provide late season color to the landscape. Pests/Problems: No new pest problems to report. With the cool weather comes a decline in mosquitoes for which many people are grateful.

East - General Conditions: No report.

Central - General Conditions: No report.

West - General Conditions: There were a couple of days of steady rainfall (on September 28 and 29) in the Pioneer Valley during the last two weeks. The recent cool weather has put the 'feel' of fall in the air, which complement the fall colors that are becoming more apparent each day. Pests/Problems: The premature defoliation of some hardwoods that began in mid-summer due to heavy leaf spot and anthracnose infections, as well as decline due to stressful growing sites, prior years of drought, and secondary insect and diseases continues. There is also a fair amount of browning and curling due to powdery mildew. The powdery mildew makes the trees look unsightly, but usually this does not significantly impact tree health if they otherwise have good vigor.

Berkshire - General Conditions: Widespread freeze throughout Berkshire County on the morning of October 6 finished off the more tender annuals. Fall foliage color is shaping up well with about 20 percent color at this time. There's plenty of soil moisture so plants should go into winter well hydrated. Pests/Problems: No particular problems are prominent.

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):

• 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. Larvae form cocoons that appear as a 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 active, especially in the coastal areas. 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 good 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 is virtually finished for this year throughout MA.
  
• Azalea Lacebug is virtually finished for this year.
  
• Sycamore Lacebug has ceased to feed for this year.

Adelgids:

• Hemlock Woolly Adelgid (HWA) can still be treated with horticultural oil even though this pest is still dormant. However, it is about to break dormancy and resume feeding. Either way, it can be treated with oil sprays as long as the weather conditions are favorable.

Spider Mites:

• Spruce Spider Mite remains active on spruces and hemlock. Being a cool-season mites, 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.

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.
  
• Elongate Hemlock Scale (Fiorinia Scale) on the undersides of hemlock needles.

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.

Wood Attackers

• 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. Now that their natural source of food is mostly gone, these insects 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. 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.
  
• Ladybugs will soon be seeking shelter, often in houses. When in large numbers, they are quite problematic. Fix all caulking and screening on windows, doors and attic vents to help keep them out.

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

DISEASES

Horsechestnut (Guignardia) leaf blotch - The development of irregular-shaped, orange-brown blotches was quite extensive on susceptible trees. 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 the leaves and flower buds on roses. In addition to having this dusty coating, infected immature leaves become yellowed, puckered and stunted. Powdery mildews are obligate parasites and derive sustenance only from living host plants. 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. 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. If replacement is an option, many beautiful, resistant varieties are available. Fungicides labeled to protect foliage on susceptible plants are listed in the UMass Extension Management Guide for Woody Ornamentals.

Dogwood anthracnose infections are evident as 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.

Ramorum blight, also known as Sudden Oak Death (SOD) - The fungus Phytophthora ramorum causes Ramorum blight. It is a severe disease of oak and tanoak in certain Pacific Northwest fog forest areas. In 2004, Phytophthora ramorum was 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. Not all of the details of how the fungus spreads have been worked out, but these reservoir plants may play an important role.

SOD (Phytophthora ramorum) surveys in nurseries and forest areas around the state were performed this year. 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.

In September, PPQ detected Phytophthora ramorum at two production farms owned by the same company. The nursery had shipped plants to other nurseries and garden centers nationwide. It is now under investigation and cannot ship susceptible material.

As of September 29, 2004, the total number of confirmed positive locales from the trace forward, national, and other survey finds is 160 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 (13), 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 possible environs find on Long Island, NY (see below).

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 20 through October 1, 2004:

• European beech - there were bleeding lesions associated with scattered dieback of branches; soil compaction/previous drought/winter freeze/worsened by Endothia canker.
• Chinese elm - dieback of twigs and branches scattered throughout the crown of 20-year-old tree; winter damage/water shortage/Tubercularia and Botryodiplodia cankers.
• London planetree - ~20-year-old street trees with yellow-brown, curled leaves falling prematurely; powdery mildew/sycamore lacebug feeding.
• Northern red oak - mature specimen tree on edge of parking area developed wilted, brown leaves throughout the crown in August; several inches of gravel parking area (containing 40% of root zone) was dug out and replaced with asphalt.
• Apple - 30-year-old tree with wilt and death of one section of a scaffold limb; black rot (Botryosphaeria) canker.

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

TURFGRASS

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

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

Weeds:

Fall broadleaf herbicide applications can continue to be made through mid to late October. Control will be slow but still effective.

Applications of glyphosate can still be made to perennials and newly emerging winter annuals. The speed of control with these applications will also be rather slow.

Monitor for annual bluegrass or Poa annua. Preemergence herbicides can be applied before germination. Some options include prodiamine -Barricade™, dithiopyr - Dimension™, pendimethalin - Pendulum™, PRE-M™ and oxadiazon - Ronstar™.

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

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 in early November, 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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