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ENVIRONMENTAL
DATA
The statewide GDD averages for this period are as follows: Total = 432.7; GDD/week = 43.8; GDD/day = 7.3 REGIONAL
NOTES Southeast Region (Hanson) - General Conditions: Cool, wet gray weather continued this past week and temperatures continue to be below normal. Hanson received 1.75 inches of rain this past week. All the wet weather continues to make mowing difficult! Doublefile viburnum and other viburnums, Rutgers hybrid dogwoods, Goldenchain tree, (Laburnum sp.), Kerria, hybrid lilacs, Wisteria, Phlox stolonifera, Arisaema, Corydalis lutea, Dicentra eximia, Dicentra spectabilis, Epimedium, tree peony, bearded iris, Lily-of-the Valley, Solomon's seal, Columbine, Helleborus foetidus, Lunaria, Pulmonaria, Polemonium, Phlox divaricata, Phlox subulata, Primula, Tiarella, Trillium, Vinca minor and ajuga are in full bloom. Crabapples, flowering dogwoods, Exochorda racemosa (pearlbush), common lilac and Fothergilla are past bloom. Cornus kousa bracts are expanding. Pests/Problems: Winter moth caterpillars are beginning to pupate. Red maples, untreated apples, crabapples, oak and ash sustained considerable damage in many areas. Caterpillar populations are mixed (cankerworm, gypsy moth, forest tent and winter moth) and in high numbers. Hanson received several calls from West Wareham concerning high numbers of forest tent caterpillars looking for places to pupate. Termites were swarming outdoors in Hanson over Memorial Day weekend. Lily leaf beetle, hemlock woolly adelgid, carpenter bees and bumble bees, mosquitoes, black flies and ticks are active. Chickweed, buttercups, and veronica are all in full bloom. The bright orange gelatinous fruiting structures are still visible on eastern red cedar. The Hanson office has received many calls regarding mosquitoes. Plymouth County Extension does not spray for mosquitoes. The number to call for Plymouth County residents is: 781-585-5450, Plymouth County Mosquito Control. Barberry and burning bush, two Massachusetts invasive plants, are in bloom. If potential seed dispersal is of concern to clients, prune or shear plants now to remove flowers. Seed production will be interrupted and plants will grow and fill in nicely while producing fewer seeds. East Region (Boston) - General Conditions:Third instar caterpillars of forest tent caterpillar are still feeding on oaks. Heavy damage caused by winter moth caterpillars is noticeable along many of the parkways causing near complete defoliation of some of the oak trees there. Central Region (Boylston) - General Conditions: No report. Pioneer Valley Region (Amherst) - General Conditions: Cool, wet weather has maintained the lush and green look of the landscape in the Pioneer Valley. Iris, columbine, Catawba rhododendron, pansies and phlox charm the person who stops to appreciate their presence in the landscape. Berkshire Region (Great Barrington) - General Conditions:The rain was much needed and soils are now moist enough to facilitate planting. More damage from the hard freezes in mid and late May are evident. Lilacs seemed to have received a lot of frost damage to flower and leave buds. Other plants with damage to flower buds included enkianthus and spirea. Pests/Problems: The rain has encouraged slug activity and damage to many herbaceous plants, especially the favored hosts such as hosta, is apparent. Other pest activity includes leaf tiers on birch and crabapples, canker worms on many species of deciduous trees, pine spittlebug, European pine sawfly, aphids and leaf hoppers. Eastern tent caterpillar larvae are nearly fully grown. White grubs are feeding on roots of turfgrass and, in turn, are being preyed upon by skunks who are digging up turf areas in pursuit of the grubs. Carpenter bees, mosquitoes and black flies are still very active. As outdoor activities increase, so has the occurrence of deer ticks on people working, hiking or playing outdoors. The level of reported occurrences seem to indicate a banner year for deer ticks. Bacterial blight on lilacs is severe on some sites. PHENOLOGYThe phenological indicators are a visual tool for correlating plant development with pest development. The following are the indicator plants and the stages of bloom observed for this period:
CAPE COD REGION - Roberta Clark, Horticulturist for Barnstable County, Barnstable. SOUTHEAST REGION - Deborah Swanson, Horticulturist for UMass Extension in Plymouth County, Hanson EAST REGION - James R. Allen, Horticulturist and Greenhouse Manager for UMass Biology Department, Boston CENTRAL REGION - Joann Vieira, Superintendent of Horticulture, Tower Hill Botanic Garden, Boylston. WESTERN REGION - Dan Gillman, Plant Pathologist, Urban Forestry Diagnostic Lab, UMass, Amherst. BERKSHIRE REGION - Ronald Kujawski, Nursery Specialist, UMass Extension Agroecology Program, Great Barrington. Now that we have finally experienced warmer days with sunshine, leaf expansion and insect activity have increased noticeably. However, all parts of the state are far beyond last year's numbers for growing degree day accumulation and things still remain behind in development. Historically, the Amherst area has around 400 B 450 GDD by the first of June. Lepidopteran caterpillars:
Horsechestnut (Guignardia) leaf blotch is just beginning to become evident, as scattered, irregular-shaped orange-brown blotches on infected leaves. They are primarily affecting lower, inside leaves, and less than 10% of the total leaf area. However, as the summer progresses the impact of the disease may be more noticeable, but chemical intervention at this time for this season is of little benefit. Likewise, it has been noted that horsechestnut that suffer repeated severe infections continue to grow vigorously in spite of Guignardia leaf blotch. Powdery mildew fungi are now barely visible as a dusty, gray to white spots on horsechestnut leaves. Other plants that are typically infected such as phlox, dogwood, sycamore and rose are not showing signs of powdery mildew yet in the Amherst area. Once established on plants, powdery mildews grow superficially on both upper and lower leaf surfaces as well as green shoots and flower buds. They are obligate parasites and derive sustenance only from living host plants. They do this using minute, tube-like structures (haustoria) that penetrate the epidermal cells and draw out material they need to survive. Later this summer spherical, black fruiting structures (cleistothecia) will be visible with a hand lens on the underside of leaves in the dusty, gray mycelia. Generally, the damage caused by powdery mildew is of minor consequence to healthy plants and does not warrant chemical control if unsightliness is not a critical concern. If chemical control is desired there are a number of unconventional applied materials that are labeled to protect susceptible plants. They include summer horticultural oil, commercial baking soda preparations (sodium bicarbonate and potassium bicarbonate), anti-transpirants, as well as a number of conventional fungicides. Chemical spray programs are most effective when begun just as symptoms of powdery mildew begin to show. Once powdery mildew is extensive on the plant, there is little benefit from chemical control that season. Applications need to coat both surfaces of all susceptible plant parts to prevent infection. Spray on a regular schedule, and repeat more often during warm, humid weather. Oak leaf blister is showing up on red and pin oak leaves as faint, yellow-green spots. Puckering is minimal but noticeable, if you look closely. This is a not a serious fungal disease problem in our area. If a severe outbreak is occurring on specimen trees, note that for future reference. Chemical control activities should be started just before buds open next spring. Apple scab is minimally visible on susceptible crab apple leaves. The heavy, prolonged rainy periods appear to have suppressed early scab infections. Many leaves are curling or cupping where lesions developed before the leaves were mature, and the dead leaf tissue constricted leaf expansion. Within weeks after infection the olive green fruiting bodies produce new spores. New infections can occur essentially the entire growing season during wet and mild conditions. Now is a favorable time to maintain scab-susceptible crabapples in the landscape in which infection has just begun with fungicides. These fungicides act primarily to prevent new infections, especially those infections that would develop on newly emerging leaves. Systemic fungicides can reduce the incidence of apple scab as the season goes on if they are applied soon, before the extent of infection is too severe, and protection is maintained at labeled intervals. Alternate every second or third systemic fungicide spray with a broad-spectrum fungicide to reduce problems with the development of fungicide resistance by the apple scab fungus. Prune to increase sunlight penetration and air circulation to promote rapid drying of wet foliage. If apple scab is a chronic problem, consider planting resistant varieties of crabapple if replacement is an option. This fall remove and destroy fallen leaves in the vicinity of the tree to reduce primary inoculum available for initial infections next spring. Sycamore, maple, and oak anthracnose are evident now as dark-green to dark-brown curling leaves and shoots, while ash anthracnose is apparent as young green leaves with tiny brown spots falling from the trees. Anthracnose is widespread on early leaves and shoots this year due to the abundance of inoculum on over-wintering twigs and fallen leaves, as well as the consistently wet weather. These diseases cause some premature leaf loss, but that is not going to seriously an otherwise healthy tree. In the fall fine prune infected twigs and collect and dispose of fallen leaves. Promote drying of foliage by pruning and spacing plants to increase the penetration of sunlight and air circulation in and around plants. Phomopsis Tip Blight . The current wet conditions, along with the development of immature scale-leaves/needles are favorable for infection of juniper by Phomopsis tip blight. Juniper shoots that are tan-gray with pinhead sized, black fruiting bodies are producing spores at this time. New growth that becomes infected this spring with Phomopsis tip blight will turn green-yellow, then brown and die within a few weeks of infection. Management begins with the removal and disposal of infected shoot tips to reduce inoculum. Cut an inch or so below the boundary between dead and healthy tissue. Now is the time to initiate fungicide control of juniper tip blight to improve plant appearance. Grow junipers in an open, sunny location to promote drying of foliage, that are adapted to the site and that have resistant to tip blight. Dogwood Anthracnose . The fruiting structures of this fungus are apparent on trees where there are buds that did not open and twigs and branches that died back. Water shortage, heat stress, compacted soils and winter damage weaken trees and increase the severity of the disease. Dogwoods receiving good cultural care are better able to limit the extent of dogwood anthracnose damage. Water during dry periods and maintain 2-4 inches of composted bark mulch over as much of the root area as possible. Prune off and dispose of diseased twigs and branches to reduce anthracnose inoculum that is in the tree and is readily splashed to nearby leaves and shoots. Four fungicide applications are usually needed to control dogwood anthracnose on susceptible trees during wet seasons. Begin now (as buds break open), when bracts have fallen, and four weeks later as well as in late summer if there is wet weather after flower buds form. If this is a persistent problem consider planting one of the many resistant cultivars of C. florida and C. kousa now commercially available. Bacterial blight , caused by Pseudomonas
syringae, blackens flowers, new leaves and shoots on lilacs,
and stone fruits, as well as frost-damaged Japanese, Norway and
red maples. The host range is actually wider, but these are the
most common hosts in our area. In severe cases shoots are girdled
and killed and flower clusters become limp and brown. Infection
begins during mild (60-70 degrees F), rainy periods. The bacteria
typically enter tender plant leaves and flowers through natural
openings (stomata, lenticels, nectarathodes, etc.) and frost
wounds. As leaves mature, they are less susceptible and leaf
infections late in the season are rare. Remove infected shoots
during dry periods at least 8-12 inches below the edge of the
lesion or where the infected branch attaches to another branch.
Disinfect pruning tools with 10% bleach or 70% ethyl alcohol
between cuts. Chemical control is not usually necessary, as the
blight does not usually kill plants. However, when appearance
is important, this is the time to initiate chemical controls
to protect flowers and new growth on nursery and specimen plants
from infection. Many copper-containing fungicides are labeled
to control this disease. One or two follow up sprays at 10-14
day intervals are needed if wet weather continues this spring.
If this is a persistent problem on lilac consider replacing susceptible
ones (Chinese [Syringa x chinensis], Japanese
[Syringareticulata],
Persian [Syringa x persica] and white-flowered
common lilac) with some of the many cultivars of resistant varieties
that are available.
Ramorum Blight, also known as Sudden Oak Death (SOD) - Since 1995, oaks and tanoaks have been dying in the coastal counties of California. Since then, other types of plants have been found to be infected or associated with this disease, referred to as Sudden Oak Death, ramorum leaf blight or ramorum dieback, or by regulation as Phytophthora ramorum. SOD was first seen in 1995 in Mill Valley (Marin County) on tanoak. Since that time, the disease has been confirmed on various native hosts in fourteen coastal California counties (Marin, Santa Cruz, Sonoma, Napa, San Mateo, Monterey, Santa Clara, Mendocino, Solano, Alameda, Contra Costa, Humboldt, Lake and San Francisco), and in Curry County, Oregon. Research being conducted by the Agriculture Research Service, US Forest Service, universities and others is under way to better identify hosts, methods of detection and effective treatments. Currently, 64 plants are regulated, two of which at the genus level (Camellia and Rhododendron). There are no chemical treatments currently available to eliminate the disease in nursery stock. Status of Phytophthora ramorum Monitoring
Surveys -
The 2005 National Nursery Survey is underway. Ten states have reported
on their progress. As of May 5, 2005, 221 sites have been surveyed
and 1744 samples have been collected; none have been confirmed
as positive for P. ramorum.
UMass Extension’s Landscape, Nursery & Urban Forestry Diagnostic Lab Report. The following are some of the interesting disease/abiotic disorder samples received at the diagnostic lab in Amherst during the period May 23 through May 27, 2005:
Diseases: No report: Visit the Landscape Message Archive for previous messages.
Randall Prostak, Weed Specialist, UMass Extension Landscape, Nursery, and Urban Forestry Program, 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
New England Guide to Weed Control in Turfgrass -
The updated 2005 New England Guide to Weed Control in Turfgrass
is now available. It
contains extensive information about currently registered turf
herbicide products, including specifics on application, timing
and environmentally responsible use. The guide is available as
a free, downloadable PDF file in the Online Publications section
of http://www.umassturf.org UMass Extension’s Turf Management Guide and IPM Facts:
For more information about the pests mentioned in this
message, you will need to refer to the following publications: the
Professional
Guide for IPM in Turf for Massachusetts, 2003-2004 DIAGNOSTIC SERVICESUMass 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 NEXT UPDATE: The next issue will be available in Friday, June 10, 2005. This message is produced by the UMASS Extension, Landscape, Nursery and Urban Forestry Program. The copy is prepared by Anna Greene from data and reports provided by the staff and faculty of the UMass Landscape, Nursery and Urban Forestry Program and the UMASS Extension Turf Program as well as cooperating horticulturists and Green Industry professionals. The text is adapted for access via the internet by Jason Lanier and made available to subscribers via electronic transmittal by Ellen Weeks. DISCLAIMER. This message is intended for commercial use. UMASS Extension assumes no liability for recommendations. The use of trade names does not imply endorsement. Similarly, there may be other products you prefer to use. Comments or suggestions in regard to the Landscape Message? Please e-mail the webmaster. Missed a previous message? Visit the Landscape Message Archive.
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- In 2004, this pest began dropping from the trees and pupating
on May 20. This year, the process started in the warmer regions
on May 29. From Boston down through Plymouth County and much
of SE MA are now seeing the end of the larval (feeding) period
and pupation. However, on the North Shore areas (above Boston)
and out on Cape Cod, where temperatures have been much lower,
this insect still has another week or so to go before pupation.
Treatments for this insect in the regions where it is finishing
feeding are no longer necessary. In the cooler areas, treatments
should be considered on a case-by-case basis. In all areas,
it is most likely too late for Bacillus thuringiensis kurstaki.
One could still apply a spinosad product (e.g., Conserve SC™) or a tebufenozide
product (e.g., Confirm™) or one of the registered pyrethroid insecticides
if deemed necessary in the areas where winter moth is still feeding. Note: A new fact
sheet entitled '
,
for current information on this pest. Report any new findings
in MA to Robert Childs, 