UMass Extension Landscape Message #15 - 2012 | UMass Extension Landscape Nursery & Urban Forestry | UMass Amherst

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UMass Extension Landscape Message #15 - 2012 June 29, 2012 Quick Links The Landscape Message is an educational newsletter intended to guide landscape, nursery and urban forestry professionals in What are YOU seeing? Scouting Information identifying pests in the landscape, monitoring their development, Regional Notes planning management strategies and creating site-specific records Please submit your observations in the Cape Cod for future management reference. UMass Extension has updated this Reader Feedback section belo Southeast issue to provide timely pest management information and the latest East regional news and environmental data throughout Massachusetts. Metro West The Landscape Message will switch to a bi-weekly schedule for the months of July, August and Central September. The next message will be available on July 13. To receive immediate notification Pioneer Valley when the next Landscape Message update is posted, be sure to join our e-mail list. Berkshire Environmental Data This Landscape Message is the last for longtime contributor Dan Gillman. Dan, who has worked for Phenology UMass Extension for 15 years as a Pathologist and Diagnostician for the UMass Extension Plant Woody Ornamentals Diagnostic Lab, will retire July 6. He looks forward to spending more time with family and the next big adventure that life has to offer. Please join us in wishing Dan farewell and the best of luck for a long Landscape Turf and fulfilling retirement! Archived Messages Scouting Information by Region Regional Notes Cape Cod Region (Barnstable) – General Conditions: The warmth of summer finally arrived on the Cape this reporting period. Temperatures soared into the upper 80s F and low 90s F for four days before a cold front brought them down. The Cape escaped the severe thunderstorms over the weekend but did receive 0.5” of rain on Saturday, June 23 and again on Monday June 25. Strong thunderstorms did come through the Cape on Tuesday, June 26, with torrential downpours, lightning, pea-sized hail, and even a reported funnel cloud in the Harwich/Chatham area. We gained 1.5” of rain from that event. Shasta daisies are beginning to bloom in the garden. Pests/Problems: The first oriental beetle has been observed and Japanese beetles are expected to emerge very soon. Asiatic garden and June beetles are active. Lily beetle larvae are beginning to pupate and second generation adults will be on the scene soon. Cottony taxus and cottony maple scale egg masses are quite visible. Begin monitoring infested for the crawler stage. Green head flies are active on the North side and near salt marshes. Mosquitoes are also becoming a nuisance. Earwigs are skeletonizing newly planted zinnias. Slugs and snails are numerous on hosta. Powdery mildew is active on phlox. Black spot is defoliating susceptible roses. Dollar spot was observed on turf.

Southeast Region (Hanson) – General Conditions: Hot weather came in last Wednesday; the beginning of a 3-day heat wave that set records in many areas. Hanson saw temperatures in the mid-90’s (96, 95, and 96). As a result of the extreme high temperatures and dry soils, unirrigated plants like Hydrangea macrophylla and Heuchera experienced scorched or foliage. Temperatures dropped to the low 80’s over the weekend, following thunderstorms which supplied the much needed rain. Thunderstorms continued into the week and were again scattered over the county, with some areas receiving significant amounts of rain and others not so much. Hanson received 2.25 inches of inches of rain this past week. It is still important to continue to remind clients to water newly planted trees and shrubs and trees defoliated or damaged by caterpillars. Stewartia pseudocamellia, Stewartia rostrata, Southern , Catalpa ovata (Chinese catalpa), Hydrangea quercifolia (Oakleaf Hydrangea), Daphne ‘Summer Ice’, Hypericum androsaemum ‘Mrs. Gladis Brabazon’, Indigofera sp., Calycanthus floridus (Common Sweetshrub), Lonicera sempervirens, Clematis, Roses, Spiraea sp., Ilex verticillata, Ilex pedunculosa, Spigelia marilandica (Indian Pink), Echinacea, Oenothera sp., Gillenia trifoliata (Bowman’s Root), Heliopsis sp., Thalictrum flavum subsp. glaucum, Campanula sp., Lysimachia punctata, Geranium sp., Persicaria polymorpha, Lamium, Asiatic lilies, Nepeta sp., Thermopsis, Alchemilla mollis, Coreopsis sp., Corydalis lutea, daylilies, Astilbe, Hosta, and Yucca filamentosa are in full bloom. European Smokebush (Cotinus coggyria) and the native American Smoketree (Cotinus obovatus) continue to provide the landscape with colorful “smoke”. Staghorn sumac seed heads are

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starting to turn red. Pests/Problems: Oriental beetles have emerged and are feeding on a wide variety of plant material. Roses are looking very good this year and many have bloomed early, avoiding damage from Japanese beetles, which have yet to emerge. Hibiscus sawfly was observed feeding and skeletonizing the foliage of perennial hibiscus. If left untreated, the foliage is often reduced to only the veins, resembling thread-like lace. Earwigs continue to be a nuisance, skeletonizing the foliage of plants like Echinops and flowers of other plants (roses, dahlias, vegetables, etc.) Insects that continue to be active: Imported willowleaf beetles, oriental beetles, Pieris or andromeda lacebug, golden tortoise beetle, Asiatic garden beetles, cottony camellia scale on blue holly and Taxus, aphids, slugs, snails, stink bugs, four-lined plant bugs, leafhoppers, lily leaf beetle (adults & larvae), wasps, hornets, carpenter bees, deer flies, mosquitoes, horse flies and deer and dog ticks are all active. Beneficial insects are also active. Peony blight (perhaps Botrytis) has been showing up on herbaceous peony. Diseases that continue to be observed include: powdery mildew on a variety of plant material; brown rot (Monilinia sp.) on Kwanzan cherry, black spot on roses; oak leaf blister, apple scab and cedar apple rust on crabapples; anthracnose on many plants; various leafspots on dogwood, witch hazel and garden phlox. Weeds in bloom observed this past week: Lonicera japonica, milkweed, nightshade, Linaria vulgaris (Yellow toadflax), Phytolacca americana (Pokeweed), oxeye daisy, clover, fleabane and Queen-Anne’s-lace. Oriental bittersweet, autumn olive and multiflora rose are forming seeds; shear back or remove, if clients wish to prevent future seed dispersal. Woodchucks, wild turkeys, chipmunks and squirrels are very active in the ‘wildlife’ arena. Mosquitoes continue to be a nuisance. Remember to remind clients to empty containers like plant saucers or perhaps to treat them and other containers (birdbaths) that contain standing water, with Bti mosquito “dunks”. The Plymouth County Mosquito Control in Kingston, MA sprays for mosquitoes and the number for Plymouth County residents to call is: 781-585-5450.

East Region (Boston) – General Conditions: Late last week we recorded three consecutive days with high temperatures in the mid-nineties. We received a total of 3.46" of precipitation this week from four rain events over 5 days. On June 22nd we received a thunderstorm delivering 0.79” of precipitation and relief from the heat. We also received steady precipitation on June 25th and later in the evening a violent thunderstorm delivered an additional 1.55” along with minor storm damage, flooding and erosion. The soil is moist. The warm temperatures, followed by the significant rainfall has resulted in thriving plants and turf. Some plants in bloom include: Aristolochia contorta (pipevine), Cornus macrophylla (bigleaf dogwood), Cornus pumila, Dierevilla sessilifolia (bush honeysuckle), Pontideria cordata (pickerelweed) and Thalictrum sp. (meadow-rue). The thornless and underutilized ornamental Rubus fraseri (Frasers Blackberry) is in full bloom. Tilia japonica (Japanes linden) much showier than the typical street tree Tilia cordata (littleleaf linden) is in full bloom and fragrant. Humulus luplus (hops) known for its multiple uses is also in bloom. Pests/Problems: Crabgrass (Digitaria sp.) is getting significantly bigger after last weeks warm temperatures. Cuscuta sp. (dotter) is beginning to wind its’ parasitic tendrils around available hosts. Queen Anne’s Lace (Daucus carota) and Goldenrod (Solidago Sp.) are in full bloom. The invasive Phellodendron amurense (Amur corktree) is forming . Lacebugs (Stephanitis takeyai) are feeding on Pieris sp. and other evergreen ericaceous plants is evident by the yellowing and the presence of the sucking insects on the underside of the leaves.

Metro West (Acton) – General Conditions: The Metro West area gained 165.5 growing degrees this past week and has received a total of 3.93” of rain for the month of June which happens to be the historic 30 year average. Woody plants seen in bloom this past week are Catalpa speciosa (Northern Catalpa), Cornus kousa (Kousa Dogwood), Hydrangea arborescens (Smooth Hydrangea), H. quercifolia (Oakleaf Hydrangea), Ilex glabra (inkberry), Kalmia latifolia (Mountain Laurel), Ligustrum spp. (Privet), Magnolia virginiana (Sweetbay Magnolia), Potentilla fruiticosa (Potentilla), Rhododendron spp., Rosa spp. (Rose), Sambucus canadensis (American Elderberry), Spirea japonica ‘Alpina’ (Daphne Spirea), Stewartia psuedocamellia (Japanese Stewartia), Syringa reticulata (Japanese Tree Lilac), Woody vines in bloom are: Campsis radicans (Trumpet vine) and Clematis spp. (Clematis) and Lonicera japonica (Japanese Honeysuckle). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Achillea millefolium (Yarrow), Aegopodium podagraria (Goutweed), Alchemilla mollis (Lady’s Mantle),Mantle), Allium giganteum (Giant Onion), A. schoenoprasum (Chives), Anemone canadensis (Canada Anemone), Aruncus aethusifolius (Dwarf Goat’s Beard), A. dioicus (Goat’s Beard), Asclepias tuberose (Butterfly Weed), Astilbe spp. (False spirea), Campanula lactiflora ‘Loddon Anna’ (Bellflower), C. persicifolia (Peach-leafed Bell ), C. takesiman ‘Elizabeth’ (Bellflower), Clematis recta ‘Purpurea’ (Clematis), Coreopsis verticillata (Threadleaf Coreopsis), Digitalis purpurea (Foxglove), Filipendula rubra (Meadow Sweet), Geranium cantabrigiense ‘Biokovo’ and ‘Cambridge’ (Hardy Cranesbill), G. macrorrhizum (Bigroot Geranium), G. sanguineum (Cranesbill Geranium), Hemerocallis ‘Stella D’Oro’, H. fulva (Daylily) and Hemerocallis spp. (Daylily), Heuchera spp. (Coral Bells), Hosta spp. (Plantain Lily), Leucanthemum superbum (Shasta Daisy), Lilium spp. (Lily), Lychnis coronaria (Rose Campion), Monarda didyma (Bee-Balm), Nepeta spp. (Ornamental Catmint), Oenothera macrocarpa (Ozark Sundrops), Paeonia spp. (Peony), Platycodon grandiflorus (Balloon Flower), Potentilla tridentata (Wineleaf Cinquefoil), Salvia nemerosa (Salvia), Sedum kamshaticum (Stonecrop), Thymus vulgaris (Common Thyme) and Tradescantia virginiana (Spiderwort). Pests/Problems: With the recent moisture and humidity powdery mildew has been seen on susceptible Filipendula sp. (Meadow Sweet), Phlox paniculata (Summer Phlox), Rosa spp. (Roses) and Syringa spp. (Lilacs). Other fungal diseases appearing in the landscape are: fungal leaf spots on Amelanchier spp. (Serviceberry), rust on Alcea (hollyhock) and anthracnose on Acer rubrum (Red Maple), Cornus florida (Flowering Dogwood) and Platanus spp. (Sycamores). Mosquitoes continue to thrive especially with the recent rains as do the weeds. One of the more aggressive weeds, Cynanchum nigrum (Black Swallowwort) is in bloom.

Central Region (Boylston) – General Conditions: The extreme heat of last week has abated and cooler conditions have prevailed since Sunday. Periodic thunderstorms brought rain just in the nick of time.

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Pests/Problems: Asiatic beetles, three-lined potato beetles, slugs, wasps, hornets, bees, and tick are all enjoying the gardens these days. The damage from fireblight continues to show up on Malus.

Pioneer Valley Region (Amherst) - General Conditions: Very hot, humid conditions dominated the early portion of this reporting period. However, a low-pressure front generated moderate to severe thunderstorms across the region on Monday, providing a soaking rain in certain locations. The front significantly reduced area temperatures, and we have once again settled into a cool and wet pattern. Therefore, while the heat wave was intense, it was short-lived and should not have caused widespread damage to the regions trees and shrubs. Shrubs and shallow-rooting trees are most susceptible to heat and drought stress during these periods. Pests/Problems: Foliar and stem blight pathogens continue to be a problem on trees and shrubs, a lasting effect of the cool, wet weather in May and early June. If we experience a prolonged dry period in July, these pathogens will go dormant. Needlecast diseases are also abundant this year, on pine, spruce and fir. Several uncommon foliar pathogens are being reported across the region, an additional testament to the ideal environmental conditions for these types of pathogens.

Berkshire Region (Great Barrington) - General Conditions: A hot and dry period has slowed growth of turfgrass. However, landscapes look to be lush and generally in good health. Soil moisture is moderate to dry. Pests/Problems: Perhaps the most common complaint of home gardeners is the high numbers of chipmunks which are digging holes in lawns and gardens, and feeding on annuals and vegetables. Rabbits and crows have also become nuisances in many gardens. Hostas and daylilies have been targets for browsing by deer. Mosquitoes, gnats, and ticks continue to pose a problem for anyone working outdoors. Japanese Beetles have emerged and are actively feeding on a wide variety of plant material. Other plant pests observed this week include: Spruce Spider Mite, Euonymus Scale (crawler stage still visible), Lily Leaf Beetle (larval stage), flea beetles, Imported Willow Leaf Beetle (in adult, larval, and egg stages), leaf hoppers, cankerworms, and slugs and snails. The most common plant diseases are leaf spots including black spot on roses, cedar-apple rust and apple scab on crabapples, anthracnose diseases on many tree and shrubs species, and fire blight – mostly on Prunus species. Iron chlorosis was observed on many plants, indicating a need for side dressing of a nitrogen fertilizer. The recent heat wave should be a reminder to outdoors workers to take precautions to protect themselves from heat stress and heat exhaustion.

Environmental Data The following growing-degree-day (GDD) and precipitation data was collected for the one-week period, June 21 through June 27. Soil temperature and phenological indicators were observed on or about June 27. Total accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments for the 2012 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

2012 GROWING DEGREE DAYS Soil Temp (°F at 4" Precipitation (1-Week Region/Location 1-Week Total accumulation for depth) Gain) Gain 2012

Cape Cod 140 925 75° 2.25"

Southeast 152 901 78° 2.25"

East 183.5 960.5 74° 3.46"

Metro West 165.5 888.5 65° 1.36"

Central 159 955 60° 1.24"

Pioneer Valley 146 975 65° 0.26"

Berkshires n/a 791 69° 0.91"

AVERAGE 189 913 69° 1.68"

n/a = information not available

Phenology Phenological indicators are a visual tool for correlating plant development with pest development. The following are indicator plants and the stages of bloom observed for this period:

Indicator Plants - Stages of Flowering (begin, b/full, full, f/end, end)

SOUTH METRO PLANT NAME (Botanic/Common) CAPE EAST CENT. P.V. BERK. EAST W.

Campsis radicans (Trumpet Vine) * * begin full * * *

Oxydendron arboreum (Sourwood) * * begin begin * begin *

Koelreuteria paniculata (Goldenrain Tree) * * begin * * * *

Hydrangea paniculata (Panicle begin begin begin begin begin * * Hydrangea)

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Lythrum salicaria (Loosestrife) * full full begin * * *

Itea virginica (Virginia Sweetspire) full end end * end * full

Hydrangea macrophylla (Bigleaf b/full full * full * begin * Hydrangea)

Hydrangea arborescens (Smooth full full full full b/full * * Hydrangea)

Tilia cordata (Littleleaf Linden) f/end full full full begin end begin

Rhus typhina (Staghorn Sumac) f/end end full full end f/end begin

Ligustrum spp. (Privet) f/end f/end end f/end f/end end end

Catalpa speciosa (Northern Catalpa) full end end f/end full end end

Sambucus canadensis (American full full f/end full f/end begin f/end Elderberry)

* = no activity to report/information not available

CAPE COD REGION - Roberta Clark, UMass Extension Horticulturist for Barnstable County - Retired, Barnstable.

SOUTHEAST REGION - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, Hanson.

EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.

METRO WEST REGION – Julie Coop, Horticulturist, reporting from Acton.

CENTRAL REGION - Joann Vieira, Superintendent of Horticulture, Tower Hill Botanic Garden, Boylston.

PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass, Amherst.

BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington. Woody Ornamentals Insects Lily Leaf Beetle larvae are feeding and can be treated with a product that contains Spinosad.

Viburnum Leaf Beetle: will begin to emerge in the adult form within 2 more weeks. Currently, no feeding activity is occurring. Plants that were damaged by the larvae last month should be kept well watered, especially during hot and dry times, to encourage re-foliation.

Imported Willow Leaf Beetle remains active. This small insect has multiple generations throughout the growing season and is capable of killing every leaf on the host tree by August. The adult beetles are quite small and round in shape. Their coloration is a very metallic deep blue to black color. Adult beetles chew holes in the foliage. The bulk of damage is the result of larval feeding. Larvae line up on upper leaf surfaces and scrape the surface of the epidermis with their mandibles. Initially this creates a ‘window-pane’ effect but it soon turns brown as the surrounding leaf tissue dies. By August, all leaves can be entirely scraped and brown from this feeding. Adults and larvae will appear together throughout the season as generations of this pest overlap. Use a product that contains Spinosad for the larvae and a pyrethroid insecticide for the adult beetle, if necessary.

Japanese beetle (scarab beetle) adults will start to become active within the next week with more appearing per day after that through July. This pest has dozens of preferred host plants. Begin visually monitoring for this pest soon and apply treatment should population numbers become too high.

Have you seen adult Japanese beetles in the landscape? Let us know in the Reader Feedback section below.

Asiatic Garden Beetle (scarab beetle) adults remain active. These beetles are a rusty red color, bullet- shaped and active only at night (usually from the time it becomes dark up until midnight); they often attracted to porch lights. They can feed on a number of ornamental plants as well as certain garden plants; often causing much defoliation in the form of creating large ragged edges on the foliage. Pyrethroid-based insecticides are usually required when management is necessary.

European Chafer (scarab beetle) adults are becoming active. The larval form of this species (grubs) feeds on grass roots but the adults can congregate at night on various trees and shrubs. The adult beetles congregate for mating purposes but are capable of causing significant feeding damage to certain plants, often in the form of creating large ragged notched on leaf margins. Inspect affected plants at night with a flashlight. Treat with a pyrethroid spray if necessary.

Rose Chafer (scarab beetle) adults are active. These slender and usually tan-colored beetles have a wide variety of host plants and can be seen actively feeding during the day. When large numbers occur, damage can reach unacceptable levels. Treat with a pyrethroid spray if necessary.

Oriental Beetle (scarab beetle) adults are active. This species feeds at night on a variety of host plants. It is smaller and brown although there is a variation in coloration within the species. Roses, phlox and petunias

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are common hosts. Treat as the other scarab beetles listed above, if necessary.

White Prunicola Scale crawlers can be treated with a horticultural oil spray. This pest is common on Japanese cherries, more so in the eastern parts of Massachusetts than the central and western regions.

Cottony Camellia Scale (a.k.a. Cottony Taxus Scale) crawlers are active. This pest can attack certain hollies, camellias and Taxus. Being a cottony soft scale it produces white waxy egg sacs and much honeydew, which leads to problems with sooty molds. Extensive feeding can significantly suppress growth of the host plant while the sooty molds render the plant to be unattractive. Systemic imidacloprid can be effective.

Hibiscus Sawfly larvae (caterpillar-like) are active. This species feeds along the margins of host plant foliage and eventually feeds down to the main vein, which is often typical of sawflies on deciduous host plants. Connecticut reports this pest to be a serious problem on ‘Rose Mallow’ (Hibiscus moscheutos). Treat the small light green larvae with a spray product that contains spinosad. This can be a serious pest if occurring in large numbers and not treated.

Oak Die-back on Cape Cod and Martha’s Vineyard: Numerous calls continue to be received concerning die-back of oak trees with the pattern often being death from the tree top downwards. At least one cynipid gall-forming wasp has been identified in some areas as being the likely culprit. Other areas appear to have one of the lecanium scales while other tree die-back is believed to be caused by repeated defoliation from winter moth caterpillars. UMass and Barnstable County Extension are investigating this problem. MDCR and university researchers are being consulted for a possible treatment strategy. Historically, these cynipids that cause galls to form on the stems of the host plant pop up unexpectedly, create die-back and sometimes complete tree death, and then disappear due to natural controls within 3 years. The use of certain systemic insecticides early in the infestation may prove to be effective and much focus is being put into that subject at this time.

The Blacklegged Tick (Ixodes scapularis) formerly known as the Deer Tick (Ixodes dammini) remains very active in most of MA. Take precautions to prevent being a blood-meal host when in tick habitat. For those bitten by this tick, especially if the tick has been attached for more than 12 hours, seeking medical advice is highly recommended in order to receive proper treatment. For more detailed information about this tick, Lyme disease, how to submit a sample, etc., visit the following web site:

http://extension.umass.edu/agriculture/index.php/services/tick-borne-disease-diagnostics

Andromeda Lacebug remains active on Japanese Andromeda and will continue into September. The tiny nymphs are feeding on the foliage undersides. Inspect plants with previous damage (yellow-stippling on the upper leaf surface) and then inspect the undersides for new lacebugs. Treat affected plants with a systemic imidacloprid (soil application) before populations become too large or spray the undersides of foliage with a horticultural oil spray (summer rate).

Azalea lacebug is active, primarily on evergreen azaleas. Plants growing in sunny locations can be severely affected. This pest remains active well into the autumn and heavily infested plants, especially if growing in sunny, hot and / or dry sites, can appear to be mostly devoid of chlorophyll by mid-August. Soil treatments with a systemic imidacloprid formulation can provide season-long protection but may take 2-3 weeks before it becomes systemic within the plant. Horticultural oil sprays targeted to the foliage undersides can also be very effective.

Hemlock Woolly Adelgid (HWA) nymphs are actively feeding and quickly developing. Populations of HWA are very active and in some cases very robust. This pest is easily controlled with horticultural oil sprays. Soil applied imidacloprid can be helpful but if watered in now, it may not become available until the insect resumes feeding in mid-October.

Bronze Birch Borer adult beetles are active and will remain active into September. This insect requires a weak tree for attack. Keep susceptible birches healthy. Some arborists choose not to prune birches during the adult beetle activity period but as long as the tree is healthy, the risk should be minimal.

Emerald Ash Borer (EAB) traps are being monitored by the state for this exotic beetle once again. Be aware of its presence (see web sites listed below) and report any potential finds.

http://www.emeraldashborer.info

Tiger beetle - http://inhs-uiuc.blogspot.com/2010/05/green-tiger-beetle.htm

Asian Longhorned Beetle (ALB) adults have not yet been reported to be active in the state but it will begin soon. The peak month for adult ALB activity is August but it is not uncommon to begin seeing a few in July. Be familiar with the damage that they cause and how to distinguish the ALB adult beetle from the look-a-like native insects. Report any potential finds to the proper authorities:

How to Recognize ALB and its Signs

How to Report, maps, etc - http://www.mass.gov/agr/alb.htm

Reported by Robert Childs, Extension Entomologist, Plant, Soil and Insect Sciences Department, UMass, Amherst

Diseases Gymnosporangium rust infections are visible as orange-yellow spots on susceptible hawthorn, apple, and crab apple leaves. In addition, there are tiny yellow-white tube-like fruiting structures beginning to extend from the underside of infected leaves. From mid-summer to autumn, spores are wind-carried from the

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broadleaf host’s leaves and, when conditions are wet, they infect green shoots and needles of junipers. Pea- sized to 2” diameter round, brown galls or red-orange bark fissures develop during rainy springs on susceptible juniper twigs and branches between 12 and 20 months after infection. The best long-term approach to manage this disease is to grow Gymnosporangium rust resistant hawthorn, apple, and crab apple as well as juniper varieties. If desired, apply fungicides to protect high value eastern red cedar and other susceptible junipers from mid-July through early September.

The yellowing and spotting of leaves is highly visible on crabapple leaves infected with apple scab. However, the best time to apply fungicides to protect emerging crabapple leaves from apple scab has passed for this season. It is still helpful to prune densely branched trees to increase air circulation and sunlight penetration that speeds drying of foliage. In addition, numerous apple scab resistant varieties of apple, crabapple, and mountain ash are available to simplify disease management.

Mushrooms in lawns often develop from thatch, buried logs, dead roots, stumps, or even construction debris. They have many different sizes, colors, shapes, and habits of growth and develop fruiting structures or mushrooms in lawns after prolonged wet weather. The fungi that produce these mushrooms are beneficial because they decompose organic matter in the soil, making nutrients available to other plants. These mushrooms usually are harmless to grasses, but some people consider them unsightly or want to get rid of them because young children play in the area. Neither spray applications nor drenches of fungicides are effective in controlling these mushrooms. Simple way to remove mushrooms is to mow the lawn while collecting the clippings or by raking them up. Elimination of excess thatch and aerating the soil to improve water penetration also helps in some cases. In addition, the mushrooms gradually disappear without interventions if the weather becomes drier.

Powdery mildew fungi are visible as a dusty, gray to white areas on leaves of leaves of susceptible horsechestnut, flowering dogwood, and lilac as well as on leaves and flowers of roses. Once established on plants, powdery mildews grow on both the upper and lower leaf surfaces as well as on green shoots and flower buds. Generally, if unsightliness is not a critical concern, the damage caused by powdery mildew is of minor consequence to healthy trees and shrubs and does not warrant chemical control. However, if considering chemical control there are a number of biorational or unconventional applied materials labeled to protect susceptible plants. They include summer horticultural oil, commercial baking soda preparations (sodium bicarbonate and potassium bicarbonate) and combinations of these, as well as a number of conventional fungicides. Chemical spray programs are most effective when begun promptly as signs of powdery mildew first begin to appear. Once powdery mildew is extensive on the plant, there is little benefit from chemical control for that season. Applications need to coat both surfaces of all susceptible plant parts to prevent infection. Spray on a regular schedule per labeled intervals, and repeat more often during warm humid weather.

Plant Problem Diagnostic Lab Woody Plant Report: The following are some of the interesting woody plant disease/abiotic disorder samples received at the UMass Extension Plant Diagnostic Lab in Amherst during the period from June 6 through June 12, 2012:

Kousa dogwood - ~25 year old tree showing stunted and chlorotic leaves and dieback on branches scattered throughout crown; Botryosphaeria cankers Picea pungens ‘Globosa’ - ~2 year transplant exhibiting needle browning and premature loss from several branch tips; Phomopsis shoot blight. Kousa dogwood - ~10 year old tree with some marginal leaf browning and distortion; dogwood anthracnose. Douglasfir - 20-year old tree is loosing many of last year’s needles while this year’s needles look healthy; both Rhabdocline and Swiss needle casts. Colorado spruce - 7-year old trees in a Christmas tree farm have scattered yellowing, browning and loss of many of the one and two year old needles; Rhizosphaera needle cast. White fir - scattered dieback of branches especially in the lower part of the tree; Leucostoma (Cytospora) canker.

Reported by Dan Gillman, Plant Pathologist, UMass Extension Plant Diagnostic Lab, Amherst. Weeds We have received several inquiries about pilewort, fireweed or American burnweed, Erechtites hieraciifolia. Pilewort is most often found in landscape beds, waste areas, roadsides, hayfields and golf course highgrass/naturalized areas. Pilewort is a member of the Aster or Sunflower Family (Asteraceae or Compositae). A native plant, pilewort is a summer annual and reproduces by seed. The smooth, upright, branched stems are stout and grooved (sometimes ribbed) with sparse hairs. The alternate leaves are elliptic to ovate, lobed pinnately, and are sharply and irregularly toothed. White to sometimes cream-colored disk florets which extend only short distant above bracts are held tight in flower heads in terminal panicles. Flower heads form 'puffballs' when mature. While there may be a temptation to ignore this weed, one should be aware that this a prolific seeder and populations can quickly become very large. Hand-pulling may result in a large amount of undesirable disturbance so a close cut at the soil level might be preferred. The overall goal is to remove this plant before it produces seed.

Scout for annual weeds in ornamental beds. Treat these weeds before they get too large. Spot spraying with a non-selective herbicide is usually a better strategy than hand-weeding because it will not break the mulch barrier.

Look for weeds that may be creeping into landscape beds from adjacent turf areas. Weeds with creeping

http://extension.umass.edu/landscape/message/lm-152012[7/2/2012 10:24:36 AM] UMass Extension Landscape Message #15 - 2012 | UMass Extension Landscape Nursery & Urban Forestry | UMass Amherst

growth habits such as groundivy, sheep sorrel, white clover, old field cinquefoil and even Kentucky bluegrass are likely candidates. Use a non-selective herbicide to edge the bed.

Inspect areas of the landscape where new trees or shrubs, especially those that were field grown, have been planted in the last year. Look for perennial weeds that may be growing from the root ball. Canada thistle, mugwort, quackgrass, bindweed and horsenettle are some of the possible culprits. Treat with a non- selective systemic herbicide (ex. glyphosate). Contact herbicides (Sycthe®, Reward®) or the non-chemical burndown materials will not provide adequate control.

Poison ivy can be treated now. Use a broadleaf brush herbicide or glyphosate based material. Remember that even after the plant is dead the oil that causes the rash will be still be active in leaves, stems and roots.

Reported by Randall Prostak, UMass Extension Landscape, Nursery and Urban Forestry Program, Amherst. Landscape Turf Agronomy The intermittent blasts of heat have resulted in a subtle reduction in the rate of turf growth on a variety of sites. With white clover still in flower, many lower-maintenance lawns in the area look like a veritable sea of white a few days after mowing. Several observations also reveal crabgrass beginning to gain the upper hand in lawn areas that did not have preemergence treatments this spring.

The subject of thatch has come up frequently this season, including as a key determinant of acceptable pesticide performance and also as a medium for fungi that give rise to mushrooms and fairy rings. This is a good reminder to scout turf areas under your care for excessive thatch accumulation, especially if you are experiencing chronic problems. Cut a triangle-shaped plug of turf and examine the spongy layer just above the mineral soil. Appropriate criteria vary based on the management program, but if this layer exceeds ½ to ¾ inch when compressed it would be in your best interest to plan for corrective action.

A moderate level of thatch is desirable to cushion the surface, contribute to wear tolerance, and aid in water retention. Actual thatch accumulation involves a balancing act between the rate that growth adds plant material to the thatch layer and the rate at which microorganisms are able to degrade that material. Any factors that favor plant material turnover (e.g. high fertilizer rates, laterally spreading grasses such as Kentucky bluegrass) and/or restrict microorganism populations (e.g. compaction, indiscriminate pesticide use) can cause thatch to build up to an undesirable level.

If excessive thatch is present, it may lead to problems this season such as decreased water infiltration, higher populations of surface-feeding insects, and reduced performance of some pest control measures. Rooting, which is so critical for summer performance, can be drastically inhibited by an out-of-control thatch layer. Although the beginnings of a thatch reduction plan (correct pH, optimize fertility, leave clippings, encourage microorganisms, etc) can be developed now, disruptive mechanical cultural practices such as dethatching and aeration are not appropriate at this time and are best reserved for when temperatures begin to moderate later in the summer.

For more information, see our “What is Thatch?” fact sheet.

Report by Jason Lanier, Extension Educator, UMass Extension Agriculture & Landscape Program, Amherst. Phot by Mary Owen, Turf Specialist & Program Coordinator, UMass Extension Turf Program.

Insects The beetles are coming!

As expected, we have been seeing flights of Japanese beetle and oriental beetle adults for the past week. This is about 10 days earlier than "normal" and almost certainly is a result of the warm temperatures we have experienced throughout much of the spring. Some of the Japanese beetle flights have been the heaviest we have seen in recent years. Some of the earliest females may start laying eggs as early as this weekend. One of the factors that dictates when and where females of these two species lay eggs is soil moisture. Right now there seems to be reasonable moisture in many turf settings as a result of the recent fronts that passed through the area. If the weather turns hotter or drier for several days, it may force females to delay egg- laying a little bit.

As for control options, this would be a perfect time to apply a neonicotinoid (products containing chlothianidin, imidacloprid, or thiamethoxam). The labels normally recommend application "when the females are laying eggs", and that is certainly the case in most of Massachusetts, Connecticut, and Rhode Island. Vermont, New Hampshire, and Maine will not be very far behind. The perfect "window of opportunity" for this year appears to be any time between now and the end of July, slightly earlier if you are dealing with European chafers.

http://extension.umass.edu/landscape/message/lm-152012[7/2/2012 10:24:36 AM] UMass Extension Landscape Message #15 - 2012 | UMass Extension Landscape Nursery & Urban Forestry | UMass Amherst

Armyworms

While we have not yet had any reports of large masses of armyworms on the move in Massachusetts, we continue to hear of situations in central and western New York where massive populations of the caterpillars have decimated fine turf or wheat fields. We did find one small armyworm caterpillar in a sample collected from a golf course near Springfield this morning. While one caterpillar does not necessarily mean an attack is imminent, you would be wise to keep watching for these caterpillars. They often have a straw-colored stripe along the side of the body, black spots where the fleshy legs meet the abdomen, and a honey-combed head capsule with light and dark brown splotches.

Crane flies

A golf course superintendent on Cape Cod who experienced damage from crane flies last winter reported to me this morning that he had very good success with an application of imidacloprid on his infested fairways yesterday. He was quite surprised at the number of larvae he found on the surface after the application. Dr. Dan Peck, formerly at Cornell and the crane fly "guru" on the East Coast, has noted that his research demonstrated that applications of imidacloprid or chlothianidin made in early July were quite effective against the European crane fly, Tipula paludosa. As far as we know, the species that is dominant on Cape Cod is the "other" invasive species, the common or marsh crane fly, Tipula oleracea. But based on the anecdotal report I received this morning, it sounds like this approach (a neonicotinoid in the next week or two) might help reduce T. oleracea populations as well.

Chinchbugs

A friend reported today that he observed a massive chinchbug outbreak earlier this week, again in southeastern Massachusetts. The hot, dry weather that we experienced last week would be to the advantage of chinchbugs. So if you have turf areas that are beginning to look like they are going into summer dormancy, take the time to look and see whether there might be chinchbugs feeding. You can see them just by getting down on your hands and knees, and teasing the grass blades apart. Look for the movement. Immature chinchbugs look just like the adults except they are much smaller, and often have distinctive red or orange markings.

Reported by Dr. Pat Vittum, Professor and Extension Entomologist, UMass Department of Plant, Soil and Insect Sciences, Amherst. Reader Feedback New! We invite you to share your observations and comments for the current message. Please note that all comments are subject to moderator approval, and please refrain from submitting requests for information in this space.

Comments Oak galls Submitted by Anonymous on July 2, 2012 - 07:12. I have been watching one oak tree in south Orleans for at least three years now. Two years ago we almost cut it down. Last year it came back, this year it looks horrible again. Every where I go I am picking up the ends of twigs with gall die back. This is getting to be very very serious.

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Black Swallow-wort Submitted by Anonymous on June 30, 2012 - 09:49. This weed is becoming more and more prevalent on the Upper-Cape, in places forming a solid blanket over existing vegetation. It is very difficult to hand weed and, from what I hear, difficult to control chemically as well. Could we please have a bio-control? Thanks, Will Clarke North Falmouth

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brown beech leaves Submitted by Anonymous on June 30, 2012 - 07:13. on several properties on aquidneck Island, I have seen brown beech leaves on branches laying just above the turf grade

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http://extension.umass.edu/landscape/message/lm-152012[7/2/2012 10:24:36 AM] UMass Extension Landscape Message #15 - 2012 | UMass Extension Landscape Nursery & Urban Forestry | UMass Amherst

Woodland natives Submitted by Anonymous on June 29, 2012 - 14:58. While still staring at much damage from previous blow-downs, early snow, etc; I see new signs that Cornus alternifolia (green osier) might be stressed. Though I don't see any yellow indication of cryptodiaporthe corni (golden canker) the leaves on a youngish specimen (maybe 5 yrs old?) are turning a reddish/burgundy. I love this small native tree. I'm glad it self seeds and need to learn how to assist its reproduction before the wildlife cleans off all of the berries.

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Beech Bark Disease Submitted by Anonymous on June 29, 2012 - 14:00. We were working at a national park in Quincy MA. and saw what appears to be Beech Bark Disease. We saw scale and Nectria cankers on the tree as well as evidence of past infections. We then looked at other Beech trees on the property and found more evidence. We then drove around Quincy MA. and we estimated around 95? of the Beech trees that we saw were infected with the Nectria canker. Just wanted to give an FYI.

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