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Landscape Message: May 22, 2015

May 22, 2015

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Green Industry professionals in the management of our collective landscape. Scouts compile and record environmental and phenological data for locations throughout Massachusetts to aid in the monitoring of plant and pest development, the planning of management strategies, and the creation of site-specific records for future reference.  Detailed reports from Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. UMass Extension has updated the following issue to provide timely management information and the latest regional news and environmental data.

The Landscape Message will be updated weekly April through June. The next message will be available on May 29. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.

Scouting Information by Region

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: Lovely weather continued for the most part for this reporting period. Daytime temperatures were generally in the low 70s F with mostly sunny skies, with the exception of 5/19 when the high temperatures were only in the 50s. Overnight temperatures ranged from the upper 40s F to the low 50s F. Some much needed rainfall occurred on Tuesday 5/19, but was not enough to put a dent in the on-going deficit. Most areas of the state, the Cape included, are averaging about 4.5” below normal since the beginning of April. Precipitation ranged from about 0.4” in Falmouth to 0.57” in Chatham. Landscapes are looking colorful, with azaleas, lilacs, crabapple, and rhododendrons providing good color.  Pests/Problems: Dry soils remain a problem, especially for newly planted material. Winter moth caterpillar populations appear high in many areas this year. Caterpillars are currently ballooning on silken strands and blowing onto new vegetation. Damage can be seen on many landscape plants including birch, viburnum, crabapple, and roses. Rose slug sawfly larvae have been observed. Lily leaf beetle adults are actively laying eggs on foliage of lilies. Aphids are becoming active. Eastern tent caterpillar webs are quite large and noticeable. Pollinators are quite active. If applying pesticides, including products containing spinosad, for winter moth management, avoid using on plants in bloom. Keep monitoring for deer ticks after working outdoors and protect yourself by using repellants containing DEET. Mosquito populations appear quite high and they are biting!

Southeast Region (Hanson)

General Conditions:The past week was pleasant and spring-like and the overlap of spring-flowering plants made for a very colorful spring. However, some plants would probably have flowered longer had the soils not been so dry. In the past 4 weeks, Hanson has received only 1.02 inches of rain, including the 0.33 inches this past week. Soils remain dry. Remind clients to water newly planted trees and shrubs. Ilex sp., Aesculus hippocastanum (Common Horsechestnut), Aesculus xcarnea (Red Horsechestnut), Rutgers hybrid dogwoods (Stellar series), Cornus florida, Rhododendron carolinianum, Wisteria floribunda (Japanese Wisteria), Calycanthus floridus (Carolina allspice), Lonicera tatarica, Daphne tangutica, Daphne x burkwoodii ‘Carol Mackie’, Kerria, numerous viburnums (including V. ‘Eskimo, V. opulus, Weigela florida ‘Versicolor’, Spiraea prunifolia (Bridalwreath Spirea), Dexter hybrid azaleas, Enkianthus campanulatus, Aristolochia durior (Dutchman's pipe), Convallaria majalis (Lily-of-the-valley), Euphorbia polychroma, Lunaria annua (honesty or money plant), Bearded Iris, Cypripedium parviflorum (Yellow Lady’s Slipper), Primula sieboldii (Japanese primrose), Anemone sp., Mazus reptans, Dicentra eximia, Dicentra spectabilis (Bleeding Heart), Buglossoides purpurocaerulea, Geranium sp., Tulips, Persicaria bistorta ‘Superbum’, Galium odoratum (Sweet Woodruff), Phlox subulata, Phlox divaricata, Phlox stolonifera, Polygonatum sp. (Solomon's Seal), Arisaema sikokianum, Arisaema dracontium, Saruma henryi, Lamium sp., Lamiastrum galeobdolon, Epimedium sp., Trillium sp., Pulmonaria sp., Myosotis sylvatica (Forget-me-not), Ajuga reptans, Tiarella cordifolia (Foam Flower), Mertensia virginica (Virginia bluebells), Violets, and Vinca minor are in full bloom. Aquilegia sp. (Columbine) and Doronicum sp. are beginning bloom. The following plants have ended or are ending bloom: Kwanzan cherry, Halesia sp. (Silverbell), Magnolia fraseri, crabapples, Exochorda racemosa (Pearlbush), Pieris japonica, Pieris floribunda (Mountain Pieris), Pieris 'Brouwer's Beauty', Viburnum 'Eskimo', Viburnum carlesii (Mayflower Viburnum), Viburnum ‘Mohawk’ and Fothergilla sp. Kousa dogwood flower bracts are expanding and beginning to show color. Hollies, damaged and partially defoliated by winter cold and wind, are beginning to produce new growth. Oak pollen has ended and it is only a matter of time when “pine pollen” will be covering everything. American hollies continue to shed their older, yellow leaves; an annual occurrence. Along with swallowtail butterflies, red admiral butterflies and dragonflies have appeared.  Pests/Problems: One of the biggest concerns right now is the damage being done by Winter moth caterpillars, which, as usual at this time of year, is becoming noticeable. There are some 3rd instar winter moth caterpillars but most are at 4th instar and some are starting to pupate. The caterpillars will continue to feed and hopefully will be done in the next week or so. The caterpillars feeding in the upper canopy are dropping their excrement (frass), which can seen, onto plants, driveways, etc. below and creating a mess. If you listen carefully, you can hear the frass dropping. We’re seeing foliar damage on Oaks, Norway maples, red maples, etc. And also damage to understory plants like Japanese maples, roses, etc. Last week in Hanson, winter moth caterpillars spun so much silk in the trees at one site that it looked like something out of a horror movie. Gypsy moth caterpillars, found on oak, are still small but more were observed this year than in previous years. Continue to monitor for them as they feed and manage if needed. Damage to deciduous azaleas from the bright green, azalea sawfly is becoming apparent. The caterpillar-like sawflies feed on the edge of the leaf, working their way in, towards the midrib and if not managed can cause considerable damage. Sawflies are not lepidopteron caterpillars and Bt (Bacillus thuringiensis) is not effective on sawfly larvae. Adult reproductive termites were observed swarming last week. Mosquitoes and blackflies are numerous.The following insects are active: woolly beech aphid, deer tick nymphs, azalea whitefly, European pine sawfly, spruce spider mites, rose slug sawfly, lily leaf beetle, imported willow leaf beetle, snails, aphids, ants, wasps, carpenter bees and bumblebees. Monitor hemlocks for Hemlock woolly adelgid. Although there was not very much rain, there was enough to initiate the formation of the strange-looking, yet colorful, orange, jelly-like galls of cedar-apple rust (Gymnosporangium rust) on Eastern red cedar and other junipers. Appearing on the trees like orange gelatinous golf or tennis balls, these galls always invite comment. Another fungal foliar disease, Azalea leaf gall (Exobasidium vaccinii) continues to be found on azalea foliage. Handpick and destroy the galls before they turn white. Buttercups, veronica, garlic mustard, ground ivy and barberry are in full bloom. Dandelions are also in bloom but many are setting seed. A few green industry folk have mentioned that they have seen a great deal of winter damage to boxwood, where the plants are dead and/or the wood above snow-line is dead and peeled-back. These were well-established, seemingly healthy plants. Another field observation to share is in regard to Cornus florida (flowering dogwood) and the apparent reduction in flowers this year and the increase in lower branch death on numerous trees, being observed around some areas on the south shore, the north shore and Southeastern MA. The pink flowering cultivars appear to be affected the most, but many flowering dogwood trees, in general, do not look healthy. Deer, chipmunks and turkeys continue to browse.

North Shore Region (Beverly)

General Conditions: Dry conditions continued during this reporting period. Long Hill received only 0.01 inches of rainfall during this period bringing this month’s total rainfall to 0.13 inches. During this period we gained 59 growing degree days. Lawns are still green but turf is starting to show signs of drought stress. Irrigate your lawn and garden if possible. Several plants are either in full bloom or beginning to bloom. Woody plants seen in full bloom include: Japanese maple (Acer palmatum), Hardy orange (Poncirus trifoliata), Japanese flowering cherry (Prunus Serrulata ‘Shogetsu’ ), Sargent crabapple (Malus sargentii), Silverbell (Halesia carolina), Common Horsechestnut (Aesculus hippocastanum), Flowering dogwood (Cornus florida), Eastern redbud (Cercis canadensis), Handkerchief tree (Davidia involucrata var. vilmoriniana), Wayfaring tree viburnum (Viburnum lantana), Beach plum (Prunus maritima), Chokecherry (Prunus maackii), Sandy Chinese lilac (Syringa chinensis), Doublefile viburnum (Viburnum plicatum var. tomentosum), Royal azalea (Rhododendron schlippenbachii), White Find rhododendron (Rhododendron vaseyi 'White Find'), Hallelujah rhododendron (Rhododendron ‘Hallelujah’), Hinodegiri azalea (Rhododendron ‘Hinodegiri’), Polar bear azalea (Rhododendron ‘Polar Bear’), Pink Shell azalea (Rhododendron vaseyi), Carolina Rhododendron (Rhododendron carolinianum), Catawba Rhododendron (Rhododendron catawbiense), Fothergilla (Fothergilla major) and Wisteria (Wisteria floribunda). Woody plants beginning to bloom include: Red horsechestnut (Aesculus x carnea), Single seed hawthorn (Crataegus monogyna), Wright viburnum (Viburnum wrightii), Little leaf lilac (Syringa microphylla) Percy wiseman rhododendron (Rhododendron ‘Percy Wiseman’), Scintillation rhododendron (Rhododendron ‘Scintillation’), Unique azalea (Rhododendron ‘Unique’), and Miss Louisa azalea. Herbaceous plants in bloom include: Honesty plant (Lunaria annua), Yellow archangel (Lamiastrum galeobdolon), Blue eyed Mary (Omphalodes verna), Vinca vine (Vinca major), Forget-me-not (Myosotis palustris), Barrenwort (Epimedium rubrum) and Trilliums (Trillium spp.), Corydalis (Corydalis lutea), Bleeding heart (Dicentra spectabilis), Rue Anemone (Anemonella thalictroides), and Tulips (Tulipa sp.).  Pests/Problems: Winter moth caterpillars are actively feeding and damage is starting to show on tree leaves especially on maples and oaks. Hemlock woolly adelgids are starting to be active. Ticks and mosquitoes are very active. Make sure you apply repellents before going to work outdoors. Many spring weeds are in bloom. Those seen in bloom include: Dandelion (Taraxacum officinale), Ground ivy (Glechoma hederacea) Garlic mustard (Alliaria petiolata) and Dead nettle (Lamium purpureum). Be aware of poison ivy when walking in the woods. Leaf spots on some azaleas are causing heavily infected leaves to fall off. Rake fallen leaves and apply a registered fungicide to protect the leaves. Some junipers are showing twig die back. Prune and destroy infected twigs.

East Region (Boston)

General Conditions: Spring temperatures have returned; the average high for the week was 70º F and the average low 48º F. The weekend of the 16th/17th saw lows in the mid 50’s and highs in the mid 70’s – perfect spring weather. We are still waiting for spring rains to return; we received only 0.22 inches of precipitation on the 19th. So far this month, only 0.25 inches have been recorded. We gained 63 GDDs, bringing us to 273 GDDs on the year. Currently in bloom: Actinidia kolomikta (Kolomikta kiwi), Akebia quinata (fiveleaf akebia), Aristolochia tomentosa (hairy dutchman's pipe), Aronia arbutifolia (red chokeberry), Calycanthus floridus (Carolina allspice), Chionanthus virginicus (white fringetree), Cornus sericea (red osier dogwood), Crataegus sp. (hawthorn), Cydonia oblonga (common quince), Enkianthus campanulatus (redvein enkianthus), Prunus laurocerasus (laurel cherry), Prunus serotina (black cherry), Rosa hugonis (Father Hugo rose), Sorbus alnifolia (Korean mountain ash), Staphylea trifolia (American bladdernut), Symplocos paniculata (Asiatic sweetleaf), and Weigela sp. (weigela). The unusual Davidia involucrata (dove tree) and Xanthoceras sorbifolia (yellowhorn) are in full bloom.  Pests/Problems: The lack of rain is of concern. Over the last month, we have received only 0.41”, far below the norm of 3.46 inches. Supplemental irrigation has begun as many young trees are showing signs of water stress. Winter moth continues to feed and balloon throughout the landscape; they are feeding heavily on crabapples and oak. Mosquitoes are out in full force, feeding and very active. The following weeds have germinated: common burdock (Arctium minus), Japanese hops (Humulus japonicus), jewelweed (Impatiens capensis), ladysthumb (Polygonum persicaria), lambsquarters (Chenopodium album) and prickly lettuce (Lactuca serriola). The following weeds are going to seed: dandelions (Taraxacum officinalis), garlic mustard (Alliaria petiolata), greater celandine (Chelidonium majus) and shepherd’s purse (Capsella bursa-pastoris). Bulbous buttercup (Ranunculus bulbosus) is flowering. Yellow nutsedge (Cyperus esculentus) has emerged and is visible.

Metro West (Acton)

General Conditions: Temperatures have moderated since last week and are more “spring-like”. The area received a mere 0.12" of rain bringing this month’s total precipitation to 0.15” and gained 63.5 GDD during this recording period. Woody plants seen in bloom this past week are Aesculus hippocastanum (Horsechestnut), Aronia arbutifolia (Black Chokecherry), Cercis canadensis (Redbud), Chaenomeles speciosa (Common Flowering Quince), Cornus florida (Dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers Hybrid Dogwood), Crataegus spp. (Hawthorn), Daphne x burkwoodii 'Carol Mackie' (Daphne), Fothergilla gardenii (Dwarf Fothergilla), F. major (Large Fothergilla), Halesia tetraptera (Mountain Silverbell), Ilex aquifolium (English Holly), Kerria japonica (Japanese Kerria), Leucothoe axillaris (Coast Leucothoe), Potentilla tridentata (Cinquefoil), Rhododendron spp., Rosa rugosa (Japanese Rose), Spiraea spp. (Bridal Wreath), Syringa vulgaris (Common Lilac), Syringa spp. (Lilac), Vaccinium angustifolium (Lowbush Blueberry), V. corymbosum (Highbush Blueberry), Viburnum plicatum var. tomentosum (Doublefile Viburnum), Viburnum x burkwoodii (Burkwood Viburnum), and V. x burkwoodii 'Mohawk' (Mohawk Burkwood Viburnum). Woody vines in bloom are: Aristolochia labiata (Dutchman's pipe), Lonicera sempervirens (Honeysuckle) and Wisteria floribunda (Japanese Wisteria). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Actaea pachypoda (White Baneberry), Ajuga reptans (Bugleweed), Allium spp. (Ornamental Flowering Onion), Amsonia hubrichtii (Arkansas Blue Star), Aquilegia canadensis (Columbine), Arisaema triphyllum (Jack-in-the-Pulpit), Asarum europaeum (European Ginger), A. canadense (Canadian Wild Ginger), Aurinia saxatilis (Basket of Gold), Caltha palustris (Marsh Marigold), Camassia scilloides (Wild Hyacinth), Chrysogonum virginianum (Green and Gold), Convallaria majalis (Lily of the Valley), Cypripedium parviflorum (Yellow Lady's Slipper), Geranium maculatum (Wild Geranium), Dicentra eximia (Fringed Bleeding Heart), D. spectabilis (Old Fashioned Bleeding Heart), D. spectabilis 'Alba' (White Flowering Old Fashioned Bleeding Heart), Gallium odorata (Sweet Woodruff), Iberis sepervirens (Evergreen Candytuft), Iris germanica (Bearded Iris), Linaria annua (Money Plant), Lupinus sp. (Lupine), Myosotis sylvatica (Forget-me-not), Narcissus spp. (Daffodil), Nepeta spp. (Ornamental Catmint), Omphalodes cappadocica (Navelwort), Phlox divaricata (Canadian Phlox), P. stolonifera (Creeping Phlox), P. x subulata (Moss Phlox), Podophyllum peltatum (Mayapple), Polygonatum commutatum (Great Solomon's Seal), P. odoratum 'Variegatum' (Variegated Solomon's Seal), Primula spp. (Primrose), Stylophorum diphyllum (Wood Poppy), Tiarella cordifolia (Foam Flower), Trillium grandiflorum (White Trillium), Vinca minor (Periwinkle), Viola spp. (Violet), Waldsteinia ternata (Barren Strawberry) and Zizia aptera (Heart-Leaved Alexander).  Pests/Problems: Lack of rain is a real concern. This is the fourth week in a row without any significant rainfall. Caterpillars are actively feeding on the foliage of Acer (Maple), Corylus (Filbert), Fagus (Beech), Malus (Crabapple) and are easy to detect this week with the naked eye. Imported Willow Leaf Beetles chewing on willow foliage. Ticks, mosquitoes and black flies are feeding and active. Many weeds are in flower including a few of the nastiest invasives of all time, Alliaria petiolata (Garlic Mustard) which is easily seen with its white flowers growing on roadsides and in woodlands, wetlands and gardens, Elaeagnus umbellata (Autumn-olive), and Lonicera maackii (Amur Honeysuckle). Other weeds seen in bloom now are Glechoma hederacea (Ground Ivy), Lamium purpureum (Purple Dead Nettle) and Taraxacum officinale (Dandelion). Be aware of Toxicodendron radicans (Poison Ivy). It is leafing out and it is fairly easy to detect its shiny red leaves of three.

Central Region (Boylston)

General Conditions: Temperatures have cooled and are back to more normal, spring-like levels. Frost warnings were issued during the reporting period but our low temperatures on the hill held steady at about 40º F. Light, scattered showers promised some relief for those with pollen allergies, but in fact provided little. Conditions remain very dry and turf and ornamental borders are now being irrigated.  Lilacs (Syringa vulgaris) are still in full bloom; Apples & Crabapples are finishing, Wild Geranium (Geranium maculatum), Pink Lady’s Slipper (Cypripedium aucaule), Fringed Polygala (Polygala paucifolia), Beach Rose (Rosa rugosa), Double-file Viburnum (Viburnum plicatum tomentosum), Catawbiense Hybrid rhododendrons, Highbush Blueberry (Vaccinium corymbosum), Silverbell (Halesia tetraptera), Periwinkle (Vinca minor), Rhododendron ‘Narcissiflorum’, Tulips, Bleeding Heart (Dicentra spectabilis), Woodland Phlox (Phlox divaricata), Moss Phlox (Phlox subulata), Phlox stolonifera, Shooting Star (Dodecatheon media), Virginia Bluebells (Mertensia virginica), Japanese Jack-in-the-Pulpit (Arisaema sikokianum), Japanese Tree Peonies, Fothergilla gardenii and F. major, Horsechestnut (Aesculus hippocastanum), Red Horsechestnut (Aesculus carnea ‘Briotii’), and Enkianthus campanulatus are among the plants flaunting color.  Pests/Problems: Eastern Tent Caterpillar, Boxwood Psyllid, and Lily Leaf Beetle remain active. Black flies, tick, mosquitoes continue to plague humans. Garlic Mustard (Alliaria petiolata), Honeysuckle (Lonicera sp.), Eleagnus umbellata, Dandelions (Taraxacum officinale), Gill-Over-The-Ground (Glechoma hederacea), Violets (Viola sp.), Buttercups (Ranunculus sp.), and Yellow Rocket (Barbarea vulgaris) are among the conspicuous weeds now showing. Dry conditions/lack of rain is a major problem.

Pioneer Valley Region (Amherst)

General Conditions: We badly needed rain in the Pioneer Valley during this past reporting period and thankfully we received some. But, it wasn’t nearly enough to assuage the abnormally dry conditions the region has experienced since late April. The Northeast Regional Climate Center ( provides a nice summary of what we already know; it was really hot and really dry during the first half of May, with temperatures in the Pioneer Valley 6−8° F above normal. At Barnes Airport in Westfield, there have been seven days in May with high temperatures ≥85° F. Temperatures have cooled to more seasonable levels during this past reporting period, with highs in the 70s and lows in the 50s. Now that temperatures have moderated, the lack of rainfall has become the main focus. Over a four week period (4/22 to 5/20), most of the valley has received only 0.2−0.4” of rainfall, well below normal for this time of year. Scattered rain showers pushed through on Saturday 5/16 but accumulations were less than 0.1”. Additional rainfall came on Tuesday, 5/19 but accumulations were again minimal, generally between 0.15−0.35”. Strong thunderstorm cells swept from northwest to southeast through the region during the evening of 5/19 with Hampden County receiving the worst of the wind and heavy rain. As is often the case, these storms bring heavy rainfall but move so quickly the accumulations are nominal. The updated U.S. Drought Monitor map for the northeast region ( shows that over half of New England is now in the “moderate drought” category, an increase from the “abnormally dry” designation one week ago. For the year to date, average precipitation in the valley is between 4−8” below normal, according to the National Weather Service Eastern Region Headquarters. While many will remember the heavy snowfall we received in late January and February, the snow was very dry and fluffy with low water content. According to the USGS Water Watch (, the Connecticut River and its main tributaries are flowing at heights well below normal. The main tributaries (Green, Millers, Deerfield, Mill, Westfield and Chicopee Rivers) have streamflow rates of 22−39% normal for this time of year, while the mighty Connecticut is only 47% of normal at the Montague discharge station. Soil temperatures dropped slightly during this past reporting period, likely due to the rain and cool nights. Despite several frost warnings over this past reporting period, temperatures haven’t even come close to the 32° F threshold. The latest frost warning was issued for the early morning hours of Thursday, 5/21 yet lows only dipped to 46° F at the Smith College Physics Department weather station in Northampton.  Pests/Problems: The dry conditions are now a serious concern for recently transplanted and young trees and shrubs in the landscape, especially those that are shallow-rooted plants and/or growing in well-drained soils. Continue to provide a deep watering for these sensitive woody plants during this dry period. Lawn sprinklers are simply not sufficient as most of the water will be absorbed by lawn grass and bone-dry mulch around the base. If hand-watering, ensure water is being absorbed into the mineral soil by moving mulch at the base. A strange phenomenon has developed in response to the dry conditions in which the upper mineral soil layer develops hydrophobic characteristics, causing water to sheet away if the soil isn’t disturbed. Lawn grass is still green and growing well in shaded settings. In exposed areas with well-drained soils, brown patches are developing and wilting of lawn weeds (clover, for example) is evident. The European pine sawfly larvae and pine needle scale crawlers are now active, or will be soon. Inspect needles on high-value trees for the dark green larvae of the sawfly and the orange-colored crawlers of the scale. This past winter was tough on yews and a Taxus mealybug infestation is an additional stress that could exacerbate dieback. Inspect interior branches for the immature mealybugs, which are now active. The rainfall during the morning of 5/19 and the cloudy conditions during the day, coupled with additional rainfall in the evening provided ideal conditions for Rhizosphaera. This problematic needle cast pathogen will attack newly developing needles on many conifers, especially blue and white spruce. Spruce needle rust, caused by Chrysomyxa weirii, is also active now after the rain. Ruptured orange-colored lesions on blue spruce needles have been observed in Hampshire County. The disease has a long latent phase which means infections appearing now occurred in spring of 2014. Many blue spruce in the valley are in a stage of development (1/2 to 3/4 needle elongation) that makes them susceptible to infection from both Rhizosphaera and Chrysomyxa. Treatment should take place immediately for high-value trees if these pathogens are causing premature needle shedding, especially on trees growing in partial to full shade. Blue spruce growing as a specimen tree in full sun and subject to winds may not require any treatment. Anthracnose fungi have mostly been suppressed this spring season but may have been provided with enough time to sporulate and infect newly developing foliage on 5/19. Careful scouting for irregularly-shaped blotches and spots can help detect the disease early.

Berkshire Region (Great Barrington)

General Conditions: It was a cold and brisk day, with a hint of frost on the horizon…sounds like the beginning of a mystery novel, but it’s no mystery that Wednesday, May 20, was much colder than what we’ve experienced for most of this month. Frost is a distinct possibility for certain locations in the Berkshires, if not on the morning of May 21, then on the morning of May 23. The National Weather Service has issues frost advisories for Berkshire County. Whether frost occurs or not, such sudden drops in temperature serve as a warning against rushing the transplanting of tender seedlings. Despite a thunderstorm which dropped almost half an inch of rain in the Great Barrington area on the evening of May 19, the region remains dry with a rainfall deficit for the year of about 5 inches. The rain came fast and furious; most of the rain likely ran across soil surfaces rather than seeping into the soil. A little bit of hail was observed at some locales but was not damaging. The combination of drought, strong gusty winds, and low humidity exacerbate the threat of fire and the County currently remains in “elevated fire risk” status. Soil moisture is low to very low and some perennials are showing signs of drought stress. Heat, high winds, and the very brief but heavy rain brought to an end the extravagant floral display of crabapples. However, the current spectacle of lilacs in full bloom…and fragrance…offer a more than adequate successor.  Pests/problems: Blacklegged ticks, wasps, carpenter bees, and mosquitoes are plentiful. Boxwood Leafminer is still in the pupal stage but the adult fly should be emerging soon. Eastern Tent Caterpillar remains active and were recently found feeding on leaves of roses. New pests observed this week include: European Pine Sawfly on mugo pine, Woolly Beech Leaf Aphid on the undersides of leaves of copper beech, Imported Willow Leaf Beetle larvae feeding on leaves of willow, Viburnum Leaf Beetle feeding on the foliage of Viburnum sargentii, leaf roller larvae on foliage of Cornus racemosa, Hydrangea paniculata, and Populus. Neatly patterned holes in the bark of crabapples are the result of drilling by the yellow bellied sapsucker. Such holes were observed on several crabapples during scouting. Animal problems continue to plague many gardens and landscapes. Browsing damage by deer, rabbits, voles, and woodchucks is very common. Sightings of black bears have also been common this spring. One in this scout’s garden was nibbling on the shoot tips of a magnolia.

Environmental Data

The following growing-degree-day (GDD) and precipitation data was collected for an approximately one week period, May 14 through May 20. Soil temperature and phenological indicators were observed on or about May 20. Total accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments for the 2015 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.


(1-Week Gain)

(Total 2015 Accumulation)

Soil Temp
(°F at 4" depth)

(1-Week Gain in inches)

Cape Cod










North Shore










Metro West










Pioneer Valley















n/a = information not available


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, BEGIN/FULL, FULL, FULL/END, END)
Syringa meyeri (Meyer Lilac) * * * begin/full * * begin/full begin
Deutzia spp. (Deutzia species) * * begin * * begin begin begin
Aesculus hippocastanum (Common Horsechestnut) begin/full full full begin full full full full
Rhododendron catawbiense (Catawba Rhododendron) begin/full full full * * begin begin begin
Enkianthus campanulatus (Redvein Enkianthus) begin full * full * full full full
Rhododendron carolinianum (Carolina Rhododendron) full full full * full full full full
Spiraea x vanhouttei (Vanhoutte Spirea) begin/full begin/full * begin * * full full
Elaeagnus umbellata (Autumn-olive) begin/full full full begin full full full begin
Syringa vulgaris (Common Lilac) begin/full full full full full full full full
Cornus florida (Flowering Dogwood) full full full full/end full full full full
Rhododendron spp. (Early Azaleas) full full full/end full/end full/end full full full
Malus spp. (Crabapple) begin/full end full end end end end full/end
Cercis canadensis (Redbud) full full/end full full/end end full/end end full
* = no activity to report/information not available
  • CAPE COD REGION - Roberta Clark, UMass Extension Horticulturist for Barnstable County - Retired, reporting from Barnstable.
  • SOUTHEAST REGION - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, reporting from Hanson.
  • NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
  • EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.
  • METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
  • CENTRAL REGION  -  Joann Vieira, Superintendent of Horticulture, reporting from the Tower Hill Botanic Garden, Boylston.
  • PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
  • BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals


Arborvitae (Thuja occidentalis) with stem cankering and needle blight caused by the following fungal pathogens: Phomopsis, Kabatina, Pestalotiopsis and Fusarium. Shrubs planted in 2014 in a shaded setting, roughly 15’ from a street, and provided with drip irrigation. There were no symptoms of decline after planting but this spring, the sides of the shrubs facing the street were dead.

Arborvitae needle blight caused by Phyllosticta thujae. This pathogen was widespread on Thuja species in 2014 and after the harsh winter, it expects to be another banner year for this fungus. Two sets of shrubs from different sites, both exhibiting scattered dieback in the canopies. Phyllosticta is actively sporulating early in the season and produces a vast number of spores from very small, black pads of tissue from the blighted needles.

Armillaria root rot of mountain laurel (Kalmia latifolia). Mature shrub, present at the current location for five years, exhibiting branch dieback and an overall lack of vigor. Dissection of the base and lateral roots uncovered an extensive infection by the soilborne pathogen Armillaria. Approximately 60% of the base was girdled.

Dogwood borer (Synanthedon scitula) infestation and poor planting technique (planted too deep) of flowering dogwood (Cornus florida). Young tree planted in autumn of 2014 exhibited symptoms of decline this spring. Larval tunnelling on the lower bole last season and freeze injury over the winter killed the bark and outer sapwood. While likely not a significant contributor to the decline, the tree was planted too deep and a mass of fine roots developed over the root flare.

Spruce needle rust, caused by Chrysomyxa weirii, on blue spruce (Picea pungens). Young tree, approximately 5- to 7-years-old, growing in full sun with good wind exposure. A minor needle rust infection was observed in 2013 and even less in 2014. This year, however, the level of infection has increased dramatically (see image below). The rain on 5/19 allowed the swollen, orange-colored lesions to rupture and release spores. Symptoms of spruce needle rust appear one year after infection, so needle lesions observed this year mean that spring of 2014 provided ideal conditions for infection. Fungicide treatment with azoxystrobin will take place to protect this year’s needles from infection.

Juniper needles infested by the juniper scale (Carulaspis juniperi). The juniper scale is a common pest in eastern North America and crawlers emerge from roughly late May to mid-June in our region.    Infestation of Norway spruce (Picea abies) by the Norway spruce gall midge (Piceacecis abietiperda). Symptoms include distorted and blighted shoot tips and galls present mostly at the base of last year's shoots.    Infestation of Norway spruce (Picea abies) by the Norway spruce gall midge (Piceacecis abietiperda). Symptoms include distorted and blighted shoot tips and galls present mostly at the base of last year's shoots.    Spruce needle rust, caused by Chrysomyxa weirii, on Colorado blue spruce (Picea pungens). The orange-colored needle lesions have ruptured to release spores that will infect newly developing needles.

For more detailed management information for woody plant diseases in the landscape, refer to UMass Extension's Professional Management Guide for Diseases of Trees and Shrubs.

Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass Amherst.

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