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Landscape Message: May 29, 2015

May 29, 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 June 5. 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: The state of Massachusetts has now been declared to be in a moderate drought by the US Drought Monitor. While the Cape has enjoyed lovely weather to work outdoors, the soil is seriously dry. Temperatures have averaged in the upper 60s F to low 70s F during the day, with nighttime temperatures in the 50s F. The exception was a low of 44º F on Saturday morning. Many spring shrubs are in bloom, including Fothergilla (Fothergilla spp.), Tea viburnum (Viburnum setigerum) Weigela (Weigela florida) and many lovely Rhododendrons. Early bearded Iris are beginning to bloom in the perennial garden.  Pest/problems: The lack of rainfall is one of the biggest problems at this time. Soils are very dry and unirrigated lawns are actually showing some browning, which is very early! Newly planted trees, shrubs, perennials and annuals will all need to be irrigated deeply to become established. The second biggest problem is the large outbreak of winter moth caterpillars this year. Defoliation is quite evident on many trees and we still have about a week before they spin down to pupate. Defoliated trees should be thoroughly irrigated on a regular basis. Understory plants such as various viburnum and roses are also showing considerable feeding damage from this caterpillar.  Tent caterpillar webs are quite large and the caterpillars are beginning to leave the webs in search of a pupation site. European pine sawfly is active. Azalea sawfly is almost finished on deciduous azaleas. Carpenter ants and carpenter bees are active. Termites are swarming. Polistes wasps are active.  Native flowering dogwood, Cornus florida, is showing considerable lower branch dieback. This has also been observed in Plymouth County, as reported last week by Deborah Swanson. It has been a very dry spring; Dogwood anthracnose is usually more pronounced in wet springs. Further investigation is needed to determine what the problem is but it appears on most native dogwoods that have been observed.  Dandelions and garlic mustard have finished bloom and will soon disperse their seeds. Manual removal before this happens is recommended. Creeping veronica is in bloom. Seedlings of poke weed and lambs quarters are up.  Dog ticks are active. Deer tick adults and nymphs are active. As nymphs are the stage most closely associated with Lyme disease, be sure to protect yourself with repellents.

Southeast Region (Hanson)

General Conditions: Warm dry summer weather for the past week and according to meteorologists, “we are in a moderate drought”. There are water bans in many towns. Hanson received no rain over the past week, bringing the total to 1.03 inches of rain in the past 5 weeks. It is critical to remind clients, that if possible, to water newly planted trees, shrubs, etc. Despite the dry weather, the spring flowering plants look great and many people are saying it is one of the best flowering years for rhododendrons. The following plants are in full bloom: Styrax obassia, Cornus controversa, Cornus alternifolia, Aesculus x carnea (Red Horsechestnut), Rutgers hybrid dogwoods (Stellar series), Laburnum x watereri (Goldenchain Tree), late blooming magnolias, Liriodendron tulipifera (Tuliptree), Prunus serotina (black cherry), Robinia pseudoacacia, Robinia hispida, Chionanthus virginicus, late Lilacs, Azaleas, Rhododendron carolinianum, Wisteria floribunda (Japanese Wisteria), Calycanthus floridus (Carolina allspice), viburnums (including Viburnum opulus, V. plicatum var. tomentosum (Doublefile viburnum), and V. sargentii), Weigela florida, Lonicera tatarica, Deutzia sp., Tree peony, Trillium, Geranium sp., Dicentra spectabilis (Bleeding heart), Dicentra eximia (Fringed Bleeding Heart), Convallaria majalis (Lily-of-the-valley), Amsonia sp., Centaurea montana, Euphorbia polychroma, Lamium sp., Lamiastrum galeobdolon, Primula sp., Corydalis lutea, Mazus reptans, Aquilegia (Columbine), Brunnera macrophylla, Ajuga, Saruma henryi, Phlox stolonifera, Phlox divaricata, Phlox subulata, Myosotis sylvatica (Forget-me-not), Lupinus sp., Dianthus sp., Lunaria annua (honesty or money plant), Tiarella cordifolia (Foam Flower), Hyacinthoides hispanica, Bearded Iris, Siberian iris, Arisaema sp. (Jack-in-the-pulpit), Cypripedium sp.(Lady's Slipper), Polygonatum sp. (Solomon's Seal), Persicaria bistorta 'Superbum' and Doronicum sp. are in full bloom. Rosa rugosa and Baptisia australis (and hybrids) are beginning bloom and the following plants are ending bloom: Aesculus hippocastanum (Common Horsechestnut), Cercis canadensis, flowering dogwoods, Fothergilla sp., Spiraea prunifolia (Bridalwreath Spirea) and Daphne x burkwoodii 'Carol Mackie'. The invasive plants Euonymus alatus (burning bush) and barberry are in bloom. Now is a good time to shear them back, along with Autumn olive, if possible, before more seed is set and spread.  Pests/Problems: Winter moth caterpillars have started and will continue to pupate. Damage to trees is sporadic with heavy defoliation in some areas of southeastern MA. Oaks appear to have the most damage but Norway maples, red maples and ash also have damage. In one neighborhood in Bridgewater, MA, ‘Crimson King’ Norway maple tree leaves were eaten back to their mid-veins. In some towns, weeping cherries and Kwanzan cherries were also severely defoliated. Driving along, it looks like trees haven’t leafed-out yet, but what we are seeing is defoliation by the caterpillars. Gypsy moth caterpillars were also observed on oak along with a few oak loopers. Although, gypsy moth numbers are not extremely high, there appear to be more this year in some areas than in previous years; continue to monitor oaks and other trees susceptible to gypsy moth.  Euonymus caterpillars are active. They are small now, but can be found feeding on the new foliage of euonymus. Look for small silk-like webs as these caterpillars web the leaves together and the webs can envelop whole branches. Iris bud fly maggots were found feeding in the flowers of Siberian iris. These maggots feed on the pollen inside the bud and in doing so, destroy the flowers, and when the flowers open they look tattered. Lily leaf beetle adults, eggs and larvae are present on true lilies. If not managed, especially now that the larvae are active, the lilies will be severely damaged. Azalea sawfly remains actively feeding on deciduous azaleas and roseslug sawfly remains active on roses. If not managed, these pests will cause serious damage to the foliage. Sawfly larvae cannot be managed with Bacillus thuringiensis. Monitor for Cottony camellia scale (Cottony Taxus scale) on Taxus and certain hollies, like Meserve hollies. The following insects remain active: pine spittlebug, azalea whitefly, snails, woolly beech aphid, ants, wasps, hornets, mosquitoes, honeybees, mason bees, imported willow leaf beetle, carpenter bees, bumblebees, and ticks. Mosquitoes are numerous and biting flies have started to appear. Deer tick nymphs remain active and this is the deer tick stage often associated with the transmission of Lyme disease and other diseases. Continue to use repellents and conduct tick checks frequently.  Larry Dapsis, Entomologist, and the Deer Tick project coordinator with the Cape Cod Cooperative Extension reported “that for many years the highest incidence rates for Lyme disease were Nantucket, Martha’s Vineyard and Cape Cod. This changed last year… Plymouth County jumped into the third spot, surpassing Barnstable County by a 2:1 margin."  Monitor the foliage on ‘Arnold Promise’ witchhazel for, Phyllosticta hamamelidis (Witchhazel blight), which will cause the foliage to turn brown. Continue to handpick and destroy the small green gall of Azalea leaf gall (Exobasidium vaccinii) on deciduous azalea foliage.

North Shore Region (Beverly)

General Conditions: At Long Hill 82 growing degree days (GDD) were gained during this reporting period. Only a mere 0.01 inches of rain were received. It has been a very dry month of May, soils are very dry and lawns are showing signs of water stress. Some lawns are browning out especially in areas with sandy soils.  Water the lawn and garden if possible. Many plants were in bloom during this period and for some plants the flower display has been more spectacular this year than in previous years. Many azaleas and rhododendrons were in full bloom. These include: Snow azalea (Rhododendron mucronatum), Hallelujah rhododendron (Rhododendron ‘Hallelujah’), Hinodegiri azalea (Rhododendron ‘Hinodegiri’), Polar bear azalea (Rhododendron ‘Polar Bear’), Carolina Rhododendron (Rhododendron carolinianum), Catawba Rhododendron (Rhododendron catawbiense), Toucan azalea (Rhododendron ‘Toucan’) Percy wiseman rhododendron (Rhododendron ‘Percy Wiseman’), Scintillation rhododendron (Rhododendron ‘Scintillation’), Unique azalea (Rhododendron ‘Unique’), Miss Louisa azalea, Gable azalea (Rhododendron ‘Rose Greeley’), Mary Bell rhododendron (Rhododendron ‘Mary Bell'), Berry Rose azalea (Rhododendron 'Berry Rose’) Narcissus flowered azalea (Rhododendron narcissiflora), Palestrina azalea (Rhododendron palestrina), Amoenum azalea (Rhododendron obtusum ‘Amoenum’) and Rhododendron ‘Blue Peter’. Other woody plants seen in full bloom include: Japanese maple (Acer palmatum), Silverbell (Halesia carolina), Common Horsechestnut (Aesculus hippocastanum), Flowering dogwood (Cornus florida), Eastern redbud (Cercis canadensis), Handkerchief tree (Davidia involucrata var. vilmoriniana), Common lilac (Syringa vulgaris), Doublefile viburnum (Viburnum plicatum var. tomentosum), Slender Deutzia (Deutzia gracilis), Wisteria (Wisteria floribunda), Red horsechestnut (Aesculus x carnea), single seed hawthorn (Crataegus monogyna), Wright viburnum (Viburnum wrightii), Little leaf lilac (Syringa microphylla), Sapphireberry (Symplocos paniculata), American cranberrybush viburnum (Viburnum trilobum), Siberian peatree (Caragana arborescens), White tree wisteria (Wisteria floribunda) and Tree Peony (Paeonia suffruticosa) . Herbaceous plants in bloom include: Peonies (Paeonia sp.), Fetterbush (Leucothoe fontanesiana), Rosa rugosa, Kenilworth ivy (Cymbalaria muralis), Sweet woodruff (Galium odoratum), Canada May flower (Maianthemum canadense), Lily of the valley (Convallaria majalis), Blue star (Amsonia hubrichtii), and summer snowflakes (Leucojum aestivum).  Pests/Problems: Winter moth caterpillars are enlarging quickly and causing a lot of damage on maple, oaks and other trees . Gypsy moth caterpillars are also causing serious damage on some trees. Hemlock woolly adelgid is also active. Eastern tent caterpillars are enlarging and causing damage especially on cherry trees. 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).

East Region (Boston)

General Conditions: We gained 82 GDDs over the last week bringing us up to 359.5 so far this year. We started the week out with four days of seasonable temperatures; highs were predominately in the 60s with lows in the 40’s. Hot temperatures returned on the 24th and continued for the rest of the week with highs in the 80’s. For the week, we had an average low of 50º F and an average high of 75º F. We received no rain over the last week and the total for the month of May stands at 0.25 inches. Currently in bloom: Cornus sp., Rutgers Hybrids (dogwoods), Cotoneaster sp. (cotoneaster), Liriodendron tulipifera (tulip tree), Lonicera sp. (honeysuckle), Magnolia sieboldii (Oyama magnolia), Paulownia tomentosa (princess tree), Prunus serotina (black cherry), Rosa spinosissima ‘Lutea Plena’ and ‘Plato’ (cultivars of Scotch rose), and Xanthorhiza simplicissima (yellowroot). Wildflower and perennials in bloom: Arisaema triphyllum (small Jack-in-the-pulpit), Maianthemum canadense (Canada mayflower), Maianthemum racemosum (false Solomon's seal), Ornithogalum umbellatum (star-of-Bethlehem), Phlox subulata (creeping phlox), Polygonatum sp. (Solomon’s seal), and Ranunculus bulbosus (bulbous buttercup). Swallowtail butterflies have been spotted, including the Eastern tiger swallowtail (Papilio glaucus), black swallowtail (Papilio polyxenes), and the Canadian tiger swallowtail (Papilio canadensis). Female turtles have mated and are laying their eggs. Pests/Problems: The lack of rain that we have been experiencing this spring has led to the United States Drought Monitor to classify the State of Massachusetts as being in a moderate drought. Supplemental watering is necessary for newly planted trees and shrubs as well as for plants that were planted in 2014. Water stress is evident throughout the grounds on both young and older trees. Grass has started to turn brown in some areas. Garlic mustard (Alliaria petiolata) and greater celandine (Chelidonium majus) continue to flower and simultaneously set seed. Weeds in bloom include: black swallowwort (Cynanchum louisae), common groundsel (Senecio vulgaris), ground ivy (Glechoma hederacea), and stinging nettle (Urtica dioica). Japanese knotweed (Polygonum cuspidatum) and pokeweed (Phytolacca americana) continue to emerge and are becoming quite visible as they grow; yellow nutsedge (Cyperus esculentus) continues to emerge. Woody weeds in flower include: burning bush (Euonymus alatus), European spindletree (Euonymus europaea), and Japanese honeysuckle (Lonicera japonica). Maple seedlings, mostly Norway maple (Acer platanoides) have germinated throughout the landscape. Lily leaf beetle (Lilioceris lilii) has emerged and has started feeding on lilies (Lilium sp.).

Metro West (Acton)

General Conditions: The area gained 81 GDD during this recording period and did not receive any measurable precipitation. The average monthly total for May is 4.04" and a mere 0.15” has been recorded for this month. Soils are dry and lawns are beginning to brown out. Woody plants seen in bloom this past week are Aesculus hippocastanum (Horse Chestnut), Chionanthus virginicus (Fringe Tree), Cornus florida (Dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers Hybrid Dogwood), Cornus sericea (Redosier Dogwood), Crataegus sp. (Hawthorn), Daphne x burkwoodii 'Carol Mackie' (Daphne), Ilex aquifolium (English Holly), Kerria japonica (Japanese Kerria), Leucothoe axillaris (Coast Leucothoe), Lonicera maackii (Amur Honeysuckle), Potentilla tridentata (Cinquefoil), Prunus japonica (Flowering Almond), P. serotina (Black Cherry), Rhododendron spp. (Rhododendron and Azalea), Robinia pseudoacacia (Black Locust), Rosa rugosa (Japanese Rose), Sorbus aucuparia (European Mountain Ash), Spiraea spp. (Spirea), Syringa spp. (mid-late blooming Lilac), Viburnum plicatum var. tomentosum (Doublefile Viburnum), V. sargentii (Sargent Viburnum), and Weigela florida (Old Fashioned Weigela). Woody vines in bloom are: Lonicera sempirvirens (Trumpet Honeysuckle), Clematis montana var. ruebens (Anemone Clematis), Clematis spp. (Clematis), and Wisteria spp. (Wisteria). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Ajuga reptans (Bugleweed), Allium spp. (Ornamental Flowering Onion), Amsonia hubrichtii (Arkansas Blue Star), Anemone candensis (Canada Anemone), Aquilegia spp. (Columbine), Baptisia australis (False Blue Indigo), Centaurea montana (Cornflower), Camassia scilloides (Wild Hyacinth), Chrysogonum virginianum (Green and Gold), Convallaria majalis (Lily of the Valley), Cypripedium parviflorum (Yellow Lady's Slipper), Dianthus deltoides (Maiden Pink), Dicentra eximia (Fringed Bleeding Heart), D. spectabilis (Old Fashioned Bleeding Heart), D. spectabilis 'Alba' (White Flowering Old Fashioned Bleeding Heart), Dictamnus albus (Gas Plant), Fragaria sp. (Strawberry), Gallium odorata (Sweet Woodruff), Geranium maculatum (Wild Geranium), G. macrorrhizum (Bigroot Geranium), G. sanguineum (Cranesbill Geranium), Helleborous niger (Christmas Rose), Hyacinthoides hispanica (Wood Hyacinth), Iberis sepervirens (Evergreen Candytuft), Iris germanica (Bearded Iris), I. sibirica (Siberian Iris), Linaria annua (Money Plant), Lupinus' 'Russell Woodfield Hybrids' (Lupine), Maianthemum dilatatum (False Lily of the Valley), Muscari sp. (Grape Hyacinth), Myosotis sylvatica (Forget-me-not), Narcissus spp. (Daffodil), Nepeta spp. (Ornamental Catmint), Paeonia spp. (Peony), Papaver orientale (Poppy), 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), Rubus spp. (Bramble, Blackberry), Salvia nemerosa (Salvia), Stylophorum diphyllum (Wood Poppy), Thymus praecox (Thyme), Veronica umbrosa 'Georgia Blue' (Speedwell), Vinca minor (Periwinkle), Viola spp. (Violet), and Zizia aptera (Heart-Leaved Alexander).  Pests/Problems: Due to the lack of rainfall this month and the unseasonably warm temperatures, the United States Drought Monitor has classified the State of Massachusetts in a moderate drought level. This is the fifth week in a row without any significant rainfall. Seen in the landscape are the following: Eastern Tent caterpillar and the web that it creates in the main branches of Malus sp. (Crabapples) and Prunus sp. (Cherry and caterpillars and their ballooning and feeding on the foliage of Amelanchier sp. (Shadbush), Corylus (Filbert), Fagus (Beech), Quercus (Oak), Malus (Apple, Crabapple), Prunus (Cherry), Rosa (Rose), Syringa (Lilac), Tilia (Linden) and Ulmus (Elm). Many weeds are in flower including some of the most invasive, Alliaria petiolata (Garlic Mustard), Elaeagnus umbellata (Autumn-olive) and Euonymous alatus (Burning Bush). Glechoma hederacea (Ground Ivy), Lamium purpureum (Purple Dead Nettle). Other weeds seen in bloom are: Senecio vulgaris (Common Groundsel), Stellaria media (Common Chickweed) and Taraxacum sp. (Dandelion). Toxicodendron radicans (Poison Ivy) continues to leaf out and it is fairly easy to detect its shiny red leaves of three. Ticks, mosquitoes and black flies are feeding and active.

Central Region (Boylston)

General Conditions: Temperatures were moderate and very spring-like for the first portion of the reporting period but have become very summer-like (mid- to upper 80’s) in the past few days. Many plants are in full bloom.  Pests/Problems: The dry conditions remain our most serious problem. We are irrigating planting beds and and new trees and shrubs that have been put in for the past two years. Turf is beginning to brown out in unirrigated, well-drained areas. Brush fires have been popping up throughout the region.

Pioneer Valley Region (Amherst)

General Conditions: This past reporting period started with more seasonable temperatures, with highs in the 60s and 70s and lows ranging from the high 30s to mid-40s. A frost warning was issued for Franklin County for the early hours of Saturday 5/23. Since then, conditions have warmed up again to unseasonable heights, with high temperatures in the upper 80s. Scattered thunderstorms developed in Franklin County on Tuesday, 5/26 but much of the valley remained dry. The following day, on 5/27, a large and strong band of thunderstorms moved through the region, finally bringing some respectable rainfall to the area (between 0.5-0.7”). More rain is forecasted for 5/28 but we’re still fully entrenched in a moderate, short-term drought. The National Weather Service Eastern Region Headquarters produced a map on their Facebook page ranking the total rainfall from 5/1 to 5/24 across the eastern United States. In southern New England, many of the weather stations are reporting the driest May on record. The recent rains will probably drop these rankings a bit. June can be quite wet, as we experienced in 2013 when the valley received over 9” of rainfall, so there is still hope of a productive growing season for trees and shrubs. Lawn grass has developed large brown patches and lawn weeds continue to wilt and die in exposed areas. Despite the drought, many trees and shrubs are green and robust, showing little signs of water stress. However, symptoms of water stress can be slow to manifest, especially for conifers. We may see drought-related symptoms develop later this season as a result of the dry conditions. New England Public Radio offered a short and interesting story about the surge of mosquitoes that emerged this month ( The rapid transition from cool to hot weather led to a mass mosquito emergence, but thankfully these mosquitoes are not the ones vectoring deadly diseases like West Nile Virus. Ensure that any buckets, etc. that could allow free standing water to linger are overturned or stored inside. Over this past reporting period, the mosquito population seems to be lessening based on this author’s anecdotal observations in the backyard.  Pests/Problems: Drought is a major predisposing stress for woody plants, weakening defenses and allowing insect pests and fungal pathogens, that would otherwise be contained, to invade and establish. Tops on this list is Armillaria, a soilborne fungal pathogen that causes root and lower trunk rot on a wide array of trees and shrubs. Continue to provide supplemental water for recently planted trees and shrubs and those that have suffered stress from insect attack, disease or abiotic events (construction, winter injury, etc.) in the past. This is best accomplished with a slow soaking of the soil surrounding the base. Lawn sprinklers are of little use and in many cases, watering this way does more harm than good if branches and foliage are wetted. One positive aspect of the drought is that many fungal pathogens cannot initiate new infections without free moisture on above ground plant parts. Therefore, don’t provide it for them by soaking the canopy with a lawn sprinkler. The dry weather has suppressed many anthracnose fungi from causing foliar blights and stem cankers. We can often look to American sycamore to find out if it’s going to be a bad anthracnose season. When disease severity is high, sycamores will be repeatedly attacked as new leaves develop, making them some of the last trees to fully leaf out. In the valley, sycamores leafed out successfully the first time with few symptoms of the disease. Once leaves are fully developed, trees are much less susceptible to the complete collapse that can ensue from an early season anthracnose outbreak. There was a major risk of fire blight on apple and crabapple in early and mid-May but without rainfall to initiate the disease, the risk failed to materialize as flowering parts came and went. However, the risk was still high prior to the thunderstorms on 5/27 which might be enough precipitation to initiate localized outbreaks of the disease. Because of the unseasonably warm weather in the valley, we’ve accrued enough GDD to begin managing crawlers of the elongate hemlock scale on landscape hemlock and true fir. Careful scouting should take place, especially in the lower canopy, to assess the severity of the infestation.

Berkshire Region (Great Barrington)

General Conditions: Over the past week, weather forecasters keep saying that thunderstorms will be “hit or miss.” That has been very true of rainfall for the Berkshires of late. Where storms have occurred, they have been torrential but very brief. A fraction of a mile could make a difference between some rain and none. On May 26, rain fell in some towns just north of here but no rain fell at this monitoring station in Great Barrington… OK, I counted 19 drops. Overall, rain has been sparse and soils are very dry. The rainfall deficit to date for 2015 in much of the County is around 6 inches. Many lawns are showing the effects of drought as patches of brown grass have become common. Earlier in spring, we were advising people not to rush to judgement on the apparent injury to shrubs from winter cold and desiccation. At this time, it can be safely concluded that stems showing no signs of growth are dead. Shrubs with the most damage include: rhododendrons, hydrangeas, Clethra, Cotinus, and Deutzia. Stems showing no signs of growth can be pruned out or back to live tissue.  Pests/Problems: Black-legged ticks, dog ticks, wasps, carpenter bees, ants, mosquitoes, Asian multicolored lady beetle, and earwigs are among the pesky critters observed now. Black-legged ticks (deer ticks) continue to be a serious problem as a high number of cases of Lyme Disease are occurring in the County. Though it’s been said repeatedly, precautions to protect oneself from ticks should be taken seriously by anyone working or playing outdoors. Among the plant pests which remain active are: Eastern tent caterpillar, viburnum leaf beetle (larvae), imported willow leaf beetle (larvae), European pine sawfly (larvae), wooly beech aphid, cankerworms, spruce spider mite, lily leaf beetle (adults), leaf rollers, and boxwood leafminer (pupal and adult stages). New pest observations this past week included Boxwood Psyllid nymphs, Oak Lacebug (Corythucha arcuate) on leaves of Quercus macrocarpa, Azalea Sawfly, and aphids and leaf hoppers on various tree and shrub species. The dry weather may have precluded development of many foliar diseases as no symptoms of apple scab or other leaf spot diseases have been observed. This is the time of year when many strange growths can be seen on the leaves of trees. These are leaf galls, growths initiated by a variety of insects (mostly wasps and midges) and mites. For the most part, these growths have no effect on the plant other than aesthetic and no remedial measures are warranted.

Environmental Data

The following growing-degree-day (GDD) and precipitation data was collected for an approximately one week period, May 21 through May 27. Soil temperature and phenological indicators were observed on or about May 27. 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)
Robinia pseudoacacia (Black Locust) * full full full full full full full
Cornus kousa (Kousa Dogwood) * begin begin begin begin begin begin begin
Weigela florida (Old Fashioned Weigela) begin full * end full full full begin/ full
Kolkwitzia amabilis (Beautybush) begin begin/full * full * full begin/full begin
Syringa meyeri (Meyer Lilac) begin full * full * full full full
Deutzia spp. (Deutzia species) begin full full begin/full * full full full
Aesculus hippocastanum (Common Horsechestnut) full full/end full end full full full full
Rhododendron catawbiense (Catawba Rhododendron) full full full/end begin full full full full
Enkianthus campanulatus (Redvein Enkianthus) full full * full * full full full
Rhododendron carolinianum (Carolina Rhododendron) full/end full full * full full full *
Spiraea x vanhouttei (Vanhoutte Spirea) full full full full full/ end full full full
Elaeagnus umbellata (Autumn-olive) full full/end full/end full full/end full/end full/end full
Syringa vulgaris (Common Lilac) full/end end full end end end full/end full/end
Cornus florida (Flowering Dogwood) full/end full/end full end full/end full/end full/end full/end
Rhododendron spp. (Early Azaleas) full/end full/end end end end end full/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


Lower canopy dieback of eastern redcedar (Juniperus virginiana) caused by cedar-quince rust (Gymnosporangium claviceps) and phomopsis blight (Phomopsis juniperovora). A very large, mature redcedar in a residential setting was damaged during a lawn regrading project a few years ago. Since that time, it has experienced a serious decline of lower canopy branches. Both pathogens were abundant on the submitted material.

Suspected winter injury on Oriental spruce (Picea orientalis). Tree is approximately 15-years-old and has been present at the site for roughly a decade. This spring, browning needles were observed in the canopy. Needles produced in 2013 were mostly healthy while needles produced in 2014 were nearly all blighted. The buds on the symptomatic shoots, however, were mostly intact and many had flushed new growth this spring. No insect pests or fungal pathogens were detected, leaving cold injury as the only reasonable explanation for the die off of only 2014’s foliage.

Needle and shoot blight on dwarf Scots pine (Pinus sylvestris) caused by Diplodia pinea and the pine shoot beetle (Tomicus piniperda). Tree resides in full sun with good wind exposure and the decline was observed in years past. The pine shoot beetle is non-native and is most often found on Scots and Austrian pine.

Anthracnose caused by Discula on Norway maple (Acer platanoides). Tree is approximately 40-years-old and has been treated for winter moth infestations. This spring, sporadic wilting of newly flushed leaves was observed. Another nearby tree exhibited similar symptoms. The trees had a similar type of dieback during autumn of 2014. Many anthracnose fungi have been suppressed due to the dry weather, but enough moisture must have been present in this particular location to initiate disease development.

Infestation of the Norway spruce gall midge (Piceacecis abietiperda). Tree is approximately 20-years-old and has been present at the site for 10 years. This spring, widespread tip dieback was observed. Last year’s shoots were stunted and deformed with clear signs of midge infestation. This non-native insect pests attacks Norway spruce only and has only recently become a major pest of landscape trees.

Pitch mass borer (Synanthedon pini) infestation of eastern white pine (Pinus strobus). Several declining white pines on a residential property. Numerous pitch masses were observed on one particular tree and intact larvae were excavated from pitch masses within reach. While the borer is a highly conspicuous pest, it causes only minor damage to infested trees. Therefore, the decline is mostly the result of unidentified stresses, with one possible cause being white pine needle blight.

Needle blight of juniper caused by Lophodermium juniperinum. Considered a weak pathogen, Lophodermium produces black, football-shaped pads on blighted needles that rupture to release large masses of clear spores.

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.

Management Practices

Irrigating Plants in the Landscape

With all of Massachusetts under moderate drought conditions, irrigation of newly planted and some established plants is necessary. Newly established plants will have different water requirements than established plants. In a nursery, container plants are usually irrigated daily. When container plants are being established in the landscape, irrigation should be similar to what it was in the nursery as plants adjust to the new conditions. For the first week, daily smaller irrigations are needed, with care being taken to ensure watering is in the root zone of the plant. Plants should be kept moist but not wet; check soil moisture a few inches below the soil surface. As the plants become established and roots explore more areas of the soil, irrigation should become less frequent (twice a week for the first month, and weekly for the rest of the growing season) and deeper (wetting 5-6” of the soil). A soaker hose or watering with an open hose set to a slow flow is more effective for watering trees and shrubs than a sprinkler. A 5 gallon bucket with a few small holes in the bottom can also be a good way of watering larger trees. Water should slowly seep into the soil; this allows for greater infiltration, saturation of the soil, and reduced runoff.

When irrigating landscape plants it’s also important to remember that there is no one-size-fits-all method of watering. Factors that will impact plant water use include:

  • Soil properties - Soil factors determine the water holding capacity and infiltration rate. For example, clay soils will hold water longer than a sandy soil.
  • Plant size – plant water use increases with plant size.
  • Production method - Plants produced in containers are watered more frequently during production than field grown plants. This difference needs to be considered during landscape establishment.
  • Location in the landscape - Plants in the landscape can compete for water. Large trees will out-compete newly established plants planted underneath. Care should also be taken to provide supplemental irrigation to plants underneath overhangs or other areas that may not receive as much rainfall. Container plants will require more frequent irrigation (every 2-3 days or more frequently as the plant grows). Plants in coco-liners and plastic pots will dry more quickly than plants in clay pots. Also make sure when planting in containers that the container has drainage!
  • Environmental conditions - Rain, light, wind, humidity, and temperature will all affect the rate of evapotranspiration. Plant water needs will change day to day due to environmental conditions. On sunny, windy days evapotranspiration will be higher than on cloudy days, resulting in higher plant water use.
  • Extent of root establishment. - Newly established plants have smaller root systems and do not benefit from deep watering, whereas deep watering is beneficial for established plants with larger root areas.

During this drought period it is important to monitor plants that were damaged over the winter. Supplemental irrigation will be important for these plants to avoid additional stress during recovery. Other irrigation tips:

  • Feel the soil! Make sure to dig down a few inches – the top few inches will dry more quickly and may not represent overall soil moisture.
  • Irrigation for turf will not be adequate for trees in the lawn.
  • Don’t wait until plants wilt to water – irrigate based on soil moisture. Wilting is a sign of drought stress and prolonged drought stress can lead to plant death.
  • Water efficiently! There is no benefit in irrigating until runoff. Do not irrigate hardscapes, sidewalks, or streets.
  • There is such a things as too much water. Excessive water reduces oxygen in the root zone and can lead to plant death.
  • Mulching can reduce evaporation and help maintain soil moisture

Report by Mandy Bayer, Extension Assistant Professor of Sustainable Landscape Hortulculture, Stockbridge School of Agriculture, UMass Amherst.

Landscape Turf

Management Practices

Turf Maintenance Levels, Stress, and Expectations

We often hear the terms ‘low maintenance’ and ‘high maintenance’ used in reference to turf management programs or specific turf sites, but what do these terms really mean?  Furthermore, how does one we go about modifying the level of management attention that is required?

After the epic winter and the tough spring we have experienced thus far, stress is the first word that comes to mind.  Stress is one of the primary ingredients that has bearing on required maintenance levels.  Just like people or animals, plants are susceptible to detrimental effects from stress.  One way to define plant stress is any agent that forces a plant to devote resources away from growth in order to combat the stress or its effects.  When the growing environment is stressful, there is a greater need to ‘assist’, or intervene, with inputs, pest control measures and/or cultural practices… thereby increasing maintenance.

We have a great deal of control over some potential stress factors (e.g. mowing height), while for others we are able to exert very little control (e.g. heat).  Some common stress factors are as follows:

Management Practices Environmental Factors Site-Specific Factors
  • Mowing height
  • Mowing frequency
  • Disruptive practices (aeration, dethatching, topdressing, etc)
  • Herbicides
  • Heat
  • Cold
  • Drought
  • Ice
  • Salinity
  • Wear/traffic
  • Shade/Exposure
  • Slope
  • Drainage
  • Soil factors (texture, pH, fertility, etc)

Another main element that influences maintenance levels is the expectations for turfgrass performance; both aesthetics and function.  While the basic survival of turf cover receives a large share of the priority in lower maintenance situations, additional practices designed to maintain a certain level of performance come into play in higher maintenance programs.  For example, while lower maintenance programs may to allow for natural dormancy, many other programs irrigate throughout the summer in order to maintain turf growth and color.

Expectations and certain stress factors, furthermore, are typically interrelated.  A great example of this relationship involves putting greens.  The very low mowing height and constant defoliation for greens minimizes the amount of leaf area available for photosynthesis.  Lower photosynthetic capacity translates to a smaller root system which is less able to capture moisture and nutrients from the soil.  Such plants, therefore, are less able ‘to provide for themselves’, are more demanding in terms of careful watering and precision fertilization, and are much more likely to fail when environmental stresses, pests, or use-related challenges upset the delicate balance.

A large part of lowering maintenance demands and reducing inputs, then, is about managing stress and also expectations.  In some ways it is more straightforward to deal with stress factors that we can directly control, such as mowing height, mowing frequency, or timing of other cultural practices.  Such practices, however, are often linked to expectations and may therefore necessitate ongoing dialog with customers, clients, or others users of the turf.  Such conversations are often more productive if there is a common goal to reduce maintenance. 

Management of stresses that we can't control is promoted by better adaptation of the grasses present, and thus better equilibrium with the growing environment.  Other approaches that support lower maintenance include reducing inputs such as fertilizer and water to the lowest level required to maintain the desired turf performance, integrated management of pests to reduce pesticide use, and investment of limited time and resources in key activities that pay future dividends (renovation or overseeding, for example). Finally, as covered in my last message, it never hurts to be prepared to shift priorities temporarily to deal with unforeseen, extenuating circumstances.

Report by Jason Lanier, Extension Educator, UMass Extension Agriculture & Landscape Program, UMass Amherst.

Additional Resources

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Diagnostic Services

A UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see Plant Diagnostics Laboratory

Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The function of the Soil and Plant Nutrient Testing Laboratory is to provide test results and recommendations that lead to the wise and economical use of soils and soil amendments. For complete information, visit the UMass Soil and Plant Nutrient Testing Laboratory web site.   Alternatively, call the lab at (413) 545-2311.

Ticks are active at this time! Remember to take appropriate precautions when working and playing outdoors, and conduct daily tick checks. UMass tests ticks for the presence of Lyme disease and other disease pathogens. Learn more