Source: http://ag.umass.edu/landscape/landscape-message-jun-16-2017
Timestamp: 2019-04-20 16:16:58+00:00

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The Landscape Message will be updated weekly April through June. The next message will be available on June 23. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.
The following data was collected on or about June 14. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2017 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.
General Conditions: The average temperature from June 7 - June 14 was 68° F with a high of 92.5° on June 13 and a low of 42° F on June 8, a significant temperature spread for the week. The temperature exceeded 90° F on both June 12 & June 13 - somewhat of a rarity on Cape Cod. The week had little precipitation (0.42 inches) most of which fell on June 9. On June 13 there were some isolated thunderstorms. The rapid warm up and plentiful sun caused many plants to wilt even under adequate soil moisture. Topsoil moisture is short, subsoil moisture is adequate.
Pests/Problems: Gypsy moth caterpillars continue to feed on susceptible hosts. Caterpillars are primarily in the fourth instar. Defoliation on the upper Cape is spotty with areas rapidly expanding as we approach the larger later instars. Viburnum leaf beetle larvae have begun to drop to the ground to pupate. Other active insects include Bristly nose roseslug sawfly, columbine sawfly, hydrangea leaftier, four lined plant bug, and earwigs. Sycamore anthracnose in many instances has blighted the trees’ first attempt to leaf out. Maple anthracnose is being seem in some spots. Brown rot damage is extensive on Kwanzan and other ornamental cherries. Weeds in bloom include; black medic (Medicago lupulina), multiflora rose (Rosa multiflora), buckthorns (Rhamnus & Frangula), black swallow-wort (Cynanchum louiseae), white campion (Silene alba), white clover (Trifolium repens), hawkweed (Hieracium pratense), red sorrel (Rumex acetosella), curly dock (Rumex crispus), goutweed (Aegopodium podagraria) and yellow woodsorrel (Oxalis stricta).
General Conditions: Summer came hard and fast after the previous cooler weather. Temperatures were in the high 80’s on June 11, and the low 90’s on June 12, and 13. High heat pushed many plants to end bloom prematurely and soils in sunny areas are drying out, while soils in the shade remain moist. Hanson received a trace amount of rain at 0.07 inches. Remind clients to water newly planted or transplanted plants and those plants defoliated by caterpillars.
The following plants are in bloom: Sinocalycanthus chinensis, Aesculus x carnea, Liriodendron tulipifera (Tuliptree), Cornus kousa, Magnolia virginiana (Sweetbay magnolia), Styrax japonicus, Weston hybrid azaleas, Hydrangea anomala petiolaris, Itea virginica, Spiraea sp., Rhododendron sp., Kalmia, Calycanthus floridus (Common Sweetshrub), Indigofera sp., landscape roses, Rosa rugosa, Clematis sp., Viburnum dilatatum (Linden Viburnum), Viburnum dentatum (Arrowwood Viburnum), Syringa x prestoniae ‘James MacFarlane’, Clematis, Robinia hispida (bristly locust), Beautybush, Lonicera sempervirens, Lonicera ‘John Clayton’, early daylilies, Alchemilla mollis, Salvia sp., Geranium sp., Thalictrum aquilegifolium, Anenome canadensis, Persicaria polymorpha, Doronicum sp., Lamium, Allium, Nepeta sp., Baptisia australis, Dianthus sp., Tradescantia, Lupines, Corydalis lutea, Valeriana officinalis, Amsonia sp. Foxgloves,Peonies, Aquilegia (Columbine) and Oriental poppies. A Rosa rugosa hybrid, ‘Linda Campbell’ is in full bloom; double red flowers on a plant 4-6 feet high and wide; usually no problem with black spot and blooms again later in the season. It is worth checking out.
Cotinus obovatus (American Smoketree) and Cotinus coggyria (European Smokebush) have ended bloom but are now producing their colorful “smoke” (plume-like hairs that form on the sterile flowers). The ‘smoke’ is an attractive landscape feature and will remain for several weeks. Chionanthus virginicus, Physocarpus opulifolius (Eastern Ninebark, Siberian Iris and bearded iris are ending bloom.
Hanson is at 1,149 GDD - Growing Degree days, Base 40.
Pests/Problems: Gypsy moth caterpillar damage appears to be sporadic. Some trees in some areas are stripped of foliage and others have little damage. At our Hanson site, there are several trees that are monitored for caterpillar damage and the large oak tree, along with the apple and crabapple trees, are almost stripped of foliage. These trees are traditionally damaged by winter moth caterpillars, but this year there was little damage by winter moth but gypsy moth caterpillars came in and stripped the leaves. Most gypsy moth caterpillars are in 4th instar; however at another site in Hanson, there were numerous 5th instar caterpillars. Along with the 4th and 5th instar caterpillars, there were many 2nd - 3rd instar small caterpillars. I asked Dr. Elkinton’s staff about that, and the answer is that the caterpillars were parasitized by a small wasp Cotesia melanoscela (http://www.entomology.wisc.edu/mbcn/kyf503.html). The parasitized caterpillars will not molt into 4th, 5th or 6th instar as a result. In areas where caterpillar numbers are high, falling frass (excrement), can clearly be heard 24 hours a day and the frass is covering everything below. Many caterpillars were observed climbing up buildings and dying, but many others appeared healthy and remain feeding. Again, the highest caterpillar numbers were found feeding on oak. For detailed Gypsy Moth information, see the Insect Section of the Landscape Message below.
Asiatic garden beetles have started to emerge and these small copper-colored beetles feed on a wide range of plant material and are often attracted to lights and feed at night. The larger copper colored beetle, European chafer, is also active.
Birch leaf miner, Fenusa pusilla, is active on grey birch and paper birch. Look for small brown lesions on the foliage. Hold the leaf to the light and you may see the small sawfly larvae feeding within the leaf. Slugs, snails and earwigs are active and are often found feeding on plant material at night. Golden tortoise beetle is feeding on sweet potato vine. Euonymus caterpillars have finished feeding and have pupated.
The following insects remain active: lacebugs on Japanese Andromeda (Pieris japonica), Rhododendron and azaleas; roseslug sawfly; White pine sawyer beetle (Asian longhorned beetle look-alike); cottony camellia scale on Merserve hollies and Taxus; Hemlock woolly adelgid; elongate hemlock scale; Taxus mealy bug; mosquitoes, aphids, stink bugs,four-lined plant bugs, leafhoppers, lily leaf beetle, wasps, pine spittlebugs, azalea whitefly, hornets, deer flies, horse flies, dog ticks and deer tick nymphs. Beneficial insects are active and it is a great year for butterflies.
The following plant diseases continue to be observed: sycamore anthracnose; maple anthracnose; dogwood anthracnose; black spot on roses; apple scab on crabapples and apples;Phyllosticta hamamelidis (Witchhazel blight) on ‘Arnold Promise’ witchhazel; Monilinia (brown rot) on Kwanzan cherry; botrytis blight on peonies.Continue to remove Azalea leaf galls (Exobasidium vaccinii) from deciduous azaleas and place them in the trash.
The following weeds are in bloom: Multiflora rose (Massachusetts invasive plant); oxeye daisy; black swallowwort (invasive); hawkweed; buttercup; veronica.White pines have finished producing pollen. Now all we need is a good downpour to clean off all the yellow pollen that is everywhere.
General Conditions: We started the first few days of this reporting period with seasonable temperatures in the low 70s on June 7th and 8th. The temperatures climbed steadily into the low to mid 80s on the 9th and the 10th and by June 11 the heat was on with temperatures climbing into the mid to high 90s with high humidity. We gained 126 growing degree days during this period. It was also dry except for June 13 when approximately 0.09 inches of rain were recorded at Long Hill, Beverly. Soil moisture was still adequate due to previous rains except for areas with sandy soils where the top moisture was inadequate and necessitated watering for some plants . Woody plants seen in bloom include: Chinese dogwood (Cornus kousa), Arrowwood viburnum (Viburnum dentatum), Magician Deutzia (Deutzia magicien), Fringe tree (Chionanthus virginicus), Mock orange (Philadelphus spp.), Beautybush (Kolkwitzia amabilis), Mountain Laurel (Kalmia latifolia), Weigela (Weigela florida), Korean dogwood (Cornus coreana), Stewartia (Stewartia rostrata), Chinese stewartia (Stewartia serrata), American holly (Ilex opaca), Japanese snowbell (Styrax japonica), and Yellowwood (Cladrastis kentukea). Non-woody plants seen in bloom include: Bush Cinquefoil (Potentilla fruticosa), Foam flower (Tiarella cordifolia), Fetterbush (Leucothoe fontanesiana), Scotch rose (Rosa spinosissima), Peony (Paeonia sp.), Cranesbill (Geranium sp.), Bleeding heart (Dicentra spectabilis), Redleaf rose (Rosa glauca), Rodger's flower (Rodgersia aesculifolia), Goat’s beard (Aruncus dioicus), Japanese primrose (Primula japonica), Water lily (Nymphaea odorata), Columbine (Aquilegia spp.), Sweet woodruff (Galium odoratum), and annuals such as petunia and million bells.
Pests/Problems: Skeletonized leaf damage by viburnum leaf beetle was observed on Arrowwood viburnum and American cranberry viburnum. Apple scab lesions were observed on leaves of some crabapple trees. Also observed were black spot (Diplocarpon rosae) fungal leaf spots on leaves of some roses. Multiflora rose (Rosa multiflora) is in full bloom and can be seen growing in and amongst trees and shrubs. Several weeds are in bloom. Take steps to control these weeds before they set seed. Ticks and mosquitoes are very active. Make sure you protect yourself with appropriate repellants before you go out into areas with vegetation, especially out in the woods.
General Conditions: Temperatures have steadily climbed over the last week. We began with a high of 67° F on the 7th, warming to the high 70’s on the 8th and 9th before reaching into the 90’s on the 11th, 12th and 13th. This marked the second heat wave of the year and summer has yet to begin! We received only 0.08 inches of precipitation, which fell during a fast moving downpour on the 9th and on the evening of the 13th. We have gained 148.5 GDDs over the last week bringing us to 580.0 GDDs. Many plants are in bloom including: Alchemilla mollis (lady's mantle), Amsonia hubrichtii (Hubricht's bluestar), Aquilegia canadensis (Eastern red columbine), Coreopsis sp. (tickseed), Cornus coreana (Korean dogwood), Cornus kousa (Kousa dogwood) Rutgers hybrids, Digitalis sp. (foxglove), Hydrangea heteromalla (Himalayan hydrangea), Iris germanica (bearded iris), Iris sibirica (Siberian iris), Lamium maculatum 'White Nancy' (dead nettle), Lamprocapnos spectabilis (bleeding heart), Leucanthemum vulgare (oxeye daisy), Lupinus perennis (wild lupine), Nyssa sylvatica (blackgum), Platycodon grandiflorus (balloon flower), Potentilla fruticosa (bush cinquefoil), Rosa canina (dog rose), Rosa pimpinellifolia (scotch rose), Rosa virginiana (Virginia rose), and hybrid roses including Carefree Beauty, Double Knock Out, ‘Julia Childs’, and ‘Mister Lincoln’ among many others, Sambucus nigra (black elderberry), Spiraea japonica (Japanese meadowsweet), Trifolium pratense (red clover), Trifolium repens (white clover), Viburnum plicatum f. plicatum 'Mary Milton' (pink Japanese snowball) and Wisteria sp. (wisteria). Populus deltoides (eastern cottonwood) and other poplars have let their seed fly, leaving fluffy cotton accumulations on the ground.
Pests/Problems: Precipitation followed by recent hot temperatures has contributed to many landscape weeds gaining in size including Convolvulus arvensis (field bindweed), Conyza canadensis (horseweed), and Fallopia japonica (Japanese knotweed). Seedlings of Ampelopsis brevipedunculata (porcelainberry), Cynanchum louiseae (black swallowwort), and Vitis spp. (grape) have germinated in sunny areas. Rumex crispus (curly dock) and Rumex obtusifolius (bitter dock) are setting seed. Weeds currently in bloom include Cynanchum louiseae (black swallowwort), Lepidium virginicum (Virginia pepperweed), Medicago lupulina (black medic), Plantago lanceolata (narrowleaf plantain), Rubus spp. (wild bramble), Solanum dulcamara (bittersweet), Tradescantia virginiana (Virginia spiderwort), Trifolium pratense (red clover), Trifolium repens (white clover), and Urtica dioica (stinging nettle). Galls are present on the leaves of many hickories. Azalea bark scale (Eriococcus azaleae) is actively laying eggs on Rhododendron vaseyi (pinkshell azalea). Euonymus webworm (Yponomeuta cagnagella) is actively feeding on the leaves of Euonymus pauciflorus as the silken webs are easily spotted. Horsechestnut leaf blotch (Guignardia aesculi) lesions are beginning to appear on Aesculus sp. (horsechestnut). Black spot (Diplocarpon rosae) is visible on the leaves of many Rosaceous trees and shrubs including Amelanchier sp. (serviceberry) and Malus sp. (crabapple and apple). Allergies have been severe over the last week; possible culprits are Carya sp. (hickory) and Quercus sp. (oak) which continue to flower.
(Japanese Tree Lilac), Viburnum cassinoides (Witherod Viburnum), V. dentatum (Arrowwood Viburnum), V. plicatum var. tomentosum (Doublefile Viburnum), V. sargentii (Sargent's Viburnum) and Weigela florida (Old Fashioned Weigela). Woody vines in bloom are: Clematis spp. (Clematis), Hydrangea anomala petiolaris (Climbing Hydrangea), and Lonicera sempirvirens (Trumpet Honeysuckle). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Achillea millefolium (Yarrow), Ajuga reptans (Bugleweed), Alchemilla mollis (Lady's Mantle), Allium giganteum (Giant Onion), A. schoenoprasum (Chives), Amsonia hubrichtii (Arkansas Blue Star), Aquilegia spp. (Columbine), Baptisia australis (False Blue Indigo), Campanula takesimana ‘Elizabeth’ (Bell Flower), C. spp. (Bell Flower), Centaurea montana (Cornflower), Chrysogonum virginianum (Green and Gold), Clematis recta 'Purpurea' (Clematis), Coreopsis spp. (Tickseed), 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), Filipendula sp. (Meadow Sweet), Geranium cantabrigiense 'Biokovo' and 'Cambridge' (Hardy Cranesbill), G. macrorrhizum (Bigroot Geranium), G. sanguineum (Cranesbill Geranium), Hemerocallis spp. (early blooming Daylily), Heuchera spp. (Coral Bells), Hosta spp. (Plantain Lily), Iris germanica (Bearded Iris), I. sibirica (Siberian Iris), Leucanthemum sp. (Shasta Daisy), Lupinus 'Russell Woodfield Hybrids' (Lupine), Nepeta spp. (Ornamental Catmint), Paeonia spp. (Peony), Papaver (Poppy), Perovskia atriplicifolia (Russian Sage), Phlox divaricata (Canadian Phlox), Salvia nemerosa (Salvia), Saponaria ocymoides (Rock Soapwort), Silene latifolia (White Campion), Thymus praecox (Thyme), Tradescantia sp. (Spiderwort), and Veronica umbrosa 'Georgia Blue' (Speedwell).
Pests/Problems: Observed in the landscape this past week were the following: damage to foliage from caterpillars feeding on Acer (Maple), Corylus (Filbert), Fagus (Beech), Malus (crabapple), Ostrya (Hophornbeam) Prunus (Cherry), Quercus (Oak), and Ulmus (Elm); Woolly Beech Aphid on the underside of European Beech leaves; evidence of anthracnose on Platanus (Sycamore); leaf spot on Tilia (Linden). Rosa multiflora, an aggressive vine is in full bloom and is now easy to detect with its white flowers and is seen growing in and amongst other trees and shrubs.
General Conditions: Cool weather gradually gave way to warmth and then leapt up to HOT with daytime temperatures in the 90’s on 6/11, 6/12 and 6/13. No rainfall in the last reporting period and the soil surface in exposed in unmulched beds is beginning to dry out. We now find ourselves irrigating recent transplants. Many plants flagged in the heat but have rebounded with the recent more seasonable weather.
In bloom in the garden: Kousa Dogwoods, Kolkwitzia amabilis, Rosa rugosa, Knockout Roses, Linden Viburnum (V. dilitatum), Weigela, Iris sibirica, Peonies (Paeonia lactiflora cultivars), Salvia 'Ostfriesland' and 'Blue Hill', Nepeta 'Joanna Reed', Oxeye Daisies (Leucanthemum vulgare), Yarrow (Achillea millefolium), Sweetbay Magnolia (M. virginiana) and Corydalis lutea are among the many things in full bloom.
Pests/Problems: Gypsy moth caterpillars grow ever larger and the canopy on oak trees grows thinner. The forest floor and areas surrounding large oaks is littered with leaf remnants and caterpillar droppings. Recent transplants are wilting in the midday heat, though in most cases soil moisture is sufficient. Leaf spot/anthracnose on sugar maples is high.
Wood chuck are an increasing problem now that the next generation is out and about and feeding heavily. Rose Slugs, Lily Leaf Beetles, and Imported Willow Leaf Beetles are all actively feeding. Rose multiflora and Galium mollugo are in full bloom.
General Conditions: Searing hot temperatures best characterized this past reporting period in the Pioneer Valley region. The 2017 season’s first heat wave took place this week, with a heat wave defined as three consecutive days of ≥90° F. Numerous weather stations throughout the northeast recorded record high temperatures on Monday, 6/12 and Tuesday, 6/13 according to the U.S. National Weather Service. Highs on Monday, 6/12 ranged from the middle to high 90s along the Connecticut River. The variation in high temperatures over one week was impressive throughout the region. In Easthampton, the high temperature on Tuesday, 6/6 peaked at 52° F while on Tuesday, 6/13 it reached 92° F. The heat wave resulted in a spike in soil temperatures over this past week. Sun and shade readings increased by 9° and 11° F, respectively, on the UMass campus. Yet, unlike the period of intense heat we experienced in mid-May, foliage on the majority of trees and shrubs is fully developed now and able to withstand high temperatures. It was also dry this past week, a stark departure from most reporting periods this spring. For established trees and shrubs, soil moisture levels remain moderate to high, especially in shaded settings. Regular watering of recently transplanted trees and shrubs is essential to ensure they survive the first year after transplant. The recent heat wave showed how quickly surface soils can dry out, especially in full sun settings. Avoid using overhead sprinklers to water trees and shrubs, as this action wets the canopy, providing the moisture many fungal pathogens need to infect and cause disease. In addition, a sufficient volume to wet the root zone is often not attained when using overhead sprinklers.
Pests/Problems: Weeds are becoming abundant and growing rapidly in ornamental beds thanks to the previous abundant rainfall and recent spike in soil temperatures. When weed growth is dense under certain conifers, such as blue spruce, it helps to retain free moisture and high humidity on lower canopy branches which can facilitate spore germination and growth of needlecast fungi. Sycamore (Platanus occidentalis) and London planetree (P. × acerifolia) plagued by sycamore anthracnose this spring are finally able to flush healthy shoots and foliage. Canopies are still thin but should fill out over the next few weeks. Guignardia leaf blotch of horsechestnut is becoming apparent. The brown-colored, angular-shaped blotches are small right now and primarily occur along the leaf margins. They will continue to expand over the course of the growing season. Kretzschmaria deusta, the carbon cushion fungus, can be readily found right now at the base of infected trees. This root and lower trunk rot pathogen is most abundant on large and old European beech but also regularly attacks American beech and sugar maple. At this time, flattened and grey-colored fruiting bodies with white margins are growing from infected bark, typically close to the soil line (see photos in ‘Disease’ section). Over the course of the season, the fruiting bodies become black and crustose and are easily masked by patches of dead bark and exposed sapwood. Anthracnose infections are widespread throughout the region on maple, beech, oak, cherry and dogwood, among many other deciduous hardwoods. If foliage is undersized, distorted in shape and either blighted or harboring angular-shaped spots and blotches, then it’s most likely infected by an anthracnose pathogen. Apple scab continues to cause premature leaf shedding on crabapples. Gypsy moth feeding damage is very high in parts of eastern Hampshire and Hampden Counties at this time. The below-average temperatures helped to slow caterpillar development but later instars are now abundant. Continue to scout for gypsy moth damage in central and western Hampden and Hampshire Counties and all of Franklin County so this destructive pest can be managed on high-value trees and shrubs.
General Conditions: Three consecutive days of temperatures in the 90s – upper 80s in the hilltowns – brought about a dramatic end to the prolonged stretch of cool, cloudy and rainy weather of much of the spring. Unfortunately, coinciding with the hot weather was a lack of rain, though the low end of the county received some t-storms on the evening of June 13th. Accumulated rainfall for the month had been well above normal, but as of today it is one inch below normal. For the year it is ½ inch above normal. Total rainfall for a month or a year can be very mis-leading since a single storm may drop considerable rain but there could be prolonged dry spells in between such storms. Nevertheless, soil moisture remains good except for the surface ½ inch or so. While some recently planted herbaceous plants are wilting due to the combination of rapid evapotranspiration and a reduced root system, the heat has had no apparent effect on woody plants…yet. Turfgrass growth is good.
Pests/Problems: Leaf spot diseases are becoming more apparent on a wide variety of trees and shrubs. Plant pests which continue to be observed: spittlebugs, woolly beech aphid (nymphs), aphids, imported willow leaf beetle (adults and larvae), boxwood leaf miners (adult flies), spruce spider mite (numbers have diminished), four-lined plantbug (adults), cutworms, and lily leaf beetle (adults and nymphs. Nymphs of magnolia scale are present on the twigs of magnolia. They are easily recognized by their large waxy powdery covering. Deer tick numbers remain high and tick bites are quite common. One option for repelling ticks is to spray clothing with a repellent containing permethrin. After the prolonged wet period, mosquito and slug populations are high. Ants, wasps, carpenter bees, millipedes, and pillbugs are plentiful.
Maple anthracnose caused by Aureobasidium apocryptum, Discula campestris and Colletotrichum. Samples originated from multiple sites and trees, representing red maple (Acer rubrum), sugar maple (A. saccharum) and Japanese maple (A. palmatum). Dark-colored, spots and blotches were present on red maple leaves while sugar and Japanese maple exhibited brown spots and blotches. On one sample, two anthracnose fungi co-occurred: Discula campestris on the foliage and Colletotrichum on the samaras. Damage was severe in most cases and abundant throughout the canopy on established landscape trees.
Arborvitae needle blight, caused by Phyllosticta thujae, on green giant arborvitae (Thuja standishii × plicata ′Green Giant′). Several trees, six-years-old, planted in May of 2015. Trees are provided with drip irrigation and receive half sun. Interior needles and the shoot tips became brown in early May and are prematurely shedding. Phyllosticta produces numerous pads of tissue that rupture through the surface of the needles and stems to release large volumes of clear spores.
Verticillium wilt and stem cankering from Phomopsis on Japanese maple (Acer palmatum). Tree is roughly 15-years-old and has been present at the site for seven years. Several branches in one area of the canopy never produced foliage this spring. Fine twigs and stems had areas of graying and blackening bark, a typical symptom of stem cankering on this host. An olive-green discoloration was found in the xylem tissue on three-year-old stems and Verticillium was later incubated from the xylem tissue. The tree resides in full sun in a mulched bed with weed cloth surrounding the tree.
Cedar-quince rust, caused by Gymnosporangium clavipes and leaf and fruit blight caused by Colletotrichum on serviceberry (Amelanchier canadensis). The shrub is 10-years-old and has been present at the site for two years. New stems are distorted and curved due to infections by the cedar-quince rust fungus. Orange-colored pads of tissue were rupturing through the bark at the site of the stem cankers and rust-colored spores were observed. Cedar-quince rust can cause serious stem cankering and dieback on certain rosaceous hosts like serviceberry. The spores produced on rosaceous hosts will disperse to infect Juniperus. One reason why the disease is so difficult to treat is the long duration of spore dispersal from infected hosts, making fungicide timing difficult. In addition, the foliage and fruit were blighted and pink-colored masses of spores produced by Colletotrichum were abundant on the blighted tissues.
Gypsy Moth: Lymantria dispar caterpillars are in various sizes or developmental stages (instars) depending upon the location in Massachusetts. However, observations indicate that in many locations, these larvae are mostly in the 4th instar stage, however some 5th instars have been spotted. Male gypsy moth caterpillars go through 5 instars and female gypsy moth caterpillars have 6 instars. These caterpillars will continue to feed for the next couple of weeks, until they pupate, typically at the end of June. Male caterpillars will pupate just prior to the female caterpillars; pupation, like the transformation between the previous stages, does not happen all at once.
At this time and until the end of June, the defoliation they cause will be most noticeable. Reports made on 6/6/17 indicate that tree canopy thinning and complete defoliation were observed along I-90, approximately 4 miles east of Palmer, MA. On 6/15/17, a “55-65 MPH Survey” (driving along the MA Pike, I-90, on the way to a previously scheduled training) was conducted from the Westfield Exit (#3) to Exit 14 toward 95 south. Gypsy moth defoliation was highly visible beginning in Wilbraham while headed east through Palmer. On either side of the MA Pike, partial or complete defoliation (mostly oaks) could be seen. At mile marker 66.5 (just before) when headed downhill in the eastbound direction over the Quaboag River, there is a certain vantage point where you are at a higher elevation than the surrounding hillsides on either side of the highway. From that point of view, the defoliation was incredible. Large swaths on either side of the surrounding hills were covered in bare trees. When continuing east down I-90, the defoliation on either side of the highway continues through Sturbridge and roughly to the Charlton Plaza. From that point on, the defoliation was significantly less, at least on the trees visible from the highway. This trend continued roughly through Worcester, with any defoliation remaining in patches and certainly not to the extent of what was seen west of there. It seemed to not pick up again until roughly mile marker 98 and then was sporadic and relatively light (again, when thinking about the previously described areas) until you reach Hopkinton and Exit 11A to 495. Defoliation in that area seemed again analogous to what was seen from Wilbraham to the Charlton plaza. By mile marker 108.7, defoliation dropped to sporadic, light patches again. This limited, quick survey ended at Exit 14 and no samples of caterpillars were taken at that time due to safety concerns and time limits. However, it will be interesting to see what the 2017 aerial survey maps from the MA Department of Conservation and Recreation look like for defoliation this year.
Caterpillars are actively crawling up and down tree trunks, a behavior which makes them more likely to be exposed to pathogens, including the fungus, Entomophaga maimaiga. Reports of the sound of frass (excrement) dropping from the canopy where these caterpillars are feeding have been made. (The sound of frass dropping could be heard in Belchertown on 6/9/17 and Hanson on 6/15/17.) Roughly, 1- 1.5-inch long gypsy moth caterpillars have been observed resting or crawling on tree trunks and branches in Amherst as of 6/14/17. These caterpillars are dark in color, hairy, and the “warts” have developed to include the characteristic blue and red coloration, along with a head capsule that is yellow and mottled with black markings. In areas where gypsy moth caterpillars are abundant, citizens are dealing with caterpillars crawling all over the sides of homes, sheds, lawn furniture, and dropping from these locations and nearby trees. Caterpillars may be found on driveways, along with shredded sections of leaves due to their feeding, which are easily visible against that background. In Amherst on 6/12/17, caterpillars were found in a cluster, hidden behind a sign that was leaned up against a Norway maple. The sign was moved from the shaded area beneath the tree to a location in full sun, in order to inspect the cluster of caterpillars on the tree. In moments, the sun heated the sign and 50+ caterpillars came crawling down from where they were hidden along the edges of said sign. See the Regional Reports above for more information about gypsy moth activity.
According to prior reports from the Elkinton Lab, successful infection of gypsy moth caterpillars with the insect-killing fungus Entomophaga maimaiga, has begun. It is important to note that even with fungal infection in the caterpillars, we may still see significant defoliation in certain areas of Massachusetts this year due to this insect. Dr. Joseph Elkinton and his lab group, along with other local cooperators, are conducting a study that he is referring to as the “Cloud of Death Experiment”! What Dr. Elkinton means by this is that the research will aim to detect the amount of air-borne spores of the Entomophaga maimaiga fungus in certain locations of Massachusetts throughout the rest of the 2017 caterpillar activity (roughly through June). He and his lab hope to compare this to a measurement of the caterpillars killed at these various locations while determining if the fungus (or virus) is responsible. The Elkinton Lab has sites in Amherst, Belchertown, Brewster, Eastham, Hanson, and West Bridgewater to conduct these observations. To date, they have reported fungal activity at some of these sites, now with approximately 30% mortality due to Entomophaga maimaiga observed in caterpillars being reared on artificial diets (in the lab) collected from these sites. Anecdotally in the field, however, some reports of gypsy moth caterpillars “disappearing in large numbers” have been made at various locations across the state. This may be, in part, due to the behavior change that occurs when caterpillars reach the 4th instar. If an observer is used to seeing the caterpillars actively feeding on foliage during the day, they may be surprised to find them missing. The 4th instar caterpillars will change their behavior such that they feed at night, while hiding during the day. That being said, in high populations, even 4th instar caterpillars will feed at any time, daytime included. Fungal spores were isolated from a caterpillar collected from Belchertown on 6/9/17; however, the majority of the (many) caterpillars observed on that date were healthy and actively feeding (even during the day) at that location. Reports of caterpillar dieback at a location in Marlborough were also made on 6/15/17. The Elkinton Lab expects the percentage of caterpillars killed by the fungus will increase, but unfortunately, we cannot determine at this time how large of an impact the fungus will have on gypsy moth this year. Look to the Landscape Message for continued updates about Dr. Elkinton’s research as well as reports concerning the activity of Entomophaga maimaiga in Massachusetts.
To treat individual, landscape ornamental and shade trees, spinosad is effective on younger and older gypsy moth caterpillars (over ¾ inch in length) but should not be applied to plants while they are in bloom due to the risk toward pollinators.
Patchy areas across mostly central and eastern Massachusetts experienced elevated populations of gypsy moth and significant amounts of defoliation in 2016 (see the Insects section of the archived 2016 Landscape Messages between April 29 and July 29). The Massachusetts Department of Conservation and Recreation aerially mapped approximately 350,000 acres of defoliation across Massachusetts last year, attributed to gypsy moth. State officials warn the public about another year of defoliation from gypsy moth as predicted for 2017: http://www.mass.gov/eea/agencies/dcr/pr-2017/another-year-of-defoliation-from-gypsy-moth-in-2017.html. That web page also links to a map of the 2016 defoliation from gypsy moth, which may provide a reference regarding areas that may be impacted by this insect again in 2017.
Eastern Tent Caterpillar: Malacosoma americanum (ETC) impacts cherry, crabapple, apple, ash, birch, willow, maple, oak, poplar, and witch-hazel. Pupation of this insect will begin in June and last for a few weeks. Adults are typically seen in late June - early July. At a site being monitored in Westfield, MA, the tents of ETC are vacant and the caterpillars are nowhere to be found. Due to the amount of poison ivy at the site, closer inspection for pupae was not possible; however, it is suspected that the caterpillars at that location have begun to pupate.
Emerald Ash Borer (EAB): Agrilus planipennis readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and most recently, cultivated olive (Olea europaea). (See: https://academic.oup.com/jee/article-lookup/doi/10.1093/jee/tox139.) Adult insects of this species are emerging at this time, as we have surpassed in most areas of the state 450-550 GDD’s (see Environmental Data above). Anyone monitoring for emerald ash borer using traps and lures should have them deployed at this time (if they have not already), otherwise they risk missing adult beetle activity. Signs of an EAB infested tree may include D-shaped exit holes in the bark, “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in/upon peeling the bark, from larval feeding beneath. Positive identification of an EAB-infested tree may not be possible with these signs individually on their own.
Forest Tent Caterpillar: Malacosoma disstria (FTC) caterpillars continue to feed on maple and oak. Other susceptible hosts such as birch, ash, elm, poplar, and basswood may also be fed upon by these caterpillars. These native insects can defoliate their host plants, but are not currently in large populations in all areas in the state. At a location in Amherst, FTC’s were observed to have perished due to a fungus (different species of Entomophaga affect these native caterpillars than the one found in gypsy moth). At a location in Belchertown on 6/9/2017, many large FTC’s were observed feeding alongside gypsy moth caterpillars. Pupation of forest tent caterpillars will begin soon, but they are still actively feeding at this time.
Two-marked Tree Hopper: The Enchenopa binotata species complex is now thought to be made up of very closely related Enchenopa spp. that are morphologically very similar but separated by the different host plants that they are found on. These particular treehoppers are found on black walnut, wafer ash (Ptelea trifoliata), and viburnum. These insects will feed on the host plants with piercing-sucking mouthparts and drink plant juices from the leaves and petioles. Leaves will become shiny and sticky with their excrement. (This was observed for the first time in Amherst on 6/14/17, although the nymphs have been active for quite some time now this season.) Still small nymphs have been observed on wafer ash in Amherst. Eggs are laid by adult females using saw-like ovipositors to insert them into plant stems. Eggs are then covered with a vivid white, sticky, frothy material that protects them but can easily be mistaken for a scale insect. Eggs have hatched and the tiny, young nymphs can be seen feeding at this time. These treehoppers, whether by their feeding activity or egg laying behavior into plant stems, are not considered to be damaging pests (even when high in numbers) and therefore management is generally not required.
Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. See the Regional Reports regarding areas where this insect has been noted to be active this season. At this time, larvae have dropped to the soil to pupate and adult beetles will be present in late-June through roughly October, or when the first frost hits. Adult beetles will create their own feeding damage, but will also mate and females will lay eggs in the stems of the viburnums, typically beginning in late-June to mid-July until October. This beetle feeds exclusively on many different species of viburnum including but not limited to susceptible plants such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum. Larvae may be treated with a product containing spinosad. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found at http://www.hort.cornell.edu/vlb/.
Woolly Elm Aphid: Eriosoma americanum is most likely the species responsible for the distorted and curled leaves observed on a plant in Amherst on 6/7/17 and again on 6/14/17. This particular aphid is known to have alternate hosts that it utilizes on a yearly basis. Elm is the overwintering and spring-time host, and by the end of June the winged, migrating generation leaves the elm in search of the roots of Amelanchier. The best time to manage for this aphid has passed (121-246 GDD, base 50°F) and although abundant, the individuals are well protected within the curled and distorted leaves at this time. This particular plant was also highly attractive to adult multicolored Asian lady beetles who were seen mating and scurrying along branches.
Hydrangea anomala subsp. petiolaris is a deciduous climbing vine native to Japan and China. Main stems climb vertically along sturdy structures or buildings while side branches grow horizontally. Climbing hydrangea can be grown as a 3-4’ mound if planted without a structure to grow on, but can reach 30’ or more as a vine when supported. The large fragrant, lacecap flower clusters are very showy against the dark green foliage in early June. The flower corymbs grow up to 10” wide and consist of non-showy fertile flowers surrounded by the showy sterile flowers. The dark green, glossy leaves are broad ovate with serrated margins. Fall color can be yellow, but leaves often remain green until they fall in autumn. Bark is exfoliating reddish brown and provides winter interest. Hydrangea anomala subsp. petiolaris has no serious insect or disease issues but needs a strong structure if grown on walls, fences, or other supports. Plants climb via aerial rootlets, or “holdfasts” and be twining. Appropriate siting is important for plant vigor and establishment. Plants are best grown in a fertile, moist, well-drained soil in full sun to part shade on a north or east side of a building. Hot, dry sites should be avoided. Climbing hydrangea can be slow to establish but is a great, multi-season vine for the landscape.

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