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Landscape Message: June 9, 2017

June 9, 2017
Issue: 
12

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Massachusetts Green Industry professionals in the management of our collective landscape. Detailed reports from scouts and Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. The following issue has been updated 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 16. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.

To read individual sections of the message, click on the section headings below to expand the content:


Scouting Information by Region

Environmental Data

The following data was collected on or about June 7. 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.

Region/Location

GDD

Soil Temp
(°F at 4" depth)

Precipitation
(1-Week Gain)

Time/Date of Readings

1-Week Gain

2017 Total

Sun

Shade

Cape Cod

61.5

325.5

63

56

1.50

12:00 PM 6/7

Southeast

40

318

64

55

2.25

5:00 PM 6/7

North Shore

53

370

54

51

1.93

9:30 AM 6/7

East

62

431.5

64

60

2.25

4:00 PM 6/7

Metro West

49

391.5

51

49

2.52

5:30 AM 6/7

Central

47

414

50

49

2.04

8:00 AM 6/7

Pioneer Valley

54

411

61

55

2.70

1:30 PM 6/7

Berkshires

46

344

55

52

1.64

8:15 AM 6/7

AVERAGE

52

376

58

53

2.10

-

n/a = information not available

Drought Conditions Update: All of Massachusetts (100%) is not under official drought status at this time.  For more information see http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?MA

Phenology

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT NAME (Botanic/ Common) CAPE S.E. N.S. EAST METRO W. CENT. P.V. BERK.
Syringa reticulata (Japanese Tree Lilac) * * * * * * Begin *
Cladrastis lutea (Yellowwood) * Full Begin Full Begin * Full Begin
Philadelphus spp.(Mockorange) Begin Begin/Full Full Full Begin Full Begin/Full *
Hydrangea anomala petiolaris (Climbing Hydrangea) * Full Begin Begin Begin Begin Begin/Full Begin
Kalmia latifolia (Mountain-laurel) Begin Begin Begin Begin Begin Begin Begin/Full *
Cotinus coggygria (Common Smokebush) Begin Full Begin/Full Full Begin/Full Full Full Begin/Full
Cornus sericea (Red Osier Dogwood) Begin/Full * Full End Full Full Full Full
Robinia pseudoacacia (Black Locust) Full Full Full/End End Full/End Full End Full
Kolkwitzia amabilis (Beautybush) Full Full Full Full Full Full Full/End Full
Weigela florida (Old Fashioned Weigela) Full Full Full Full Full Full Full Full
Deutzia spp. (Deutzia species) Full Full Full Full Full Full Full Full
Enkianthus campanulatus (Redvein Enkianthus) Full/End Full/End Full/End Full/End Full/End Full/End End Full
Rhododendron carolinianum (Carolina Rhododendron) End Full/End End End Full/End * End *
Rhododendron catawbiense (Catawba Rhododendron) Full/End Full Full/End End Full/End Full Full/End Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature from May 31 - June 7 was 57.5° F with a low of 45° F on June 3 and a high of 76° F on June 1. A total of 1.50 inches of precipitation feel over several events on May 31, June 4, 5, & 6. The pattern of a few sunny days followed by several cloudy/rainy days continues. Soil moisture remains adequate.

Pests/Problems: Gypsy moth caterpillars continue to feed and range in size from about 1"-2" in length. Some complete defoliation can be seen on White Oaks on the upper Cape. Winter moth can no longer be found on trees and have dropped to the ground to pupate. Viburnum leaf beetle continues to feed heavily on Viburnum. Both European and Bristly nose sawfly larvae can be found feeding on rose. Columbine sawfly can be found feeding on columbine. Hydrangea leaftier damage can be seen on H. arborescens. Foliar anthracnose is being seen on Sycamore and Maple. Brown rot is causing a lot of twig dieback on Kwanzan and other ornamental cherries. Iris leaf spot can be seen causing water soaked lesions on iris. Botrytis is causing damage to peony buds. Weeds in bloom include; bulbous buttercup (Ranunculus bulbosus), creeping buttercup (Ranunculus repens), black medic (Medicago lupulina), wild strawberry (Fragaria virginiana), multiflora rose (Rosa multiflora), buckthorns (Rhamnus & Frangula), black swallow-wort, Cynanchum louiseae, autumn olive (Elaeagnus umbellata), honeysuckle (Lonicera spp.), plantain (Plantago major & lanceolata), white campion (Silene alba), white clover (Trifolium repens), hawkweed (Hieracium pretense), red sorrel (Rumex acetosella) and curly dock (Rumex crispus).

Southeast Region (Hanson)

General Conditions: June started off in the low 70’s then temperatures went down. It was 49 degrees at 7 AM June 3rd and the next few days were in the 50’s and 60’s with some temperatures in the 40’s at night. The weather folk reported that the first 6 days of June were 5 degrees below average for Boston. Cool weather and rain came in late on the afternoon of June 4th and continued into June 6th; Hanson received 2.25 inches of rain in that period; total for the week. High, gusty winds and downpours on the 5th caused some minor tree limbs to break and ‘slammed’ some perennials, like peonies and Baptisia, to the ground. The winds and rain also ‘whipped’ the blossoms off many trees and shrubs. Soils are moist and lawns are green.

The following plants are in bloom: Physocarpus opulifolius (Eastern Ninebark), Sinocalycanthus chinensis, Aesculus x carnea, Liriodendron tulipifera (Tuliptree), Cornus kousa, Cornus controversa, Cornus alternifolia, Cladrastis kentukea, Weigela florida, Indigofera sp., numerous Rhododendrons, numerous viburnums, Chionanthus virginicus, late lilacs like Syringa x prestoniae ‘James MacFarlane’ and Syringa ‘Miss Kim’, Clematis, Hydrangea anomala petiolaris, Wisteria floribunda (Japanese Wisteria), Robinia hispida (bristly locust), Calycanthus floridus (Common Sweetshrub), Beautybush, Lonicera sempervirens, Lonicera ‘John Clayton’, Clematis sp., Stephanandra incisa ‘Crispa’, Aristolochia durior (Dutchman's pipe), Alchemilla mollis, Thalictrum aquilegifolium, Anemone canadensis, Geranium sp., Persicaria bistorta 'Superbum', Doronicum, Amsonia sp., Siberian Iris, Bearded Iris, Foxgloves, Allium, Nepeta sp., Salvia 'May Night', Baptisia australis, Dianthus sp., Tradescantia, Lupines, Aquilegia (Columbine), Oriental poppies, Corydalis lutea, Arisaema (Jack-in-the-pulpit), Cypripedium sp. (Lady's Slipper). Cotinus coggygria (Smokebush) and Cotinus obovatus (American Smoketree) continue in full bloom with small greenish flowers and soon the ‘smoke’ will appear!

Styrax obassia, Rutgers hybrid dogwoods (Stellar series), Prunus serotina (black cherry), Laburnum watereri (Goldenchain Tree), Abelia mosanensisand Buglossoides purpurocaerulea are ending bloom.

Hanson is at 965 GDD - Growing Degree days, Base 40.

Pests/Problems: Winter moth caterpillars have finished feeding and have pupated. Damage from this year’s caterpillars appears to be significantly down in most areas. A probable reason for the 2017 reduced number of winter moth caterpillars can be traced back to the cold, freezing weather the first few days of April 2016, just as the winter moth eggs began to hatch. This cold wet, freezing rain and snow came in and killed many of the newly hatched exposed caterpillars, reducing their numbers dramatically and resulting in fewer caterpillars pupating and then fewer adult moths emerging in November to lay eggs for the 2017 hatch.

Gypsy moth caterpillars remain numerous and were observed in 3rd and mostly 4th instars. They were found feeding on a wide range of plant material (apples, crabapples, maples, Fothergilla, Hamamelis, etc), but the largest numbers were found feeding heavily on oak. They were also found feeding on plants, like small white pines, in the understory of oak. According to staff from Dr. Joe Elkinton’s UMass lab, many understory small pines in Wompatuck State Park, Hingham, MA, have been completely defoliated. Gypsy moth frass (feces) can be heard dropping through the trees as they feed. This sound will continue as the gypsy moth caterpillars continue to feed and grow larger over the next few weeks. owever, there may be some relief. The cool, wet weather has been conducive to the caterpillar-killing fungus, Entomophaga maimaiga, and many dead, fungus-killed caterpillars were seen hanging down on oak and pine foliage; staff from Dr. Elkinton’s lab are predicting that these numbers will increase.

Monitor perennials and if you see numerous, small, round, brown-black spots coalescing on the foliage, it could be the damage from the feeding of four-lined plant bug nymphs (orange-red with black coloration), which are active. Nymphs and adults (gold-green, with 4 longitudinal black stripes) have piercing-sucking mouthparts and the resulting damage often resembles a leaf spot disease.

Clients may be seeing native white-spotted pine sawyer and thinking it is the Asian Longhorned Beetle, but it is just one of the many Asian Longhorned Beetle (ALB) look-alikes”. http://massnrc.org/pests/albdocs/ALBLookalikes_Massachusetts.pdf

Lacebugs remain active and will be active for a long time. Monitor the undersides of foliage of Pieris, Rhododendron and azaleas for lacebug and manage if found.

Euonymus sawflylarvae (cream-colored larvae with black spots), remain active and the webs at, or near, the ends of branches are growing larger. Manage as needed and remember that Bacillus thuringiensis (Bt) does not work on sawfly larvae.

Roseslug sawfly remains active and will skeletonize rose plant foliage if not managed.

Azalea sawfly is done feeding for the year.

Continue to monitor Taxus and Meserve hollies for cottony camellia scale (also known as Cottony Taxus Scale) and manage as needed

The small white maggot of the Orthacheta Bud Fly (Iris bud fly) remains active. Remove and destroy the newly damaged flowers and stems.

The following insects remain active: mosquitoes, earwigs, lily leaf beetles, elongate hemlock scale, aphids, hemlock woolly adelgid, spruce spider mites, spittlebugs, deer tick nymphs, dog ticks, biting flies, carpenter ants, azalea whitefly, snails, woolly beech aphid, ants, wasps, hornets, carpenter bees, and bumblebees.

Beneficial insects like ladybugs (adults and larvae) and six-spotted green tiger beetles are also active.

Foliar diseases continue to make their appearance: Sycamore anthracnose is prevalent on Sycamore and foliage is very slow to appear; anthracnose is also showing up on maples and dogwood; apple scab on crabapples and apples;Phyllosticta hamamelidis (Witchhazel blight) is very noticeable on the foliage of ‘Arnold Promise’ witchhazel; Monilinia (brown rot) on Kwanzan cherry; botrytis blight on peonies. Shiny green galls of the fungal disease, Azalea leaf gall (Exobasidium vaccinii) continue to show up on deciduous azaleas; hand-pick and destroy the galls before they turn white.

While scouting for this Landscape Message, it was sad to see so many Eastern white pines with thinning canopies and brown needles. See the White Pine Needle Damage Report, in the Disease section if the May 12, 2017 Landscape Message.

The following weeds are in bloom: Multiflora rose (Massachusetts invasive plant); oxeye daisy; black swallowwort (Invasive); hawkweed; buttercup; veronica. Clearweed has sprouted; if found, weed it out with all the other weeds and apply mulch, before the weeds become large, flower and produce more seed.

White pine pollen was falling heavily before all the rain and the rain helped clean off plants, cars, etc. More pollen is expected to fall.

North Shore (Beverly)

General Conditions: The unseasonable cool temperatures continued during this reporting period. The weather was cool, damp and wet on most of the days. The average temperature during this period was about 54° F with day temperatures ranging from the mid 50s to the low 70s except for June 1 when the day temperature rose to 80° F. The night temperatures were mostly in the low 50s. We gained 53 growing degree days and approximately 1.93 inches of rainfall at Long Hill, Beverly. Woody plants seen in bloom include: White Catawba Rhododendron (Rhododendron catawbiense), Kousa dogwood (Cornus kousa), Arrowwood viburnum (Viburnum dentatum), Chinese Neillia (Neillia sinensis), Slender Deutzia (Deutzia gracilis), Fringe tree (Chionanthus virginicus), American cranberrybush viburnum (Viburnum trilobum), Constellation Rutgers dogwood (Cornus x rutgersensis), Mock orange (Philadelphus spp.), Beautybush (Kolkwitzia amabilis), Flame azalea (Rhododendron calendulaceum), Wellfleet Rhododendron (Rhododendron ‘wellfleet’), Catawba Rhododendron (Rhododendron catawbiense), Jonathan Shaw Rhododendron (Rhododendron ‘Jonathan Shaw’), Mountain Laurel (Kalmia latifolia), Weigela (Weigela florida), Mapleleaf viburnum (Viburnum acerifolium), Black Locust (Robinia pseudoacacia) and Tulip tree (Liriodendron tulipifera). Non-woody plants seen in bloom include: Fetterbush (Leucothoe fontanesiana), Scotch rose (Rosa spinosissima), Peony (Paeonia sp.), Cranesbill (Geranium sp.), Bleeding heart (Dicentra spectabilis), Rodger's flower (Rodgersia aesculifolia), Goat’s beard (Aruncus dioicus), Japanese primrose (Primula japonica), Water lily (Nymphaea odorata), Columbine (Aquilegia spp.), Yellow Corydalis (Corydalis lutea), Sweet woodruff (Galium odoratum), Solomon’s seal (Polygonatum odoratum) and several annuals.

Pests/Problems: Viburnum leaf beetles continue to cause serious damage on viburnums. Apple scab was observed on some crabapple trees. Eastern Tent caterpillars and their webs were also observed on branches of some crabapples (Malus sp.) and cherry (Prunus sp.). Mosquitoes and ticks are still very active. Protect yourself with a repellent when working outdoors.

East Region (Boston)

General Conditions: This spring continues to be very wet and cool. Since spring officially began on March 20th, we have received 15.45 inches of rain, approximately 6 inches more than the typical spring – and we still have two weeks before summer officially arrives. The wet trend continues into June, having received 2.25 inches of precipitation over the first 7 days. Temperatures remain more than 5° F below average, averaging 67° F this week; high temperatures ranged from 51° F to 78° F with cloudy conditions prevailing over most of the week. Despite the lack of solar radiation, many plants continue to come into bloom. Currently in flower: Baptisia australis (blue wild indigo), Baptisia 'Carolina Moonlight' (false indigo), Centaurea montana (mountain cornflower), Chionanthus retusus (Chinese fringe tree), Chionanthus virginicus (white fringe tree), Cladrastis kentukea (Kentucky yellowwood), Clematis sp. (clematis) cultivars, Cornus kousa (Kousa dogwood), Dianthus sp. (pinks) cultivars, Gleditsia triacanthos (honeylocust), Iris germanica (bearded iris) cultivars, Iris sibirica (Siberian iris) cultivars, Liriodendron tulipifera (tulip tree), Lonicera periclymenum (common honeysuckle), Lonicera sempervirens (trumpet honeysuckle), Nepeta × faassenii (catmint), Philadelphus coronarius (sweet mockorange), Pyracantha coccinea 'Lalandei' (firethorn), Rhododendron sp. (rhododendron) cultivars, Rosa sp. (species rose), Viburnum bracteatum (bracted viburnum),and Viburnum rhytidophyllum (leatherleaf viburnum). Snapping turtles have been moving throughout the landscape, actively laying in mulched beds and on sun slopes.

Pests/Problems: Soils are very moist and saturated, making mowing very difficult in low-lying areas. Grass and weeds continue to grow and flourish with the excess moisture. Chelidonium majus (greater celandine) has gone to seed. Newly flowering weeds include Cynanchum louiseae (black swallowwort), Plantago lanceolata (narrowleaf plantain), Rumex crispus (curly dock), and Vitis sp. (wild grape). Froghoppers (spittlebugs) are visible on susceptible plants. Azalea galls are gaining in size. Lymantria dispar (gypsy moth), Malacosoma americanum (eastern tent caterpillar), and Malacosoma disstria (forest tent caterpillar moth) remain active throughout the landscape. Olethreutes ferriferana (hydrangea leaftier) caterpillars are actively forming protective pockets on the tips of hydrangea plants, and actively sewing leaves together.

Metro West (Acton)

General Conditions: A year ago, in my Landscape Message, I wrote about the lack of rain! Now, a year later, I’m writing about the lack of warm and sunny temperatures! We continue to experience early spring-like temperatures rather than late spring like temperatures during this reporting period with cool, damp and wet weather. The average monthly rainfall for May is 4.04” and we exceeded that total with 5.11” of precipitation recorded! The historical monthly average rainfall for June is 3.93” and the total for the month so far is now at 2.17” and it’s only June 6th and the forecast is calling for more rain later this week. Woody plants seen in bloom this past week are Chionanthus retusus (Chinese Fringe Tree), C. virginicus (Fringe Tree), Cladrastis kentukea (Yellowwood), Cornus kousa (Kousa Dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers Hybrid Dogwood), C. sericea (Redosier Dogwood), Cotinus coggygria (Common Smokebush), Kalmia latifolia (Mountain Laurel), Kerria japonica (Japanese Kerria), Kolkwitzia amabilis (Beautybush), Leucothoe axillaris (Coast Leucothoe), Philadelphus coronarius (Sweet Mock Orange), Physocarpus opulifolius (Common Ninebark), P. opulifolius 'Summer Wine' (Summer Wine Ninebark), Potentilla fruiticosa (Potentilla), P. tridentata (Cinquefoil), Rhododendron spp.(Rhododendron and Azalea), Rosa rugosa (Rugosa Rose), R. 'Knockout' (The Knockout family of Roses), Rosa spp. (Rose), Rubus spp. (Bramble, Blackberry), Spirea japonica 'Alpina' (Daphne Spirea), Spiraea spp. (Spirea), 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), Lonicera sempirvirens (Trumpet Honeysuckle), and Wisteria spp. (Wisteria). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: 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), Centaurea montana (Cornflower), Chrysogonum virginianum (Green and Gold), 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. maculatum (Wild Geranium), G. macrorrhizum (Bigroot Geranium), G. sanguineum (Cranesbill Geranium), Hemerocallis spp. (early blooming Daylily), Heuchera spp. (Coral Bells), Iris germanica (Bearded Iris), I. sibirica (Siberian Iris), Lupinus 'Russell Woodfield Hybrids' (Lupine), Nepeta spp. (Ornamental Catmint), Paeonia spp. (Peony), Papaver orientale (Poppy), Phlox divaricata (Canadian Phlox), Podophyllum peltatum (Mayapple), Polemonium reptans (Jacob's Ladder), Salvia nemerosa (Salvia), Saponaria ocymoides (Rock Soapwort), Silene latifolia (White Campion), Stylophorum diphyllum (Wood Poppy), Thymus praecox (Thyme), Tradescantia sp. (Spiderwort), and Veronica umbrosa 'Georgia Blue' (Speedwell).

Central Region (Boylston)

General Conditions: The cool, wet weather pattern continued through this reporting period, leaving many questioning what month we are in! Among the many things in bloom are Fringetree (Chionanthus virginicus), Korean Abelia (A. mosanensis), Rhododendron catawbiense hybrids, Magnolia sieboldii, Magnolia ‘Aashild Kalleberg’, Philadelphus coronarius, Rosa rugosa, Nectaroscordum siculum subsp. bulgaricum, Cynanchum ascyrifolium, Geranium psilostemon, Geranium maculatum, Geranium macrorrhizum, Dicentra spectabilis, Baptisia australis, Dianthus deltoides, Tradescantia ‘Sweet Kate’, Amsonia hubrichtii, Leucanthemum vulgare, Iris sibirica, Iris germanica, and Paeonia cultivars are beginning to bloom.

Pests/Problems: Soils are extremely wet and we are limiting foot and vehicle traffic across turf to reduce damage. Gypsy moth caterpillars are abundant and damage is becoming evident on Oak (Quercus sp.) Witchhazel (Hamamelis sp.), Crabapples (Malus sp.) and a host of other plants including Maple (Acer sp.), Carpinus sp., Fagus sp. Fothergilla, Betula nigra, and Betula papyrifera. The Imported Willow Leaf Beetle is feeding on a variety of Salix species. Spittlebugs are now prominent on field grasses and Leucanthemum vulgare. Anthracnose is showing up on leaves of Sugar Maple (Acer saccharum).

Pioneer Valley Region (Amherst)

General Conditions: Another week during this 2017 growing season, another soaking rainstorm. The first week of June is complete and already we have accumulated up to and over 2.5ʺ of precipitation at many weather stations in the Connecticut Valley, continuing the trend of wet weather that dominated April and May. Temperatures were mild to cool over this past reporting period, peaking in the upper 70s and bottoming out in the lower 40s near the valley bottoms. However, it wasn’t all rain this past week as we did experience consecutive days with bright sun and calm winds that made for fantastic early summer weather. The latest rain event was another major soaker, lasting two days with intermittent bands of heavy precipitation. Overshadowed by the soaking rain we just experienced was a brief, but intense thunderstorm during the evening hours of May 31. Strong winds and hail were reported throughout western Franklin, Hampshire and Hampden Counties. The hailstones in some locations, such as Southwick and Williamsburg, were nickel-sized and crop damage was reported at scattered locations. Overall, the landscape remains vibrant and green with the abundant rainfall. Turf grasses are continuing to grow at a strong rate and it has been a great spring to establish new lawns. For trees and shrubs stressed by drought the last two summers, these soaking rains are just what they needed to help recover. The below-average temperatures have prolonged flowering for many annuals, perennials and trees/shrubs. That may change quickly, as the long-term forecast calls for a big warm-up, with temperatures in the upper 80s to low 90s and more sun than rain. We may be finally shedding the cool and wet weather that has characterized the season so far.

Pests/Problems: Bladder gall mites are abundant on a variety of deciduous hardwoods such as maple, linden and elm. While highly conspicuous, the eriophyid mites that create these galls cause little harm to the tree. The woolly elm aphid is locally abundant on a variety of American elm cultivars. Infested leaves become curled and distorted on the margins, becoming yellowish-red in color. The winged females will complete their life cycle on serviceberry (Amelanchier) in early summer. The abundant rain has provided ideal conditions for development and spread of anthracnose fungi. Foliar lesions have been observed on flowering dogwood (Cornus florida) and European beech (Fagus sylvatica) on the UMass campus. With kousa dogwood in flower right now, it’s a good reminder that this species is an excellent alternative to flowering dogwood if anthracnose has degraded and/or killed trees in the landscape. There have been numerous samples and reports of foliar anthracnose on Japanese maple, red maple, sugar maple, white oak, sweetgum and katsura, among others. Little can be done for existing foliage that is diseased at this time but for trees continuing to flush new growth (e.g. red maple), applications of appropriate fungicides may help to protect leaves from becoming infected. Most anthracnose infections do not cause lasting injury when trees and shrubs are healthy. However, when trees and shrubs are stressed by drought and defoliating insects, anthracnose can be an important contributor to decline and death. Gypsy moth continues to feed on a wide array of hosts in the area, such as oak, maple, elm and apple. The cool weather has slowed their development but with the forecast calling for warm weather next week, we should see their sizes increase soon. The regular, soaking rains have almost certainly initiated infections by spruce needle cast fungi, Rhizosphaera and Stigmina. Older and young needles can be infected, especially on lower canopy branches. The cool weather has prolonged the active period for the spruce spider mite, which continues to cause major problems for many landscape conifers. Carefully scout spruce, fir, hemlock, falsecypress and arborvitae for this pest and treat if necessary. Scout properties for any lingering rain water in buckets, pails, etc. to reduce egg-laying sites for mosquitoes. Even depressions in overturned buckets and pots can provide enough stagnant water for egg laying. Weeds in ornamental beds are numerous thanks to the rain.

Berkshire Region (Great Barrington)

General Conditions: It seems unusual that soil temperature would decrease from the previous week at this time of year but with persistent chilly and damp weather, that was the case this past week. Plant growth progressed slowly, especially with tender annuals. The three day rainy period of June 4-6 accounted for most of the precipitation during the reporting period. Currently soil moisture is high, even saturated where soils are heavy or poorly drained. Rainfall for the year is about 4.5 inches above last year and 1.5 inches above normal. With more showers predicted for the week ahead, drought is not currently a concern. However, a dramatic increase in temperature is about to occur with some predictions of highs in upper 80s to 90° F by June 13. Such dramatic change may affect some plants, especially annuals and recently planted herbaceous perennials and woody plants. Transplants have a poorly developed root system and with rapid evapotranspiration due to high air temperatures wilting of plants is possible. Some dieback or total plant death is also possible. Shading of newly planted herbaceous specimens could help reduce risk of damage. Turfgrass which was seeded earlier this spring is also at risk. Attention should be paid to rapid drying of soil.

Pests/Problems: Elderberry borer (Desmocerus palliatus) was found on Black Lace elderberry (Sambucus nigra 'Eva'). The wilting of shoot tips of elderberry is the first symptom of this borer infestation. The borer will bore down to the roots of the plant. Wilted shoot tips should be pruned as soon as wilting is apparent.

Roseslug sawfly (larvae) damage was visible on roses. Roses were also under attack by aphids. Euonymus scale crawlers were observed and this would be the time to apply an appropriate control measure. Viburnum leaf beetle larvae were few in number indicating that the larvae have moved down to the soil where they will pupate. Emergence of adults should occur in early July.

Ongoing plant pest activity observed this week: boxwood psyllid, boxwood leaf miner adults, woolly beech aphid, four lined plant bug (nymphs), lily leaf beetle (adults), imported willow leaf beetle (larvae), spruce spider mites on spruce, pear blister mites, spittlebug on herbaceous plants, forest tent caterpillar, European pine sawfly (few remain), spittlebugs, leaf tiers and leaf rollers.

Other active pests include: deer ticks (numbers are very high), mosquitoes, wasps, black flies, earwigs, millipedes, and slugs.

Powdery mildew continues to spread on foliage of Physocarpus opulifolius ‘Coppertina’. The cultivar ‘Diablo’ is also affected but to a lesser degree.

Regional Scouting Credits

  • CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, 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 - Kelly Allen for 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

Diseases

Recent pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab:

Fire blight, caused by Erwinia amylovora, on a bosc pear (Pyrus communis ‘Bosc’). Tree resides in a small home orchard and is roughly 15-years-old. In May, shoot tips and leaf margins blackened and collapsed. Sunken cankers with callused margins were present on one-year-old stems where the pathogen overwintered. The cool weather has helped to suppress fire blight in many locations but the abundant rainfall initiated the disease outbreak on this particular tree.

Lacebug infestation, caused by Stephanitis, suspected winter injury and a secondary foliar blight caused by Phyllosticta on catawba rhododendron (Rhododendron catawbiense). Large shrub, approximately 15- to 20-years-old, resides in a half sun setting in well-drained soils. The lacebug infestation was severe on the submitted foliage, with the characteristic yellow flecking symptoms abundant on the upper leaf surface. The injury likely predisposed the foliage to winter injury and secondary attack from Phyllosticta.

Maple anthracnose, caused by Discula campestris, and stem cankering caused by Phomopsis on Japanese maple (Acer palmatum). Two bonsai trees, both over 100-years-old, showing symptoms of foliar blight and canopy dieback. The symptoms were present in previous years. The leaf margins were necrotic and harboring the maple anthracnose pathogen. Small stems were gray in color and blighted by the cankering pathogen Phomopsis. Stem cankering is very common on Japanese maple and regular sanitation pruning is necessary to remove blighted stems from the canopy.

Oak anthracnose, caused by Apiognomonia errabunda, on white oak (Quercus alba). Four white oaks, approximately 50-years-old, showing symptoms of infection in a residential landscape. Trees reside in full sun on what gravelly, excessively-drained soils. Symptoms included stunting and deformation of the foliage, spots/blotches and a total collapse of young leaves. The upper canopy is nearly defoliated from the infection but the managing arborist notes a strong flush or new growth taking place near the center of the tree.

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

Insects

Woody ornamental insect and non-insect arthropod pests to consider, a selected few:

  • Gypsy moth caterpillars observed at a site in Amherst on 6/7/17 are mostly in the 4th instar at this time. Some 3rd instar caterpillars remain. Now is the time that defoliation from these insects will be noticed most, and reports of this activity are increasing. These larger, more developed caterpillars (4th instar) are much less susceptible to Btk. Spinosad is effective on older caterpillars. (Simisky, 2017) Exfoliating bark with an “exfoliating” gypsy moth caterpillar. This caterpillar has molted into the 4th instar (yellow and black mottled head capsule) and can be seen resting next to a cast skin (exuviae). These cast skins should not be confused for fungus-killed caterpillars. (Simisky, 2017) 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 in the 3rd and mostly 4th instar stage. These caterpillars will continue to feed for the next couple of weeks, until they pupate, typically at the end of June. It is this month that 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. The Elkinton Lab reports that caterpillars have begun 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. Roughly, ¾ - 1-inch long gypsy moth caterpillars have been observed resting on or crawling on tree trunks and branches in Amherst as of 6/8/17. Most caterpillars are now approaching 1-inch in length in Amherst. 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. Larval instars seen locally will vary. See the Regional Reports above for more information about gypsy moth activity.

According to reports from the Elkinton Lab, successful infection of gypsy moth caterpillars with the insect-killing fungus Entomophaga maimaiga, has now 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. However, it is clear at this time that the cool, rainy weather we have been experiencing in the state has been beneficial for 2017 fungal activity. 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, with less than 10% 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 phenomenon has been reported recently in Amherst. See the Southeast Regional Report above from Hanson, MA that describes dieback of many gypsy moth caterpillars. On 6/8/17, reports came from Ware, MA indicating that dieback of gypsy moth caterpillars was also observed in that location. The Elkinton Lab expects the percentage of caterpillars killed by the fungus will increase. 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 using the active ingredient Btk (Bacillus thuringiensis Kurstaki) for gypsy moth, be sure that the caterpillars are roughly between ¼ - ¾ inch in length and actively feeding. Larger caterpillars (over ¾ inch) are less susceptible to Btk. (In most locations, gypsy moth caterpillars are growing larger than ¾ inch at this time and therefore will be much less susceptible to Btk. Local monitoring is very important when making decisions about what active ingredient to use, if choosing chemical management options.) These applications should be made when very young caterpillars are actively feeding on host plant leaves, as it must be ingested to be effective. 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.

Gypsy moth host plants include but are not limited to oak (favored), maple, birch, poplar, and many others. Caterpillars will feed on conifers (such as eastern white pine, hemlock, and spruce) when favored resources have been exhausted. Gypsy moth damage has also been reported on blueberry crops in Massachusetts this year. Caterpillar dispersal occurs earlier in the season by crawling to the canopy of their host plant, where they can scatter using a technique known as “ballooning”. Ballooning occurs when very young caterpillars spin a silken thread and catch the wind to blow onto a new host plant once the thread breaks. This method of dispersal can lead to host plants becoming defoliated that previously did not have egg masses directly on them, however egg masses may be present on nearby oaks, for example, and provide a local population of caterpillars.

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.

We can also hope areas in Massachusetts that did not experience much gypsy moth defoliation last year (areas such as most of Berkshire County) will be mostly spared in 2017 in comparison to those areas who suffered last year in southern central and eastern Massachusetts. However, due to the ballooning ability of the young caterpillars, where egg masses may exist nearby, previously unaffected host plants may be found to have gypsy moth caterpillars present on them this year. For more information about gypsy moth, please visit: http://ag.umass.edu/landscape/fact-sheets/gypsy-moth and return to the Landscape Message for timely updates about this pest and others throughout the season. An excellent article written by Dr. Joseph Elkinton and Jeff Boettner of the University of Massachusetts about the 2016 outbreak and the history of this insect in Massachusetts may be found here: http://www.mass.gov/eea/agencies/dfg/dfw/publications/gypsy-moth-outbreak-of-2016.html.

  • Winter Moth: Operophtera brumata caterpillars have dropped to the soil where they will pupate. Because pupation has begun, management of this insect in the 2017 season is no longer warranted or possible at this time. The winter moth population in 2017 was consistently reported as low in the eastern areas of the state where this insect occurs. The next period of winter moth activity will not be until this fall, roughly around Thanksgiving, when adults will emerge to mate and females begin laying eggs.

For more information about the life cycle of winter moth, please visit this newly updated (March, 2017) fact sheet: Winter Moth Identification and Management (https://ag.umass.edu/landscape/fact-sheets/winter-moth-identification-management).

Winter moth is a non-native insect that was identified in Massachusetts for the first time in 2003 following persistent reports of defoliation in eastern areas of the state such as Cape Anne and on the North Shore near Cohasset, Hingham, and Rockland on the South Shore in the late 1990’s. For more detailed information about the history of this insect pest in North America and Massachusetts, please visit the newly updated (March, 2017) fact sheet: Winter Moth in Massachusetts: History and Biological Control (https://ag.umass.edu/landscape/fact-sheets/winter-moth-in-massachusetts-history-biological-control).

  • Azalea Bark Scale: Eriococcus azaleae was discovered in CT in 1917 and has since been reported in other states. It is found on the bark of twigs and stems and commonly settles in branch crotches. It has been reported on azalea, rhododendron, andromeda, and others. Female scales are approximately 2-3 mm. in length and covered in a white, waxy coating. The females are purple in color and may resemble a mealybug, although they are a soft or felt scale. These females have overwintered and are going to lay eggs which will hatch into crawlers toward the end of June through mid-July. Crawlers will settle into branch crotches, bark crevices, or on the axils of leaves. There is a parasitic wasp that will attack these insects. When high in number, these scales can cause yellowing of the foliage and their sugary excrement can lead to the promotion of sooty mold. Because these are soft scales, they may be targeted with horticultural oils or insecticidal soaps while observing label instructions to prevent phytotoxicity.
  • Black Vine Weevil: Otiorhynchus sulcatus damage is apparent on rhododendron and taxus, but can also be seen on azalea, mountain laurel, and Euonymus. Adult weevils feed along the leaf/needle margins and create rounded notches. Inspect foliage of these plants for notching from last season’s feeding. Larvae, which dwell in the soil, are pupating. Adults will emerge in June and create new damage to leaves for this season. All individuals are females and reproduce asexually. This insect has developed resistance to many chemical insecticides. Entomopathogenic nematodes such as Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacterio-phora work well against this insect, particularly on containerized plants. Results in the landscape vary. Wetting the soil thoroughly prior to application and keeping it wet for at least 5 days following application can help increase the efficacy of the nematodes. Burlap laid around the base of plants during the time adults are active, through August, can be inspected weekly for adult weevils which can be killed before egg laying.
  • Boxwood Psyllid: Psylla buxi is feeding on boxwood foliage with its piercing-sucking mouthparts. This feeding may not cause yellowing or loss of foliage, but will lead to the cupping of new leaves which can be an aesthetic issue for some. If population numbers are low, management of this pest may not be necessary. Nymphs of this insect may be managed between 290-440 GDD’s.
  • Cottony Taxus Scale: Chloropulvinaria floccifera, also referred to as the cottony camellia scale, utilizes such hosts as taxus, camellia, holly, hydrangea, Japanese maple, euonymus, magnolia, jasmine, and Callicarpa americana. This insect was observed on taxus in Amherst on 5/31/17. Females are laying the long, narrow, white colored egg sac that makes them much more noticeable. This was observed again on 6/8/17. Eggs will hatch over an extended period of 6 weeks and crawlers may be treated between 802-1388 GDD’s. This insect can cause the host to appear off-color. They also produce honeydew which promotes sooty mold growth. Target the underside of the foliage. Horticultural oil, neem oil, and insecticidal soaps may be used to manage these soft scales. They may also be washed from plants with a strong jet of water.
  • 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.
  • Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. Crawlers will be present throughout the growing season and the overlap of many developmental stages at any given time can be observed.
  • Female European elm scales observed on 6/7/17 in Amherst. They have produced white fibers around their black, oval bodies and by the end of this month will lay eggs that hatch into bright yellow crawlers (immatures) that can be seen with magnification on the undersides of leaves (along leaf veins). (Simisky, 2017) European Elm Scale: Gossyparia spuria is a type of felt scale and was observed on an elm on 6/7/17 in Amherst. First noted in New York in 1884, this non-native scale is now widespread in North America and is found on native and European elms, but also rarely on hackberry and Zelkova. This insect can cause yellowing of foliage, premature leaf drop, and eventually dieback on its host. Honeydew and thus sooty mold are produced. The females observed in Amherst have produced a ring of white fibers around their black, oval bodies. By the end of June, these females will lay eggs that hatch into bright yellow crawlers, which will disperse to the midrib and leaf veins on the underside of elm leaves where they will remain to feed. Crawlers are tiny and magnification is necessary to observe. Natural enemies such as parasitic wasps and predatory insects have been reported as successful in managing this insect.

     
  • Dead, desiccated female fletcher scales remain at the base of Taxus spp. needles in Amherst on 6/8/17. These soft scales, when removed and viewed under magnification, hide the presence of hundreds of white, tiny eggs laid by the female before she perished. (Simisky, 2017) Fletcher Scale: Parthenolecanium fletcheri (soft scale) was observed on taxus (yew) in Amherst on 6/8/17. Several effective parasites will impact these scale populations and any management decisions should seek to preserve them. Dead, desiccated female scales appear at this time as covers (test) that one might expect from an armored scale and should not be confused for one. When removed, it is easy to find hundreds of tiny, white colored eggs beneath the female (you will need a hand lens to observe). This scale is commonly found on yew and arborvitae (but has also been reported on juniper and hemlock). It may be confused with the European fruit lecanium (P. corni), which has a much broader host range. Depending upon the host plant, crawlers of the fletcher scale will hatch by the end of June and management may be targeted between 1029-1388 GDD’s, base 50°F. Large populations of this scale may lead to host plant yellowing, premature needle drop, and production of honeydew giving way for sooty mold. Each female produces on average 500-600 eggs. The degree of impact this insect may have depends on the host. Some hosts, such as yew, are reportedly more heavily impacted by this scale as when compared to arborvitae, where visible damage may be seldom. Horticultural oil, insecticidal soap, or neem oil may be used according to label instructions in order to preserve natural enemies.
  • 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). Pupation of any remaining caterpillars will begin soon.
  • Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will hatch by early June. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary. Anecdotal reports of increasing hemlock looper populations in certain areas of western Massachusetts (Berkshire County) have been made this season.
  • Lily leaf beetles continue to mate and lay eggs which hatch into the tiny larvae pictured feeding in Amherst here on 6/8/17. (Simisky, 2017) Lily leaf beetles continue to mate on 6/8/17. (Simisky, 2017) Lily Leaf Beetle: Lilioceris lilii adult beetles were still causing feeding damage, mating, and eggs were laid on plants in Amherst on 6/8/17. More frass or excrement-covered larvae of this insect were also found feeding in Amherst at this time. See Regional Reports for local activity of this insect. Management can be achieved by hand-picking and removing adults and larvae. Some chemical management options are available for this insect, but if caught early mechanical management may be effective. (Although when many plants are involved, mechanical management may not be practical.)

The University of Rhode Island Biological Control Lab is researching ways to find a natural method to combat these beetles. Small parasitic insects have been established in lily plots in Cumberland, RI and Wellesley, MA in hopes that these insects will disperse naturally to reduce the effects of the lily leaf beetle. If you have larvae in your yard (or a customer’s yard), please send to URI, following the instructions on the URI Biocontrol Lab website: http://web.uri.edu/biocontrol/home/lily-leaf-beetle-larval-collections-2016-mailing-instructions/

  • Multicolored Asian Lady Beetle (Ladybug): Harmonia axyridis is a native of eastern Asia and was previously introduced into the USA as a biological control agent by the USDA. They tend to be larger than some of our native lady beetles and the adults have a characteristic black “M” shape (or “W” depending upon your viewing direction) on the white pronotum (plate-like structure that covers the thorax of some insects). Adults and larvae can be predators of certain aphids, mites, and thrips. In the landscape, this insect can be considered a natural enemy of pests. This species can be annoying to some in the fall and winter, when the adults will sometimes gather in homes and other indoor structures in large amounts. They do not cause structural damage in the home, but can be annoying home invaders when they seek overwintering shelter.
  • Roseslugs: Two species of sawfly can be found on the leaves of roses at this time. These small, caterpillar-like larvae will skeletonize the upper leaf surface and leave a “window-pane” like pattern behind. When present in large numbers, these insects are capable of defoliating their entire host. Management options include an insecticidal soap spray or a product containing spinosad.
  • Taxus Mealybug: Dysmicoccus wistariae was spotted on taxus in Amherst on 5/31/17 and again on 6/8/17. This insect will produce honeydew and lead to sooty mold growth, yellowing of needles, and sparsely foliated plants. Eventual dieback may be possible. This species is commonly associated with taxus in New England, but can be occasionally found on dogwood, rhododendron, Prunus spp., maple, andromeda, and crabapple. These mealybugs are found on stems and branches and particularly like to congregate at branch crotches. Management may be targeted between 246-618 GDD’s. Horticultural oil and neem oil may be used.
  • Two-marked tree hopper nymphs on wafer ash in Amherst on 6/7/17. Nymphs have dispersed among the foliage and stems and are still very small. (Simisky, 2017) 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. Tiny 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 thus far this season. 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/.
  • White Spotted Pine Sawyer (WSPS): Monochamus scutellatus adults have been previously reported from Middlesex and Worcester counties in MA. (One was also observed in Jaffrey, NH while hiking in Monadnock State Park on Saturday, June 3.) Adults will continue to be active through July. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults, which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers; however, the difference in the color of the scutellum is a key characteristic. See the Asian longhorned beetle entry below for more information about that non-native insect.
  • Woolly elm aphids seen when pulling apart curled foliage in Amherst on 6/7/17. This aphid alternates between elm and an additional host. Winged individuals are present that will soon migrate to the roots of Amelanchier. Multicolored Asian lady beetles were seen in very large numbers on this particular tree, and their brightly colored yellow eggs were laid expertly right next to this crowded aphid colony. (Simisky, 2017) 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. 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. (See photo of lady beetle eggs laid next to a crowded colony of aphids.)
  • Chilli Thrips: *A non-native insect has been confirmed in Massachusetts for the first time.* The non-native, exotic chilli thrips (Scirtothrips dorsalis) has been recently confirmed from two samples of damaged Hydrangea spp. foliage from two residential landscapes located in Barnstable County, MA submitted to the UMass Plant Diagnostics Laboratory. At this time, this pest has not been confirmed in nurseries or greenhouses in Massachusetts or on any other host plants. Due to the limited number of samples, the significance of chilli thrips in Massachusetts is not yet known. This species of thrips is a significant global pest of economically important ornamental, vegetable, and fruit crops in southern and eastern Asia, Oceania, and parts of Africa. It was first determined to be established in the United States in 2005 in Florida, although previous interceptions of this pest were detected. It is reportedly a pest of over 100 host plants belonging to over 40 plant families, including, but not limited to, pepper, strawberry, blueberry, cotton, rose, peanut, Japanese privet, Rhododendron spp., Viburnum spp., eggplant, grapes, melon, tobacco, and tomato. For more information, please visit this Chilli Thrips Fact Sheet (https://ag.umass.edu/landscape/fact-sheets/chilli-thrips) available on the UMass Extension Landscape, Nursery, and Urban Forestry Program web page.
  • Asian Longhorned Beetle, Anoplophora glabripennis, ALB: Look for signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity.

The regulated area for Asian longhorned beetle is 110 miles2 encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn. If you believe you have seen damage caused by this insect, such as exit holes or egg sites, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938. Adult insects of this species will not be present until July.

To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: http://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report.

  • 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 will soon be emerging this season around 450 GDD’s (see Environmental Data above). Signs of an EAB infested tree may include (at this time) 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 the bark, from larval feeding beneath. Positive identification of an EAB-infested tree may not be possible with these signs individually on their own.

For a map of the known locations of emerald ash borer in the state, as well as further information about this insect, please visit: https://ag.umass.edu/fact-sheets/emerald-ash-borer . If you believe you have located EAB-infested ash trees, particularly in an area of Massachusetts not identified on the map provided, please follow the instructions below.

Concerned that you may have found an invasive insect or suspicious damage caused by one? Need to report a pest sighting? If so, please visit the Massachusetts Introduced Pests Outreach Project: http://massnrc.org/pests/pestreports.htm.

Pollinator Protection Resource Online: The Massachusetts Department of Agricultural Resources has developed a Massachusetts Pollinator Protection Plan. It is a set of voluntary guidelines that discuss best management practices for stakeholders seeking to promote the health of the European honeybee and other pollinators. This document includes information for beekeepers, pesticide applicators, land managers and farmers, nurseries and landscapers, and homeowners and gardeners. Please locate the MA Pollinator Protection Plan for more information here: http://www.mass.gov/eea/docs/agr/farmproducts/apiary/pollinator-plan.pdf.

A note about Tick Awareness: deer ticks (Ixodes scapularis), the American dog tick (Dermacentor variabilis), and the lone star tick (Amblyomma americanum) are all found throughout Massachusetts. Each can carry their own complement of diseases. Anyone working in tick habitats (wood-line areas, forested areas, and landscaped areas with ground cover) should check themselves regularly for ticks while practicing preventative measures. Have a tick and need it tested? Visit the web page of the UMass Laboratory of Medical Zoology (www.tickdiseases.org) and click on the red Test a Tick button for more information.

For information about managing ticks in landscapes, among other topics, please visit the following publication from the Connecticut Agricultural Experiment Station: “Tick Management Handbook”: http://www.ct.gov/caes/lib/caes/documents/publications/bulletins/b1010.pdf.

Report by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program

Management Practices

Cladrastis kentukea, yellowwood Cladrastis kentukea, yellowwood Cladrastis kentukea, yellowwood Plant of the Week: Cladrastis kentukea, yellowwood

Cladrastis kentukea is native to the southeastern United States, although it is not common throughout its range. It is a medium sized tree with a broad, rounded crown and upright spreading branches. The main trunk is short, with branches starting within 6’ of the ground. The common name of yellowwood comes from the yellow heartwood. Yellowwood is an excellent specimen landscape tree, having beautiful late spring blooms, nice summer foliage and fall color, and attractive bark in the winter. The white flower clusters are pea-like and resemble those of wisteria. The fragrant, 10-16” long clusters appear in early June. Plants flower heavily every 2-3 years. Young trees may take many years to bloom. Cladrastis kentukea has large, pinnately compound leaves that are 8-12” long with individual leaflets being ovate and 2-3” long. Leaves emerge yellow-green maturing to bright green during the summer. Fall color is a mix of yellow and gold. The smooth light gray bark provides winter interest. Yellowwood is best planted in well-drained soil in full sun. It is best protected from winter wind and the bark can be susceptible to sunscald, but plants have good cold hardiness. Pruning should be done in summer, as bleeding occurs when pruned at most times. Yellowwood has no serious insect or disease problems.

Report by Mandy Bayer, Extension Assistant Professor of Sustainable Landscape Horticulture, UMass Stockbridge School of Agriculture


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