Landscape Message: June 10, 2022

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 in June. The next message will be posted on June 17. 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:

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Scouting Information by Region

Environmental Data

The following data was collected on or about June 8, 2022. Total accumulated growing degree days (GDD) represent the heating units above a 50º F baseline temperature collected via regional NEWA stations (http://newa.cornell.edu) for the 2022 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.

MA Region/Location	GDD		Soil Temp (°F at 4" depth)		Precipitation (1-Week Gain)	Time/Date of Readings
	1-Week Gain	2022 Total	Sun	Shade
CAPE	99	391	64	60	0.93	12:00 PM 6/8
SOUTHEAST	105	499	76	66	1.15	3:00 PM 6/8
NORTH SHORE	93	425	65	60	1.17	11:30 AM 6/9
EAST	110	551	71	67	0.23	4:00 PM 6/8
METRO	103	516	60	57	0.17	5:00 AM 6/8
CENTRAL	108	509	66	62	0.02	3:30 PM 6/8
PIONEER VALLEY	115	543.5	69	62	0.28	1:00 PM 6/8
BERKSHIRES	82	433	66	60	0.71	8:00 AM 6/8
AVERAGE	102	484	67	62	0.58	_
* = information not available

As of 6/7, all counties except Berkshire are either in a "Moderate Drought" or classified as "Abnormally Dry":  Massachusetts | U.S. Drought Monitor (unl.edu)

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.
Catalpa speciosa (Northern catalpa)	*	*	*	*	Begin	*	*	*
Sambucus canadensis (American elderberry)	*	Begin	*	*	*	*	Begin	Begin
Kalmia latifolia (mountain laurel)	Begin	Full	*	Begin/Full	Begin	Begin/Full	Full	Begin
Cotinus coggygria (common smokebush)	Begin	Full	Begin/Full	Full	End	Full	Full	Begin/Full
Weigela florida (old fashioned weigela)	Full	End	Full	Full/End	Full/End	Full/End	Full/End	Full
Robinia pseudoacacia (black locust)	Full	End	Full/End	Full/End	End	Full/End	Full/End	Full
Syringa meyeri (Meyer lilac)	Full/End	End	Full/End	Full/End	Full/End	Full	Full/End	Full/End
Enkianthus campanulatus (redvein enkianthus)	Full	*	End	End	End	Full/End	End	Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions:The average temperature for the period from June 1 thru June 8 was 61ºF with a high of 76ºF and a low of 48ºF both occurring on June 6. June 1, 2, 3 & 4 were cloudy or mostly cloudy, June 5, 6 & 7 were sunny or mostly sunny. Just under 1 inch of precipitation fell during the period; the majority of that was on June 8, with minuscule amounts received on June 1, 2 & 3. The precipitation has broken the month long trend of less than ½ inch per week. More precipitation is still needed, soil moisture remains short. Some unirrigated lawns have begun browning out and are showing soil moisture stress. Some herbaceous plants seen in bloom include bearded iris (Iris x germanica), siberian iris (Iris sibirica), lupines (Lupinus spp.), bloody/red crane’s bill (Geranium sanguineum), common foxglove (Digitalis purpurea), Chinese peony (Paeonia lactiflora), catmint (Nepeta spp.) and oxeye daisy (Leucanthemum vulgare). Some woody plants seen in bloom include rhododendrons, black cherry (Prunus serotina), Kousa dogwood (Cornus kousa), deutzia (Deutzia spp.), many viburnums (V. cassinoides, V. dentatum, V. opulus), roses (Rosa spp.) and sheep laurel (Kalmia angustifolia). Pollen is still abundant, primarily from pines and cool season grasses.

Pests/Problems: There have been a couple of reports of beech leaf disease (BLD) in the upper Cape region in past weeks, definitely something to keep an eye out for. Winter moth and cankerworm have been observed feeding on numerous tree species. A couple of gypsy moth larvae have also been spotted on oak. Turpentine beetle is active, viburnum leaf beetle was observed on arrowwood viburnum, rose slug sawfly larvae on rose, dogwood sawfly larvae on alternate leaf dogwood, sawfly larvae on white oak, erineum mite on linden, hydrangea leaftier on smooth hydrangea, earwig damage observed on butterfly bush and some herbaceous perennials, slug damage on lupine and other herbaceous perennials, and aphids have been spotted on numerous plants. Disease symptoms or signs observed during the period include needlecast on pitch pine, tip blight and branch dieback on Leyland cypress, anthracnose on sycamore, brown rot on ornamental cherries, Exobasidium gall on azalea, cedar apple rust galls active on eastern red cedar, Volutella blight on boxwood, hosta virus X (HVX) on hosta, stem rot on Baptisia, Botrytis on peony, and red thread in turf. Weeds and invasive plants in bloom include sheep sorrel (Rumex acetosella), white clover (Trifolium repens), red clover (Trifolium pratense), narrowleaf plantain (Plantago lanceolata), creeping buttercup (Ranunculus repens), black medic (Medicago lupulina), black swallowwort (Cynanchum louiseae) and multiflora rose (Rosa multiflora). Ticks are everywhere – keep yourself protected.

Southeast Region (Dighton)

General Conditions: Dry. Until the last day of the period we had no precipitation. Every herbaceous plant seemed to be wilted. Lawns are drought dormant. Mercifully, passing thundershowers on Wednesday morning brought some relief with slightly over an inch of rainfall. Fledgling robins are out of their nests and attended by anxious parents. Tiger swallowtail butterflies are about. Male carpenter bees can be encountered jealously patrolling their territories. Plants in flower: Achillea millefolium (yarrow), Baptisia australis (blue false indigo), Chionanthus virginicus (fringetree), Clematis spp. (leather flower), Coreopsis spp. (tickseed), Cornus kousa (Chinese dogwood), Dasiphora fruticosa (cinquefoil, potentilla), Digitalis lutea (perennial yellow foxglove), Geranium sanguineum (bloody cranesbill), Hemerocallis 'Stella d'oro' (early yellow daylily), Heuchera spp. (coral bells), Hosta sieboldiana (Siebold's plantain lily), Kalmia latifolia (mountain laurel), Leucanthemum x superbum (Shasta daisy), Lilium spp. (Asiatic lilies), Linnaea amabilis (Kolwitzia, beauty bush), Lonicera sempervirens (eastern U.S. native honeysuckle vine), Oenothera spp. (sundrops, evening primrose), Penstemon spp. (jupiter's beard), Philadelphus spp. (mock orange), Physocarpus opulifolius (ninebark), Rosea spp. (rose), Sedum stenopetalum (golden constellation stonecrop), Silene latifolia (white champion), Viburnum dentatum (arrowwood), and Vicia sativa (vetch),

Pests/Problems: Observed in the regional landscape were drought dormancy on unirrigated lawns, wilting and premature senescence of herbaceous plants, hedge bindweed (Calystegia sepium) already waist high, and two-spotted spider mite (Tetranychus urticae) on dwarf Alberta spruce.

North Shore (Beverly)

General Conditions: The weather this reporting period was pleasant late spring weather with mostly sunny or partially sunny skies except for June 8 and 9 when we had cloudy weather with rain showers. A low-pressure system passed through and brought much needed rain. Approximately 1.17 inches of rainfall were recorded at Long Hill during this period. Daytime temperatures ranged from low 60s to high 70s and nighttime temperatures ranged from mid 50s to mid 60s. The average daily temperature was 62ºF with the highest temperature of 79ºF recorded on June 7 & 8, and the lowest temperature of 57ºF recorded on June 3. Woody plants seen in bloom include: Chinese dogwood (Cornus kousa), arrowwood viburnum (Viburnum dentatum), magician deutzia (Deutzia x hybrida ‘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), American holly (Ilex opaca), and Japanese snowbell (Styrax japonica). Non-woody plants seen in bloom include: catmint (Nepeta spp.), salvia (Salvia spp.), foam flower (Tiarella cordifolia), leopard's bane (Doronicum spp.), goat’s beard (Aruncus dioicus), fetterbush (Leucothoe fontanesiana), peony (Paeonia sp.), Rodger's flower (Rodgersia aesculifolia), Japanese primrose (Primula japonica), columbine (Aquilegia spp.), sweet woodruff (Galium odoratum), and annuals such as petunia and million bells.

Pests/Problems: Likely beech leaf disease continues to be observed and reported in several areas in Essex county. Skeletonized leaf damage by viburnum leaf beetle larvae continued to be observed on American cranberry viburnum and arrowwood viburnum. Leaf and flower galls (Exobasidium vaccinii) continue to enlarge and become white with spores. Prune out the galls and discard in trash (not compost) before they release the spores. Magnolia scale was observed on some magnolia trees. Juniper twig blight was noted on some junipers; tips of branches die and turn brown. Prune and destroy the infected twigs. Multiflora rose (Rosa multiflora) and wild raspberry (Rubus occidentalis) weeds are in bloom and easy to identify. 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.

East Region (Boston)

General Conditions: Temperatures averaged 72ºF over the past week with a high of 82ºF on June 7. Overnight lows averaged 54ºF with a low of 49ºF on the 6th. We received 0.23 inches of precipitation with one rain event on June 1st accounting for 0.16 inches. There is an abundance of color throughout the landscape as many plants are in bloom. Some plants adding interest to the landscape include: Clematis spp. (clematis), Cornus kousa (kousa/Chinese dogwood), Nepeta spp. (catmint), Philadelphus spp. (mock orange), and Rosa spp. (roses). Pollinators are prolific throughout the landscape.

Pests/Problems: Unirrigated soils are consistently dry. There is a thick layer of pollen coating everything as typical landscape weeds continue to thrive in mulched beds. The invasive multiflora rose (Rosa multiflora) is in flower and very noticeable along roadways and in disturbed woodlands.

Metro West (Acton)

General Conditions: Spring to early summer-like weather continued into this week’s reporting period. High temperatures were recorded in the 60s, 70s and low 80’s all week with a high temperature of 82ºF recorded on the 6th and 7th. Keeping the GDD in check, a low temperature of 45ºF was recorded on the 5th and 6th. The historical monthly average rainfall for June is 3.93” and a meager 0.17” of rain has been recorded for the first week in this month so far. Observed in some stage of bloom this past week were the following woody plants: Catalpa speciosa (northern catalpa), Chionanthus retusus (Chinese fringe tree), C. virginicus (American white fringetree), Cornus sericea (redosier dogwood), Gymnocladus dioicus (Kentucky coffeetree), Kolkwitzia amabilis (beautybush), Liriodendron tulipifera (tulip tree), Philadelphus spp. (mock orange), Potentilla fruticosa (potentilla), Physocarpus opulifolius 'Summer Wine' (summer wine ninebark), Rosa spp. (rose), R. rugosa (Japanese rose), R. 'Knockout' (knockout family of roses), Rubus spp. (blackberry, bramble, raspberry), Spiraea spp. (bridal wreath), and Viburnum dentatum (arrowwood viburnum). Woody vines observed in bloom include Clematis spp. (clematis), Hydrangea anomala petiolaris (climbing hydrangea), and Lonicera sempervirens (trumpet honeysuckle). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Baptisia australis (blue false indigo), Campanula takesimana ‘Elizabeth’ (bell flower), Chrysogonum virginianum (green and gold), Dictamnus albus (gas plant), Geranium cantabrigiense 'Biokovo' and 'Cambridge' (hardy cranesbill), G. sanguineum (bloody cranesbill), Hemerocallis 'Stella D'Oro' (early flowering daylily), Iris germanica (bearded iris), Nepeta spp. (ornamental catmint), Papaver orientale (oriental poppy), Penstemon digitalis 'Husker Red' (beardtongue), Salvia nemerosa (woodland sage, Balkan clary), and Tradescantia spp. (spiderwort).

Pests/Problems: The continued lack of any significant rainfall this spring and in this area continues to be a real concern. On May 31st, the US Drought Monitor declared this reporting area as having “abnormally dry” conditions”. Rosa multiflora, an aggressive and invasive thorny vine/shrub, is just coming into bloom and is very easy to detect with its abundant white flowers seen growing in, amongst and over other trees and shrubs in the planted and/or wild landscape.

Central Region (Boylston)

General Conditions: It was very comfortable for the unofficial start to the summer season. High temperatures largely held in the 70’s, although the first day of the reporting period felt cold with a high of only 61ºF. Another week of abnormally high pollen counts made conditions quite uncomfortable in spite of the lovely temperatures and dry air. There is much in bloom throughout the landscape, including Cornus kousa (Korean dogwood) and the last of the peonies. The star of the show this week was certainly Kalmia latifolia, our native mountain laurel, which came on strong and most cultivars are in full bloom.

Pests/Problems: Given the lack of precipitation, foliar diseases are virtually non-existent. However, many plants in natural areas are showing signs of drought stress with yellowing and senescing foliage, and established herbaceous plants wilting. Unirrigated lawns are already brown and looking like mid-summer. The US Drought Monitor report as of May 31 showed a widening band of areas in abnormally dry or moderate drought status. I anticipate that the next report will follow that trend despite the forecast for precipitation to start the next reporting period. (See the above link to the drought monitor map, located just below the Environmental Data table.)

Pioneer Valley Region (Amherst)

General Conditions: After weeks of widely fluctuating temperatures, conditions were pretty even over the past week. Highs ranged in the upper 70s to low 80s with nighttime temperatures in the low 50s to low 60s. Humidity levels were mostly low and overall, it was a beautiful stretch of early summer weather. But at this point, we need rain. June precipitation has been scant, with only trace amounts from storms that never really materialized. Lawns in full sun are browning but most perennials and woody plants appear lush and healthy. At the time of writing, there’s hope for some heavy rain on 6/9, but we will need some considerable accumulation to thoroughly wet the upper soil horizon. Given the patchy nature of summer rainfall, a high-quality rain gauge sited in an unobstructed setting is a must to determine accumulations at individual properties. Weeds are still coming up strong and supplemental water is necessary for young and recently transplanted plants in full sun. As tedious as weeding and watering can be, it does allow for close inspection of trees and shrubs to assess their overall health. Hand check soils after watering to ensure the soils have been properly wetted. Pollen levels continue to be high but the volumes generated by white pine seem to be on the downside. The lack of rain has meant a nearly constant coating of pollen on every outdoor surface (and indoor if the windows are open). Tree frog mating calls can be heard and lightning bugs are appearing in greater numbers. Shallow toad burrows have been found under ground cover plants and low-growing junipers. White clover (Trifolium repens) appears to be having a good year, spreading and flowering widely on untreated lawns.

Pests/Problems: White pine needle damage (WPND) is on full display, depending on individual tree location. Disease severity in New England has been found to be significantly correlated with latitude. In areas of northern New England, white pines suffering needle blight are distributed evenly across the landscape. However, in southern New England, disease incidence and severity is variable, with some white pines free of the disease. On hardwoods, no major foliar diseases have been observed so far with anthracnose levels at low levels in Hampshire County. Sycamore anthracnose severity is vastly lower than it’s been over the past few years and even horse chestnut leaf blotch has yet to establish. Some apple scab leaf shedding has been found but new growth continues to accrue. Hopefully, the below-average precipitation is suppressing rust diseases caused by Gymnosporangium, which did very well in 2021. Black fly populations are still high, especially in the morning hours. Invasive scarab beetles are just starting to emerge and will persist into August. These common pests can be destructive to certain plants as defoliators and root feeders. More information can be found here.

Berkshire Region (Great Barrington)

General Conditions: For the most part, it was a pleasant week, though temperatures, rainfall, and wind varied from the top of the county at the Vermont border to the bottom at the Connecticut border. Average and max/min temperatures for the period from June 1 – 7 were: North Adams at 67ºF (max of 83ºF on 6/6 and min of 45ºF on 6/5); Pittsfield at 62ºF (max of 76ºF on 6/6 and min of 49ºF on 6/5); Richmond at 64ºF (max of 79ºF on 6/6 and min of 41ºF on 6/6). Rainfall varied even more from north to south. From June 1 to the morning of June 8 the totals were: North Adams collected a total of 0.28 inches; Pittsfield had 0.80 inches, Richmond picked up 0.59 inches, and at this site in West Stockbridge rainfall total was 0.71 inches. Prior to the rain which began on the afternoon of June 7 and extended into the early daylight hours, soils were beginning to get rather dry, though no part of the county falls into any drought category at this time. Nevertheless, recently transplanted herbaceous specimens, especially annuals, which were not irrigated daily were showing various levels of wilt. This was exacerbated by the frequent gusty winds. That alone stresses the importance of watering soils a few hours before transplanting and immediately afterwards, as well as daily until symptoms of wilt are no longer evident. The rain on the night of June 7th did relieve that stress to a large extent. Wilt was not observed with any established plantings and the beauty of the succession of spring blooming bulbs, herbaceous perennials, shrubs, and trees continues to be spectacular. Weather conditions did not deter growth of turfgrass. Lawns are lush and growing rapidly, as are lawn weeds.

Pests/Problems: The big story regarding pests continues to be the very heavy infestation of spongy moths through much of the county, but mostly in southern areas and along the border with New York State and Connecticut. Some serious defoliation is beginning to occur. Oaks and beech seem to be most affected, but a wide variety of woody plants are hosting the caterpillars. Interestingly, the larvae vary from barely ¼ inch to over 1 inch in length. This range in larval stages may be an indication of a long period of defoliation. To the consternation of many folks, the caterpillars are crawling on house walls, vehicles, picnic tables and benches, and just about any object in the path of spongy moth caterpillars. Other problems observed over the past week include: aphids on many herbaceous and woody species, lily leaf beetle (adults and larvae) on Asian lilies, hemlock elongate scale (settled crawlers), willow leaf beetle (larvae), hickory leaf stem gall (Phylloxera), and boxelder twig borer (larvae). Few diseases are evident at this time. Apple scab and cedar apple rust on crabapple were the only plant diseases observed this week. Weeds are growing rapidly. The black-legged tick population remains very high as are reported tick bites. Mosquitoes are not too bad at this time but they are around. Damage to landscape plants by deer, rabbits, and voles is common.

Regional Scouting Credits

• CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
• SOUTHEAST REGION - Brian McMahon, Arborist, reporting from the Dighton area.
• 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 Boston area.
• METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
• CENTRAL REGION - Mark Richardson, Director of Horticulture reporting from New England Botanic Garden at Tower Hill, Boylston.
• PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from 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, a select few:

• Root and lower trunk rot of white oak (Quercus alba) caused by Armillaria. Large, roadside tree (43” dbh) with canopy dieback that has worsened over the past several years. The lower trunk had major symptoms of decay with dead, sloughing bark, decaying sapwood, evidence of carpenter ants, woodpecker excavation and saprot fungal colonization (see photo). In early October of 2020 and 2021, large clusters of Armillaria mushrooms were observed at the base of the tree. Typically, it’s uncommon to find Armillaria fruiting from living trees, suggesting the decay in the lower trunk was extensive. To better assess decay severity, sonic and electrical resistance tomography scans were performed at heights of 50 cm (~20”) and 150 cm (~60”) above the soil line. Shockingly, the tomograms revealed that the decay was restricted to the outer sapwood and did not penetrate into the heartwood. Considering the size, location and progressive decline, the tree was removed in late May. Examination of the stump confirmed the decay was restricted to the outer sapwood where the symptoms were visible. The results reaffirm how difficult it can be to estimate decay severity based on a visual assessment of symptoms and signs alone.
• Pine needle rust, caused by Coleosporium asterum s.l., on pitch pine (Pinus rigida). Numerous forest trees, both overstory and understory, were showing symptoms of needle blight during a recent survey. The symptoms include blighted needle tips and scattered, yellow-orange spots. Upon closer inspection of the spots, white-colored “flaps” of fungal tissue (aecia) and orange-colored spore masses (aeciospores) were also visible (see photos). Pine needle rusts occur across the northern hemisphere on a variety of two- and three-needle pines. The alternate hosts of C. asterum s.l. are members of the Asteraceae, such as goldenrod and aster. Needle rust outbreaks can reduce growth and the aesthetic value of landscape trees, but are not considered a serious threat to overall health. The majority of rust fungi that attack pines in North America create branch cankers and galls, which cause decidedly more damage. In addition to the needle rust, the needles were also harboring Ploioderma needle cast, caused by Ploioderma lethale. This common pathogen of pitch pine can cause significant needle loss during years of ample spore production and dispersal. Symptoms also include blighted needle tips.
• Infestation of the Norway spruce gall midge (Piceacecis abietiperda) on Norway spruce (Picea abies). The tree is roughly 10-years-old and was transplanted three years ago. The site includes high shade and no supplemental irrigation in soils with good drainage. Last year, shoot tip dieback and interior canopy thinning was observed. The submitted shoots were distorted and curved in an irregular pattern and mostly devoid of needles. At the base of the shoots, the small, overwintering galls produced by the midge could be observed microscopically. The tree was possibly infested upon planting. Some of the interior canopy thinning is likely due to the shaded setting.
• Infestation of the cryptomeria scale (Aspidiotus cryptomeriae) and shoot tip blight caused by Pestalotiopsis on eastern redcedar (Juniperus virginiana). Several trees planted along a driveway in full sun surrounded by lawn. During the winter, the trees started to take on an overall brown appearance in the canopy and a shoot tip blight developed. The cryptomeria scale is most often found on true fir in landscape settings but has a broad host range among conifers. Like many armored scales, it is non-native in North America. Pestalotiopsis is common on species of Juniperus that are suffering from various landscape stresses.
• Herbicide injury (glyphosate) on kousa dogwood (Cornus kousa ‘Milky Way’). The tree is approximately 20-years-old and has been suffering from stunted and deformed leaves, witches’ brooming and shoot dieback since 2020. The tree resides in full sun near a path that was treated for weeds in 2020 and 2021. The path was not treated this year and while the tree’s appearance has improved, symptoms are still visible. Minor amounts of spray drift from the glyphosate treatments was enough to cause repeated, non-lethal injury. The injured shoots were subsequently colonized by the cankering pathogen Phomopsis, which is creating an additional problem for the tree. Now that the problem has been identified, blighted tissues can be pruned and removed and hopefully over time, the tree will reemerge in good health.
• Severe canopy dieback of a European beech (Fagus sylvatica ‘Riversii’) infected by the beech leaf disease nematode (Litylenchus crenatae ssp. mccanii). The tree is approximately 40-years-old and resides in a part-sun setting with sandy, well-drained soils in Plymouth County. It started leafing out normally this spring and then abruptly stopped. Leaves that had developed normally began shedding from the canopy. The submitted shoots had leaves with interveinal banding and convex puckering, typical of the disease. Only a very small portion of the uppermost canopy has foliage. Based on submitted photos, the tree appears to have <15% of its normal foliage. Symptoms of BLD were not observed last year, but the tree was infected. Symptoms that developed this season (2022) are the result of bud infestations that occurred in 2021. In its current state, it’s difficult to see how the tree will survive beyond this growing season.

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

Insects

An Update about Neonicotinoid Use in Massachusetts:

Beginning July 1, 2022 systemic insecticide active ingredients known as neonicotinoids will become state restricted use for tree and shrub uses in Massachusetts. If an individual works in the commercial industry (landscapers, arborists, etc.), then a Commercial Certification License is needed. (Example: Category 36 Commercial Certification License, Shade Trees & Ornamentals.) Someone can use a state or federal restricted use pesticide if they have a Commercial Applicators License as long as they are working under the direct supervision of someone with a Commercial Certification. Unlicensed or uncertified individuals will no longer be able to apply neonicotinoids to manage insect pests of trees and shrubs in Massachusetts.

More information is available, here: https://www.mass.gov/service-details/pesticide-newsupdates

Helpful Information from Taryn LaScola-Miner, Director, Crop and Pest Services Division of the MA Department of Agricultural Resources:

“As you know, products that contain neonicotinoids and have certain use patterns will have a classification change from General Use to Restricted Use on July 1, 2022. In order to help inform the manufacturers, dealers, sellers and applicators of which products will be changing from general use to restricted use, the Department has created the list of neonicotinoid products that currently are and will become restricted use beginning July 1st. You may find the list at the link below. Please note that this list is subject to change.

Additionally, MDAR is anticipating that there will be more of a need for companies to follow the Direct Supervision regulations with this change. Therefore, MDAR has updated its Direct Supervision Frequently Asked Questions document as well.

Although an email will be sent to all licensed applicators within the next few weeks as a final reminder of the change, please pass this information along to your members and customers as an effort to make this transition as smooth as possible. If you have any questions, please let me know. Thank you!”

List of Neonicotinoid Products: https://www.mass.gov/doc/list-of-neonicotinoid-pesticides/download

Direct Supervision Frequently Asked Questions: https://www.mass.gov/doc/direct-supervision-frequently-asked-questions-faq/download

Interesting Insects Reported Recently:

• Dicerca spp. Jewel/Wood boring Beetles: Dicerca spp. are in the Family Buprestidae (jewel beetles, flatheaded borers). There are at least 24 species of jewel beetles in the genus Dicerca in North America, 16 of which are present in the northeast. The larvae of these insects have been reared from both conifers and deciduous trees, and the adults of nearly all but one of the species known to North America preferentially select damaged or dying trees to lay their eggs on. (The exception is D. pugionata, whose larvae feed on alder, witch hazel (Hamamelis virginiana), and common ninebark.) As such, these native insects should be preserved and do not require management. They are providing an ecosystem service by aiding in the decomposition of dead or dying plants. Two common species in this genus include Dicerca caudata whose larvae feed on alder and river birch, and D. divaricata whose larvae feed on maple, birch, redbud, ash, hophornbeam, oak, and elm. Finding these beetles is a sign that the tree or shrub has other primary stressors that are causing its decline.

• ​​​​ ​​​​​Eyed Mustard & Mustard Sallow Caterpillars: Three species of sallow caterpillar feed on witch hazel in eastern North America. Pyreferra citrombra (eyed mustard sallow), P. hesperidago (mustard sallow), and P. ceromatica. It is very difficult to distinguish between the caterpillars of these three species and Wagner (2005) calls for further study of this genus. Caterpillars may be found on witch hazel, hazel, and hophornbeam in woodlands and forests from Ontario to Georgia. One generation occurs annually with mature caterpillars in May and June. Adults are brown/tan and white winged moths. This genus belongs to the Family Noctuidae (owlet moths). These are native moth caterpillars that while noticeably active some years, are not typically considered pests. Lithophane querquera (shivering pinion) is a species with a caterpillar similar in appearance that is found on apple, ash, cherry, hickory, and oak. This species was noticed on witch hazel in Granville State Forest by Dr. Nick Brazee. His excellent photos are included here. Mustard sallow caterpillars were also reported in 2015 on witch hazel in the Berkshires. See report here: https://ag.umass.edu/landscape/landscape-message-jun-12-2015, which states:

"A very colorful yellow and white striped caterpillar was found feeding on the foliage of witch hazel. The caterpillar was identified as belonging to the genus Pyreferra. Deb Swanson of Plymouth County believes the species to be Pyreferra hesperidago (mustard sallow caterpillar) which she has seen there in past years."

Insects and Other Arthropods

• Deer Tick/Blacklegged Tick: Ixodes scapularis adults are active all winter and spring, as they typically are from October through May, and “quest” or search for hosts at any point when daytime temperatures are above freezing. Engorged females survive the winter and will lay 1,500+ eggs in the forest leaf litter beginning around Memorial Day (late May). Larval and nymphal deer ticks may be encountered at this time. Larvae are encountered in New England from roughly May through November, with peak risk reported in August. Nymphs are encountered from April through July with a peak risk reported in June in New England. Nymphs may also be encountered again in October and November. For images of all deer tick life stages, along with an outline of the diseases they carry, visit: https://web.uri.edu/tickencounter/species/blacklegged-tick/ .

Anyone working in the yard and garden should be aware that there is the potential to encounter deer ticks. The deer tick or blacklegged tick can transmit Lyme disease, human babesiosis, human anaplasmosis, and other diseases. Preventative activities, such as daily tick checks, wearing appropriate clothing, and permethrin treatments for clothing (according to label instructions) can aid in reducing the risk that a tick will become attached to your body. If a tick cannot attach and feed, it will not transmit disease. For more information about personal protective measures, visit: https://web.uri.edu/tickencounter/prevention/protect-yourself/

The Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing resources here: https://ag.umass.edu/resources/tick-testing-resources .

• Mosquitoes: According to the Massachusetts Bureau of Infectious Disease and Laboratory Science and the Department of Public Health, there are at least 51 different species of mosquito found in Massachusetts. Mosquitoes belong to the Order Diptera (true flies) and the Family Culicidae (mosquitoes). As such, they undergo complete metamorphosis, and possess four major life stages: egg, larva, pupa, and adult. Adult mosquitoes are the only stage that flies and many female mosquitoes only live for 2 weeks (although the life cycle and timing will depend upon the species). Only female mosquitoes bite to take a blood meal, and this is so they can make eggs. Mosquitoes need water to lay their eggs in, so they are often found in wet or damp locations and around plants. Different species prefer different habitats. It is possible to be bitten by a mosquito at any time of the day, and again timing depends upon the species. Many are particularly active from just before dusk, through the night, and until dawn. Mosquito bites are not only itchy and annoying, but they can be associated with greater health risks. Certain mosquitoes vector pathogens that cause diseases such as West Nile virus (WNV) and eastern equine encephalitis (EEE).

For more information about mosquitoes in Massachusetts, visit: https://www.mass.gov/service-details/mosquitoes-in-massachusetts

There are ways to protect yourself against mosquitoes, including wearing long-sleeved shirts and long pants, keeping mosquitoes outside by using tight-fitting window and door screens, and using insect repellents as directed. Products containing the active ingredients DEET, permethrin, IR3535, picaridin, and oil of lemon eucalyptus provide protection against mosquitoes. Be aware that not all of these can be safely used on young children. Read and follow all label instructions for safety and proper use.

For more information about mosquito repellents, visit: https://www.mass.gov/service-details/mosquito-repellents and https://www.cdc.gov/mosquitoes/mosquito-bites/prevent-mosquito-bites.html

• Wasps/Hornets: Many wasps are predators of other arthropods, including pest insects such as certain caterpillars that feed on trees and shrubs. Adult wasps hunt prey and bring it back to their nest where young are being reared, as food for the immature wasps. A common such example are the paper wasps (Polistes spp.) who rear their young on chewed up insects. They may be seen searching plants for caterpillars and other soft-bodied larvae to feed their young. Paper wasps can sting, and will defend their nests, which are open-celled paper nests that are not covered with a papery “envelope”. These open-celled nests may be seen hanging from eaves or other outdoor building structures. Aerial yellow jackets and hornets create large aerial nests that are covered with a papery shell or “envelope”. Common yellow jacket species include those in the genus Vespula. Dolichovespula maculata is commonly known as the baldfaced hornet, although it is not a true hornet. The European hornet (Vespa crabro) is three times the size of a yellow jacket and may be confused for the Asian giant hornet (Vespa mandarinia). The European hornet is known to Massachusetts, but the Asian giant hornet is not. If you are concerned that you have found or photographed an Asian giant hornet, please report it here: https://massnrc.org/pests/report.aspx . A helpful ID tool, although developed for Texas by the USDA, depicts common look-a-like species that we also have in MA that can be confused for the Asian giant hornet and is found here: https://agrilife.org/lubbock/files/2020/05/Asian_Giant_Hornet_Look-alikes_101_Xanthe_Shirley.pdf . Paper wasps and aerial yellowjackets overwinter as fertilized females (queens) and a single female produces a new nest annually in the late spring. Queens start new nests, lay eggs, and rear new wasps to assist in colony/nest development. Nests are abandoned at the end of the season. Some people are allergic to stinging insects, so care should be taken around wasp/hornet nests. Unlike the European honeybee (Apis mellifera), wasps and hornets do not have barbed stingers, and therefore can sting repeatedly when defending their nests. It is best to avoid them, and if that cannot be done and assistance is needed to remove them, consult a professional.

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

Invasive Insects & Other Organisms Update:

• Spongy Moth: Lymantria dispar egg hatch was first reported to UMass Extension by arborists in Great Barrington, MA in early May, and activity has intensified since that time. Professionals and property owners working and living in Berkshire County continue to be on high alert as they monitor and manage spongy moth caterpillar feeding. At this time, the caterpillars are still small in size, but by the end of June the extent of their defoliation in western MA should be very apparent as the caterpillars grow.

If high-value specimen trees in Berkshire County are currently being defoliated by young spongy moth caterpillars, consider applying the reduced risk insecticide Bacillus thuringiensis Kurstaki (Btk) to host plant leaves if caterpillars are still small and actively feeding, but before caterpillars are over ¾ inch in length. Spinosad is an additional reduced risk active ingredient for the management of spongy moth caterpillars. Once spongy moth caterpillars are large (2-3 inches in length) and very noticeable, they are very difficult to manage and will have already done much of their feeding. It is preferable to treat the early instar caterpillars, if chemical management is deemed necessary on ornamental plants in the landscape. Keep in mind that most healthy trees can survive a single year of defoliation, if they do not have other stressors. Specimen trees that were defoliated last year in Berkshire County, that have caterpillars feeding on them again this year, should be prioritized.

Why did the common name for Lymantria dispar change recently? More information is available here: https://entsoc.org/news/press-releases/spongy-moth-approved-new-common-name-lymantria-dispar

To learn more about the life cycle and natural enemies of this insect, visit: https://ag.umass.edu/landscape/education-events/insectxaminer

• Spotted Lanternfly: (Lycorma delicatula, SLF) is a non-native, invasive insect that feeds on over 103 species of plants, including many trees and shrubs that are important in our landscapes.

The MA Department of Agricultural Resources (MDAR) recently published the following press release, urging professionals and the general public to search all nursery stock, particularly maples and crabapples, purchased this year for spotted lanternfly egg masses: https://www.mass.gov/news/state-agricultural-officials-ask-public-to-be-on-alert-for-hatching-of-invasive-spotted-lanternfly-eggs . In particular, the press release warns:

“MDAR recently received reports that nursery stock from SLF-infested areas may have been sent to Massachusetts growers. Due to this, anyone who has recently purchased trees or shrubs or had them planted on their property, particularly maple or crabapple trees, is being asked to inspect the trunk and branches to ensure there are no SLF egg masses or any hitchhiking nymphs, and to report any finds to MDAR. Landscapers and plant nurseries are also being reminded to stay on the lookout for this pest.”

Currently, the only established populations of spotted lanternfly in Massachusetts are in a small area in both Fitchburg and Shrewsbury, MA. Therefore, there is no reason to be preemptively treating for this insect in other areas of Massachusetts. If you suspect you have found spotted lanternfly in additional locations, please report it immediately to MDAR here: https://massnrc.org/pests/slfreport.aspx . If you are living and working in the Fitchburg and Shrewsbury areas, please be vigilant and continue to report anything suspicious.

For More Information:

From UMass Extension:

Check out the InsectXaminer Episode about spotted lanternfly adults and egg masses! Available here: https://ag.umass.edu/landscape/education-events/insectxaminer

Fact Sheet: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly

From the MA Department of Agricultural Resources:

Fact Sheet and Map of Locations in MA: https://massnrc.org/pests/pestFAQsheets/spottedlanternfly.html

• 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 square miles 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.

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 .

• Browntail Moth: Euproctis chrysorrhoea is an invasive insect originating from Europe and first detected in the US in Somerville, MA in 1897. Currently, browntail moth is limited to a small portion of eastern Massachusetts, particularly areas near the coast.  Report suspected browntail moth life stages here: https://massnrc.org/pests/pestreports.htm . Due to a persistent outbreak of this insect in Maine since approximately 2016, it is a good idea for us to again familiarize ourselves with this pest. (For more information and the latest updates about the status of this insect in Maine, visit: https://www.maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm .)

Caution: hairs found on the caterpillar and pupal life stages of this insect can cause a rash similar to poison ivy. Some individuals are very sensitive to browntail moth hairs and may also experience allergic reaction. The chance of interacting with browntail moth hairs increases between May and July, although they could be a problem at any time of year.

The larval or caterpillar stage of this insect is present from August until the following June (spending the winter in webs they create on the tips of host plant twigs). In the fall, groups of caterpillars are found creating webs around a tightly wrapped leaf (covered in bright white silk) where they will overwinter in groups of 25-400. These 2-4 inch long webs can be found on the ends of branches often on apple or red oak. As soon as leaves begin to open in the spring (usually by April), the caterpillars will crawl from their webs to feed on the new leaves. Caterpillars are fully grown around June and spin cocoons in which they pupate. These cocoons are also full of the irritating hairs and should be dealt with extreme caution. Adult moths emerge in July and females lay eggs on the undersides of leaves in masses of 200-400, covering them with hairs from their bodies. (Adults do not typically cause skin rashes.) Eggs hatch around August and September and larvae feed shortly before forming their overwintering webs.

The primary concern with this insect are the poisonous hairs found on the caterpillars. Contact with the caterpillar or its hairs can cause a rash similar to poison ivy in susceptible individuals. If hairs break off and blow around in the wind, they can cause difficulty breathing and headaches. While this insect can act as a defoliator in the larval stage, feeding on the leaves of many deciduous trees and shrubs, this activity may be secondary to concerns about public health risks. Care should be taken to avoid places infested with these caterpillars, exposed skin or clothing should be washed, and the appropriate PPE should be worn if working with these insects. Consult your physician if you have a reaction to the browntail moth.

• Emerald Ash Borer: (Agrilus planipennis, EAB) has been detected in at least 11 out of the 14 counties in Massachusetts. A map of these locations across the state may be found here: https://ag.umass.edu/fact-sheets/emerald-ash-borer . Additional information about this insect is provided by the MA Department of Conservation and Recreation, here:https://arcg.is/j8TiD .

This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and has been reported in cultivated olive (Olea europaea). Signs of an EAB infested tree may include D-shaped exit holes in the bark (from adult emergence), “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. It is interesting to note that woodpeckers are capable of eating 30-95% of the emerald ash borer larvae found in a single tree (Murphy et al. 2018). Unfortunately, despite high predation rates, EAB populations continue to grow. However, there is hope that biological control efforts will eventually catch up with the emerald ash borer population and preserve some of our native ash tree species for the future. For an update about the progress of the biological control of emerald ash borer, visit Dr. Joseph Elkinton’s archived 2022 webinar now available here: https://ag.umass.edu/landscape/education-events/invasive-insect-webinars .

• Jumping Worms: Amynthas spp. earthworms, collectively referred to as “jumping or crazy or snake” worms, overwinter as eggs in tiny, mustard-seed sized cocoons found in the soil or other substrate (ex. compost) that are impossible to remove. The first adults appear in the end of May – June, but the numbers are low and infestations are rarely noticed at that time. It is easy to misidentify earthworms if only immatures found. By August and September, this is when most observations of fully mature jumping worms occur. At that time, snake worms become quite abundant, infestations become very noticeable, and may cause a lot of concern for property owners and managers.

For More Information:

UMass Extension Fact Sheets:

Earthworms in Massachusetts – History, Concerns, and Benefits: https://ag.umass.edu/landscape/fact-sheets/earthworms-in-massachusetts-history-concerns-benefits

Jumping/Crazy/Snake Worms – Amynthas spp.:

https://ag.umass.edu/landscape/fact-sheets/jumpingcrazysnake-worms-amynthas-spp

A Summary of the Information Shared at UMass Extension’s Jumping Worm Conference in January 2022:

https://ag.umass.edu/news-events/highlights/jumping-worms-conference

 

Tree & Shrub Insect Pests, Continued:

• Arborvitae Leafminer: In New England and eastern Canada, four species of leafminers are known to infest arborvitae. These include Argyresthia thuiella, A. freyella, A. aureoargentella, and Coleotechnites thujaella. The arborvitae leafminer, A. thuiella, is the most abundant of these and has the greatest known range when compared to the others. (It is also found in the Mid-Atlantic States and as far west as Missouri). Moths of this species appear from mid-June to mid-July and lay their eggs. The damage caused by all of these species is nearly identical. Trees, however, have been reported to lose up to 80% of their foliage due to arborvitae leafminer and still survive. At least 27 species of parasites have been reported as natural enemies of arborvitae leafminers, the most significant of which may be a parasitic wasp (Pentacnemus bucculatricis). Arborvitae leafminer damage causes the tips of shoots and foliage to turn yellow and brown. If infestations are light, prune out infested tips.

• Azalea Sawflies: There are a few species of sawflies that impact azaleas. Johnson and Lyon's Insects that Feed on Trees and Shrubs mentions three of them. Amauronematus azaleae was first reported in New Hampshire in 1895 and is likely found in most of New England. Adults of this species are black with some white markings and wasp-like. Generally green larvae feed mostly on mollis hybrid azaleas. Remember, sawfly caterpillars have at least enough abdominal prolegs to spell “sawfly” (so 6 or more prolegs). Adults are present in May, and females lay their eggs and then larvae hatch and feed through the end of June. There is one generation per year. Nematus lipovskyi has been reared from swamp azalea (Rhododendron viscosum). Adults of that species have been collected in April (in states to the south) and May (in New England) and larval feeding is predominantly in late April and May in Virginia and June in New England. One generation of this species occurs per year, and most mollis hybrid azaleas can be impacted. A third species, Arge clavicornis, is found as an adult in July and lays its eggs in leaf edges in rows. Larvae are present in August and September. Remember, Bacillus thuringiensis Kurstaki does not manage sawflies.

• Bagworm: Thyridopteryx ephemeraeformis is a native species of moth whose larvae construct bag-like coverings over themselves with host plant leaves and twigs. This insect overwinters in the egg stage, within the bags of deceased females from last season. Eggs may hatch and young larvae are observed feeding around mid-June, or roughly between 600-900 GDD’s. Now is the time to scout for and remove and destroy overwintering bags. More information can be found here: https://ag.umass.edu/landscape/fact-sheets/bagworm   

• Boxwood Leafminer: Monarthropalpus flavus partly grown fly larvae overwinter in the leaves of susceptible boxwood. Yellowish mines may be noticeable on the undersides of leaves. This insect grows rapidly in the spring, transforming into an orange-colored pupa. After pupation, adults will emerge and white colored pupal cases may hang down from the underside of leaves where adults have emerged. Adults may be observed swarming hosts between 300-650 GDD’s, or roughly the end of May through June. Most cultivars of Buxus sempervirens and B. microphylla are thought to be susceptible. If installing new boxwoods, resistant cultivars such as ‘Vardar Valley’ and ‘Handsworthiensis’ are good choices at sites where this insect has been a problem.

• Boxwood Mite: Eurytetranychus buxi overwinter as tiny eggs on boxwood leaves and hatch mid-spring. These mites are tiny (about the size of a period) and difficult to detect. Feeding may cause plants to appear off-color. If management is deemed necessary, the timing for treatment may be between 245-600 GDD’s.

• Boxwood Psyllid: Psylla buxi feeding can cause cupping of susceptible boxwood leaves. Leaf symptoms/damage may remain on plants for up to two years. English boxwood may be less severely impacted by this pest. While foliar applications may be made between 290-440 GDD’s, the damage caused by this insect is mostly aesthetic. Therefore, typically, management is not necessary.

• Dogwood Borer: Synanthedon scitula is a species of clearwing moth whose larvae bore not only into dogwood (Cornus), but hosts also include flowering cherry, chestnut, apple, mountain ash, hickory, pecan, willow, birch, bayberry, oak, hazel, myrtle, and others. Kousa dogwood appear to be resistant to this species. Signs include the sloughing of loose bark, brown frass, particularly near bark cracks and wounds, dead branches, and adventitious growth. The timing of adult emergence can be expected when dogwood flower petals are dropping and weigela begins to bloom. Adult moth flights continue from then until September. Emergence in some hosts (ex. apple) appears to be delayed, but this differs depending upon the location in this insect’s range. Eggs are laid singly, or in small groups, on smooth and rough bark. Female moths preferentially lay eggs near wounded bark. After hatch, larvae wander until they find a suitable entrance point into the bark. This includes wounds, scars, or branch crotches. This insect may also be found in twig galls caused by other insects or fungi. Larvae feed on phloem and cambium. Fully grown larvae are white with a light brown head and are approx. ½ inch long. Pheromone traps and lures are useful for determining the timing of adult moth emergence and subsequent management.

• Dogwood Sawfly: Macremphytus tarsatus has one generation per year. The larvae of the dogwood sawfly overwinter in decaying wood and occasionally compromised structural timber. An overwintering "cell" is created in this soft wood. Pupation occurs in the springtime and adults can take a lengthy time to emerge, roughly between late May and July. 100+ eggs are laid in groups on the underside of leaves. Eggs hatch and the larvae feed gregariously, initially skeletonizing leaves. As the caterpillars grow in size, they are capable of eating the entire leaf with the exception of the midvein. Larval appearance varies greatly throughout instars, so much so that one might mistake them for multiple species. Early instars are translucent and yellow, but as the caterpillars grow they develop black spots (over yellow) and become covered in a white powder-like material. Larvae and their shed skins may resemble bird droppings. Full grown larvae begin to wander in search of a suitable overwintering location. Rotting wood lying on the ground is preferred for this. Foliage of dogwood, especially gray dogwood (Cornus racemosa) may be impacted. Skeletonizes leaves at first, then eats all but the midvein.

• Eastern Tent Caterpillar: Malacosoma americanum eggs overwinter on host plant twigs. Egg hatch typically occurs when wild cherry leaves begin to unfold and young caterpillars may emerge by late-April through the first two weeks in May (90-190 GDD’s). Susceptible hosts include cherry and crabapple. Other host plants whose leaves are fed upon by this native insect can include apple, ash, birch, willow, maple, oak, poplar, and witch-hazel. Where practical, prune out and remove new eastern tent caterpillar tents before they become larger as the caterpillars continue to feed. Eastern tent caterpillars are large and beginning to wander from their nests in parts of Hampshire County, MA as of 5/30/2022. Eastern tent caterpillars are native to Massachusetts and have many associated natural enemies (parasites and predators) that help regulate populations. Unless these caterpillars are actively defoliating specimen trees in a landscaped setting, we can coexist with this particular herbivore native to our forests.

• Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. The elongate hemlock scale may overwinter in various life stages and overlap of many developmental stages at any given time can be observed throughout much of the season. Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F. Nitrogen fertilizer applications may make elongate hemlock scale infestations worse.

 

• Euonymus Caterpillar: Yponomeuta cagnagella is of European origin and widespread in distribution throughout Europe. It was first reported in North America in Ontario in 1967. The euonymus caterpillars (larvae) feed in groups and envelop the foliage of the host plant in webs as they feed. Hosts include: Euonymus europaeus (tree form), E. kiautschovicus, E. alatus, and E. japonicus. Mature caterpillars are just under an inch in length, creamy yellow-gray in color with black spots and a black head capsule. By late June, these larvae pupate in white, oval-shaped cocoons which are typically oriented together vertically either on host plants or non-hosts in the area. Cocoons can be found in cracks and crevices, or webbed together leaves. The adult moth emerges in late June in most locations. The adult female secretes a gummy substance over her eggs which will harden, making them even more difficult to see. Eggs hatch by mid-August, at which time the tiny larvae prepare to overwinter beneath their eggshell-like covering. These larvae are inactive until the following year, when caterpillars group together to feed on newly emerging leaves, creating a mess of webs as they feed. There is one generation per year. Plants may be partially or entirely defoliated. Management of young, actively feeding caterpillars with Bacillus thuringiensis is possible if deemed necessary, however many species of Euonymus are considered invasive themselves.

Check out Episode 3 of InsectXaminer to see the euonymus caterpillar in action and learn more about its life cycle: https://ag.umass.edu/landscape/education-events/insectxaminer

• Euonymus Scale: Unaspis euonymi is an armored scale that can be found on euonymus, holly, bittersweet, and pachysandra. This insect can cause yellow spotting on leaves, dieback, and distorted bark. For crawlers, early June timing is suggested between 533-820 GDD’s. (Eggs begin to hatch in early June.)
• European Elm Scale: Gossyparia spuria is a type of felt scale. 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. By the end of June, 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.

• Forest Tent Caterpillar: Malacosoma disstria egg hatch occurs between 192-363 GDD’s, base 50°F, by mid-late May and caterpillars may be active for at least 5-6 weeks following. Susceptible hosts whose leaves are fed on by this insect include oak, birch, ash, maple, elm, poplar, and basswood. This native insect has many natural enemies, including some very effective pathogens that typically regulate populations. However, outbreaks of this insect can occur on occasion.

• Hemlock Borer: Phaenops (Melanophila) fulvoguttata is in the Family Buprestidae (jewel beetles, flatheaded borers). The hemlock borer belongs to the genus Phaenops whose northeastern species are different enough that they can be relatively easily separated by their coloration and pronotal and elytral sculpturing. As such, it is easier to identify adult beetles by photograph (without observing a specimen with a dissecting microscope and looking at specific features with a dichotomous key). 15 species are known to this genus in North America, and five of those have been recorded in the northeast. Coniferous hosts are the only known larval hosts for this genus, and in the case of P. fulvoguttata, the larvae have been recorded from balsam fir, American larch, white spruce, black spruce, red spruce, eastern white pine, and eastern hemlock. The hemlock borer is considered “infrequently collected”. This native species is likely a secondary pest or decomposer, and not the primary cause of decline in its hosts. 

• 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 late May or early June. (L. fiscellaria caterpillars may be active between 448-707 GDD’s.) Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary. Hemlock loopers have several effective natural enemies.

• Hydrangea Leaftier: Olethreutes ferriferana is a moth in the Family Tortricidae whose caterpillars use silk applied to the edges of two newly expanding hydrangea leaves to tie them together to create an envelope-like structure within which they feed. These leaf-envelopes tend to occur near the tips of plant stems and can be very obvious. As a result, the two tied leaves may not fully expand when compared to healthy, non-impacted leaves. Hydrangea leaftier activity was seen on 5/15/2022 in Pittsfield, MA. Many envelope or purse-like structures were seen throughout the plants and could be found from the base to the top of the plant. By gently pulling apart the tied-together leaves, tiny caterpillars were revealed within and able to be mechanically managed by crushing the individual caterpillars.

Caterpillars are green and partially transparent with a black head capsule and a black thoracic shield which is found on the top of the body segment located directly behind the head. Pupation is thought to occur in the ground nearby host plants, so the insect drops to the ground to pupate where it overwinters. Pupation occurs sometime in June. Adults are found in the spring and are small white and brown moths. Eggs are laid on branch tips of various species of hydrangea. Only one generation is known per year. This insect, although creating visible and interesting damage to hydrangea, is not usually considered to be a serious pest – although occasional localized problematic populations have been reported. Removing leaf-envelopes in the early spring or pinching them to kill the caterpillar within can help reduce populations on individual plants.

• Imported Willow Leaf Beetle: Plagiodera versicolora adult beetles overwinter near susceptible hosts. Adult beetles will chew holes and notches in the leaves of willow once they become available. Females lay yellow eggs in clusters on the undersides of leaves. Larvae are slug-like and bluish-green in color. They will feed in clusters and skeletonize the leaves. Most plants can tolerate multiple years of feeding from this insect, and foliage will appear brown. Repeated yearly feeding can occasionally be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water. 

Check out Episode 4 of InsectXaminer to see the imported willow leaf beetle in action: https://ag.umass.edu/landscape/education-events/insectxaminer

• Lacebugs: Stephanitis spp. lacebugs such as S. pyriodes can cause severe injury to azalea foliage. S. rhododendri can be common on rhododendron and mountain laurel. S. takeyai has been found developing on Japanese andromeda, leucothoe, styrax, and willow. Stephanitis spp. lace bug activity should be monitored through September. Before populations become too large, treat with a summer rate horticultural oil spray as needed. Be sure to target the undersides of the foliage in order to get proper coverage of the insects. Certain azalea and andromeda cultivars may be less preferred by lace bugs.

• Lecanium Scales (Oak): Parthenolecanium quercifex overwinters as a second instar nymph on oak twigs. Females will begin feeding and mature in the spring, from mid-April to early May and eggs may be laid between late May and into June. Eggs hatch in June or early July and crawlers migrate to host plant leaves where they spend the summer and migrate as second instars back to host plant twigs in the fall. 

• Lilac Borer: Podosesia syringae is a clearwing moth pest of lilac, privet, fringetree, and ash. (It is also known as the ash borer, not to be confused with the emerald ash borer.) Adults mimic paper wasps. Larvae are wood-boring, and signs and symptoms include branch dieback, holes, and occasionally, sawdust-like frass accumulated on bark. Larvae bore into stems, trunks, and branches, chewing an irregularly shaped entrance hole. Peak adult moth flights may occur in the northern portion of this insect’s range in June and are usually over by August 1st. Pheromone traps can be used to time adult emergence. Adult females lay flattened, oval, and tan eggs that are deposited singly or in clusters on bark crevices, ridges, and sometimes smooth bark; but usually laid in or near wounds in the bark. On average, 395 eggs are laid by each female. After hatch, larvae chew into the bark and feed laterally and then vertically in phloem tissue. Larvae overwinter in tunnels in the final instar and resume feeding in the spring. Adults emerge through a round exit hole (4-5 mm. in diameter). This insect may be targeted between 200-299 GDD’s, base 50°F.

• Magnolia Scale: Neolecanium cornuparvum overwinters as first instar nymphs which are elliptical, and dark slate gray in color and can usually be found on the undersides of 1 and 2 year old twigs. Nymphs may molt by late April or May and again by early June at which time the scales may be purple in color. Eventually nymphs secrete a white powdery layer of wax over their bodies. 

• Rhododendron Borer: Synanthedon rhododendri is one of the smallest of the native clearwing moths. Rhododendrons are preferred hosts, although mountain laurel, and deciduous azaleas can be heavily infested, especially if they are planted in close proximity to rhododendrons. Injury may be first noticed in the fall (leaves lose their sheen, then become pale green, then olive, then chlorotic) and can look similar to drought stress. On branches that seem to be stunted, look at limb crotches, scars, and other irregularities for sawdust stuck on bark or on the ground beneath these areas. In late May and early June, holes may contain pupal shed skins extending halfway out. Moth emergence occurs in the late-spring, early-summer. After mating, female moths seek out suitable egg laying locations (preferring wounded areas or limb crotches). The female lays her eggs and dies. Eggs hatch and larvae tunnel into the inner bark where they feed in tunnels that become packed with reddish frass pellets. By late fall, larvae move to the sapwood where they overwinter and resume feeding by mid-March. Pupation occurs in the spring and there is one generation per year. Prune out and destroy infested branches before late May/June.
• 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. Caterpillars may feed until roughly mid-June, at which time they will pupate. Management options include an insecticidal soap spray or a product containing spinosad.

• Spruce Spider Mite: Oligonychus ununguis is a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir, and occasionally other conifers. This particular species becomes active in the spring and can feed, develop, and reproduce through roughly June. When hot, dry summer conditions begin, this spider mite will enter a summer-time dormant period (aestivation) until cooler temperatures return in the fall. This particular mite may prefer older needles to newer ones for food. Magnification is required to view spruce spider mite eggs. Tapping host plant branches over white paper may be a useful tool when scouting for spider mite presence. (View with a hand lens.) Spider mite damage may appear on host plant needles as yellow stippling and occasionally fine silk webbing is visible. Be sure to also scout for predatory mite adults and eggs which can help regulate spruce spider mite populations. Avoid broad spectrum chemical management options that kill predatory mite populations, often making spruce spider mite outbreaks worse.

• Taxus Mealybug: Dysmicoccus wistariae 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. Taxus mealybug feeds in the inner bark tissue of the trunk and branches. Adult females are present from June to August and give birth to living young in the summer. Immatures overwinter. A single generation may occur per year in New England, but areas to the south can have multiple generations of this insect. Management may be targeted between 246-618 GDD’s, base 50°F. Horticultural oil and neem oil may be used.

• Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. This beetle feeds exclusively on many different species of viburnum, which includes, but is not limited to, susceptible plants such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum. 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 can emerge in late May throughout July, depending on local temperatures. 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 above for more information about that non-native insect.

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 .

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

Weeds

Do not attempt to control Japanese knotweed, Polygonum cuspidatum, as herbicide applications are not effective when applied in the early part of the growing season. In preparation for a late season herbicide application, cut or mow stands of knotweed to the ground in late May and early June. This practice is done to facilitate herbicide application by removing the dried stems from the previous year’s growth and will control plant height so knotweed will be shorter at time of treatment in late summer. There is also some indication that the plant’s carbohydrate reserves may be reduced with this early season mowing.

Many landscape trees commonly produce vegetative suckers at their trunk base. Suckers are commonly seen on crabapple, flowering cherry, flowering pear, plum, linden, maple and sometimes oak. Honeylocust commonly produces vegetative sprouts along the entire length of their truck. If these suckers or sprouts are not controlled the landscape will look very shabby and untended. Pruning is effective but very time consuming and not effective in the long run. Another option would be to use the product Scythe that contains pelargonic acid to remove these vegetative suckers and sprouts when they are very small, meaning less than one inch in length. Pelargonic acid is a contact herbicide. If Scythe is applied to small suckers and sprouts the product will desiccate them and physical removal will not be required. Larger growth will first need to be physically removed and then Scythe can be used as a maintenance program. Products that contain glyphosate should not be used as glyphosate is a translocated/systemic herbicide and whole tree injury is possible.

Poison ivy can be treated now. Glyphosate or triclopyr are the best herbicides for poison ivy control. Triclopyr products should be selected over glyphosate products in areas where grasses need to be saved. Contact (Scythe, Reward) or the non-chemical/organic herbicide products will provide “burndown” activity only and will not adequately control poison ivy.

A comment about the use of spray surfactants with herbicide applications. The rule is: “If an herbicide requires the addition of a surfactant then one should be added per the label; if a surfactant is not required then one should not be added”. If a required surfactant is not used the efficacy can be significantly decreased to the point that the herbicide might not work. If a surfactant is added that is not needed herbicide selectivity can be decreased leading to the possibility of injury or death of normally tolerant plants.

Summer annual grass and broadleaf weeds are becoming increasingly more apparent in mulched landscape beds. Most summer annuals have germinated and are getting larger with the warmer weather. Some weeds have become sizable and spraying them will result in unsightly dead vegetation, so hand weeding may be necessary. However, spot spraying with a non-selective herbicide is usually a better strategy than hand-weeding because it does not break the mulch barrier unless the plant is clipped below the stem base. Determination on a site-by-site basis will be needed to select the best strategy. Inspect the mulch layer to ensure that it is thick enough to control future weed problems.

Do not delay, treat garlic mustard, Alliaria petiolata, now. Plants have matured to a point where seedpods have formed and the seeds are now mature. Plants with mature seedpods will need to be physically removed from the site. First year plants can still be treated with an herbicide.

Reported by Randy Prostak, Weed Specialist, UMass Extension Landscape, Nursery and Urban Forestry Program

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Diagnostic Services

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

Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The lab provides test results and recommendations that lead to the wise and economical use of soils and soil amendments. For more information, including current turn-around times, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. The lab is currently accepting new orders for Routine Soil Analysis (including optional Organic Matter, Soluble Salts, and Nitrate testing), Particle Size Analysis, Pre-Sidedress Nitrate (PSNT), and Soilless Media (no other types of soil analyses available at this time). Turnaround time: Please plan for the fact that date of receipt in the lab is affected by weekends, holidays, shipping time, and time for UMass Campus Mail to deliver samples to the lab.

Tick Testing - The UMass Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing options at: https://ag.umass.edu/resources/tick-testing-resources.

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