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Landscape Message: May 31, 2019

May 31, 2019
Issue: 
10

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 7. 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 May 29, 2019. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2019 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

2019 Total

Sun

Shade

CAPE

72

202

59

57

0.59

12:00 PM 5/29

SOUTHEAST

71.5

238.5

60

54

0.68

12:45 PM 5/29

NORTH SHORE

63.5

243

57

51

0.39

9:30 AM 5/29

EAST

79

286

59

54

0.91

3:00 PM 5/29

METRO

81

260.5

54

52

0.93

5:45 AM 5/29

CENTRAL

67

271.5

50

46

0.73

7:30 AM 5/29

PIONEER VALLEY

74

293

62

56

1.24

9:00 AM 5/30

BERKSHIRES

63.5

256

59

54

1.60

9:30 AM 5/29

AVERAGE

71

256

58

53

0.88

-

n/a = information not available

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.

Weigela florida (old fashioned Weigela)

*

*

*

*

*

Begin

Begin/Full

*

Deutzia spp. (Deutzia species)

Begin

Full

Begin/Full

Begin

*

Begin

Begin/Full

Begin

Enkianthus campanulatus (redvein Enkianthus)

*

Full

Full

Begin/Full

Begin/Full

Begin/Full

Full

Begin/Full

Rhododendron carolinianum (Carolina Rhododendron)

Full

Full

Full

Full

Full

Full

Full

Full

Aesculus hippocastanum (common horsechestnut)

Full

Full

Full

Full

Full

Full

Full

Full

Rhododendron catawbiense (Catawba Rhododendron)

Begin/Full

Full

Full

Begin/Full

Full

Full

Full

Full

Elaeagnus umbellata (autumn olive)

Full

Full

Full

Full

Full

Full

Full

Begin/Full

Spiraea x vanhouttei (Vanhoutte Spirea)

Full

Full

Full

*

*

Begin/Full

Full

Full

Rhododendron spp. (early azaleas)

End

Full/End

Full/End

Full/End

Full/End

Full/End

End

Full

Syringa vulgaris (common lilac)

Full/End

Full/End

Full/ End

End

Full/End

End

End

Full

* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature from May 22 – 29 was 59˚F, with a low of 44˚F on May 25 and a high of 78˚F on May 26. During the period, 0.59 inches of precipitation fell primarily during the night of May 28. Weather was conducive for outside work. Topsoil and subsoil moisture are adequate. Soil temperatures remain cool.

Pests/Problems: Winter moth is still feeding on susceptible hosts – no defoliation expected. Lecanium scale, which is fairly widespread on the Cape, is becoming more noticeable. Over the weekend, honeydew could be seen glistening on the understory beneath infested oaks. If you see honeydew or sooty mold check nearby trees for the presence of lecanium scale - a large soft scale that can be found on the twigs of oaks and many other tree species. Other insect pests or damage seen this past week include Viburnum leaf beetle feeding on V. dentatum, Hydrangea leaf tier on H. arborescens, boxwood psyllid on boxwood, boxwood leafminer on boxwood, rose slug sawfly (adults, presumably laying eggs) on rose, and lily leaf beetle on Asiatic lily. Disease symptoms or signs seen over the past week include brown rot on Prunus spp, anthracnose on sycamore, anthracnose on dogwood, Volutella on boxwood, Iris leaf spot on Iris, and winter burn on white pine and Rhododendron. Weeds in bloom include mouse ear chickweed (Cerastium vulgatum), yellow rocket (Barbarea vulgaris), black medic (Medicago lupulina), cypress spurge (Euphorbia cyparissias), and cinquefoil (Potentilla simplex). Slugs are actively causing damage to bearded Iris and Hosta. Be vigilant and protect yourself from ticks!

Southeast Region (New Bedford)

General Conditions: What a beautiful weekend! The weather warmed up for the Memorial Day Holiday - with many folks planting their annuals and vegetable gardens. The high temperature reached 82˚F. The low dropped to 40˚F in the evening and cooler temperatures are back for the beginning of this week. On reporting day it’s overcast and chilly in the high 50’s - what a difference from the weekend. Many of the Syringa have passed peak bloom with the heat and Cornus florida is also dropping petals. The Rhododendrons are coming into their own with beautiful blossoms. The gardens as well as the forests look lush from all the spring rains. The winds were high this week so areas yet to be mulched have dried out a bit and may need supplemental water already. Alliums are in full bloom but the last of the late season tulips and daffodils have passed here in New Bedford. Our Hydrangeas are beginning to bud up nicely, while Hostas have fully leafed out and many Iris spp. are blooming. Phlox divaricata, Tiarella cordifolia, Geranium maculatum, and Cypripedium parviflorum are blooming in our woodland gardens.

Pests/Problems: Slug damage has been spotted in the Hosta and Woodland Garden plants. Tent caterpillars are present on Prunus spp. Garlic mustard, cress, and creeping fig are going to seed. Groundhogs, rabbits, mosquitos, and deer are active in the gardens. Many grubs have been noted in gardens and lawns. There is no sign of winter moth but see the insect section for further details.

Attention Southeast region readers: Would you be a good scout for the Landscape Message? UMass Extension is seeking a capable individual to take over reporting duties for the Southeast region starting ASAP. Candidates must be able to scout and report weekly through June, bi-weekly through July, August, and September, and monthly in October, November, and December. Ideally this person would be located in roughly the Brockton-Bridgewater-Taunton area (or able to regularly scout that area), although we will entertain inquiries from throughout Bristol and Plymouth Counties. The scouting and reporting for each message is estimated to take approximately 1/2 day per message week, and UMass Extension is able to pay a stipend for scouts. If interested, see the "Description of Responsibilities" here:  https://ag.umass.edu/sites/ag.umass.edu/files/content-files/alerts-messages/2018_scout_expectations.pdf  then contact Ellen Weeks at weeks@umass.edu or 413-545-2685 to apply.

North Shore (Beverly)

General Conditions: The weather during this reporting period was variable. The first two days of this period were nice, sunny, late spring days with day temperatures in the high 60s. Memorial Day weekend was very pleasant with sunny skies and day temperatures in the low to mid 70s. The highest day temperature was recorded on Sunday when the temperature climbed to 84 degrees Fahrenheit with bright sunny skies. The weather conditions changed on Tuesday and Wednesday (May 28 and 29) to cloudy and rainy days with highest temperatures at 58˚F. Night temperatures during this period were mostly in the mid - 40s to mid - 50s. Approximately 0.39 inches of rain was recorded at Long Hill. Many plants were in bloom during this period and for most plants the flower display has been very spectacular this year. Many azaleas and Rhododendrons were in full bloom. Other woody plants seen in full bloom include: common horse chestnut (Aesculus hippocastanum), Constellation® Rutgers flowering dogwood (Cornus x rutgersensis), handkerchief tree (Davidia involucrata var. vilmoriniana), common lilac (Syringa vulgaris), doublefile Viburnum (Viburnum plicatum var. tomentosum), slender Deutzia (Deutzia gracilis), Wisteria (Wisteria floribunda), Wright Viburnum (Viburnum wrightii), little leaf lilac (Syringa microphylla), Siberian pea tree (Caragana arborescens), silver bell (Halesia carolina), umbrella tree (Magnolia tripetala) and tree peony (Paeonia suffruticosa). Herbaceous plants in bloom include: Solomon’s seal (Polygonatum odoratum), honesty plant (Lunaria annua), yellow archangel (Lamiastrum galeobdolon), Vinca vine (Vinca major), water forget-me-not (Myosotis palustris), barrenwort (Epimedium rubrum), Trillium (Trillium spp.), Corydalis (Corydalis lutea), bleeding heart (Dicentra spectabilis), Father Hugo rose (Rosa hugonis) and fetterbush (Leucothoe fontanesiana).

Pests/Problems: Leaf and flower gall disease (Exobasidium vaccinii) was observed in azalea. The fungus causes cells in leaf and flower tissue to multiply rapidly forming large fleshy galls. The disease can be controlled by hand picking the galls and burning or burying them. To prevent new infections, pick the galls before the white spore layer appears. Cedar apple rust (Gymnosporangium juniperi-virginianae) galls with orange gelatinous telial horns were also observed on cedar. This fungus attacks crabapples and apples(Malus spp.) and eastern red cedar (Juniper). Remove galls from the juniper before the telial horns form to prevent the spores from moving to crab apple or apple trees nearby. The larvae of Viburnum leaf beetle (Pyrrhalta viburni) are getting larger and starting to cause damage on the leaves of susceptible Viburnum cultivars. (See Insect Report below.) Dandelion (Taraxacum officinale) seeds are maturing and being blown over the landscape by wind. Other spring weeds seen in bloom include: violets (Viola spp.), ground ivy (Glechoma hederacea), garlic mustard (Alliaria petiolata) and dead nettle (Lamium purpureum). Take measures to control weeds before they set seed. Mosquitoes and ticks are very active so protect yourself with repellents when working outdoors.

Leaf and flower gall disease of azalea. Leaf and flower gall disease of azalea 2. Cedar apple rust gall with telial horns on cedar. Cedar apple rust gall with telial horns on cedar.

East Region (Boston)

General Conditions: Temperatures varied over the past week. We had several warm days before a return to cool damp conditions. We had a high temperature of 86˚F on the 26th and a low of 46˚F on the 25th. We received 0.91” of precipitation. We received 79 GDDs bringing us to 286 (base 50˚F) for the year. Azaleas, Rhododendrons, Spirea and Viburnum are adding color to the landscape. Soils are adequately moist. Pollinators are active.

Pests/Problems: Viburnum leaf beetle larvae continue defoliating susceptible Viburnum. Boxwood mite and psyllid are active. Slugs are abundant on herbaceous vegetation. Annual and perennial weeds are thriving.

Metro West (Acton)

General Conditions: At last, we experienced a gorgeous weekend to enjoy the outdoors and it was a 3-day holiday at that! The temperatures rose into the 80’s with the highest temperature of 87°F recorded for this week on the 26th and the lowest temperature recorded was 43°F on the 24th. The average monthly rainfall for May is 4.04” and as of the 28th, I have recorded 3.72” of rain. Much is in bloom at this time of the year, including the following woody plants: Aesculus hippocastanum (horsechestnut), Cercis canadensis ‘Alba”(white flowering redbud), Cornus florida (dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers hybrid dogwood), Cornus sericea (red twig dogwood), Crataegus spp. (hawthorn), Daphne x burkwoodii 'Carol Mackie' (Daphne), Ilex aquifolium (English holly), Kerria japonica (Japanese Kerria), Laburnum x watereri (golden chain tree), Leucothoe axillaris (coast leucothoe), Magnolia 'Elizabeth' (Elizabeth Magnolia), Prunus spp. [cherry, including P. japonica (flowering almond) and P. serotina (black cherry)], Rhododendron spp. (Rhododendron/azalea), Sorbus aucuparia (European Mountain Ash), Spiraea spp. (bridal wreath), Syringa spp. (mid-late blooming lilac), Viburnum plicatum var. tomentosum (doublefile Viburnum), and V. sargentii (Sargent Viburnum). Woody vines in bloom are: Aristolochia macrophylla (Dutchman’s pipe) and Wisteria spp. (Wisteria).

Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Ajuga reptans (bugleweed), Allium spp. [ornamental flowering onion, including A. schoenoprasum (chives)], Amsonia hubrichtii (Arkansas blue star), Aquilegia vulgaris (columbine), Aurinia saxatilis (basket of gold), Camassia scilloides (wild Hyacinth), Chrysogonum virginianum (green and gold), Convallaria majalis (lily of the valley), Cypripedium parviflorum (yellow lady's slipper), Dianthus deltoides (maiden pink), Dicentra eximia (fringed bleeding heart), D. spectabilis (old fashioned bleeding heart), D. spectabilis 'Alba' (white flowering old fashioned bleeding heart), Dictamnus albus (gas plant), Gallium odorata (sweet woodruff), Geranium maculatum (wild geranium), G. macrorrhizum (bigroot geranium), G. sanguineum ( bloody cranesbill), Hyacinthoides hispanica (wood hyacinth), Iberis sempervirens (evergreen candytuft), Iris cristata (crested iris), I. germanica (bearded Iris), I. sibirica (Siberian Iris), Linaria annua (money plant), Muscari sp. (grape Hyacinth), Myosotis sylvatica (woodland forget-me-not), Narcissus spp. (daffodil), Nepeta spp. (ornamental catmint), Papaver orientale (Oriental poppy), Phlox x subulata (moss phlox), P. divaricata (Canadian Phlox), P. stolonifera (Creeping Phlox), Podophyllum peltatum (Mayapple), Polemonium reptans (Jacob’s ladder), Polygonatum commutatum (great Solomon’s seal), P. odoratum 'Variegatum' (variegated Solomon’s seal), Salvia nemerosa (Salvia), Stylophorum diphyllum (wood poppy), Tiarella cordifolia (foam flower), Veronica umbrosa 'Georgia Blue' (speedwell), Vinca minor (periwinkle), Viola spp. (violet), and Waldsteinia ternata (barren strawberry).

Pests/Problems: Soils are well saturated and ideal for planting and weeding. A few of our most invasive weeds are in flower including: Alliaria petiolata (garlic mustard), Elaeagnus umbellata (autumn-olive), and Euonymous alatus (burning bush). Ticks, mosquitoes and black flies are feeding and active.

Central Region (Boylston)

General Conditions: We had a gorgeous holiday weekend here in Central Massachusetts, with temperatures well into the 80’s on Sunday, and just ¾ inch of rainfall this week. What a week for Rhododendrons! While the lilacs have largely finished up for the season, large-leaved Rhododendrons like R. catawbiense burst into bloom with the warmer temperatures. Shrubs like Deutzia gracilis (slender Deutzia), Cornus sericea (red-twig dogwood), Weigela florida (old-fashioned Weigela), and Syringa meyeri (Meyer lilac) began flowering this week. Small trees like Magnolia sieboldii (Oyama magnolia) and Crataegus viridis ‘Winter King’ (green hawthorn) are flowering nicely, but perennials are really starting to shine in the garden. Geranium macrorrhizum (rock cranesbill), Camassia leichtlinii (great camas), Baptisia australis (blue false indigo), Ajuga reptans (bugleweed), Zizia aptera (heart-leaved golden alexanders), and Polygonatum spp. (Solomon’s seal) are putting on quite a show.

Pests/Problems: Nothing new to report this week. Gypsy moth appear to be slow to size up this spring, and as a result we are seeing less damage, even on trees that haven’t received treatment in previous years. Slugs are active, ticks are out in force.

Magnolia sieboldii, Oyama magnolia Magnolia x wieseneri 'Aashild Kalleberg', Aashild Kalleberg magnolia Geranium macrorrhizum, rock cranesbill Hydrangea anomala petiolaris, climbing hydrangea Paxistima canbyi 'Compacta', cliff green
Rhododendron 'Narcissiflorum', hybrid azalea Zizia aptera, heart-leaved golden alexandersBaptisia sphaerocarpa 'Screamin' Yellow' Cornus sericea 'Bailey', red-twig dogwoodPterostyrax corymbosus, little epaulette tree

Pioneer Valley Region (Amherst)

General Conditions: We experienced some incredible late spring weather in the Pioneer Valley over this past week. High temperatures ranged from 62°F to 87°F while low temperatures spanned from 43°F to 56°F. The majority of days in this reporting period boasted bright sun and temperatures in the 70s and 80s. However, as is spring, conditions were unsettled at times with strong and persistent winds on 5/22 and 5/23, continuing the trend from our previous report. We also received over an inch of rain from scattered storms on 5/23-24 and 5/28. None of the rain events provided any deep watering but were sufficient for lawns and herbaceous perennials. The mercury steadily climbed from 5/23 to 5/27, peaking at a summer-like 87°F in Easthampton. After a near-perfect Memorial Day weekend, we got a respite from the heat and sun with cool and rainy days on 5/28 and 5/29. The cool-down was nice for transplants still adjusting to their new locations. New growth continues at a steady rate with shoots elongating and leaves continuing to expand and harden off. Overall, managed landscapes and forests are lush and green. Closely monitor soil moisture for transplanted trees and shrubs now that temperatures are exceeding 80°F. Pay particular attention to trees and shrubs with undersized root balls and conifers with dense canopies that can shield rainfall from soaking the root zone. Under most landscape settings, a once-weekly soaking of the roots is sufficient for woody plants. If it’s particularly hot and dry this summer, twice-weekly may be warranted. Avoid light, daily watering, which only saturates the uppermost soil layer. Rhododendrons, azaleas, Spirea, hawthorn, kousa dogwood and Viburnums are providing beautiful late spring color at this time. The neon green shoots and needles of hemlock, white fir, arborvitae, and false cypress are abundant too. Crabgrass is now clearly visible in untreated lawns with its bluish-green hue. Last year, it grew to mower-clogging heights and thickness with all the mid- and late-summer rainfall, creating a plentiful seed bank for this year.

Pests/Problems: If you’ve waited to remove large Rhododendrons badly injured from last winter’s weather, you might be rewarded for your patience. Look closely at the base of the main trunk and primary branches and you may find new buds emerging. Aphids and eriophyid mites are abundant now on a variety of trees and shrubs. Woolly aphids were observed on elm and larch. Now that white pine candles are elongated and needles are pushing out, new symptoms of white pine needle blights are appearing on landscape and forest trees. Needle browning and shedding has been observed throughout the area. While the decline of eastern white pine has generated a lot of attention, and deservedly so, there’s been a related increase in needle blight pathogens on hard pines due to the overwhelming amount of inoculum. Most of the primary needle blight pathogens that attack eastern white pine, such as Lecanosticta and Septorioides, can also infect hard pines such as Austrian and mugo. Furthermore, these fungi can also cause problems for lesser-common soft pines in the landscape, like Korean and limber pines. During this period of peak needle shedding, any rainfall event, no matter the total accumulation, facilitates spore production, dispersal and infection of newly developing white pine needles. Gypsy moth feeding continues but damage remains light at this time. Scattered pockets of building defoliation can be found but injury has been slow to develop this season.

Berkshire Region (Great Barrington)

General Conditions: Moist conditions persist as at least some rain fell on 5 of the 7 days from May 23 to May 29. Rainfall for the year is about an inch above normal and slightly below last year’s level at this time. Soil moisture remains high. This has been a problem for those sowing seeds of vegetables and annuals but has been somewhat ideal for planting perennials and woody plants as no watering of the plants has been necessary. Even on the sunniest days only the surface of the soil has dried. Well drained soils are workable but heavy soils have enough moisture to form clods when tilled. Also, recommendations for restricted traffic on turfgrass remain in place due to the high soil moisture levels. Temperatures during the period ranged from a low of 45˚F on the morning of May 25 to a high of 81˚F early in the afternoon of the following day. Turfgrass growth has been rapid and lawns are lush but no disease has been observed. The moist and somewhat cool conditions have extended the bloom period for many flowering trees and shrubs. That is good news for many but no so for sufferers of pollen allergies. This has been one of the worst pollen seasons in several years.

Pests/Problems: For the first time this season, gypsy moth caterpillars were observed on oaks. The caterpillars are in their early stages and can be recognized at this point by a row of orange spots down the back. Older caterpillars have pairs of blue and red dots down the back. Also found for the first time this spring was sawfly caterpillars on foliage of river birch. Willow leaf beetle (adults), Viburnum leaf beetle (larvae), Eastern tent caterpillars and boxwood leafminer (pupal stage) remain active. Diseases observed included fire blight on sand cherry, anthracnose of mountain laurel, Weir’s cushion rust on spruce, cedar-apple rust and apple scab on crabapples, and wilting shoots of ‘Black Lace’ Sambucus. Leaf gall have appeared on foliage of oaks. Formation of the galls is stimulated by egg laying of midges or wasps. There are many types of galls. Winter related death of branches, evergreen foliage, and in some cases, death of entire plants continues to be observed in varied landscapes.

Regional Scouting Credits

  • CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
  • SOUTHEAST REGION - Kristin McCullin, Horticulturist reporting from Haskell Public Gardens, New Bedford.
  • 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 Tower Hill Botanic Garden, Boylston.
  • PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
  • BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals

Diseases

Recent pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab https://ag.umass.edu/services/plant-diagnostics-laboratory:

Dark-colored spots and blotches caused by rose downy mildew (Peronospora sparsa). Dark-colored spots and blotches caused by rose downy mildew (Peronospora sparsa). Rose downy mildew, caused by Peronospora sparsa, on container roses (Rosa spp.). A large number of plants, representing several cultivars, were purchased for retail and developed symptoms shortly after arriving. Rose downy mildew thrives under cool and humid weather, when high temperatures reach the low to mid-60s and relative humidity exceeds 85%. Dark-colored spots and blotches appear on the upper surface of the foliage (see photos) while a grey-colored, fuzzy mass of spores develops on the underside (abaxial surface). When disease severity is high, plants can shed a large majority of leaves. In addition to Rosa, the pathogen can also infect Rubus (raspberries/brambles) and spores can remain viable on dried and discarded leaves for up to one month.

Undersized, distorted and collapsed foliage caused by oak anthracnose (Apiognomonia errabunda). Oak anthracnose, caused by Apiognomonia errabunda, on swamp white oak (Quercus bicolor). The tree is approximately 12-years-old and has been present at the site for less than five years. This spring, dark-colored spots and blotches developed on emerging foliage in the middle and lower canopy leading to distortion and collapse of some leaves (see photo). The tree resides in a managed landscape with full sun and overhead lawn irrigation. Oak anthracnose is widespread but damage is often minor on established trees. However, in some cases the disease can result in a serious foliar blight. White oaks are most susceptible to infection, but red oaks can be infected by the pathogen. While finding ways to control anthracnose diseases can be difficult at times, in this case the overhead watering should cease immediately.

Brown rot, caused by Monilinia fructicola, on Okame flowering cherry (Prunus x incam ′Okame′). The tree is 20-years-old and has been present at the site for six years. Over the past five years, symptoms of brown rot have developed each spring. Symptoms include browning and premature shedding of flowers and leaves and the presence of stem lesions. Drainage at the site is poor but the tree receives full sun. Despite active management, the disease continues to appear each season. Like black knot, brown rot can be a pervasive and persistent disease of Prunus that can continue to develop despite regular fungicide treatment.

Maple anthracnose, caused by Discula campestris, and secondary stem cankering on sugar maple (Acer saccharum). Tree is roughly 40-years-old and was planted over 30 years ago. Over the past few years, canopy dieback has worsened within the middle and upper 1/3 of the tree. Typical anthracnose symptoms were present on the submitted foliage and the pathogen was found readily sporulating. In addition to anthracnose, the fungal pathogen Steganosporium was also abundant on blighted stems and small branches. Considered a weak pathogen, the fungus can be readily found on declining sugar maples as an opportunist. It produces black-colored spore masses that can often be readily observed on blighted stems and branches.

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 may still be seen feeding on oak in Amherst, MA on 5/30/19.  (Tawny Simisky, UMass Extension) Gypsy moth caterpillars can be seen resting on the trunk of a young oak in Amherst, MA as observed on 5/30/19. These caterpillars have begun to develop the “warts” on their dorsal side which will turn into the 5 pairs of blue followed by 6 pairs of red raised spots that are distinctly visible in 4th instar and older caterpillars. (Tawny Simisky, UMass Extension) Gypsy Moth:(Lymantria dispar) host plants include but are certainly not limited to oak (favored), maple, birch, poplar, and many others. Gypsy moth caterpillars were again observed on elm and oak in Amherst, MA on 5/30/19. Late 2nd instar. Gypsy moth caterpillars were again observed on elm and oak in Amherst, MA on 5/30/19. Late 2nd instar caterpillars were seen feeding on leaves, while 3rd instar caterpillars were again seen resting on areas of the trunk. During the day, 2nd instar caterpillars can be found feeding on the leaves of susceptible hosts, while the 3rd instar caterpillars may be seen (if local populations are in relatively low densities) gathered in groups on areas of the trunk or branches. In high populations, this daytime hiding behavior stops and older caterpillars will still be seen feeding on the leaves. Anecdotally, at this time, gypsy moth caterpillar densities on host plant leaves in certain areas, such as parts of Amherst, are lower than what was expected given the number of overwintering egg masses. While we have had reports of caterpillar activity and feeding across the state, we suspect that an early mortality event (that cannot yet be explained) may have occurred. While this is certainly excellent news, we should remain cautiously optimistic and continue to monitor gypsy moth populations and feeding damage, particularly in the areas mentioned below in the 2018 overwintering egg mass survey conducted by MA DCR.

Gypsy moth caterpillars may be considered in the 4th instar or older when the head capsule becomes yellow in color and mottled with black markings that have been described to look like eye spots. The raised “warts” or bumps on the dorsal or back side of the caterpillar will become the distinctive, familiar colors seen on larger gypsy moth caterpillars. Five pairs of blue warts occur behind the head of the caterpillar, followed by six pairs of red warts or spots. It was recently mentioned to me that a good way to remember the order these colors occur in is to consider the red spots as “tail lights” (hence occurring at the rear end of the caterpillar).

Despite the fungal outbreak that swept through the 2017 caterpillar population, some lucky caterpillars survived to pupation and emerged as adult moths. (However, adults were present in 2017 in far fewer numbers than would have existed without the fungus.) In 2018, the Massachusetts Department of Conservation and Recreation (DCR) reported that approximately 159,705 acres were defoliated by gypsy moth caterpillars in pockets across the state. While this may seem negligible in comparison to the 923,186 acres of defoliation due to gypsy moth in 2017, for many communities the impact was still significant. MA DCR also surveyed multiple locations across the state for overwintering gypsy moth egg masses in December of 2018. They provide a map of their predictions of where pockets of defoliation may occur in 2019 based on the densities of egg masses they observed in monitored areas across the state. Many of these areas correspond with the locations previously defoliated by gypsy moth caterpillars in 2018. MA DCR predicts gypsy moth activity will occur this season in regionalized pockets of Essex, Hampden, Hampshire, Middlesex, Norfolk, Plymouth, and Worcester Counties. Maps of previous year’s defoliation as well as the 2018 overwintering gypsy moth egg mass survey may be found here, courtesy of the MA DCR:  https://www.mass.gov/guides/gypsy-moth-in-massachusetts .

While it is very difficult to predict how much defoliation Massachusetts will see in 2019 due to gypsy moth caterpillar feeding, we can be certain that in areas where many egg masses overwintered, pockets of defoliation could still occur in certain areas of the state this year.

  • Winter Moth: (Operophtera brumata) The winter moth population in eastern Massachusetts continues to be at record lows in most locations, and Dr. Joseph Elkinton, Professor of Environmental Conservation at the University of Massachusetts, is declaring victory over this pest! In case you have missed this news from last year, a recent edition of the UMass Magazine discusses the winter moth story and successes with the biological control of this insect (along with some fun and excellent illustrations): https://www.umass.edu/magazine/spring-2019/winter-moth .

See the Regional Reports above for current updates. Pupation of winter moth caterpillars typically occurs in late May/early June in Massachusetts, depending upon the location. Coastal areas including Cape Cod are usually a week or two behind more inland locations. Upon maturity, winter moth caterpillars will be approximately one inch in length and drop to the soil to pupate. Once pupation occurs, management of winter moth is no longer feasible.

Be sure that management of winter moth is necessary by monitoring for damaging populations before making applications in landscape settings. There may be some locations where winter moth caterpillars can be found while Cyzenis albicans catches up with the population. For more information about the life cycle and management of winter moth, please visit this 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 Ann 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 this fact sheet: Winter Moth in Massachusetts: History and Biological Control https://ag.umass.edu/landscape/fact-sheets/winter-moth-in-massachusetts-history-biological-control .

  • 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.

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 .

  • Deer Tick/Blacklegged Tick: Check out the archived FREE TickTalk with TickReport webinars available here: https://ag.umass.edu/landscape/education-events/webinars . The next live webinar will be held on October 9, 2019 with Dr. Stephen Rich of the UMass Laboratory of Medical Zoology. Previous webinars including information about deer ticks and associated diseases, American dog ticks and lone star ticks and associated diseases, ticks and personal protection, and updates from the Laboratory of Medical Zoology are archived at the link above.

Ixodes scapularis adults have been active all winter, as they typically are from October through May, and “quest” or search for hosts at any point when daytime temperatures are above freezing. Deer tick nymphs (immatures) are also active at this time, and may be encountered now through August. For images of all deer tick life stages, along with an outline of the diseases they carry, visit: http://www.tickencounter.org/tick_identification/deer_tick .

Anyone working in the yard and garden on springtime cleanup and planting 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: http://www.tickencounter.org/prevention/protect_yourself .

Have you just removed an attached tick from yourself or a loved one with a pair of tweezers? If so, consider sending the tick to the UMass Laboratory of Medical Zoology to be tested for disease causing pathogens. To submit a tick to be tested, visit: https://www.tickreport.com/ and click on the blue “Order a TickReport” button. Results are typically available within 3 business days, or less. By the time you make an appointment with your physician following the tick attachment, you may have the results back from TickReport to bring to your physician to aid in a conversation about risk.

The UMass Laboratory of Medical Zoology does not give medical advice, nor are the results of their tests diagnostic of human disease. Transmission of a pathogen from the tick to you is dependent upon how long the tick had been feeding, and each pathogen has its own transmission time. TickReport is an excellent measure of exposure risk for the tick (or ticks) that you send in to be tested. Feel free to print out and share your TickReport with your healthcare provider.

  • Eastern Tent Caterpillar: Malacosoma americanum caterpillars can be seen feeding on susceptible hosts and creating their webs (“tents”). See regional reports above for updates. 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. 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. Crawlers will be present this month and throughout the growing season and the overlap of many developmental stages at any given time can be observed. 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.
  • Emerald Ash Borer: (Agrilus planipennis, EAB) Since the New Year, the Massachusetts Department of Conservation and Recreation has confirmed 26 new community detections of emerald ash borer in Massachusetts. While the cities and towns with recent detections of EAB are too numerous to list here, they are in areas of Berkshire, Hampden, Hampshire, Middlesex, and Worcester counties. A map of these locations and others previously known across the state may be found here: https://ag.umass.edu/fact-sheets/emerald-ash-borer .

This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash, has also been found developing in white fringe tree (Chionanthus virginicus), and has been reported in cultivated olive (Olea europaea). Adult insects of this species will not be present at this time of year. Signs of an EAB infested tree may include (at this time) D-shaped exit holes in the bark (from adult emergence in previous years), “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 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 report here: http://massnrc.org/pests/pestreports.htm .

  • Common spindle tree foliage observed in Amherst, MA on 5/28/2019. Groups of ever larger euonymus caterpillars continue to feed. (Tawny Simisky, UMass Extension) Common spindle tree foliage observed in Amherst, MA on 5/28/2019. Groups of ever larger euonymus caterpillars continue to feed. (Tawny Simisky, UMass Extension) Webbing from the euonymus caterpillar is becoming more extensive on common spindle tree as observed in Amherst, MA on 5/28/2019. (Tawny Simisky, UMass Extension) Webbing from the euonymus caterpillar is becoming more extensive on common spindle tree as observed in Amherst, MA on 5/28/2019. (Tawny Simisky, UMass Extension) 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. Euonymus caterpillars continue to feed and grow in size on European spindle tree foliage in Amherst, MA as observed on 5/28/2019. Caterpillars can be seen webbing foliage together, feeding, and packing that webbing full of their tiny, black frass pellets. As these caterpillars grow in size, so do their webs and entire branches may become defoliated or unsightly. At this particular location, webs are growing in size and beginning to engulf entire small branches.

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.

  • European Pine Sawfly: Neodiprion sertifer caterpillars are active roughly between 78-220 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine, and also on white, Austrian, ponderosa, shortleaf, and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned or plucked out of host plants and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis kurstaki is not effective against sawflies.
  • A forest tent caterpillar observed in Amherst, MA on 5/30/2019 wandering on a young oak. These native caterpillars are at least double the size of gypsy moth caterpillars at this time. (Tawny Simisky, UMass Extension) Forest Tent Caterpillar: Malacosoma disstria caterpillars were observed wandering on oak in Amherst, MA on 5/30/19. Individuals of this native insect may be found feeding alongside gypsy moth caterpillars in the same location. Forest tent caterpillars are at least twice the size of gypsy moth caterpillars in this location, at this time. Forest tent caterpillars are hairy, with black and blue coloration in addition to white, “key-hole” shaped markings along the dorsal side of the caterpillar. (Some also describe these markings as looking like little penguins.) Susceptible hosts whose leaves are fed on by this insect include oak, birch, ash, maple, elm, poplar, and basswood.
  • 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. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary.
  • An adult imported willow leaf beetle feeding as observed in Chesterfield, MA on 5/29/19. The yellow eggs of this species can be seen on the vertically oriented leaf below the beetle. (Tawny Simisky, UMass Extension) Imported Willow Leaf Beetle: Plagiodera versicolora adult beetles overwinter near susceptible hosts. A few adult imported willow leaf beetles were seen feeding on willow foliage in Chesterfield, MA on 5/11/19 and no mating or egg laying was seen at the time.By 5/22/19, it was very easy to spot adult imported willow leaf beetles feeding and mating, as well as the damage they cause to the leaves. Egg laying was also observed on 5/22/19. On 5/29/19, feeding adult beetles and clusters of eggs were still observed. No larvae were yet seen at this particular location. See Regional Reports above for further updates. Adult beetles will chew holes and notches in the leaves of willow. Adult beetles mate and lay eggs through the end of this month. 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 the feeding from this insect, and foliage will appear brown. Repeated yearly feeding can be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water.
  • Bright red, adult lily leaf beetles were found mating on host plant foliage in Amherst, MA as observed on 5/30/19. (Tawny Simisky, UMass Extension) The eggs of the lily leaf beetle may still be seen on host plant foliage in Amherst, MA as observed on 5/30/19. (Tawny Simisky, UMass Extension) The orange-yellow larvae of the lily leaf beetle continue to grow larger in size as found on host plant foliage in Amherst, MA on 5/30/19. (Tawny Simisky, UMass Extension)The larvae of the lily leaf beetle continue to grow larger in size and pile themselves with their own excrement, as found on host plant foliage in Amherst, MA on 5/30/19. (Tawny Simisky, UMass Extension) Lily Leaf Beetle: Lilioceris lilii overwintering adults have been reported by scouts in the Southeast Region previously. Adults overwintered in sheltered places and are now active with warm temperatures and available food sources. Although adult beetles were not seen during the chilly weather on 5/13/19 in Amherst, MA, previously laid eggs were located on host plant foliage in this location. As of 5/21/19, egg hatch had occurred and larvae of various sizes could be seen feeding on foliage in groups. Smaller larvae skeletonize leaves, whereas larger larvae can eat the entire leaf. By 5/30/19, large lily leaf beetle larvae were observed eating entire leaves. Conditions were also favorable to see adults mating, and eggs could also still be found at this location on 5/30. Susceptible hosts include Lilium spp. (Turk’s cap, tiger, Easter, Asiatic, and Oriental lilies) and Fritillaria spp. (Note: daylilies are not hosts.) Typically, in May, mating will occur and each female will begin to lay 250-450 eggs in neat rows on the underside of the foliage. If there are only a few plants in the garden, hand picking and destroying overwintering adults can help reduce local garden-level populations.
  • Snowball Aphid: Neoceruraphis viburnicola becomes active on certain species of Viburnum roughly between 148-298 GDD’s or around redbud bloom. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. Damage caused by this insect pest is mostly aesthetic.
  • Spotted Lanternfly: (Lycorma delicatula, SLF) is not known to occur in Massachusetts landscapes (no established populations are known in MA at this time). However, officials with the Massachusetts Department of Agricultural Resources (MDAR) recently urged residents to check plants for spotted lanternfly. On February 21, 2019 MDAR announced the discovery of a single dead spotted lanternfly adult at a private residence in Boston. As a result of this discovery, officials asked the public to check potted plants they purchase and report any suspicious insects. MDAR reports that this particular individual appeared to have been unintentionally transported this past December in a shipment of poinsettia plants originating from Pennsylvania. Officials also report that there is currently no evidence that this pest has become established in MA. For more information about this finding, please visit the MA Department of Agricultural Resources press release: https://www.mass.gov/news/state-agricultural-officials-urge-residents-to-check-plants-for-spotted-lanternfly .

This insect is a member of the Order Hemiptera (true bugs, cicadas, hoppers, aphids, and others) and the Family Fulgoridae, also known as planthoppers. The spotted lanternfly is a non-native species first detected in the United States in Berks County, Pennsylvania and confirmed on September 22, 2014.

The spotted lanternfly is considered native to China, India, and Vietnam. It has been introduced as a non-native insect to South Korea and Japan, prior to its detection in the United States. In South Korea, it is considered invasive and a pest of grapes and peaches. The spotted lanternfly has been reported from over 70 species of plants, including the following: tree of heaven (Ailanthus altissima, preferred host), apple (Malus spp.), plum, cherry, peach, apricot (Prunus spp.), grape (Vitis spp.), pine (Pinus spp.), pignut hickory (Carya glabra), Sassafras (Sassafras albidum), serviceberry (Amelanchier spp.), slippery elm (Ulmus rubra), tulip poplar (Liriodendron tulipifera), white ash (Fraxinus americana), willow (Salix spp.), American beech (Fagus grandifolia), American linden (Tilia americana), American sycamore (Platanus occidentalis), big-toothed aspen (Populus grandidentata), black birch (Betula lenta), black cherry (Prunus serotina), black gum (Nyssa sylvatica), black walnut (Juglans nigra), dogwood (Cornus spp.), Japanese snowbell (Styrax japonicus), maple (Acer spp.), oak (Quercus spp.), and paper birch (Betula papyrifera).

The adults and immatures of this species damage host plants by feeding on sap from stems, leaves, and the trunks of trees. In the springtime in Pennsylvania (late April - mid-May) nymphs (immatures) are found on smaller plants and vines and new growth of trees and shrubs. Third and fourth instar nymphs migrate to the tree of heaven and are observed feeding on trunks and branches. Trees may be found with sap weeping from the wounds caused by the insect’s feeding. The sugary secretions (excrement) created by this insect may coat the host plant, later leading to the growth of sooty mold. Insects such as wasps, hornets, bees, and ants may also be attracted to the sugary waste created by the lanternflies, or sap weeping from open wounds in the host plant. Host plants have been described as giving off a fermented odor when this insect is present.

Adults are present by the middle of July in Pennsylvania and begin laying eggs by late September and continue laying eggs through late November and even early December in that state. Adults may be found on the trunks of trees such as the tree of heaven or other host plants growing in close proximity to them. Egg masses of this insect are gray in color and, in some ways, look similar to gypsy moth egg masses.

Host plants, bricks, stone, lawn furniture, recreational vehicles, and other smooth surfaces can be inspected for egg masses. Egg masses laid on outdoor residential items such as those listed above may pose the greatest threat for spreading this insect via human aided movement. For more information about the spotted lanternfly, visit this fact sheet: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly

  • 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. When damaging spruce spider mite populations are known from last season, dormant oil applications can be made (when temperatures are appropriate according to label instructions) between 7-121 GDD’s, base 50°F. 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.
  • Clusters of tiny taxus mealybugs can be found feeding on yew hosts in Amherst, MA on 5/30/19. (Tawny Simisky, UMass Extension) Taxus Mealybug: Dysmicoccus wistariae was spotted on Taxus in Amherst on 5/30/19. 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 according to label instructions.

 

 

  • The larvae of the viburnum leaf beetle hard at work defoliating viburnum in Amherst, MA on 5/29/19. (Tawny Simisky, UMass Extension) The larvae of the viburnum leaf beetle skeletonizing a viburnum leaf in Amherst, MA on 5/29/19. At least 7 larvae can be seen on the bottom of this single leaf. (Tawny Simisky, UMass Extension) The larvae of the viburnum leaf beetle skeletonizing viburnum leaves in Amherst, MA on 5/29/19. Eventually, they can defoliate the entire shrub, leaving only leaf mid-veins behind. (Tawny Simisky, UMass Extension)    Eventually, they can defoliate the entire shrub, leaving only leaf mid-veins behind. (Tawny Simisky, UMass Extension) 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 Regional Reports above for updates regarding the activity of this pest. In Amherst, MA on 5/29/19, Viburnum leaf beetle larvae were observed causing significant feeding damage on Viburnum. The population appears high enough to cause complete defoliation of the shrubs in this location. 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. Larvae may be treated with a product containing spinosad once they appear. 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 will be pupating this month and 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.
  • The woolly apple aphids which previously caused rosette-shaped clusters of elm leaves to form are now producing ample amounts of honeydew and cast (shed) “skins” in Amherst, MA as observed on 5/30/19. (Tawny Simisky, UMass Extension) Woolly Apple Aphid: Eriosoma lanigerum may be found on apple, crabapple, hawthorn, mountain-ash, Pyracantha, and elm hosts. The primary (winter) host is elm, on which aphids infest emerging spring leaves, causing leaves to curl or close into stunted, rosette-like clusters found at twig tips. Woolly apple aphid was observed on elm on 5/30/2019 in Amherst, MA. Rosettes at this location are full of honeydew producing aphids. On apple and crabapple, this species of aphid colonizes roots, trunks, and branches in the summer and is commonly found near previous wounds or callous tissue. On roots, the aphids cause swelled areas which can girdle and kill roots. The aphids, when found in above ground plant parts such as elm leaves are covered with white wax. Eggs are the overwintering stage on elm, which hatch in the spring in time for the nymphs to infest new elm foliage. Following a few generations on elm, the aphids will develop into a winged form, which will disperse and seek out apple and crabapple. Multiple generations will occur on these alternate hosts in the summer and by the fall, a winged form will return to elm and mated females will lay eggs near elm buds.
  • Curled leaves surround woolly elm aphids in Amherst, MA as observed on 5/30/19. (Tawny Simisky, UMass Extension)   Opening the curled elm leaves in Amherst, MA on 5/30/19 reveals ample numbers of honeydew-producing woolly elm aphids. (Tawny Simisky, UMass Extension)Woolly Elm Aphid: Eriosoma americanum females lay a single egg in the cracks and crevices of elm bark, where the egg overwinters. Eggs hatch on elm in the spring as leaves are unfolding. A young, wingless female hatched from the egg feeds on the underside of leaf tissue. This female aphid matures and gives birth to 200 young, all females, without mating. These aphids feed, and the elm leaf curls around them and protects them. Curled leaves, due to the activity of the woolly elm aphid, were observed in Amherst, MA on 5/30/19. Opening these curled leaves will reveal ample numbers of honeydew producing aphids within. By the end of June, winged migrants mature and find serviceberry hosts. Another set of females is produced. These new females crawl to and begin feeding on the roots of serviceberry. Multiple generations occur on the roots of serviceberry through the summer.

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 .

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 https://www.tickreport.com/ and click on the blue Order a TickReport button for more information.

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


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