Back to top

Landscape Message: May 20, 2022

May 20, 2022
Issue: 
7

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 May. The next message will be posted on May 27. 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 18, 2022. Total accumulated growing degree days (GDD) represent the heating units above a 50° 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

14

129   (BE=203)

60

56

0.45

12:00 PM 5/18

SOUTHEAST

98.5

195.5

74

59

0.18

3:00 PM 5/18

NORTH SHORE

91

157

61

53

0.15

10:00 AM 5/18

EAST

111

222

71

65

0.13

4:00 PM 5/18

METRO

109

194

61

57

0.14

5:15 AM 5/18

CENTRAL

108

179

57

55

0.36

3:00 PM 5/18

PIONEER VALLEY

107.5

200

63

57

0.59

1:00 PM 5/18

BERKSHIRES

83

153

59

54

1.27

6:30 AM 5/18

AVERAGE

90

163

63

57

0.41

_

* = information not available

As of 5/19, nine of our 14 counties are classified as D0 = 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.

Aesculus hippocastanum (common horsechestnut)

*

Begin

Begin

Begin

Begin

*

Begin

*

Enkianthus campanulatus (redvein enkianthus)

Begin

*

Begin

Begin

Begin/Full

Begin

Begin/Full

Begin

Rhododendron carolinianum (Carolina rhododendron)

Begin

Full

Begin/Full

Begin/Full

Begin/Full

Begin

Begin/Full

*

Rhododendron catawbiense (catawba rhododendron)

Begin

Begin

Full

Begin/Full

Begin/Full

Begin

Full

*

Spiraea x vanhouttei (Vanhoutte spirea)

Begin/Full

Full/End

Full

Full

Full

Full

Full

Begin

Elaeagnus umbellata (autumn-olive)

Begin/Full

Full/End

Full

Full

Full

Full

Full

Begin

Syringa vulgaris (common lilac)

Full

End

Full

Full

Full

Full

Full

Begin/Full

Rhododendron spp. (early azaleas)

Full

Full/End

Full

Full

Full

Full

Full

Full

* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: This period was not like the last, but a complete rebound. The average temperature for the period from May 11 – May 18 was 59ºF with a low of 47ºF on May 11 and a high of 80ºF on May 14. The period was dominated by mostly sunny days. Light precipitation was recorded on May 11, 15 & 16 totaling just under a half inch. Rain is needed, soil moisture is short*. Herbaceous plants seen in bloom during the period include bleeding heart (Dicentra spectabilis, D. eximia), yellow alyssum (Aurinia saxatilis), little merry bells (Uvularia sessilifolia), pink lady’s slipper (Cypripedium acaule), foam flower (Tiarella cordifolia), Solomon’s seal (Polygonatum falcatum), spotted geranium (Geranium maculatum), and bearded iris (Iris x germanica). Woody plants in bloom include crabapple (Malus spp.), redbud (Cercis canadensis), highbush blueberry (Vaccinium corymbosum), black chokeberry, (Aronia melanocarpa), sassafras (Sassafras albidum), beach plum (Prunus maritima) and Japanese cherry ‘Kwanzan’ (Prunus serrulata ‘Kwanzan’). The pollen season has begun with oaks in the red group flowering.

Pests/Problems: Scouting for winter moth has been easier over the period with minor damage seen across a large number of woody species. Caterpillars were approximately 1-1.5cm in length at this time. Winter moth is no longer considered an important forest pest on the Cape nor is it likely to impact the health of ornamentals and thus no longer requires widespread management. Control may be required for fruit bearing apples and blueberries. Other insects or insect damage observed during the period include the start of viburnum leaf beetle feeding on arrowwood viburnum, eastern tent caterpillar on black cherry, damage from boxwood leafminer on boxwood, azalea lacebug damage on azalea, and aphids on sedum. Slugs are active and causing damage to various herbaceous plants. Disease symptoms or signs observed include needlecast on pitch pine (quite noticeable in some areas with dense young pitch pine, leaf spots on rhododendron and red thread on home lawns. Hollys are starting natural leaf drop, this often looks like disease because the leaves rapidly turn yellow and often have spots on them. Weeds and invasive plants in bloom include yellow rocket (Barbarea vulgaris), shepherd's purse, thymeleaf speedwell (Veronica serpyllifolia), garlic mustard (Alliaria petiolata), dandelion (Taraxacum officinale), common violet (Viola sororia), cypress spurge (Euphorbia cyparissias), white clover (Trifolium repens), common cinquefoil (Potentilla simplex), bush honeysuckles (Lonicera tatarica) and autumn olive (Elaeagnus umbellata).

  *updated  Massachusetts | U.S. Drought Monitor (unl.edu)

Southeast Region (Dighton)

General Conditions: The weather has become decidedly warmer, even hot, during the day. Unfortunately there's also been very little in the way of precipitation. Unirrigated soils are drying up. Many herbaceous plants, particularly those on exposed and south facing slopes, are showing midday wilt. Plants observed in flower: Aquilegia spp. (columbine), Allium spp. (ornamental onion), Cornus florida (flowering dogwood), C. sericea (red osier), Fragaria x ananassa (strawberry), Geranium cantabrigiense (prostrate crane's bill), G. maculatum (wild geranium), G. sanguineum (bloody geranium), Hyacinthoides hispanica (wood hyacinth), Iris germanica (bearded iris), I. siberica (siberian iris), Leucanthemum x superbum (shasta daisy), Leucothoe axillaris (dog-laurel), Lupinus spp. (bluebonnet), Lunaria annua (honesty), Nepeta cataria (catnip), Papaver orientale (oriental poppy), Phlox stolonifera (creeping phlox), Polygonatum biflorum (Solomon's seal), Rosa rugosa (beach rose), Trifolium repens (white clover), Vaccinium corymbosum (highbush blueberry), Viburnum plicatum (doublefile viburnum), Viola sororia (common violet), and V. tricolor (wild pansy).

Pests/Problems: It's very dry - category D0 (Abnormally Dry)*. This has been the second week without significant precipitation. Even so, insects are numerous and active. Customers are calling for mosquito control. Non-native, invasive plants in bloom include Ajuga reptans (bugleweed), Convallaria majalis (lily of the valley), Euonymus alatus (burning bush), Hesperis matronalis (dame's rocket), and Lonicera tatarica (bush honeysuckle).            *updated  Massachusetts | U.S. Drought Monitor (unl.edu)

North Shore (Beverly)

General Conditions: Dry weather with clear sunny skies and strong winds persisted most of the days during this period. Very little precipitation was recorded at Long Hill during the last seven days*. Approximately 0.15 inches of rainfall was recorded at Long Hill. There was a shift in temperatures at the beginning of this period from below normal to above normal for this time of the year. Daytime temperatures ranged from low 70s to high 70s and nighttime temperatures ranged from mid 50s to low 60s. The average daily temperature was 64ºF with the highest temperature of 86ºF recorded on May 14 and the lowest temperature of 50ºF recorded on May 13. Many plants are in bloom with a spectacular display of color in the landscape. Woody plants seen in bloom include: silver bell (Halesia carolina), Wright viburnum (Viburnum wrightii), handkerchief or dove tree (Davidia involucrata), hardy orange (Poncirus trifoliata), beach plum (Prunus maritima), large Fothergilla (Fothergilla major), dwarf Fothergilla (Fothergilla gardenii), wisteria (Wisteria floribunda), flowering dogwood (Cornus florida), little leaf lilac (Syringa microphylla), pink shell azalea (Rhododendron vaseyi), royal azalea (R. schlippenbachii), Sargent crabapple (Malus sargentii), tree peony (Paeonia suffruticosa), and highbush blueberry (Vaccinium corymbosum). Herbaceous plants seen in bloom include: honesty plant (Lunaria annua), yellow archangel (Lamiastrum galeobdolon), blue-eyed Mary (Omphalodes verna), Solomon's seal (Polygonatum biflorum), bleeding heart (Dicentra spectabilis), water forget-me-not (Myosotis palustris), red barrenwort (Epimedium x rubrum), bleeding heart (Dicentra spectabilis), rue anemone (Anemonella thalictroides), and fetterbush (Leucothoe fontanesiana).

Pests/Problems: Cedar-apple rust (Gymnosporangium juniperi-virginianae) galls with tentacle-like projections (known as telial “horns) were found on twigs of a young cedar tree. The telial horns release infectious spores (basidiospores) that drift on local air currents, mostly during the night and early morning, to infect the foliage of susceptible apple and crabapple. Do not plant eastern red cedar and juniper plants within a few hundred yards of susceptible apple/crabapple plants. For more information on cedar-apple rust and how to manage it go the following link :https://ag.umass.edu/landscape/fact-sheets/cedar-apple-rust. Ticks and mosquitoes are very active. Make sure you apply repellents before going to work outdoors. Dandelion (Taraxacum officinale) seeds are maturing and are 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.

*updated:  Massachusetts | U.S. drought Monitor (unl.edu)

East Region (Boston)

General Conditions: We went from early spring to mid summer temperatures over the past week. Temperatures averaged 76ºF with a high of 86ºF on May 14th tying a record high for the day set in 1879. Low temperatures averaged 56ºF. We have reached 222 growing degree days, doubling in one week what we had previously gained for the entire 2022 growing season. The canopy has filled in and the landscape is lush and colorful. Plants in bloom include; Aristolochia macrophylla (Dutchman’s pipe), Camassia scilloides (wild hyacinth), Chrysogonum virginianum (green and gold), Deutzia gracilis (deutzia), Geranium maculatum (wild geranium), Hyacinthoides hispanica (wood hyacinth) and Viburnum plicatum var. tomentosum (doublefile viburnum). The beautiful Rhododendron ‘Mist Maiden’ (Rhododendron degronianum ssp. yakushimanum) is flowering. The unusual pink variety of lily of the valley (Convallaria majalis var. rosea) is also flowering.

Pests/Problems: Lack of precipitation and dry soils continue to present challenges*. We received 0.13 inches of precipitation over the past reporting period for a total of 0.48 inches in May. Raised beds, vegetable gardens and new plantings require supplemental irrigation. Viburnum leaf beetle (Pyrrhalta viburni) larvae have begun defoliating susceptible viburnum. Roseslug sawfly (Endelomyia aethiops) have begun skeletonizing rose foliage. Winter moth (Operophtera brumata) caterpillars have been observed in small numbers. Landscape weeds continue to thrive in the dry heat. Rabbits and woodchucks have been ravaging new perennial plantings, annual flower gardens as well as vegetable and herb gardens. Many pines are flowering and responsible for the high pollen count.

*updated:  Massachusetts | U.S. drought Monitor (unl.edu) 

Metro West (Acton)

General Conditions: ​​Dry, windy, and hot sums up this last week’s weather. Little precipitation was recorded, strong winds continued, and summer-like temperatures were recorded for this past week. We went from spring to summer in one week. A high temperature of 88ºF was recorded on the 14th and was preceded by a high of 84ºF on the 13th and followed by 81ºF and 83ºF on the 15th and 16th respectively. On three of these warmer days, the evening temperatures remained in the 60s and did not provide much respite from the heat. The landscape is exploding with color and in addition to plants reported in the phenology table above, the following woody plants were observed in some stage of bloom: Aesculus x carnea 'Briotii' (red horse chestnut), Aesculus hippocastanum (horse chestnut), Aristolochia macrophylla (Dutchman’s pipe), Cornus florida (dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers hybrid dogwood), Halesia Carolina ‘Arnold Pink’ (Arnold pink silverbell), Halesia tetraptera (mountain silverbell), Rhododendron vaseyi (pink shell azalea), Rosa rugosa (rugosa rose), Spiraea spp. (bridal wreath), Viburnum sargentii (Sargent viburnum), and Wisteria spp. Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Amsonia hubrichtii (Arkansas blue star), Aquilegia spp. (columbine), Camassia scilloides (wild hyacinth), Chrysogonum virginianum (green and gold), Galium odorata (sweet woodruff), Geranium maculatum (wild geranium), G. macrorrhizum (bigroot geranium), Hyacinthoides hispanica (wood hyacinth), Iris cristata (crested iris), I. germanica (bearded iris), Myosotis sylvatica (forget-me-not), Phlox x subulata (moss phlox), Phlox divaricata (Canadian Phlox), P. stolonifera (creeping phlox), Podophyllum peltatum (mayapple), Polygonatum commutatum (great Solomon's seal), P. odoratum 'Variegatum' (variegated Solomon'sseal), Stylophorum diphyllum (wood poppy), Tiarella cordifolia (foam flower), Trillium erectum (red flowering trillium), T. grandiflorum (white flowering trillium), and Waldsteinia ternata (barren strawberry).

Pests/Problems: According to NOAA, the 20-year average rainfall total for the month of May is 3.37” and as of the 17th, I have recorded a scant 0.14”. High temperatures recorded this past week were into the 70s and 80s and that, combined with little to no precipitation, creates a lot of stress for plants*. Many weeds are in flower including some of the most invasive: Alliaria petiolata (garlic mustard), an herbaceous plant which is in full bloom at this time and can easily be spotted because of its white flowers and can be seen growing anywhere and everywhere including on roadsides and in woodlands, wetlands, and gardens. Elaeagnus umbellata (Autumn-olive), a woody invasive shrub/small tree is also flowering and can easily be detected by its silvery leaves and thorny branches. Lonicera maackii (Amur honeysuckle), a woody invasive shrub, is also flowering and can easily be detected by its delicate white/yellow flowers. Toxicodendron radicans (poison ivy) continues to leaf out and it is easy to see with its shiny red leaves of three. Ticks, mosquitoes, and black flies are feeding and active.

*updated:   Massachusetts | U.S. drought Monitor (unl.edu)

Central Region (Boylston)

General Conditions: We seemed to move directly from early spring to mid-summer this week, with temperatures well into the 80’s for much of the reporting period. Surprisingly, despite the high temperatures and the lack of significant precipitation over the last several weeks, the landscape feels lush, with many of our tall canopy trees fully leafed out by this point. There is plenty in bloom across the garden, including many of our native woodland perennials like Trillium grandiflorum (white wakerobin), and Phlox stolonifera (creeping phlox). The first of the broadleaf evergreen rhododendrons are showing color and starting to open and many of our viburnums are starting to flower as well. Viburnum acerifolium (maple-leaf viburnum) is just about to open. This lesser used, lesser known native shrub does well in dry shade.

Pests/Problems: Mosquitoes, ticks, blackflies and slugs are all active. Soils are dry and without substantial rainfall soon, we will be into drought territory*.

* updated:   Massachusetts | U.S. drought Monitor (unl.edu)

Pioneer Valley Region (Amherst)

General Conditions: The landscape is lush and vibrant as we round the corner into the last third of May. This is usually one of the best months of the year, so it’s bittersweet to see it closing out. Conditions changed dramatically over this past reporting period with a brief, but significant stretch of heat and humidity. The dew point continuously hovered at or above 60ºF from 5/13 through 5/16, giving us an early preview of the summer heat. The long-term forecast calls for a return to the heat once again, with near record temperatures predicted for 5/21–22. Mid-May is a tough time for such intense heat, as many trees and shrubs have tender shoots and foliage. Leaf scorch and heat stress may develop on deciduous hardwoods in full sun as a result of these conditions. The heat accelerated the flowering period for certain trees and shrubs in the landscape. This was disappointing, given that we wait all year for these displays, but totally out of our control. The dry start to the month continued until patchy thunderstorms occurred on 5/15 and a cold front ushered through a massive band of strong thunderstorms on 5/16. Alas, accumulations from the two storms were nothing to write home about in South Deerfield (0.43”) and Easthampton (0.59”). Hampden County fared a bit better, muscling towards an inch in Springfield (0.94”). We need more rainfall as the upper soil surfaces are drying in certain locations and with the intense heat on tap, this will only continue to become a problem. Sugar maple and red oak seedlings are everywhere right now. Red maple samaras are falling in vast quantities and will start seeding soon. Crabgrass seed has germinated and is actively growing, which feels early. Pollen levels are high and oaks are responsible for a large share at present. But overall, the landscape looks very healthy and robust, we just need a good dose of rain to ensure things stay that way.

Pests/Problems: Now is the time to begin a regimen of carefully scouting trees and shrubs for any symptoms or signs of insect activity and disease. Plants may appear healthy from a distance even when significant infestations or disease is present. Careful disease and pest scouting is a core component of any PHC program. The UMass Cold Spring Orchard in Belchertown noted a high risk for fire blight during the overnight hours of 5/15–5/16. Apple and pear cultivars are most susceptible to infection and symptoms include blackened and curled terminal shoots and leaves. Any rain event or period with heavy fog or dew that coincides with mild temperatures during the bloom is enough to initiate the disease. Hemlock woolly adelgid populations are locally abundant in Hampshire County. The dry start to May has allowed sycamores to flush a healthy set of foliage and some trees are starting to appear full. Many years, the trees are still devoid of any significant foliage and we typically don’t expect a full canopy until late June. Hopefully, the dry conditions in May have also suppressed maple anthracnose, which thrived last year on a range of maple species.

Berkshire Region (Great Barrington)

General Conditions: The weather in the Berkshires did a flip flop again as daytime high temperatures went from the low 80s on the 12 and 13th down to daytime highs in the mid-60s at the end of the scouting period. Night time lows dropped from a very mild temperature of 60ºF on the 14th and 15th to 45ºF on the morning of the 18th. After a bit of a dry spell which left soil moisture levels low, showers and a heavy thunderstorm on Monday, May 16th brought some needed rain. Soil moisture levels are currently very good. One weather factor which has remained fairly consistent is the wind. The T-storm on the 16th was accompanied by some very strong gusts. There had been tornado watches posted for much of the county on that day but fortunately none came to fruition. After a slow start in plant development, the pace has picked up and many flowers can be seen both in managed landscapes and in unmanaged woodlands and fields. Weed growth and flowering also accelerated this past week. Garlic mustard (Alliaria petiolata) continues to flower and is setting its slender green fruit. Creeping Charlie or ground ivy (Glechoma hederacea) is rampant.

Pests/Problems: The pest drawing the most attention now in South County and especially along the border with New York State is the spongy moth (Lymantria dispar). The caterpillars which began hatching around May 5 have been ballooning and appearing on everything from trees and shrubs to any object in their pathway, including humans. Plants infested with the caterpillars during scouting this week included oaks, beech, birch, apple, cherry, and roses. Except for saplings, the extent of the damage to foliage has not been extensive yet, but, given the huge number of the caterpillars, that is sure to change. Serious defoliation seems inevitable. Not only is this caterpillar a problem for trees and shrubs, but is also affecting humans. Skin rashes caused by the fine hairs on the caterpillar are very common and painful. Other pests observed this week are hydrangea leaf tier, spruce spider mite on dwarf Alberta spruce (Picea glauca 'Conica'), and lily leaf beetle adults and eggs on emerging lilies. The black-legged tick population is very high and reports of tick bites are equally high.

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:

Please continue to report any potential beech leaf disease (BLD) findings to the UMass Extension Plant Diagnostic Lab. The disease is caused by a foliar nematode (Litylenchus crenatae ssp. mccannii) and occurs on all species of beech (Fagus) in our forests and landscapes. Reports from southern Connecticut, where the disease has been present for several years now, are not optimistic. In stands where the disease is established, beech saplings in the understory have flushed very few to no leaves and mature trees have less than 1/3 of a full canopy. Look for dark, interveinal banding, convex puckering of the interveinal region (when viewing the upper surface of the leaf), leaf curling and distortion. Some trees may be struggling to flush any new growth at this time.

  • Symptoms of anthracnose, caused by Discula sp., on seven-son flower (Heptacodium miconioides). Anthracnose of seven-son flower (Heptacodium miconioides) caused by a species of the fungal pathogen Discula. The tree is less than 15-years-old and has been present at the site for seven years. It resides in a raised bed and receives full sun with drip irrigation into well-drained soils composed of sand and loam. The tree is the only one of several that showed symptoms this spring. Symptoms on the submitted sample included: dark-colored necrosis of the leaf margins, angular spots on interior portions of the foliage, collapse of newly emerging leaves and stem dieback (see photo). Diseases of seven-son flower are not well-studied but there are a variety of Discula species in the landscape that can attack an array of deciduous trees and shrubs. Depending on the host, the foliage or foliage and newly emerging shoots can be killed.
  • Orange-colored, gelatinous telia (spore-bearing structures) produced by the cedar-quince rust pathogen (Gymnosporangium clavipes) on eastern redcedar (Juniperus virginiana). Branch cankering caused by the cedar-quince rust pathogen (Gymnosporangium clavipes) on eastern redcedar (Juniperus virginiana). The tree is roughly 40-years-old and resides in full sun with thin soils over limestone bedrock. Turfgrass surrounds the trees and is annually fertilized, potentially providing some nutrients to the tree. This spring, significant needle browning occurred throughout the canopy, which had not been observed in previous years. The submitted branch segments had numerous orange-colored pads of fungal tissue rupturing from the bark. These represent the spore-bearing structures of G. clavipes. During the spring, spores are liberated and dispersed to infect rosaceous plants (the fungus is most damaging to serviceberry and hawthorn). The branch was submerged in water for five minutes to wet the spore-bearing pads, which became swollen and gelatinous (see photos). Even minor rain events are enough to induce this swelling, which allows the spores to disperse more readily. These pigmented spores can travel for long distances (several miles) before they infect a new host. Typically, the cankers on Juniperus don’t kill infected stems and branches. They can become perennial inoculum sources for the G. clavipes. However, in some cases they are so numerous that branches are killed, resulting in needle browning and dieback. Very little can be done to manage rust diseases like cedar-quince rust. The spores are produced over a period of weeks to months (depending on the host and setting) and their pigmentation allows them to travel considerable distances. Fungicide trials have shown very limited success in containing these dynamic and destructive fungi.
  • Canopy dieback on Green Giant arborvitae (Thuja plicata x standishii ‘Green Giant’) caused by transplant shock and winter burn. The trees are 8–10’ in height and were transplanted one year ago. They were planted on the side of a private road with a mixture of sun and shade in well-drained, loam soils. It’s not clear if they were provided with supplemental irrigation but from July onward, there was ample precipitation. The submitted sample contained branches that were pale green to brown and desiccated. There was no evidence of any insects or disease. The possibility of road salt damage is being explored as well by the arborist.
  • Stem and branch cankering caused by Botryosphaeria s.l. on Japanese holly (Ilex crenata), blue holly (Ilex x meserveae) and rosebay rhododendron (Rhododendron maximum). The Japanese holly is mature (~20-years-old) and resides as a driveway hedge in full sun with drip irrigation. Several leaders in the canopy on one of eight plants exhibited symptoms of stem cankering (discolored and cracking bark) and a foliar blight. The blue holly is mature (>15-years-old) and is situated in a shaded setting. In early spring, symptoms of cankering (discolored, cracking and sloughing bark) were observed on the main stem and the foliage is dying back. The rhododendron was transplanted one year ago and at the end of the ’21 growing season was exhibiting branch dieback and wilting foliage. It was planted into a shade garden on the border of a residential property with drip irrigation provided. The sample tested negative for Phytophthora. There are a range of species in Botryosphaeria s.l. that can readily attack evergreen shrubs like holly and rhododendron. In addition to the symptoms on the bark, vascular staining/browning will also be present. In some cases, foliar pathogens can co-occur, taking advantage of stressed and weakened plant parts.
  • Cenangium canker, caused by Cenangium ferruginosum, on Japanese red pine (Pinus densiflora). The tree is mature, having been present at the current location for over 15 years. It resides in an ornamental garden adjacent to an organically managed lawn, exposed to full sun with soils composed of clay and loam and no supplemental irrigation. Last year, the tree began showing symptoms of dieback, which included a thinning canopy, needle tip browning and large clusters of partially matured cones. Cenangium is not a common pathogen in the landscape but attacks a wide array of pines. It is often associated with drought-stressed trees. It’s possible the heat and dry summer of 2020 was enough to facilitate disease development, which manifested as symptoms in 2021.

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

Mammal Damage to Trees, Sometimes Blamed on Insects:

  • Twig Pruning by Squirrels: (Sciurus carolinensis) the eastern gray squirrel can cause damage to trees that is sometimes blamed, incorrectly, on insects. While the eastern gray squirrel primarily feeds on the fruits (nuts) of forest trees such as oak, beech, and hickory, they will also consume mushrooms, tree flowers and buds, caterpillars and plant shoots. They are omnivores and have been reported to consume a diverse array of foods. In addition to clipping off branch tips, the eastern gray squirrel is also known to create injuries in tree bark by chewing small pits or in some cases completely stripping away bark in larger sections. This behavior often occurs in early spring and again in early fall. Why do eastern gray squirrels do this? One journal article by Kenward and Parish (1986) suggested that bark stripping is initiated by young squirrels, perhaps as exploratory feeding, or by older squirrels that have learned the habit. Those authors found that severe damage only occurs where tree phloem is suitable (related to average phloem width). Sometimes the phloem and cambial tissues or phloem sap is consumed. Squirrels have also been reported to eat shoots and the pith from young shoots. Such damage is often sporadic, and when plant tissues are not being consumed, some theories include behavioral reasons such as agonistic encounters between juvenile and adult squirrels; however, presence of juveniles (and lack of other food sources) does not always explain why they do this (Gill, 1991).

Insects and Other Arthropods

  • Deer Tick/Blacklegged Tick: Ixodes scapularis adults have been 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). 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

 

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 on 5/5/2022. Since then, the MA Department of Conservation and Recreation has seen eggs hatching in parts of Williamstown, Hancock, Pittsfield, Erving, and Wendell, MA (reported on 5/12/2022). They also report limited bud break on the oaks in these areas as of the end of last week (this is rapidly changing), but are seeing spongy moth caterpillars already feeding on beech leaves. Ballooning spongy moth caterpillars have been seen dispersing on fine strands of silk, using the wind to move them, as is typical. MA DCR and others also report seeing caterpillars still resting on their egg masses, and some of them dying there (similar observations have been seen in previous years).

If egg masses are plentiful near high-value specimen trees in Berkshire County this year, consider applying the reduced risk insecticide Bacillus thuringiensis Kurstaki (Btk) to host plant leaves once caterpillars begin to feed, but before caterpillars are over ¾ inch in length. Spinosad is an additional reduced risk active ingredient for the management of spongy moth caterpillars.

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 .

  • Spotted lanternfly egg masses. (Photo: Tawny Simisky) 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. It overwinters as an egg mass, which the adult female insect lays on just about any flat surface. Pictures of egg masses can be seen here: https://massnrc.org/pests/linkeddocuments/SLFChecklistForResidents.pdf .

Take the new spotted lanternfly egg mass identification quiz from MDAR! Available here: bit.ly/SLFEggMassQuiz .

The MA Department of Agricultural Resources (MDAR) recently released the following “Notice to Nursery and Landscape Industry” regarding spotted lanternfly, an excerpt of which is included here:

Last year, the Massachusetts Department of Agricultural Resources (“MDAR”) detected populations of the invasive pest known as spotted lanternfly (Lycorma delicatula) in multiple locations throughout the state. Since this is the time of year that nurseries are receiving shipments of stock for the spring planting season, we are sending this notice to remind growers and landscapers to inspect any plant material coming from states where SLF has been found, to ensure it does not harbor SLF egg masses, and to report any finds to MDAR. This reminder is especially important as MDAR has recently received several reports that nursery stock from SLF-infested areas was sent to Massachusetts growers.

To read the FULL NOTICE, visit: https://massnrc.org/pests/blog/?p=2933 .

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.

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 .

  • Hemlock woolly adelgid wooly masses at the base of hemlock needles. (Photo: Tawny Simisky) Hemlock Woolly Adelgid: Adelges tsugae (HWA) is present on eastern and Carolina hemlock. The overwintering hemlock woolly adelgid generation (sistens) is present through mid-spring and produces the spring generation (progrediens) which will be present from early spring through mid-summer. HWA, unlike many other insects, does most of its feeding over the winter. Eggs may be found in woolly masses at the base of hemlock needles beginning in mid-March. Each woolly mass is created by a female who may then lay 50-300 eggs. Hemlock woolly adelgid eggs were observed in samples collected in Amherst, MA on April 13, 2022. Eggs hatch and crawlers may be found from mid-March through mid-July.

Nicole Keleher, Massachusetts Department of Conservation and Recreation (DCR) and the Director of their Forest Health Program, reports some curious observations about the hemlock woolly adelgid population in Massachusetts this year. Out of 17 sites across the state that they monitored for HWA winter mortality, they averaged approximately 47% mortality of the adelgid over the winter. This is relatively low, in the context of recent year’s winter mortality. The 17 sites had adelgid winter mortality that ranged from 23% to 80% of the insects sampled, but most sites were in the 40-50% range – providing us with the 47% average. Given those percentages, and the fact that these insects reproduce parthenogenetically (females lay viable eggs without mating), MA DCR notes that they are seeing lower than expected densities of HWA right now. Anecdotally, they suspect this may be because of mortality in the spring progrediens generation, rather than the more typical winter mortality of the sistens generation. What is the reason for this? We are uncertain. Anecdotally, it also seems that hemlock woolly adelgid populations in western MA may be higher this season than those in eastern MA. Again, the reasons for these observations are currently unknown, and this information should be considered mostly anecdotal at this time.

What does all of this mean for hemlock woolly adelgid management this season? I am not sure. Perhaps trees in eastern MA may experience a bit of a reprieve from this insect in 2022, whereas those in western MA may not. However, as DCR notes there is site variability with their observations – so this information cannot be applied for every scenario. The important thing is to monitor specimen hemlock trees and shrubs in managed landscapes and make management decisions based on site-specific observations and historical recordkeeping at each individual location.

  • Winter Moth: (Operophtera brumata) data since 2017 has indicated that the winter moth population in eastern Massachusetts has been on the decline while the percent of winter moth pupae parasitized by Cyzenis albicans has increased! Dr. Joseph Elkinton’s laboratory at UMass Amherst has released this biological control of winter moth since 2005 and conducted the rigorous sampling required to determine where the insect has established and what its impact on the winter moth population has been at multiple sites in eastern MA. More information about the Elkinton Lab’s research and the biological control of winter moth can be found here: https://www.fs.fed.us/foresthealth/technology/pdfs/FHAAST-2018-03_Biology_Control_Winter-Moth.pdf .

The take-home point? Do not worry about winter moth this spring! In fact, management of this insect in landscaped settings will likely not be necessary in most locations. Blueberry and apple growers may still, on the other hand, be interested in scouting and continuing to monitor for this insect, as only very low numbers of winter moth caterpillars might be tolerated in those systems. For an April 16, 2022 update about winter moth in blueberry and apple production from Heather Faubert, University of Rhode Island, visit: https://web.uri.edu/ipm/2022/04/2667/ .

In recent years, it is worthwhile to note that some areas on the Cape and other locations in eastern MA have reported noticeable cankerworm populations in the spring, which are often confused for winter moth. Read more about cankerworms below.

Winter moth caterpillars will drop to the soil to pupate by late May/early June in Massachusetts. Once pupation occurs, management is no longer practical or necessary.

  • 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 bag. (Photo: Tawny Simisky) 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   A note about bagworms: there are approximately 28 different species of bagworm moths in North America belonging to the family Psychidae. The larvae of the common bagworm (T. ephemeraeformis) is not active right now, but other species may be.

  • Black Turpentine Beetle: Dendroctonus terebrans adults may begin to be active between mid-April to mid-May. Host plants include: black pine (Pinus thunbergiana), eastern white pine (Pinus strobus), Japanese black pine (Pinus thunbergii), loblolly pine (Pinus taeda), pitch pine (Pinus rigida), red spruce (Picea rubens), Scots pine (Pinus sylvestris), and slash pine (Pinus elliottii).

This is one of the largest native North American bark beetles. In the northern parts of its extensive range, the black turpentine beetle overwinters as an adult in the bark of its hosts. In the southern portions of its range, all life stages may be present throughout the year. Egg laying and feeding is usually kept to the basal 6 feet of the host plant. Mated pairs of adult beetles work to excavate galleries that may be 9.8 inches wide and 11.8 inches long. 100-200 eggs may be laid on one side of the gallery. Once hatched, larvae feed in groups on the inner bark. Fully grown larvae are legless, white, and almost 1/2 inch in length. Pupation occurs and adults eventually emerge from the bark to re-infest the same tree, or disperse to another susceptible host.

Stumps and buttress roots of freshly cut trees are favored by this insect. Attacked trees may exhibit browning of needles and oozing of large masses of pitch. Masses of pitch (pitch tubes) may cover holes in the trunk and may be considerably larger than those of southern pine beetle. Pitch hardens and is first white but may turn red as it ages. Pitch is irregular in shape and up to 1.6 inches in diameter. Pitch tubes are not visible when the area below the soil line is attacked. Healthy trees are usually not attacked, however it has been reported on occasion.

Check drought-stressed or otherwise stressed trees for needles turning light green to rust color. Check the lower 6 feet, particularly the lower 18 inches of the trunk for 1.6 inch in diameter pitch tubes or small entrance holes from the adults. Reddish-brown boring dust may be found near the base of the tree as well.

  • 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.

  • Cankerworms: Alsophila pometaria (fall cankerworm) and Paleacrita vernata (spring cankerworm) are often confused for winter moth (Operophtera brumata). Cankerworm populations in eastern MA, particularly on areas of Cape Cod, were confused for winter moth in 2019. Spring cankerworm adults are active in February and March, and fall cankerworm adults are active in late November into early December. During these times, both species lay eggs. These native insects most commonly utilize elm, apple, oak, linden, and beech. Eggs of both species hatch as soon as buds begin to open in the spring. Caterpillars occur in mixed populations and are often noticeable by mid-May in MA. Young larvae will feed on buds and unfolding leaves. There are two color forms (light green and dark) for caterpillars of both species. Like winter moth, they will drop to the soil to pupate. This usually occurs in June. Fall cankerworm larvae have three pairs of prolegs (one of which is small so it is sometimes referred to as ½) and spring cankerworm have two pairs. (Winter moth caterpillars also have 2 pairs of prolegs.) If populations are large and damage is noticeable on hosts, reduced risk insecticides such as Bacillus thuringiensis Kurstaki or spinosad may target larvae between approximately 148-290 GDD’s.

  • 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 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.

  • Elm Leaf Beetle: Xanthogaleruca (formerly Pyrrhalta) luteola is found on American elm (Ulmus americana; not preferred), Chinese Elm (Ulmus parvifolia; not preferred), English Elm (Ulmus procera; preferred host), Japanese Zelkova (Zelkova serrata), and Siberian Elm (Ulmus pumila; preferred host).

This species was accidentally introduced into the eastern United States early in the 1800's. Since then, it has been found throughout the USA anywhere elms are located. It also occurs in eastern Canada. The adult elm leaf beetle overwinters in protected areas, such as the loose bark of trees, but can also be a nuisance when it tries to invade homes in search of overwintering protection. Beetles will try to enter houses or sheds in the fall.

In the spring, the adult beetles will fly back to the host plant and chew small, semi-circular holes in the leaves. The adult female can lay 600-800 yellow eggs in her life. Eggs are laid in clusters on the leaves and resemble pointy footballs. Larvae are tiny, black, and grub-like when they hatch from the egg. Young larvae will skeletonize the undersides of leaves. As they grow in size, the larvae become yellow-green with rows of black projections. Oldest larvae may appear to have two black stripes along their sides, made from the black projections. There are 3 larval instars. Mature larvae will wander down the trunk of the host tree and pupate in the open on the ground at the tree base or in cracks and crevices in the trunk or larger limbs. They spend approximately 10 or so days as a pupa, and then the adults emerge. Those adults will fly to the foliage of the same host plant or other adjacent potential hosts in the area, where they will lay eggs. In the fall, the adults will leave the host plant in search of overwintering shelter. In most locations in the USA, two generations of this insect are possible per year. In warmer locations, 3-4 generations per year are possible.

Leaves are skeletonized by the larvae. Skeletonization may cause the leaf to turn brown or whitish. Adults are capable of chewing through the leaf, often in a shothole pattern. When in very large populations, they are capable of completely defoliating plants. Populations of this insect can fluctuate from year to year, and often management is not necessary if populations are low. However, defoliation for consecutive seasons may lead to branch dieback or death of the entire tree.

  • Elongate hemlock scale adult females and crawlers. (Photo: Tawny Simisky) 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 Pine Sawfly: Neodiprion sertifer overwinters in the egg stage. Eggs are laid by females the previous season by cutting slits in needles using their ovipositors and depositing 6-8 eggs in each of 10-12 needles. Egg hatch occurs from late-April to mid-May and caterpillars become 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. It is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when planted 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. 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.

  • Fletcher Scale: Parthenolecanium fletcheri is a soft scale pest of yew, juniper, and arborvitae. Feeding scales, especially on yew, result in honeydew and sooty mold, needle yellowing, and at times, premature needle drop. There is one generation per year. Overwintered second instar nymphs can be targeted between 38-148 GDD’s, base 50°F. Nymphs develop and adult females lay eggs (on average 500-600) in May that hatch by June. Dead females conceal egg masses beneath. Crawlers migrate short distances to branches and may be concentrated on certain branches of a particular plant.

  • Large forest tent caterpillars. (Photo: Tawny Simisky) 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 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.

  • Holly Leafminers: Seven species of leaf miners feed on holly. Phytomyza ilicicola is usually referred to as the native holly leafminer. This species is known to feed on Ilex opaca, I. crenata, and related cultivars; however, it only lays its eggs in American holly (Ilex opaca). Some research suggests that the native holly leafminer may lay its eggs in other Ilex species, but that the larvae are unable to complete their development. This insect is found throughout the native range of its host plants. Larvae overwinter in leaf mines and pupation occurs in March and April and adult emergence by mid-May (192-298 GDD’s, base 50°F). Adult flies are known to emerge over a period of 6 or so weeks in the spring. Females lay eggs using their ovipositor on the underside of newly formed leaves. A tiny green blister forms on the leaf as the first symptom of injury. Larvae hatch from the egg and create a narrow mine that may appear brown from the upper leaf surface. Mines are broadened in the fall and a large blotch is completed in the winter. Larvae are yellow maggots and reach 1.5 mm. in length when mature. Current year’s mines are easily overlooked due to the slow feeding patterns of the larvae. Premature leaf drop may occur. Remove and destroy mined leaves before May. Phytomyza ilicis is usually only referred to as the holly leafminer, and it is a non-native species introduced from Europe and only feeds on Ilex aquifolium. (The native holly leaf miner does not develop in I. aquifolium.) The biology and damage this insect causes is similar to that of the native holly leafminer, with the exception of the fact that eggs are laid in the midvein of the leaf and young larvae tunnel in the vein until the fall. Remove and destroy mined leaves before May. Adults may be present mid-late May (246-448 GDD’s, base 50°F).
  • Honeylocust Plant Bug: Diaphnocoris chlorionis feeding results in tiny yellowish-brownish spots on leaves, leaf distortion, and in some cases, defoliation. (There are at least 7 species of plant bugs that feed on honeylocust, Gleditsia triacanthos.) There is one generation per year. Immatures and adults feed on foliage and light to moderately damaged foliage may persist throughout the growing season. Honeylocust plant bugs overwinter as eggs laid just beneath the bark surface of 2- and 3-year-old twigs. Eggs hatch just after vegetative buds of the host begin to open. Young nymphs crawl to the opening leaflets and begin feeding and the most significant damage occurs at that time, when the insect is hidden from view. Nymphs develop into adults around May-July. This insect can be targeted between 58-246 GDD’s, base 50°F.
  • The caterpillars of the hydrangea leaftier moth web together leaves to create a purse or envelope-like structure around themselves. Three of these can be seen in this photo taken in Pittsfield, MA on 5/15/2022. (Photo: Tawny Simisky) Opening the webbed together leaf structure of the hydrangea leaftier moth caterpillar will reveal the larva within, along with tiny black frass and webbing, as seen in Pittsfield, MA on 5/15/2022. (Photo: Tawny Simisky) 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 adults. (Photo: Tawny Simisky) 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

  • 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.

  • Lily leaf beetle adults. (Photo: Tawny Simisky) Lily Leaf Beetle: Lilioceris lilii adults overwinter in sheltered places. As soon as susceptible hosts such as Lilium spp. (Turk’s cap, tiger, Easter, Asiatic, and Oriental lilies) and Fritillaria spp. break through the ground, the adult lily leaf beetles are known to feed on the new foliage. (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 at that time.

Check out Episode 3 of InsectXaminer to see the lily leaf beetle in action: https://ag.umass.edu/landscape/education-events/insectxaminer

  • 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. Monitor for adults in mid-May (192-298 GDD’s, base 50°F).
  • Roseslugs: Two species of sawfly can be found on the leaves of roses at this time. These small, caterpillar-like larvae will skeletonize the upper leaf surface and leave a “window-pane” like pattern behind. When present in large numbers, these insects are capable of defoliating their entire host. Management options include an insecticidal soap spray or a product containing spinosad.
  • Snowball Aphid: Neoceruraphis viburnicola eggs overwinter on viburnum twigs and buds. Eggs hatch and this aphid 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.

  • Spruce Bud Scale: Physokermes piceae is a pest of Alberta and Norway spruce, among others. Immatures overwinter on the undersides of spruce needles, dormant until late March. By April, females may move to twigs to complete the rest of their development. Mature scales are reddish brown, globular, 3 mm. in diameter, and found in clusters of 3-8 at the base of new twig growth. They closely resemble buds and are often overlooked. Crawlers are present around June.

  • 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. Viburnum leaf beetle overwinters as eggs laid in capped pits on the newest growth of susceptible viburnum branches. Scout for overwintered eggs and prune out and destroy before they hatch. Egg hatch occurs in late-April to early-May as temperatures warm and foliage becomes available. Monitor for larvae in mid-May (80-120 GDD’s). 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.

  • 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. 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. These aphids are a favorite snack for insect predators such as the multicolored Asian lady beetle, Harmonia axyridis. Elm can withstand multiple years of woolly apple aphid infestation and this insect is primarily aesthetic in its impact to trees. Management may not be necessary.

  • 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. Aphids may be active from 121-246 GDD’s, base 50°F on elm. 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. 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. Elm can withstand multiple years of woolly elm aphid infestation and this insect is primarily aesthetic in its impact to trees. Management may not be necessary. Lady beetle larvae and adults often feed on these insects.

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

Landscape mulch should be the first defense against weeds in landscape beds. Mulching can be done now at the beginning of the season before summer annual weeds germinate. Small winter annual weeds can be smothered with mulch. Freshly mulched landscape beds will not immediately require a preemergence herbicide application because the fresh mulch should supply adequate summer annual weed control in the short term. Preemergence herbicide application should be considered on mulched areas that have not been freshly mulched or can be applied later in the season in those areas that were freshly mulched this spring. Preemergence herbicides should be applied on top of landscape mulches, not underneath them. Compost is not recommended as a mulching material.

Inspect areas of the landscape where new trees or shrubs, especially those that were field grown, have been planted in the last year. Look for perennial weeds that may be growing from the root ball. Canada thistle, mugwort, quackgrass, bindweed and horsenettle are some of the possible culprits. Perennial weeds can be spot treated with glyphosate-based products.

Do not attempt to control Japanese knotweed (Polygonum cuspidatum) currently 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 trunks. If these suckers or sprouts are not controlled, the landscape will be a contender for the “Shabby Landscape Award”. Pruning is effective but very time consuming. 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. Very small means 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 injury to the whole plant is possible.

Do not delay, treat garlic mustard, Alliaria petiolata, now. Second year plants are flowering. Garlic mustard is a biennial and herbicide applications at this time of year will control second-year plants before they go to seed as well as the first-year seedlings.

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


Additional Resources

Pesticide License Exams - The MA Dept. of Agricultural Resources (MDAR) is now holding exams online. For more information and how to register, go to: https://www.mass.gov/pesticide-examination-and-licensing

To receive immediate notification when the next Landscape Message update is posted, join our e-mail list or follow us on Facebook.

For a complete listing of upcoming events, see our upcoming educational events https://ag.umass.edu/landscape/upcoming-events

For commercial growers of greenhouse crops and flowers - Check out UMass Extension's Greenhouse Update website

For professional turf managers - Check out Turf Management Updates

For home gardeners and garden retailers - Check out our home lawn and garden resources

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.

Acknowledgements: UMass Extension gratefully acknowledges the support of the following funding sources for the production of the Landscape Message –

  • The Massachusetts Nursery and Landscape Association Fund
  • The Massachusetts Department of Conservation and Recreation, Award #ISADCR28219926UMA22A
  • Stakeholders like you! The Landscape Message is partially supported by educational program user fees.