Landscape Message: April 26, 2019

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.

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

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Scouting Information by Region

Environmental Data

The following data was collected on or about April 24, 2019. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2019 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

MA Region/Location	GDD		Soil Temp (°F at 4" depth)		Precipitation (1-Week Gain)	Time/Date of Readings
	1-Week Gain	2019 Total	Sun	Shade
CAPE	26	46	56	51	1.08	12:00 PM 4/24
SOUTHEAST	33.5	61.5	54	50	1.35	8:10 AM 4/24
NORTH SHORE	45.5	81	55	48	1.06	12:00 PM 4/24
EAST	49.5	95	58	53	3.02	3:30 PM 4/24
METRO	54.5	90.5	58	52	2.66	4:30 PM 4/24
CENTRAL	50.5	86	54	49	2.83	4:15 PM 4/24
PIONEER VALLEY	56.5	91	59	53	2.34	9:30 AM 4/24
BERKSHIRES	46	77	56	52	1.21	9:00 AM 4/24
AVERAGE	45	79	56	51	1.94	-
n/a = information not available

Phenology

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT NAME (Botanic/ Common)	CAPE	S.E.	N.S.	EAST	METRO W.	CENT.	P.V.	BERK.
Cercis canadensis (redbud)	*	Begin	*	*	Begin	Begin	Begin	*
Amelanchier spp. (shadbush, serviceberry)	*	Begin	*	Begin	Begin	Begin	Begin/Full	*
Pyrus calleryana (Callery pear)	Begin	Begin	*	Begin/Full	Begin	Begin	Full	*
Chaenomeles speciosa (common flowering quince)	Begin/Full	Begin/Full	*	Begin/Full	Begin	Begin/Full	Begin	Begin
Magnolia soulangiana (saucer Magnolia)	Begin/Full	Begin	*	Begin/Full	Begin	Full	Begin/Full	*
Rhododendron ‘P.J.M.’	Full	Begin/Full	*	Full	Full	Begin	Begin/Full	Begin
Prunus serrulata (Japanese flowering cherry)	Full	Full	Full	Full	Full	Full	Full	Begin/Full
Rhododendron mucronulatum (Korean Rhododendron)	Full	Full	Full	Full	Full	Full	Full	Begin/Full
Magnolia stellata (star Magnolia)	Full/End	Full	Full/ End	Full/End	Full/ End	Full	Full	Full
Forsythia x intermedia (border Forsythia)	Full/End	Full	Full	Full	Full	Full	Full	Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature over the last week was 52˚F, with a high of 64˚F on April 20 and a low of 36˚F on April 18. The period included at least a little bit of rain each day from April 18 – 23, keeping things moist and totaling just over an inch. Lawns are green, growing, and some have seen the first mow.

Pests/Problems: Winter moth larvae can be observed in buds of susceptible hosts. In general, winter moth populations are expected not to be significant enough to warrant treatment in most areas of the Cape. They should be monitored in fruit bearing apple and blueberry crops. Lecanium scale on oak, which was widespread on the Cape last year causing a lot of sooty mold, is still abundant in some locations. The nymphs overwinter on the twigs of susceptible hosts, which are numerous, but most populations are mainly on oak. There are numerous parasites that often control populations; however, treatment maybe warranted in areas with large populations. Standard treatment is dormant oil applied between 35-145 GDD. Other pests observed over the last week include: black knot on Prunus, winter damage to boxwood, boxwood leafminer damage and larvae, and azalea lacebug damage. Weeds in bloom include bittercress (Cardamine hirsuta), whitlow grass (Draba verna), mouse-ear cress (Arabidopsis thaliana), mouseear chickweed (Cerastium vulgatum), lesser celandine (Ranunculus ficaria) and dandelion (Taraxacum officinale). Rabbits are abundant. Black legged ticks are active.

Southeast Region (New Bedford)

General Conditions: Day temperatures have been in the 60’s all week with low evening temperatures ranging from 32˚F to 57˚F. The rain and cloud cover have made the warmer temperatures still feel cool. With almost an inch and a half of rain this week, garden soils continue to feel heavy and fungus has started to emerge. With the warmer day temperatures, we have seen a vast emergence of leaves and blooms this week. The yellow Magnolias are blooming, both M. ‘Butterflies’ and M. ‘Elizabeth’. Magnolia x soulangeana are just beginning in warmer microclimates. Epimediums have started to bloom as well. Lawns are greening up and some lawn care companies have begun their mowing schedules. The sun has finally emerged on reporting day 4/24!

Pests/Problems: Ranunculus ficaria (lesser celadine) is in full bloom, while Bittercress is beginning to pass and go to seed. Turkeys, chipmunks and voles are very active in the landscape and squirrels are energetically messing with spring plantings. Lily leaf beetle has been spotted. Winter moth is being monitored on target species. No see ums, mosquitos, bees, and ticks are active.

North Shore (Beverly)

No conditions report this week.

East Region (Boston)

General Conditions: April showers continued; from April 20-23 we received 3.02 inches of precipitation. 2.72 inches of that fell between the afternoon of the 22nd through the morning of the 23rd. We have received 5.49 inches of total precipitation so far for April, well above the historical average for the month. Low temperatures over the last week ranged from 36˚F to 61˚F, averaging 49˚F. High temperatures ranged from 55˚F to 75˚F, averaging 65˚F. We gained 49.5 GDDs for a total of 95 so far this year. The turf is greening up and the soil is plenty moist. Some plants in bloom include: Amelanchier canadensis (serviceberry), Cercis chinensis (Chinese redbud), Chaenomeles spp. (flowering quince), Prunus subhirtella ‘Pendula’ (Higan cherry), Rhododendron schlippenbachii (royal azalea) and Spiraea prunifolia f. Simplicifolia (bridal wreath Spiraea). Hummingbirds have returned for the season. Bees were observed visiting maple trees in flower.

Pests/Problems: Ranunculus ficaria (pilewort) is in full bloom. Dandelions and violets are flowering in turf. Garlic mustard rosettes are beginning to flower. Norway maple seedlings are coming up in beds as well as in turf. Rabbits are abundant.

Metro West (Acton)

General Conditions: Happy belated Earth Day and Happy Arbor Day! The landscape is filled with color as a result of the recent warm weather, longer days and rain. The wet and rainy weather continued into this week with precipitation recorded for this area on four of the past seven days, bringing our total rainfall recorded for this month to 5.62 inches, thereby surpassing the April monthly average of 4.16 inches. Rain is in the forecast for the next several days so that number will surely climb. Observed in some stage of bloom this past week were the following woody plants: Amelanchier spp. (Shadbush, Serviceberry), Cercis canadensis (redbud), Chaenomeles speciosa (common flowering quince), Cornus mas (Cornelian cherry dogwood), C. officinalis (Japanese Cornelian cherry), Forsythia spp., Lindera benzoin (common spicebush), Magnolia x loebneri 'Merrill', (Merrill Magnolia), M. x soulangeana (saucer Magnolia), Pieris japonica (Japanese Pieris), Prunus spp. (cherry), Pyrus spp. (pear), Rhododendron mucronulatum (Korean Rhododendron), R. 'P. J. M.' (PJM Rhododendron), Vaccinium angustifolium (lowbush blueberry), V. corymbosum (highbush blueberry), and Viburnum x burkwoodii (Burkwood Viburnum). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Anemone nemorosa (wood Anemone), Asarum europaeum (European ginger), Caltha palustris (marsh marigold), Chionodoxa luciliae (glory of the snow), Crocus spp. (Crocus), Dicentra cucullaria (Dutchman's breeches), D. spectabilis (old-fashioned bleeding heart), Epimedium versicolor 'Sulphureum' (yellow flowering barrenwort), Helleborus niger (Christmas rose), Hyacinthus spp. (Hyacinth), Mertensia virginica (Virginia bluebells), Muscari spp. (grape Hyacinth), Narcissus spp. (daffodil), Omphalodes verna (blue-eyed Mary), Pachysandra procumbens (Allegheny spurge), Petasites japonicus (Japanese butterbur), Primula spp. (primrose), Pulmonaria longifolia (lungwort), P. rubra (salmon colored lungwort), Puschkinia libanotica (striped squill), Sanguinaria canadensis (bloodroot), S. canadensis 'Multiplex' (double bloodroot), Scilla siberica (Siberian squill), Trillium erectum (red flowering Trillium), Tulipa spp. (tulip), Vinca minor (periwinkle) and Viola spp. (violet).

Pests/Problems: Soils are well saturated which could be an issue for planting and digging in some areas. Acer platanoides (Norway maple) is in full bloom. This invasive tree is hard to miss now that it is in bloom because its flowers are a bright yellowish-green and are easily seen on trees found growing almost everywhere. Continuing to flourish in too many places in the landscape is the basal foliage of Alliaria petiolata (garlic mustard). Other weeds seen in bloom but without the invasive tendency of the previously mentioned two are: Draba verna (spring whitlow grass), Glechoma hederacea (ground ivy) and Lamium purpureum (purple deadnettle), Stellaria media (common chickweed), and Taraxacum officinale (dandelion).

Central Region (Boylston)

General Conditions: It’s hard to keep up with all that’s in bloom at this time of year. Lindera benzoin (spicebush), Sanguinaria canadensis (bloodroot), Jeffersonia diphylla (twinleaf), Houstonia caerulea (bluets), and Erythronium americanum (trout lily) all opened within the last week. The wind and rain are causing Magnolias (Magnolia x soulangeana, M. stellata, M. x loebneri) to pass a little more quickly than any of us would like, but better that than frost wiping out all the blossoms at once. Temperatures have been quite mild, reaching a maximum of 60˚F or higher each day and barely dropping into the 40’s each night, but it’s been rainy or cloudy just about every day, making it feel cooler. The warmer temperatures and ample moisture have made us think about mowing, so I expect we’ll need to mow turf areas for the first time in the next week.

Pests/Problems: The biggest problem is moisture and there’s the expectation that it’s going to be a good year for fungal pathogens, although there’s no evidence of disease yet. Ticks continue to be very active. We have observed some early tent caterpillar activity and gypsy moth hatching has begun. Weeds have exploded, including Cerastium (chickweed), Cardamine (bittercress), Ranunculus ficaria (lesser celandine), and Alliaria petiolata (garlic mustard).

Pioneer Valley Region (Amherst)

General Conditions: If April showers bring May flowers, then we’re in for an eruption of petals next month. It was a very wet week since our last report, with more than 1.5” – 2.5” of rainfall at Pioneer Valley weather stations. The brunt of the rainfall accumulated on Saturday, 4/20 and Monday, 4/22 as scattered showers intermixed with heavy downpours. With the continued rain over the past week, the mighty Connecticut remains swollen and just above flood stage (>112’) at the Northampton gauge. We’re on track for more than 6” of precipitation this April, significantly above the ~3.75” average for the month. Despite all the rain, conditions were actually pretty good over the past week, with bursts of bright sun, high temperatures mostly in the upper 60s to 70s and only light to moderate winds. Unless the landscape is fully saturated with water, it’s an ideal time for transplanting. The long-term forecast calls for additional rainfall and more seasonable high temperatures in the 50s and lower 60s, so the unsettled conditions will continue. The recent stretch of above-average temperatures has really accelerated plant development and the majority of landscape trees and shrubs are pushing new growth at this time on the UMass campus. Cherries are the current star of the spring flowering show with serviceberry, callery pear, Magnolias, Forsythia and 'PJM' Rhododendron also providing beautiful color at this time. Turfgrasses continue to green and are growing rapidly. While the majority of lawns haven’t yet received their first mowing, it’s easy to find those that have.

Pests/Problems: Gypsy moth hatching has been observed in Hampshire County so we will soon be experiencing feeding damage from this omnivorous pest. Apple scab infections are taking place at this time as crabapple and apples continue to leaf out ahead of most other trees. Fungicide applications are not necessary for many landscape ornamentals but for recently transplanted trees in shaded locations, protectants may be warranted to limit the initial infection. Pruning of dense, interior canopy shoots and branches helps to reduce the initial inoculum that spreads throughout the canopy and increases air flow. Removing suckers also improves the appearance of landscape trees, especially for older crabapples. Once Andromeda (Pieris) shrubs have finished flowering, treatment for lacebug infestations, if present, should take place with a labeled insecticide. For sprays, thorough coverage on the underside of the leaves is required to ensure proper control. As Rhododendron buds continue to swell, it’s becoming clearer which branches are completely dead from winter injury compared to those that may have a chance to recover. Prune out obviously dead shoots and branches at this time, but if there’s any hope the buds and shoots are alive, continue to be patient and avoid pruning. While ubiquitous on the landscape, 'PJM' Rhododendrons appear mostly unscathed from this past winter while more prized species and cultivars were badly damaged. Fruiting bodies of the wood-rotting fungal pathogen Kretzschmaria deusta are developing at this time. The primary host in the landscape is European beech, but American beech and sugar maple are also hosts. Right now, the fruiting bodies appear as amorphous, white-colored growths on the bark. As they expand, they remain flattened against the bark, become grey in the center while the margins remain bright white. For landscape beech trees with Phytophthora cankers, wait until trees have fully leafed out before phosphites are applied. This dual mode of action fungicide is highly effective against Phytophthora canker as a lower bole drench and may help to slow the progression of bark death caused by Kretzschmaria as well. Invasive plants like honeysuckle, barberry, Japanese knotweed and multiflora rose are actively growing at this time in the valley.

Berkshire Region (Great Barrington)

General Conditions: Temperatures through the period were well above normal, topping off at 74˚F on 4/19. Two other days, 4/22 and 4/23, hit the 70˚F mark. The warm conditions spurred bud break on maples and many other trees and shrubs. Spring flowering bulbs also continued to burst into bloom. Bloodroot (Sanguinaria canadensis), liverwort (Hepatica spp.), Trilliums (Trillium spp.), dogtooth violets (Erythronium spp.), and skunk cabbage (Symplocarpus foetidus) are some of the wildflowers now in bloom. While rain was not torrential, it was frequent, usually late in the day. Soils have yet to dry but are less saturated than they were in previous weeks. Except for clayey soils, most soils were workable and farmers are now plowing. Still, it is advisable to minimize traffic on the wettest soils. A return to cooler conditions lies ahead. Combined with moist soils, this is a good time for planting. The warm, t-shirt weather accelerated the growth of grass. Mowing season is about to begin.

Pests/Problems: Eastern tent caterpillars have hatched and the first tents were spotted this past week. Spruce spider mite was found on dwarf Alberta spruce. Boxwood leaf miners are still in the larval stage. Ticks, sowbugs, ants, mosquitoes, and wasps are active. The warm weather also brought out slugs. Winter desiccation on evergreen shrubs is more apparent than it was last week. Most affected are shrubs were in full sun.

Regional Scouting Credits

• CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
• SOUTHEAST REGION - Kristin McCullin, Horticulturist reporting from Haskell Public Gardens, New Bedford.
• NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
• EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.
• METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
• CENTRAL REGION - Mark Richardson, Director of Horticulture reporting from Tower Hill Botanic Garden,Boylston.
• PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
• BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals

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

Diseases

Phomopsis canker on umbrella pine (Sciadopitys verticillata). Tree is approximately 20-years-old and has been present at the site for many years. Over the past several years, two to three branches decline and die. The full sun, landscape setting has well-drained soils and supplemental irrigation is provided by hand during extended dry periods. Umbrella pine has very few pests and pathogens but Phomopsis is often associated with declining trees, causing a shoot blight and perennial stem cankers.

Boxwood blight, caused by Calonectria pseudonaviculata, on winter gem boxwood (Buxus microphylla var. japonica ʹWinter Gemʹ). Fifty boxwoods planted in a residential setting with full sun and overhead irrigation. The plants are eight-years-old and have been present at the site for five years. The hedge was tightly planted and is exposed to strong winter winds and snow loading. More than 25% of the plants are exhibiting boxwood blight symptoms, which include: dark-colored, circular leaf spots, blackened stem lesions, excessive leaf shedding and death. Symptoms were not present in previous years.

Dogwood anthracnose, caused by Discula destructiva, on flowering dogwood (Cornus florida). Tree is roughly eight-years-old and has been present at the site for five years. The first year after planting, symptoms of dogwood anthracnose developed and have been present ever since. Symptoms include stunted growth, stem and leaf blight and sparse flowering. The site is full sun with wet, sandy-loam soils. While newer cultivars of flowering dogwood have good resistance to anthracnose, kousa dogwood is highly resistant to the disease and rarely suffers any significant dieback from the disease.

Severe winter burn and secondary foliar blight caused by Pestalotiopsis and Phyllosticta on Pacific Rhododendron (Rhododendron macrophyllum). Mature plants, approximately 40-years-old, residing in a full sun, south-facing landscape setting. The plants are exposed to winter winds and snow loading. Copper-colored spots and blotches with marginal browning were abundant on the submitted foliage. The buds and stems were healthy and exhibited no signs of injury. Both fungal pathogens are common on Rhododendron and other evergreen shrubs as secondary pathogens of damaged leaves and stems.

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

Insects

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

Balsam Twig Aphid: Mindarus abietinus is active between 30-100 GDD’s, base 50°F. Inspect the needles of Balsam fir, Fraser fir, and other true firs for “stem mothers” that will soon be reproducing. Young aphid feeding will lead to distorted foliage. (Needles curl.) Excessive amounts of honeydew are produced and cause needles to stick together. Monitor for the presence of reproducing females and treat with an oil application as weather permits, according to label instructions.

Cooley Spruce Gall Adelgid: Adelges cooleyi is active between 22-81 GDD’s, base 50°F. This insect can be found in the crevices of bark on terminal twigs and bases of buds of blue and Norway spruce. Manage overwintering nymphs prior to gall formation on spruce (roughly 22-81 GDD). Oil applications on Douglas fir should be made before bud break to avoid phytotoxicity. On Douglas fir, this insect does not form galls. On that host, they feed within tiny, white, cottony balls on current year and older needles. Do not plant spruce and Douglas fir close together. Do not fertilize either host (spruce or Douglas fir) if it is infested with this insect.

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

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

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

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

Eastern Spruce Gall Adelgid: Adelges abietis is a pest of Norway spruce primarily, but occasionally damages other spruce species. This adelgid overwinters as a partially grown female, often referred to as a stem mother. This overwintering individual will mature around bud break and lay 100-200 eggs. The eastern spruce gall adelgid may be targeted for management between 22-170 GDD’s, base 50°F.

Eastern Tent Caterpillar: Malacosoma americanum eggs hatch between 90-190 GDD’s, base 50°F, which typically coincides with unfolding cherry leaves in the spring. Egg masses of Malacosoma americanum vary from those of Malacosoma disstria, the forest tent caterpillar, as they have a rounded edge whereas M. disstria egg masses have square edges. Scout for and remove eastern tent caterpillar egg masses prior to hatch on susceptible hosts such as cherry and crabapple. Other host plants impacted by this native insect can include apple, ash, birch, willow, maple, oak, poplar, and witch-hazel.

Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. Crawlers will be present this month and throughout the growing season and the overlap of many developmental stages at any given time can be observed. Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F.

European Pine Sawfly: Neodiprion sertifer caterpillars will be active roughly between 78-220 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine and is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned or plucked out of host plants and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis Kurstaki is not effective against sawflies.

Forest Tent Caterpillar: Malacosoma disstria egg hatch will occur between 192-363 GDD’s, base 50°F, which typically coincides with sugar maple bud break. Scout for and prune out or otherwise remove any reachable forest tent caterpillar egg masses, which can hold 100’s of eggs, on susceptible hosts such as oak, birch, ash, maple, elm, poplar, and basswood at this time.

Gypsy Moth: (Lymantria dispar) Overwintered egg masses laid by female moths in 2018 can be seen in certain areas of the state at this time. Egg masses are “fuzzy” or hairy and brownish-tan in color. Each egg mass can hold up to 500-1000 eggs. These masses may be found on host plant trunks and branches such as oak (favored), maple, birch, poplar, and many others, but are also laid on inanimate objects including the surfaces of homes, outdoor furniture, camping equipment, firewood piles, etc. This may make the accidental movement of gypsy moth egg masses possible. The number of egg masses seen in a particular area can be used as a general indicator of whether there will be a significant number of caterpillars in that area again this year.

Gypsy moth egg hatch typically occurs between 90-100 Growing Degree Days, using a base of 50°F and average temperatures. This is usually around the first week in May in Massachusetts, but variations in temperature may lead to early egg hatch in the last week in April.  [See Pioneer Valley regional report above.] This can also coincide with serviceberry (Amelanchier) bloom.

After egg hatch, groups of tiny gypsy moth caterpillars may remain on their egg mass just before crawling to the canopy of their host plant, where they can disperse using a technique known as “ballooning”. Ballooning occurs when very young caterpillars spin a silken thread and catch the wind to blow onto a new host plant once the thread breaks. This method of dispersal can lead to host plants becoming defoliated that previously did not have egg masses directly on them. Egg masses may be present on nearby oaks, for example, and provide a local population of caterpillars.

Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October and eggs will hatch by late May or early June. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary.

Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. Infested trees may be treated with foliar sprays in late April to early May, using Japanese quince as a phenological indicator. Look for the females, covered in a white, woolly, waxy material and settled at the base of hemlock needles.

Imported Willow Leaf Beetle: Plagiodera versicolora overwintered adults are present and have been reported as active and found on willow foliage on 5/2/2018 in Hanson, MA. Adult beetles will chew holes and notches in the leaves of willow. Egg laying will continue through the end of this month. Females lay yellow eggs in clusters on the undersides of leaves. Larvae are slug-like and bluish-green in color. They will feed in clusters and skeletonize the leaves. Most plants can tolerate the feeding from this insect, and foliage will appear brown. Repeated yearly feeding can be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water.

Snowball Aphid: Neoceruraphis viburnicola becomes active on certain species of viburnum roughly between 148-298 GDD’s or around redbud bloom. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. Damage caused by this insect pest is mostly aesthetic.

Spruce Spider Mite: Oligonychus ununguis is a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir, and occasionally other conifers. This particular species becomes active in the spring and can feed, develop, and reproduce through roughly June. When hot, dry summer conditions begin, this spider mite will enter a summer-time dormant period (aestivation) until cooler temperatures return in the fall. This particular mite may prefer older needles to newer ones for food. When damaging spruce spider mite populations are known from last season, dormant oil applications can be made (when temperatures are appropriate according to label instructions) between 7-121 GDD’s, base 50°F. Magnification is required to view spruce spider mite eggs. Tapping host plant branches over white paper may be a useful tool when scouting for spider mite presence. (View with a hand lens.) Spider mite damage may appear on host plant needles as yellow stippling and occasionally fine silk webbing is visible.

Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. This beetle feeds exclusively on many different species of viburnum. This insect overwintered in the twigs of the host plant as eggs, which hatch soon after bud break. Now is the time to inspect susceptible plants (including but not limited to viburnum such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum) for over-wintered eggs on stems toward branch tips. Inspect branches for egg laying sites created by female viburnum leaf beetles last season. These will appear as small holes approximately 1 mm. in diameter that have been capped with a lid made of chewed bark and excrement, which may appear raised above the surface of the twig. Larvae, when they are present, may be treated with a product containing spinosad once they appear soon after bud break. Larvae are typically first present between 80-120 GDD’s, base 50°F, which often coincides with redbud bloom. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found at http://www.hort.cornell.edu/vlb/ .

White Spotted Pine Sawyer (WSPS): Monochamus scutellatus will be pupating this month and adults can emerge in late May throughout July, depending on local temperatures. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults, which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers; however, the difference in the color of the scutellum is a key characteristic. See the Asian longhorned beetle entry above for more information about that non-native insect.

Winter Moth: (Operophtera brumata) The winter moth population is continues to be at a record low, according to the research of Dr. Joseph Elkinton, Professor of Environmental Conservation at the University of Massachusetts, Amherst, MA. The 2019 outlook concerning winter moth caterpillar population numbers in Massachusetts is very positive for areas in the eastern part of the state accustomed to dealing with damaging populations of this insect. For more information about the life cycle and management of winter moth, go to UMass Extension’s fact sheet: Winter Moth Identification and Management https://ag.umass.edu/landscape/fact-sheets/winter-moth-identification-management

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.

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

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

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

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