Landscape Message: April 20, 2018

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 18, 2018. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2018 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	2018 Total	Sun	Shade
Cape Cod	1	4.5	47	42	0.86	3:00 PM 4/18
Southeast	7	17	54	45	2.00	5:10 PM 4/18
North Shore	9	26	41	36	1.02	9:00AM 4/18
East	8	41.5	51	48	2.72	5:20 PM 4/18
Metro West	8.5	24	39	35	2.11	5:45 AM 4/18
Central	5	27	40	38	2.65	7:30 AM 4/18
Pioneer Valley	8	23	44	39	2.12	9:00 AM 4/19
Berkshires	10	25	40	38	1.75	9:30 AM 4/18
AVERAGE	7	24	45	40	1.90	-
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.
Magnolia stellata (Star Magnolia)	Begin	*	Begin	Begin	*	Begin	Begin	*
Forsythia x intermedia (Border Forsythia)	Begin/Full	Begin/Full	Begin	Full	Begin	Begin	Begin	*
Rhododendron mucronulatum (Korean Rhododendron)	*	Full	Begin/Full	Begin/Full	*	*	Begin	*
Pieris japonica (Japanese Pieris)	Begin/Full	Full	Begin/Full	Begin/Full	Full	Full	Full	*
Cornus mas (Cornelian cherry Dogwood)	Full	Full	Full	Full	Full	Full	Full	Begin/Full
Acer rubrum (Red Maple)	Begin	Full	Full	Full/End	Full	Full	Full	Full
Acer saccharinum (Silver Maple)	Full	End	Full/End	Full/End	Full	Full	End	Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions:  Over the last week temperatures averaged 44°F with a high of 56°F on April 13 and a low of 34°F on April 18. Light frost occurred in many locations on April 12 and 18. 0.86 inches of precipitation fell primarily on April 15 and 16. There were a few sunny days during the period. Topsoil and subsoil moisture conditions remain adequate. Lawns are starting to green up, however plant development is still very slow.

Pests/Problems:  Winter moth egg hatch is likely to begin any day now, at this time no larvae have been detected in host plants. Winter burn is widespread and can be seen on a large number of broadleaf and needled evergreens, many hedges of Leyland cypress, Cupressus × leylandii, have a brownish cast on the more exposed outer needles. Black knot, Dibotryon morbosum a fungal disease of Prunus is very visible at this time of year and is abundant in some locations on black cherry, P. serotina. Browning of needles on White Pine, Pinus strobus can be seen in many areas. The browning may be a result of numerous causes including several needle pathogens, winter burn and salt burn. Damage to buds of bigleaf hydrangea, Hydrangea macrophylla can be seen in parts of the upper Cape. Butterfly bush, Buddleja davidii also appears to be damaged, in some cases killed to the ground. Bittercress, Cardamine hirsuta is in flower. GDD BE 50 = 22.2, GDD 40 =173

Southeast Region (Hanson)

General Conditions:  This is one of the coldest Aprils in years. The cold weather continues and plant and insect development remain behind schedule. April 15^th brought rain, sleet, snow and more rain, which continued all day on April 16^th, with high winds and driving rain. Hanson received 2.0 inches of rain. Soils are very moist.

Lonicera fragrantissima (winter honeysuckle), Cornus officinalis, Cornus mas (Corneliancherry dogwood), Abeliophyllum distichum (White Forsythia), Corylopsis spicata, Stachyurus praecox, Pieris japonica, Pieris floribunda, Pieris 'Brouwer's Beauty', Omphalodes verna, Helleborus foetidus, H. x hybridus, Corydalis solida, Trillium, Chionodoxa luciliae, Hyacinths, Scilla, Pulmonaria rubra (Red Lungwort) are in full bloom. Forsythia is in full bloom in a few areas, where there is full sun, but the majority of Forsythia is in beginning bloom. The flower buds of some Magnolia stellata trees that are growing in full sun, have developed and are white, but have not yet started to open. Hopefully, warmer weather which is forecast for this weekend will bring the magnolias and other plants into bloom. Early daffodils are in full bloom but the majority have yet to open. Petasites japonicus (Japanese butterbur) and Dicentra cucullaria (Dutchman's breeches) are beginning bloom.

Lawns continue to green up and clean ups continue. Driving around Plymouth County, it is amazing to see the number of downed trees and branches from the March nor’easters, still needing to be removed. Hanson has recorded 108 GDD at base 40.

Pests/Problems:  Winter moth caterpillars should be at an all-time low in most areas this year. However, continue to monitor susceptible plants like blueberry, apple, maples, oaks and crabapples and manage if found. For complete information, see the Insect Section of the Landscape Message.

Monitor hemlocks, fir and spruce for elongate hemlock scale (Fiorinia externa), which may cause significant damage and is difficult to manage: https://ag.umass.edu/home-lawn-garden/fact-sheets/elongate-hemlock-scale

Continue to monitor eastern and Canadian hemlocks for the white, cottony egg masses of hemlock woolly adelgid (HWA). HWA may cause significant damage and, ultimately, death to eastern and Canadian hemlocks if found and left untreated. https://entomology.ca.uky.edu/ef452

Deer ticks continue to be a concern to anyone working or active outdoors, especially in areas where ticks are usually found (grassy fields, leaf litter, etc). See the Insect Section of the message for more information. Bittercress continues to bloom. Deer continue to browse rhododendrons, hollies, tulips, and other ornamentals.

Usually carpenter bees, bumblebees, honeybees, solitary bees, snowball aphids and chipmunks are active at this time, however, no sign of them yet - probably waiting for warmer weather - aren’t we all?.

North Shore (Beverly)

General Conditions:  The weather this reporting period was variable with snow, rain and sunshine occurring at some times. It was unseasonably cold for this time of the year with average temperatures in low to mid 40s. 

Winter-like weather occurred on Sunday morning and overnight into Monday bringing snow and sleet with some slight accumulation on grassy areas. Approximately 1.02 inches of rain were received at Long Hill during this period with most of the rainfall occurring on Monday April 16. During this reporting period we accumulated 9 growing degree days at Long Hill. All of the degree day accumulation occurred on Friday April 13. Woody plants beginning to bloom or in bloom include: Red maple (Acer rubrum), Cornelian Cherry Dogwood (Cornus mas), Anise Magnolia (Magnolia salicifolia), ‘Golden Times’ Forsythia (Forsythia giraldiana), Winter honeysuckle (Lonicera x purpusii), February Daphne (Daphne mezereum), ‘Winterthur’ winterhazel (Corylopsis winterthur), Pieris (Pieris floribunda), and Fragrant viburnum (Viburnum farreri) . Non woody plants seen in bloom include: Siberian squill (Scilla siberica) and Puschkinia (Puschkinia libanotica), Glory of the Snow (Chionodoxa), Hellebores (Helleborus orientalis), and mini daffodils (Narcissus sp.).

Pests/Problems:  The heavy rains and winter-like weather is slowing down the spring cleanup and pruning. The heavy rains also caused some soil erosion in some areas. Fungal leaf spot of mountain laurel continue to be observed on some shrubs in the landscape. Cultural practices that promote plant vigor such as proper watering, fertilizing, properly timed pruning and raking and removing fallen leaves in the fall can help in the management of the disease. Yellow buttercup weed (Ranunculus ficaria) is starting to bloom on lawns. Ticks are active. Take precautions when working outdoors, like applying repellents such as DEET.

East Region (Boston)

General Conditions:  The past week has again been unseasonable. The weather continues to vary with snow flurries on the 15^th, to downpours on the 16^th and ending with sun on the 18^th. Cool conditions have prevailed with highs averaging 53°F and lows averaging 36°F. The highlight of the week was Friday the 13^th as temperatures reached 68.5°F and we accumulated 8 GDDs, the total gain for the week. We have gained 41.5 GDDs for the year and 201 GDDs (base 40). Overcast and cloudy conditions dominated over the last week. A storm on the 15^th and 16^th delivered 2.68 inches of rain most of which fell on the 16^th and included heavy downpours. This storm left the landscape moist and low-lying areas flooded. The lack of both sunny conditions and warm temperatures has left the landscape dreary as we await spring. Buds are slowly swelling but there remains very little leaf out at this time. Even turf has yet to green up!

Plants coming into bloom: Anemone nemorosa (European wood anemone), Corylopsis glandulifera (winter hazel), C. sinensis var. calvescens (Chinese winter hazel), Forsythia x intermedia cultivars ‘Courdijau’ GOLDEN PEEP™ and ‘Spectabilis’ (border forsythia), F. suspensa (weeping forsythia), Lonicera standishii (Standish honeysuckle), L. x purpusii (Purpus honeysuckle), Magnolia salicifolia ‘Grape Expectations’ (willow-leaved magnolia), M. stellata ‘Centennial’ (star magnolia), Narcissus sp. (daffodil), Prunus incisa forma serrata (Fuji cherry), Rhododendron dauricum (Dahurian rhododendron), R. mucronulatum ‘Cornell Pink’ (Korean rhododendron), and R. sichotense. Still going strong are many bulbs: Chionodoxa sp. (glory-of-the-snow), Crocus sp. (crocus), Galanthus elwesii (greater snowdrop), G. nivalis (snowdrop), Puschkinia scilloides (striped squill), and Scilla siberica (Siberian squill). Putting on a spectacular show on Bussey Hill at this time is Rhododendron praevernum (February rhododendron).

Pests/Problems:  The cool temperatures and overcast conditions have slowed weed seed germination. Biennial rosettes continue to develop such as Alliaria petiolata (garlic mustard) and Chelidonium majus (greater celandine). The winter annual Cardamine hirsuta (hairy bittercress) remains in full bloom. The winter perennial Ficaria verna (lesser celandine) continues to grow making it visible amongst dormant turf and in mulched beds. Acer sp. (maple) has just germinated as the cotyledons of new seedlings are popping up throughout the landscape. Winter moth has not yet been observed on susceptible Malus sp. (crabapple) species just beginning to leaf out.

Metro West (Acton)

General Conditions:  Winter-like weather continued into this reporting period with a snow/sleet combination event on Sunday and wet snow falling again overnight into Monday morning lightly covering the landscape. And just when we haven’t had enough, weather forecasters are predicting a snow rain mix for later this week! Yes indeed, we are having a good winter this spring. As the proverb says, April showers, bring May flowers. The average rainfall total for the month of April is 4.16” and I have recorded 3.19” for this month so far. 2.06” of that total was recorded on Monday, Patriots Day. Despite the cool damp weather, 8.5 GDD were recorded this past week on Friday the 13^th with a high of 72° F. Observed in bloom this past week were the following woody plants: Acer rubrum (Red Maple), Acer saccharinum (Silver Maple), Cornus mas (Cornelian cherry dogwood), C. officinalis (Japanese Cornelian cherry), Forsythia spp. (Forsythia), and Pieris japonica (Japanese Pieris).The following bulbs and herbaceous plants were seen in bloom: Adonis amurensis (Adonis), Chionodoxa luciliae (Glory of the Snow), Crocus spp. (Crocus), Galanthus nivalis (Snowdrop), Helleborus niger (Christmas Rose), Narcissus spp. (Daffodil), Petasites japonicus (Japanese Butterbur), Pulmonaria longifolia (Lungwort), P. rubra (Salmon colored Lungwort), Puschkinia libanotica (Striped Squill), Scilla siberica (Siberian Squill), Symplocarpus foetidus (Skunk Cabbage), Vinca minor (Periwinkle) and Viola spp. (Violet). Landscape crews are out in full force completing spring and winter storm clean ups, planting pansies and spreading mulch.

Pests/Problems:  With the recent heavy rain event on Monday the 16^th, there has been some erosion and soils are well saturated. Much woody debris ranging in sizes from whole trees to branches remain scattered throughout the landscape from the March nor’easters. Clean up has been challenging and slow.

Central Region (Boylston)

General Conditions:  Spring is still struggling to make an appearance this year. A very cool and wet start with a total 3.85” of precipitation coming in a mix of heavy rain, slushy snow, and a bit of sleet and freezing rain. Only a few more spring blooming plants can be added to last week's list - Liverwort (Hepatica nobilis), additional Daffodil cultivars such as Narcissus ‘Jetfire’, Narcissus ‘Rip Van Winkle’, and Narcissus ‘Tete et Tete’ to name a few.

Many of the early bloomers have been in a holding pattern, continuing to bloom for a longer duration than normal. Finally ending their bloom are Winter Aconite (Eranthis hyemalis), Witchhazels (Hamamelis spp.), and the snowdrops are just starting fade.

Pests/Problems:  Deer activity remains high and rains have contributed to decreasing the longevity of repellants applied, requiring additional applications. Soggy soils persist and heavy rains have created washouts along road edges and on gravel paths. Great blue heron, wood ducks, and turkey vultures have been spotted.

Pioneer Valley Region (Amherst)

General Conditions:  What a fickle April this has been so far, as the rollercoaster of spring weather continued over this past reporting period. We experienced one of the nicest days of 2018 on Friday, April 13 when temperatures peaked at 74°F and there was plentiful sunshine. Only two days later, on Sunday, April 15 the high reached only 35° F and was accompanied by full cloud cover and blustery winds. Such is life in New England. Patriots’ Day was no better, with rainfall that can only be described as fierce. Waves of intense rain pummeled the valley, with total accumulations ranging from 1.75 – 2.5” across the tri-county region. Swollen creeks and streams with localized urban and suburban flooding ensued, but nothing out of the ordinary for spring in the Connecticut Valley. On the bright side, we creep ever closer to May, which is often one of the nicest months of the year. Rosaceous hosts like apple, crabapple and serviceberry continue to slowly leaf out, tempted by the few warm days but then delayed by the continued wind and cold. The long-term forecast predicts warmer temperatures and additional rainfall. Soils are again wet at this time, but conditions are still good for transplanting once soils dry a bit from the recent deluge. Buds are swelling on landscape conifers, such as hard pine, Douglas-fir, true fir, spruce, yew and hemlock. Lawn grass continues to green and is surprisingly mowable in some locations. Soil temperatures have held mostly steady since last week, with the full sun reading hovering in the middle 40s while the shade reading still lingers just below 40° F.

Pests/Problems:  The continued cool weather means that pathogen pressure still remains low at this time. Pruning of cankered and blighted stems and branches during spring clean-ups can help to avoid infections of new succulent stems produced later this spring and early summer. In many landscapes, it appears that decisions need to be made regarding the fate of recently transplanted broad-leaved evergreen shrubs like azalea, rhododendron, mountain laurel and holly, among others. These plants were badly burned by the extreme cold temperatures the region experienced as we welcomed in 2018. The decision to replace or nurse them back to respectability is not an easy one. Winter injury is common for these plants, but when any tree or shrub is recently transplanted, their ability to naturally harden off for cold weather is affected, making them more sensitive compared to established plants. One option for treatment against secondary foliar and stem blight pathogens that may colonize the burned foliage is OxiPhos (Phosphorous acid + hydrogen peroxide). Phytotoxicity trials using azalea at the UMass greenhouse in 2017 showed no injury after multiple foliar applications at varying rates.

Berkshire Region (Great Barrington)

General Conditions:  And the beat goes on. Another week of yo-yo weather with a low temperature of 21° F on the morning of April 12th and the high temperatures rising to 66° F on April 13th and 62° F on the 14th before dropping precipitously on the night of the 14th down to 32° F. A mix of wet snow, sleet, and freezing rain occurred on Patriot’s Day, April 16th. What made matters worse were the strong, gusty winds which brought down numerous trees and branches and caused many power outages throughout the county. It should be noted that many of the toppled trees showed signs of internal decay. A light, wet snow also occurred on the night of April 17, leaving a light coating on turfgrass areas. There are still remnants of the early March snow on wooded hillsides and shady sites. Plant development has been slow with mostly spring bulbs in bloom. Daphne mezereum has been in bloom for a week or so and remains in bloom. Bud swell can be seen on forsythia and magnolias but no flower buds are yet open. With the frequent precipitation, soil moisture levels are very high; soils are saturated and subject to compaction if traversed by feet or tires. Yet, much tree and shrub planting is taking place. Lawns are steadily greening but growth has been slow and there is no need to begin mowing.  

Pests/Problems:  No new pest development has been observed or reported. Deer ticks remain a concern and precautions should always be taken when working outdoors. Deer, rabbit and vole damage to landscape plants is the most common problem at this time. Perhaps the main problem now is avoiding activities which will result in compacted soils. As noted above, soils are saturated.

Regional Scouting Credits

• CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
• SOUTHEAST REGION - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, reporting from Hanson.
• NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
• EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.
• METRO WEST REGION - Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
• CENTRAL REGION  - Dawn Davies, Interim Horticulture Manager, reporting from Tower Hill Botanic Garden, Boylston.
• PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
• BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals

Diseases

Leaf and stem blight of bearberry (Arctostaphylos uva-ursi ‘Massachusetts’) caused by Pestalotiopsis, Phomopsis and Cytospora. One-year-old plant from a nursery that exhibited purple-colored spots and blotches on the foliage and blackened shoot tips. The low, overlapping nature of growth exhibited by this plant coupled with constant overhead watering in the nursery contributed to disease development.

Winter burn and Volutella leaf and stem blight of common boxwood (Buxus sempervirens). A boxwood parterre that was established 10 years ago has experienced repeated problems in recent years. New stock that was planted in 2017 died over the winter with browning leaves and shoot dieback. Boxwood mite has been an issue in the past but has been treated. There was no evidence of the boxwood blight pathogen, Calonectria, from the submitted sample. Plants are provided supplemental water through both drip and overhead irrigation. Overhead irrigation should not be used with boxwoods, regardless of the setting, as disease problems often develop due to the repeated introduction of free moisture onto above ground tissues.

Transplant shock and winter burn of Norway spruce (Picea abies). Trees are eight-years-old and were transplanted last summer. The site has full sun and clay soils, with supplemental irrigation provided by lawn sprinklers. The 2017 growth was stunted and brown while the 2016 growth was mostly unaffected. Not all of the trees are damaged, with some specimens showing the injury while nearby trees appear healthy.

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:

• 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 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? If so, consider sending the tick to the UMass Laboratory of Medical Zoology to be tested for disease causing pathogens. To submit a tick to be tested, visit: https://www.tickreport.com/ and click on the 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.

• Winter Moth: (Operophtera brumata) The winter moth population is at a record low! The 2018 outlook concerning winter moth caterpillar population numbers in Massachusetts is very positive for those of you in the eastern areas of the state accustomed to dealing with damaging populations of this insect. Dr. Joseph Elkinton, Professor of Environmental Conservation at the University of Massachusetts, Amherst, MA, has excellent news: data from his lab’s research locations in eastern Massachusetts suggest that this invasive pest’s population size is at an all-time low. In fact, the 2017 winter moth population was the lowest they have seen since studying and working toward the biological control of this insect for the past 13 years. The populations of winter moth are so low in Massachusetts at this time, that Dr. Elkinton’s lab and scouts for UMass Extension’s Landscape Message are having a very difficult (to impossible) time locating winter moth eggs to monitor egg color change, development, and hatch for the 2018 season.

Spring has been cool thus far, and many eastern MA locations where winter moth has historically been a problem are still slowly accumulating growing degree days. Over the weekend, UMass Extension’s Fruit Program reports that McIntosh apple green tip has been observed in Belchertown, MA. See the image of McIntosh apple green tip observed on 4/17/18 here: http://ag.umass.edu/fruit/bud-stages/current-bud-stages-april-17-2018 . This can be a great phenological indicator of winter moth egg hatch. That being said, reports from a blueberry grower in Hanson, MA indicate that on 4/18/2018, of the limited 20 eggs she has available to monitor on a banded tree, the eggs are still orange at this time. Reports from a blueberry grower in Franklin, MA mention that on 4/18/2018, 10 of approximately 60 eggs have turned blue on the south side of a single tree being monitored. On the remaining area of that same tree, the other approximately 50 eggs are orange at this time. The report indicates that it took about 1 and ½ weeks for the eggs on the south facing side of the tree to turn blue. With the mostly cool, but fluctuating, spring temperatures this year, winter moth egg hatch is slowly beginning in Massachusetts. Winter moth egg hatch timing will vary depending upon the eastern MA location, and can vary at a single site. Areas with winter moth around Boston, which have accumulated more degree days than areas like Cape Cod or the Southeast Region, may be further along with the egg hatch process than the cooler eastern MA locations. For region-specific information, see the Scouting Reports above.

Those protecting blueberry and apple crops in eastern Massachusetts should be vigilant, even with the low winter moth population numbers, and continue to plan crop protection accordingly. In landscape settings in eastern Massachusetts, there may still be pocketed areas where ornamental trees and shrubs also need protection from winter moth in 2018. For protection in landscapes, it is best to wait until the leaves of susceptible hosts completely unfold and monitor for feeding caterpillars, prior to treatment, especially since populations in Massachusetts are so low this year.

The eggs of this insect, if they can be found, were laid by the females who emerged in November of 2017 and were active through the winter months (mainly November through December when temperatures are above freezing). Eggs are currently present in the landscape and hidden in cracks and crevices of bark or beneath lichen on host plants such as oak, maple, apple, blueberry, crabapple, etc. Eggs are tiny and green when first laid, but quickly turn a red-orange color soon after. As the egg develops, it will turn a bright blue color, shortly prior to egg hatch. Reports from Rhode Island indicate that 30-50% of eggs at sites being monitored in their state have turned blue or hatched as of 4/18/2018. In Rhode Island, egg color change and hatch has been slowly and steadily occurring whenever warmer temperatures are available. The prolonged time period for egg hatch can make management of winter moth in blueberry and apple crops difficult. For more information about the life cycle and management of winter moth, please visit thisfact sheet: Winter Moth Identification and Management https://ag.umass.edu/landscape/fact-sheets/winter-moth-identification-management .

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

This fact sheet also includes updates regarding the progress of the work of Dr. Joseph Elkinton’s laboratory group at the University of Massachusetts and their efforts toward the biological control of winter moth using Cyzenis albicans, a tachinid fly. The fly parasitizes the caterpillars of winter moth specifically. In other areas, such as Nova Scotia where winter moth was also problematic, this fly used for biological control has been successful in reducing winter moth to a non-pest. C. albicans has been released across 43 sites in Massachusetts and has been established in at least 32 of those locations as evidenced through the recovery of flies in winter moth in subsequent years. The Elkinton Lab now has data showing that at six of these locations (Falmouth, Hanson, Hingham, Wellesley, Wenham and Yarmouth, MA) the fly populations have increased alongside an observed decrease in the winter moth population there. For more information about the progress of winter moth biological control in Massachusetts, visit the following article in Hort Notes found under “Trouble Maker of the Month”, here: https://ag.umass.edu/landscape/newsletters/hort-notes/hort-notes-2018-vol-292 .

• Gypsy Moth: (Lymantria dispar) The outlook for the 2018 season in regard to gypsy moth is significantly better than it would have been if Entomophaga maimaiga didn’t infect the gypsy moth caterpillar population in late June of 2017. At that time, many dead caterpillars were seen hanging from tree trunks and branches, killed by the fungus, which was aided by the wet spring weather earlier in the year. Need a reminder of what that looked like? Go to https://ag.umass.edu/landscape/news/gypsy-moth-caterpillars-dying-across-massachusetts . Unfortunately, prior to the fungal epizootic, gypsy moth caterpillars were able to defoliate over 923,000 acres across Massachusetts in 2017, according to the MA Department of Conservation and Recreation. For a map of where this occurred, visit: https://www.mass.gov/guides/gypsy-moth-in-massachusetts .

Egg masses laid by female moths in 2017 can be seen at this time. This is the stage of the insect that overwinters. 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.

Egg hatch for this insect is not yet upon us, and occurs after winter moth egg hatch. 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. This can also coincide with serviceberry (Amelanchier) bloom. After egg hatch occurs, 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, however egg masses may be present on nearby oaks, for example, and provide a local population of caterpillars.

Now (roughly until before the last week in April) is a great time to scout the landscape and count the number of gypsy moth egg masses present not only on valuable landscape specimens that are hosts for this insect, but on nearby forested hosts such as oak which might provide sources of ballooning caterpillars. Egg mass counts can help us make decisions regarding whether or not to manage for this insect. Some individuals also use this opportunity to scrape egg masses into a container of soapy water, although this is time consuming and some egg masses will be missed.

Despite the fungal outbreak that swept through the 2017 caterpillar population, some lucky caterpillars survived to pupation and emerged as adult moths. (However, adults were present in far fewer numbers than would have existed without the fungus.) While it is very difficult to predict how much defoliation Massachusetts will see in 2018 due to gypsy moth caterpillar feeding, we can be certain that in areas where many egg masses are currently seen overwintering, pockets of defoliation could still occur in certain areas of the state this year. Thanks to the gypsy moth caterpillar-killing fungus, however, the population should be on the decline, but we cannot expect the caterpillars to disappear completely from Massachusetts landscapes this season.

• 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. These particular signs of damage from the beetle may be more visible at this time of year, when host trees such as maples are leafless. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity.

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

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 .

• 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.

• 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. Dormant oil applications for this insect can occur in April, or roughly between 7-120 GDD’s, base 50°F.

• Emerald Ash Borer: (Agrilus planipennis, EAB) 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 most recently, has been reported in cultivated olive (Olea europaea). Adult insects of this species will not be present at this time of year. Signs of an EAB infested tree may include (at this time) D-shaped exit holes in the bark (from adult emergence in previous years), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in the bark, from larval feeding beneath. Positive identification of an EAB-infested tree may not be possible with these signs individually on their own.

For further information about this insect, please visit: https://ag.umass.edu/fact-sheets/emerald-ash-borer . If you believe you have located EAB-infested ash trees, particularly in an area of Massachusetts not identified on the map provided, please report here: http://massnrc.org/pests/pestreports.htm .

• 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.

• Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. Infested trees may be treated with a dormant application of horticultural oil when weather conditions allow. Foliar sprays can occur 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.

• Lily Leaf Beetle: Lilioceris lilii overwintering adults have been spotted by scouts in central Massachusetts (Worcester County) during recent spring clean-up activities. Adults prefer to over winter in such sheltered places, like in soil or plant debris in the garden or in the woods, and not always in close proximity to host plants. As daily temperatures begin to rise and 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 will begin 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 this time.

• Magnolia Scale: Neolecanium cornuparvum is a species of soft scale insect (Family: Coccidae) that is native to the eastern United States. Adult female magnolia scales can measure up to ½ inch or more in length.Host plants include Magnolia stellata (star magnolia), M. acuminata (cucumber magnolia), M. lilliflora ‘Nigra’ (lily magnolia; formerly M. quinquepeta), and M. soulangeana (saucer magnolia). Other species may be hosts for this scale, but attacked to a lesser degree. M. grandiflora (southern magnolia) may be such an example. This scale overwinters as a young nymph (immature stage) which are elliptical in shape, mostly a dark-slate gray, except for a median ridge that is red/brown in color. These overwintering nymphs may be found on the undersides of 1st and 2nd year old twigs. The first molt (shedding of the exoskeleton to allow growth) can occur by late April or May in parts of this insect’s range, and the second molt will occur in early June. A dormant oil application may be used to target nymphs that are overwintering between 7-35 Growing Degree Days, base 50°F.

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

• Spotted Lanternfly: (Lycorma delicatula, SLF) is not known to occur in Massachusetts. This insect is a member of the Order Hemiptera (true bugs, cicadas, hoppers, aphids and others) and the Family Fulgoridae, also known as planthoppers. This insect is a non-native species first detected in the United States in Berks County, Pennsylvania and confirmed on September 22, 2014. Until November 2017, this invasive insect was only known to Pennsylvania. It has now been reported from Delaware (November 20, 2017), New York (November 29, 2017), and most recently in Virginia (January 10, 2018). The Delaware Department of Agriculture announced the finding of a single female spotted lanternfly in New Castle County in the Wilmington, Delaware area. At this time, officials in Delaware note that it is unclear if this individual was an accidental hitchhiker, or evidence of an established population in the state. For more information about the find in Delaware, visit: https://news.delaware.gov/2017/11/20/spotted-lanternfly-confirmed-delaware/ . The New York State Department of Agriculture and Markets reported on November 29, 2017 the finding of a single dead individual spotted lanternfly in the state from earlier in the month. A single dead specimen was confirmed at a facility in Delaware County, New York, which is located south-west of Albany. The NYS Dept. of Agriculture and Markets states that this dead individual may have come in on an interstate shipment. For more information about the find in New York, visit: https://www.agriculture.ny.gov/AD/release.asp?ReleaseID=3637 . Most recently, Virginia Cooperative Extension announced the finding of a spotted lanternfly population in Frederick County, Virginia, on January 10, 2018. It was noted that at the location in Virginia, numerous adult lanternflies and egg masses were discovered, in addition to more at another site approximately 400 yards away. For more information about the find in Virginia, visit: https://ext.vt.edu/agriculture/commercial-horticulture/spotted-lanternfly.html .

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

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

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

Host plants, bricks, stone, lawn furniture, recreational vehicles and other smooth surfaces can be inspected for egg masses. Egg masses laid on outdoor residential items such as those listed above may pose the greatest threat for spreading this insect via human aided movement.

For more information about the spotted lanternfly, visit this fact sheet: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly .

• Spruce Spider Mite: Oligonychus ununguis is a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir and occasionally other conifers. This particular species becomes active in the spring and can feed, develop and reproduce through roughly June. When hot, dry summer conditions begin, this particular 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 is now overwintering in the twigs of the host plant as eggs, which will 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-wintering 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. Removal and destruction of infested stems, if small in number, can help reduce populations of this insect pest. If management this way is not possible, larvae 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 Pine Weevil: Pissodes strobi is a pest of eastern white pine, spruce, hemlock and occasionally Douglas-fir. Adults overwinter in leaf litter near susceptible hosts. Mating occurs on host plant leaders and females excavate round holes in the bark and may deposit 1-5 eggs in the cavity created. A plug of chewed bark is then used to fill the hole. On susceptible hosts that have shown white pine weevil damage in recent seasons, or where the rust-colored weevils with long snout-like “noses” are detected, adult females may be targeted for management between 7-58 GDD’s, base 50°F or just before forsythia bloom.

• 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 .

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

Plant of the Week

One of spring’s early bloomers, the PJM Rhododendron group also offers evergreen foliage and good winter hardiness. https://extension.umass.edu/plant-identification/pjm-rhododendron-group

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

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