Landscape Message: April 6, 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 4, 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 (2-Week Gain)	Time/Date of Readings
	2-Week Gain	2018 Total	Sun	Shade
Cape Cod	0	3.5	45	40	1.43	3:00 PM 4/4
Southeast	4	10	47	45	2.50	5:10 PM 4/4
North Shore	3	17	40	37	0.54	10:00 AM 4/4
East	5	33.5	43	42	0.90 (includes 1.1" snow)	12:00 PM 4/4
Metro West	2	15.5	38	35	1.63	6:00 AM 4/4
Central	n/a	n/a	n/a	n/a	n/a	n/a
Pioneer Valley	0	15	42	40	0.84	11:00 AM 4/4
Berkshires	0	15	38	36	0.67	9:00 AM 4/4
AVERAGE	2	16	42	39	1.22	-
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.
Pieris japonica (Japanese Pieris)	Begin	Begin	Begin	Begin/Full	*	*	Begin	*
Cornus mas (Cornelian cherry Dogwood)	Begin	Begin	Begin	Begin	*	*	Begin	*
Acer rubrum (Red Maple)	*	*	Begin	Full	*	*	Begin	*
Acer saccharinum (Silver Maple)	*	End	Begin	Full/End	*	*	Begin/Full	*
Hamamelis mollis (Chinese Witchazel)	Full/End	Full/End	Full	End	Full/End	*	Full/End	*
Hamamelis x intermedia (Witchhazel hybrids)	Full/End	Full/End	Full	Full/End	Full/ End	*	Full/End	Full/End
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: Over the last two weeks the temperature has averaged 40° F with a high of 57° F on April 1 and a low of 26° F on April 3. Precipitation has been mixed with both occasional rain and snow showers totaling 1.43 inches since the last message. Overall the period has been dominated by cloudy or partly cloudy days, with a few sunny days mixed in. Topsoil moisture is adequate to excessive as are subsoil moisture conditions.

Pests/Problems: The cleanup from the string of storms in March continues, the sound of chainsaws can be heard anytime it isn’t raining or snowing and sometimes even when it is. There are a large number of pitch pine, Pinus rigida that have been uprooted or have damaged crowns from the storms. The damage is likely to attract black turpentine beetle, Dendroctonus terebrans. 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. Bittercress, Cardamine hirsute, can be found with flowers in various protected or southerly facing locations.

Southeast Region (Hanson)

General Conditions: The last two weeks of March into April were mostly cold, overcast and windy. Plant development is behind. Hanson received 2.25 inches of rain. Five inches of light, fluffy snow fell on the morning of April 2^nd, but it melted by 5 PM that day.

Abeliophyllum distichum (white forsythia), Daphne mezereum (February Daphne), Crocus, Scilla sibirica, and snowdrops are in full bloom. Winter aconites are past bloom. Cornus mas (Cornelian-cherry dogwood), Lonicera fragrantissima (Winter honeysuckle) Omphalodes verna, Helleborus x hybridus, Helleborus foetidus, Corydalis solida are beginning bloom. This is late for these plants some of which are often in bloom in March and sometimes, as early as February. There appears to be damage to the flower buds of Hydrangea macrophylla, Abeliophyllum distichum, Corylopsis spicata and even Helleborus x hybridus and Helleborus foetidus, resulting in reduced flowers or blasted buds. This may be the 3^rd or 4^th year in a row that Hydrangea macrophylla flower buds will have been blasted due to cold weather. The damage to the flower buds was probably caused by the early and extended cold weather and low temperatures in December through January.

Flower buds are swelling and showing a bit of color on Forsythia, Magnolia stellata and Chaenomeles. Lawns are slowly greening up and peepers are peeping; hopefully signs that warmer, spring-like weather is on the way.

Pests/Problems: The biggest landscape problem right now may be cleaning up after the nor’easters that plagued the area this past winter. There are so many trees down, broken branches and many areas remain littered with branches and debris.

Winter moth eggs have not hatched yet according to reports coming in (see the Insect Section of the Landscape Message below). At the Hanson site, there are no eggs to monitor for the first time in many, many years. This is a good thing! Hopefully, winter moth caterpillars will not be a problem in most areas this year, however, people growing apples and blueberries need to remain vigilant, as it does not take many winter moth caterpillars to cause crop damage.

Continue to monitor for Hemlock Wooly Adelgid and if found, manage when weather conditions permit. Monitor ornamental and fruit-bearing cherries, plums and other susceptible plants in the Prunus genus, for black knot disease. Black knot disease is very visible at this time, and if found, prune out and destroy the “black knots”. For more information: https://ag.umass.edu/landscape/fact-sheets/black-knot-of-prunus

Foliar burn, due to low temperatures, high winds etc., is starting to show up on hollies and other evergreens. Deer continue to heavily browse favorite plants.

North Shore (Beverly)

General Conditions: The two weeks since the last message were unseasonably cold with average temperatures ranging from the mid 30s to the low 40s Fahrenheit. The weather forecast called for a fourth nor’easter in the last week of March but fortunately the storm did not materialize and brought less than an inch of snow. Monday, April 2nd brought in the first snow of the month with about an inch of accumulation, mostly on grassy areas. The snow is now completely melted and the ground is completely devoid of snow. We have experienced a number of days of precipitation and the soils are very moist and not suitable to be worked until they dry out. The cold weather in the last several weeks has significantly slowed down the flowering of most plants that bloom during this time of the year. However there are signs of spring in the landscape with some plants blooming or starting to bloom. Woody plants seen in bloom or beginning to bloom include Cornelian Cherry Dogwood (Cornus mas), Goat willow (Salix caprea), February daphne (Daphne mezereum), Chinese witchhazel (Hamamelis mollis), Arnold promise witchhazel (Hamamelis x intermedia), American Filbert (Corylus americana) and Viburnum farreri. Early spring flowering bulbs seen in bloom include: Siberian squill (Scilla siberica) and Puschkinia (Puschkinia libanotica), Glory of the Snow (Chionodoxa), Snowdrops (Galanthus spp.) and Hellebores (Helleborus orientalis).

Pests/Problems: Deer browsing continues to be observed in the landscape especially on young yew shrubs (Taxus spp.). Vole activity has also been observed on lawns. Cleaning up from the damage caused by March storms that brought heavy snow and high winds continues. Homeowners and landscapers have been busy pruning off damaged branches and removing downed trees. Winter burn is seen on some broad leaved evergreens such as boxwood (Buxus spp.) and some rhododendrons and azalea (Rhododendron spp.). Fungal leaf spots are widely observed on mountain laurel (Kalmia latifolia) and browning of needles of white pines (probably caused by some of the needle pathogens) is also seen in some areas.

East Region (Boston)

General Conditions: At the end of the last message, we were awaiting snow as the fourth nor’easter approached. Fortunately, the storm delivered only half an inch of snow and a few showers accounting for only 0.10 inches of rain equivalent. March was unseasonably cool averaging 37° F, the same average temperature as February. March high temperatures ranged from 37° F to 65° F and low temperatures ranged from 27° F to 44° F. We hit a high of 65° F on March 30^th, accumulating 5.0 GDDs, the only gain since March 1^st. A cool stormy weather pattern returned in early April as snow fell on the morning of the 2^nd. Half an inch accumulated in the landscape, but by the afternoon all had melted away. Cooler temperatures are predicted to continue into next week. Magnolia buds have begun to swell. A few early bloomers, Magnolia sprengeri (Sprenger's magnolia) and Magnolia zenii (zen magnolia) and cultivar M. z. 'Pink Parchment' began to open on the 1^st. The cold temperatures and snow accumulation on the 2^nd caused minor cold damage to these magnolia blooms. The landscape is slowly beginning to green up as Ribes sp. (currant) and Prinsepia sinensis (cherry prinsepia) have leafed out. Some Lonicera sp. (honeysuckle), Viburnum sp. (viburnum) and others are just beginning to leaf out. Many early flowering shrubs are beginning to flower: Abeliophyllum distichum (Korean abelialeaf, white forsythia), Cornus officinalis (Japanese cornel dogwood), Corylopsis coreana (winter hazel), Corylopsis sinensis var. calvescens (Chinese winter hazel), Daphne mezereum f. alba (white February daphne), Forsythia ovata (early forsythia, Korean forsythia), Hamamelis japonica 'Tsukubana-kurenai' (Japanese Witch-hazel), Lonicera x purpusii (Purpus honeysuckle), Lindera obtusiloba (Japanese spicebush), and Viburnum x bodnantense 'Dawn' (bodnant viburnum). Several species of Alnus sp. (alder), Betula sp. (birch), and Ulmus sp. (elm) are in flower. Bulbs in bloom include: Chionodoxa sp. (glory-of-the-snow), Crocus sp. (crocus), Galanthus nivalis (snowdrop), and Scilla siberica (Siberian squill). Along the meadow’s edge Symplocarpus foetidus (eastern skunk cabbage) has emerged. The distinctive Petasites japonicus (fuki) is in full bloom.

Pests/Problems: Scattered branches remain throughout the landscape as storm cleanup continues. Bud development has slowed due to the recent cooler temperatures. Alliaria petiolata (garlic mustard) rosettes are leaving out and visible in mulched beds. Allium vineale (wild garlic) continues to flourish. The winter annual Cardamine hirsuta (hairy bittercress) is in full bloom. A number of annual weeds have germinated as cotyledons can be seen emerging from the soil. Scouting for Viburnum leaf beetle (Pyrrhalta viburni) egg masses continues in an effort to remove egg masses before plants leaf out.

Metro West (Acton)

Metro West (Acton)

General Conditions: When writing this landscape message just two weeks ago, the landscape was covered in a thick blanket of snow and a fourth nor’easter was bearing down on us and predicted to hit this area in a matter of hours. Luckily, the nor’easter did not materialize and fondly was referred to as the no’easter. Today most of that blanket of snow has melted with the exception of a pocket or two of snow here and there. With the snowmelt, some of the early signs of spring have come to reveal themselves, including flowering Crocus spp., Galanthus nivalis (Snowdrop), and Petasites japonicus (Japanese Butterbur). Others signs of spring observed in the landscape are buds swelling on Acer rubrum (Red Maple), Forsythia spp. and also heard were the sounds of peepers in the early evening hours.

Pests/Problems: Storm debris cleanup has begun in earnest now that the snow has melted and the woody debris is accessible. Despite the efforts, the landscape continues to be a mess. Uprooted, windthrown trees and trees with hangers and breaks of all sizes, some exposing heartwood, others not, are scattered throughout the landscape.

Central Region (Boylston)

No report available this week.

Pioneer Valley Region (Amherst)

General Conditions: We’ve turned the calendar into April, but the cool and unsettled weather has continued since our last report. We’ve had a mixture of sunny days with temperatures above 50° F along with overcast days with rain and temperatures lingering in the upper 30s to lower 40s. The National Weather Service reported that at several major weather stations in Massachusetts, the mean February temperature was higher than the mean March temperature. The valley received some needed precipitation over the past week, in the form of wet snow and rain. The snowfall on Monday, April 2 was for many the epitome of variable spring weather in New England. The snow was heavy at times and accumulated on non-roadway surfaces throughout the morning. However, by late afternoon it was mostly sunny and the snow had long since melted. The lack of precipitation throughout much of March and persistent spring winds left many surface soils in exposed areas somewhat dry, although soil moisture was still plentiful at depths beyond 3-4″. The recent precipitation has erased this problem and lawn grasses are greening rapidly. Soil temperatures have increased steadily since our first report in late March, and now hover near 40° F at the UMass monitoring site. While the minimum soil temperature threshold for new root growth varies widely by plant and site conditions (e.g. soil type, elevation, soil moisture, etc.), several studies have shown that temperatures above ~43° F are generally necessary for new root development for trees and shrubs at our northern latitude. In general, conditions are ideal right now for new spring plantings with moist but not wet soils and cool temperatures that will help minimize shock. Plants that are afforded an entire season to regain lost root tissue before autumn will be better suited to establish given the many stresses associated with transplanting. Buds on trees and shrubs that flush new growth early, such as honeysuckle, serviceberry, forsythia and elm are swollen or breaking at this time. We have gained substantial amounts of daylight in recent weeks and the sun is now setting well past 7 PM.

Pests/Problems: If you manage properties with Douglas-fir that have a history of needle cast diseases (Rhabdocline needle cast and Swiss needle cast), it’s time to start planning for treatment. Scout 2017 needles for symptoms of Rhabdocline (purple to brown lesions scattered on the needle) and SNC (very small, black-colored fruiting bodies emerging from the stomata on older needles). Similarly, if Rhizosphaera needle cast is a problem on blue/white spruce and white fir, scout for purple to brown needles on blue/white spruce and browning needles or ash-grey needle tips on white fir. Fungicide treatment to protect newly developing needles should take place when new growth is approximately 0.5” long and on regular intervals until fully developed. For blue spruce that are heavily diseased with significant canopy dieback, even the most successful treatment is only likely to maintain the current appearance. Therefore, in many cases fungicide treatment will do little to improve appearance and is not warranted. Now that daytime highs can surpass 50° F, scouting for the white pine weevil should begin on susceptible conifers. Eastern white pine, Norway spruce and Douglas-fir, in decreasing order of susceptibility, are the most common hosts of this destructive insect pest in the region. Overwintering adults feed on the main stem beneath the terminal shoot, which may be difficult to access from the ground on maturing trees. Elongate hemlock scale treatment can begin when new growth starts on eastern hemlock and true fir. Carefully examine any hemlock or true fir nursery stock, on the underside of needles on the lowest canopy branches, to determine if the pest is present prior to planting.

Berkshire Region (Great Barrington)

General Conditions: For all but two days (March 30, 31), high temperatures over the past two weeks (the reporting time frame) have been at or below normal. In other words, it has been colder than normal. Plant development over this time has been very slow or non-existent. Witchhazel (Hamamelis x intermedia) has been the only woody species to have been in bloom. Snowdrops (Galathus nivalis) continue to bloom despite having been buried under snow for much of March. A few crocus (Crocus tommasinianus, C. chrysanthus) have come into bloom, along with the dwarf irises, Iris reticulata, and Iris histrioides. Species and hybrid hellebores (Helleborus) are showing floral buds but they have not yet opened except in sunny, protected sites. The period has been quite dry but soil moisture is high, being inundated with moisture from melting snow. Some snow remains in shady sites and at higher elevations. The heavy snows of early and mid-March resulted in deep piles where snow had been plowed and most of these remain. Turfgrass has been slow to green up and most lawns are quite brown.

Pests/Problems: Other than browsing by deer, rabbits, and woodchucks, and gnawing by voles, no pest problems are apparent, though it would not be unusual to find deer ticks among the packed leaf litter in landscapes and gardens. Regarding the deep snow piles, it can be expected that snow mold would be developing in the moist turf below. Spreading the snow piles and raking the matted grass would help contain this turfgrass disease. This is a good time to prune off twigs of flowering cherry and crabapple encircled with the black-brown and shiny egg masses of Eastern tent caterpillar.

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  -  Joann Vieira, Horticulturist, reporting from Princeton.
• PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
• BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals

Diseases

Recent pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab:

Shoot dieback and decline of mountain laurel (Kalmia latifolia) caused by Phomopsis and Pestalotiopsis. Two of seven plants, approximately 20-years-old, are showing symptoms of stress (yellowing and premature shedding of foliage). Symptoms began during the summer of 2017 and are worsening. The plants are mulched and irrigated and anti-desiccant is applied twice per winter. Both fungal pathogens are opportunistic and common on broad-leaved evergreen shrubs in the landscape. Stem cankering and girdling resulted in the foliar symptoms.

Oak anthracnose, caused by Apiognomonia errabunda, on swamp white oak (Quercus bicolor). Trees are six-years-old and were planted in late May of 2017. This past December, symptoms of canopy dieback were observed and included: shoot tip blight, splitting and desiccated bark, and dark red to dark brown patches of bark with underlying lesions in the sapwood. The landscaper noted poor pruning of the trees and rough handling by the nursery at the time of installation. Soils at the planting site are very wet, almost saturated. Inspection in the lab revealed numerous stem cankers with callus tissue developing on the margins. Necrotic phloem and sapwood was also abundant under the discolored bark. Stem cankering is often secondary to a foliar blight with oak anthracnose but in certain cases, the fungus can cause considerable damage as a cankering pathogen. Rough handling, transplant shock and wet soils were all stresses that facilitated disease development.

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

http://ag.umass.edu/diagnostics

Insects

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

• 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.

Heather Faubert, with the University of Rhode Island, reports far fewer winter moth eggs present at the locations she typically monitors. To date (as of 4/4/18) she has reported that less than 10% of the winter moth eggs she is monitoring are undergoing the color change from orange to blue at a location in Rhode Island. She is also monitoring sites in Connecticut and two sites in Massachusetts and all of those eggs are still orange. In her latest update, Heather Faubert notes that the eggs turning blue (not yet hatching) are outliers and that the vast majority of the winter moth eggs she is observing are still orange, and not ready to hatch.

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. At this time, anyone monitoring winter moth eggs will most likely see that they are orange in color. As the egg develops, it will turn a bright blue color, shortly prior to egg hatch. 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).

Management of winter moth in 2018 may only be necessary for high-value agricultural crops (such as blueberry) or where landscape practitioners are actively monitoring winter moth eggs and have observed numbers of eggs consistent with previous years when damage occurred. It is expected, however, that in most locations in eastern Massachusetts, a reprieve from damaging winter moth caterpillar populations will occur in 2018. That being said, pockets of activity may still be seen with this insect, so continue to refer to the appropriate Regional Reports above.

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 impact 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 also 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 (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 (roughly 120-190 GDD). 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 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.

• 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.

• 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 - 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/.

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.

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

Plant of the Week

The dwarf forms of Chamaecyparis obtusa provide a unique evergreen form to the landscape:

https://extension.umass.edu/plant-identification/hinoki-falsecypress

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

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