Landscape Message: April 13, 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 11, 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	0	3.5	45	40	0.36	4:00 PM 4/11
Southeast	0	10	43	40	0.30	7:00 PM 4/12
North Shore	0	17	39	35	0.57	9:30 AM 4/11
East	0	33.5	47	44	0.50	4:20 PM 4/11
Metro West	0	15.5	36	34	0.77	6:00 AM 4/11
Central	n/a	22	31	28	1.08	8:00 AM 4/11
Pioneer Valley	0	15	42	37	0.57	1:00 PM 4/11
Berkshires	0	15	35	35	0.65	9:15 AM 4/11
AVERAGE	0	16	40	37	0.60	-
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.
Forsythia x intermedia (Border Forsythia)	Begin	*	Begin	Begin	*	*	*	*
Rhododendron mucronulatum (Korean Rhododendron)	*	*	*	Begin	*	*	*	*
Pieris japonica (Japanese Pieris)	Begin	Begin/Full	Begin	Begin/Full	Full	Full	Full	*
Cornus mas (Cornelian cherry Dogwood)	Begin/Full	Begin/Full	Begin/Full	Full	Full	Full	Begin/Full	Begin
Acer rubrum (Red Maple)	Begin	Full	Begin/Full	Full	Full	Full/Begin	Begin/Full	Begin
Acer saccharinum (Silver Maple)	Begin/Full	End	Full	Full/End	Full	Full	Full	Begin
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: Over the last week temperatures have averaged 38°F with a high of 54°F on April 4 and a low of 26°F on April 6 and April 11. 0.36 inches of precipitation has fallen in the form of both rain and snow. Topsoil and subsoil moisture conditions remain adequate. The cold conditions have resulted in very slow plant development. Lawns are slow to green up. Flowering is reduced on some forsythia due to bloom in late November.

Pests/Problems: Winter moth has not begun to hatch. What few eggs can be found are still orange. The cleanup from the string of storms in March continues. 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. Damage to buds of big leaf hydrangea (Hydrangea macrophylla) can be seen in parts of the upper Cape, Buddleia davidii also appears to be damaged, in some cases killed to the ground. Bittercress (Cardamine hirsute) can be found with flowers in various protected or southerly facing locations. GDD BE50 = 18.2, GDD 40 = 138.6

Southeast Region (Hanson)

General Conditions: The cold beginning to April continues. One half of an inch of snow fell on April 2 and quickly melted. However, the weather did not warm up and it remains cool and raw. Hanson received 0.3 inches of precipitation and soils are moist. This cool entry to spring has delayed plant and insect development and to date, it is not a very colorful spring. Some Hellebores are in bloom while others are still emerging. Forsythia buds are yellow and beginning to expand. The freezing winter temperatures do not seem to have affected forsythia buds. However, some plants like Abeliophyllum distichum (White Forsythia), Corylopsis spicata and Stachyurus praecox are displaying reduced flower buds do to cold injury. Buddleia stems appear cold injured but new growth should emerge from the base. Daphne mezeurem (February Daphne, Abeliophyllum distichum (White Forsythia), Trillium, Helleborus niger, H. foetidus, H. x hybridus, Corydalis solida, Chionodoxa luciliae, and Pulmonaria sp.are in full bloom. Cornus mas (Cornelian cherry dogwood), Cornus officinalis, Lonicera fragmentissima (Winter honeysuckle), Pieris japonica (Japanese Pieris),and Omphalodes verna are slowly coming into full bloom. Even weeds are slow to flower this year with only bittercress starting to bloom in the site in Hanson, MA.

Soils are moderately moist and able to be worked. Transplanting trees, shrubs and perennials is doable now, as is planting new plants, unless we get more rain and soils become too moist to work. Remember to water plants after planting or transplanting, even if soils are moist or rain may be predicted. When applying mulch, remember not to mound mulch up and around trunks and stems of plants; an incorrect and potentially plant damaging practice that is referred to as “volcano mulching”. Crews continue to work at removing downed trees and branches that were felled by previous storms. Lawns are greening up nicely.

Pests/Problems: As mentioned, there is not much to report due to the cold spring. Also as mentioned in previous reports, it is anticipated that winter moth caterpillar numbers will be at an all-time low in most areas this year. In Hanson, we cannot find any eggs to monitor winter moth hatch, which is a bit late this year due to the cold winter and spring. For a full update on winter moth hatch, see the Insect Section of the Landscape Message. Deer ticks are active and people have been reporting finding them on themselves and their pets on warm days even in January and February. Continue to take preventative measures when working outdoors and continue to conduct tick checks frequently. Remember that deer ticks are active any time the weather is above freezing.

Using a hand lens, monitor spruce, arborvitae, and other conifers for cool-season mites. Continue to monitor hemlocks for the white, cottony egg masses of hemlock woolly adelgid. Continue to monitor ornamental and fruit-bearing cherries, plums and other susceptible plants in the Prunus genus for black knot disease and if found, prune out and destroy the “black knots”. https://ag.umass.edu/landscape/fact-sheets/black-knot-of-prunus

Deer continue to browse and eat their favorite plants of the day.

North Shore (Beverly)

General Conditions: Unseasonably cold weather continues to persist through this reporting period. The average temperatures were in the mid-30s. Day temperatures were mostly in the low to mid 40s and night temperatures were mostly below freezing. There were no degree day accumulations during this reporting period. Soils are well saturated as a result of the rains in the last few days. It is difficult to work the soil in these conditions. Wait for the soil to dry out before digging or planting. Approximately 0.57 inches of rain was received at Long Hill during this reporting period. The cold weather has significantly slowed down the flowering of most plants that bloom during this time of the year. However, the weather forecast for next week calls for temperatures in the upper 50s. This will help accelerate plant growth and flowering for some trees and shrubs. Woody plants continuing to bloom include Cornelian Cherry Dogwood (Cornus mas), Goat willow (Salix caprea), Chinese witchhazel (Hamamelis mollis), ‘Arnold’s 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: Ticks are active so begin to monitor yourself for them. Continue to prune off broken branches, but wait for some time until growth begins before pruning branches and twigs showing dieback to make sure they are actually dead.

East Region (Boston)

General Conditions: Not much has changed in the landscape since last week. Temperatures have remained unseasonably cold. Over the last six days (April 5^th to April 10^th), high temperatures have been in the low to high 40s. We received precipitation twice over the last week, rain on the 4^th and snow squall-like conditions on the 6^th which left grassy areas covered in half an inch of snow. Fortunately, snow did not accumulate on paved areas and all melted away by the 7^th. We have made no gains in GDD (base 50); for those tracking GDDs (base 40), we have gained 12 GDDs, totaling 163 for the year. Bulbs in bloom include: Chionodoxa sp. (glory-of-the-snow), Crocus sp. (crocus), Galanthus nivalis (snowdrop), Puschkinia scilloides (striped squill), and Scilla siberica (Siberian squill). Despite the cold temperatures, a limited number of plants continue into bloom: Corylopsis coreana (Korean winter hazel), Erica carnea 'Springwood White' (spring heath), Forsythia ‘Meadowlark’, F. giraldiana (Girald's Forsythia), F. x intermedia cultivars ‘Arnold Brilliant’ and 'Courtasol' Gold Tide, F. mandschurica, F. ovata (early forsythia), Jasminum nudiflorum (winter jasmine), and Viburnum × bodnantense 'Dawn' (Pink Dawn viburnum). For those of you yearning for a little color, just coming into bloom is Rhododendron praevernum (February rhododendron).

Pests/Problems: The unusually cold temperatures have been consistent throughout April. Fortunately, most early bloomers have remained in bud and have resisted opening, keeping their flowers protected. However, several buds of Magnolia zenii ‘Pink Parchment’ (Zen magnolia) opened last week and were damaged by cold temperatures leaving the petals brown. Thankfully, most buds remain closed, waiting for warmer conditions. There has been minimal insect activity; however Twice-stabbed lady beetles (Chilocorus stigma) have been observed on eastern hemlock (Tsuga canadensis) albeit moving very slowly. The winter perennial Ficaria verna (lesser celandine) has greened up and is just barely beginning to flower. Landscape weeds are slow to emerge. Alliaria petiolata (garlic mustard) rosettes continue to develop. Allium vineale (wild garlic), Chelidonium majus (greater celandine), Lamium amplexicaule (henbit deadnettle), L. purpureum (purple deadnettle), and Taraxacum sp. (dandelion) can be observed in mulched beds.

Metro West (Acton)

General Conditions: Winter-like weather persisted into this first full week of the April reporting period with a snow event on Friday that completely covered the landscape with a wet blanket of snow. Cool, windy days and sub-freezing nighttime temperatures continued into this reporting period. I heard someone say the other day that 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 1.31” for this month so far. Since the last report one week ago, there has not been any gain in growing degree-days and as a result little is in bloom. 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), 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), and Symplocarpus foetidus (skunk cabbage). Landscape crews are out in full force completing spring and winter storm clean ups and spreading mulch.

Pests/Problems: The wind has been persistent with gusts that were recorded up to 29 mph on April 4^th and 27 mph on the 5^th_. This has caused a number of residual, broken tree limbs to litter the ground. In most cases these were hangers that were previously broken in one of our March winter storms. With the snow melted, the rodent damage to plant materials and lawn is now visible.

Central Region (Boylston)

General Conditions: The warm spring weather has been slow to arrive this year, with many days of snow, snow showers and heavy morning-settling frosts. Last Friday brought 2” of heavy wet snow, but it had melted by the next day. Many of the plants that normally bloom at this point still have their buds tightly closed. Prolonged blooming has been the case with others like snowdrops (Galanthus nivalis), crocus (Crocus sp. + cvs.), reticulated Iris (Iris reticulata), and winter aconite (Eranthis hyemalis). The daffodils are starting to bloom, with Narcissus ‘Rijnveld's Early Sensation’ being the first. Hellebores (Helleborus sp. + cvs.) are just beginning to bloom. The soils are still very wet, delaying work in some areas of the garden.

Pests/Problems: Woodchucks are starting to become active, vole damage is apparent (but has been worse), and deer activity noted. On the warmer days, ticks are out in full force. A lone morning cloak butterfly was noted last week and the mating dance of the turkey has begun, unhampered by the cold weather and snow.

Pioneer Valley Region (Amherst)

General Conditions: Conditions have not changed much since our last report. Cool and unsettled weather dominated over the past week, with high temperatures primarily in the upper 30s to upper 40s. Winds were vicious at times, with gusts near 50 mph reported at Barnes Airport in Westfield on 4/4. Spring is particularly windy in the valley bottomlands, owing to the open expanse of farm fields in the region. The forecast calls for a brief warmup, where temperatures should peak into the lower 70s on Saturday, 4/14. More importantly, low temperatures are forecasted to stay above 40°F, breaking the cycle of sub-freezing nighttime temperatures we’ve experienced this April. This should allow rosaceous hosts to start leafing out. Serviceberry, hawthorn, crabapple and apple buds are breaking at this time. In isolated, protected areas a few crabapples have been observed leafing out on the UMass campus. Forsythia, elm and magnolia buds are also breaking as we inch closer to May. However, temperatures are expected to plunge downward once again, as is typical of April in the region.

Pests/Problems: Reports from the UMass Cold Spring orchard in Belchertown note that overwintered apple scab spores are mature and ready for release. If you plan to treat apple or crabapple for scab, the first window for treatment is rapidly approaching. In most landscape settings, treatment for apple scab is not warranted, since the disease is so widespread and often results in only minor growth losses. The prolonged wet weather early in the 2017 growing season resulted in high disease pressure, but even for trees that were defoliated by early autumn, the lasting damage should be minimal. Pruning to remove heavily shaded interior canopy branches can help to reduce disease severity. Rabbits, deer, voles and to a lesser extent squirrels are still actively feeding on landscape ornamentals. Skunk damage to lawn grass has also been observed as they feed on maturing grubs approaching the surface. Overall, pathogen and pest pressure remains low at this time due to the cold weather. Continue to scout for white pine weevil on eastern white pine, Norway spruce and Douglas-fir. Also, continue to scout for evidence of spruce spider mites on spruce, fir, hemlock, false cypress and arborvitae, especially in cases where imidacloprid has been used in the past. Treatment with soap, oil or a registered miticide will be effective in reducing their populations before additional damage is done.

Berkshire Region (Great Barrington)

General Conditions: It was another cold week with daily high and low temperatures well below normal for this time of year. There was no gain in GDD. Snow fell on two days: April 6 and 10. The total snowfall for the two days was about 3 inches. On sunny sites, that snow has since melted. However, snow from March storms covers the ground on the wooded slopes of hills, in the shadow of tree lines, and on the shaded sides of buildings. Soils for the most part are saturated; it is mud season. To prevent soil compaction, care should be taken to avoid excessive foot traffic or driving vehicles on lawns and other landscape soils. Turfgrass is slowly beginning to show signs of growth but lawns are far from being at mowing height. While few woody species are showing signs of renewing their growth, except for Hamamelis and the species mentioned in this week’s Phenology table, early spring flowering herbaceous plants are showing off their blossoms. Primarily, these are crocus, dwarf iris species (Iris histrioides, I. danfordiae, I. reticulata), hellebores, striped squill (Puschkinia scilloides), and winter aconite (Eranthus hyemalis).

Pests/Problems: Volcano-shaped mounds of soil have become apparent as snows melt on lawns. These have been created by moles. On the other hand, vole presence on many lawns is indicated by runways through the turfgrass. Gnawed bark on smooth-barked trees and on shrubs has appeared as snows receded. The offending critters are voles and rabbits in most cases. Deer browsing on trees and shrubs is also quite common in home landscapes. Snow mold can be seen on many lawns, especially where snow had been piled up. No insects are yet active in landscapes but those such as the western conifer seed bug and the multicolored Asian lady beetleare common visitors in houses. Deer tick activity is very high and reports of their presence and hitch-hiking on those working in landscapes are frequent. The ticks I have observed are in the adult stage. All the usual precautions to prevent attachment of the ticks should be taken when working outdoors. Finally, high winds on April 4 and 5 resulted in many fallen limbs and a few toppled trees. It would be wise to survey affected trees for pruning and to assess possible decay in trunks and branches.

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

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

Volutella leaf and stem blight of common boxwood (Buxus sempervirens) and Korean boxwood (B. microphylla var. koreana). The common boxwood is approximately 30 years-old and resides in a shaded landscape setting without any irrigation. For the past five years, foliage has been dying, resulting in progressive branch dieback. The Korean boxwood is a young plant and was planted only last year. Within the past month, leaves began browning throughout the canopy. This plant resides in full sun with overhead lawn watering providing supplemental water. Volutella is common and opportunistic on boxwoods in the landscape, leading to leaf spots, leaf blight, stem cankers and branch dieback.

Needle browning and branch dieback on Pfitzer juniper (Juniperus chinensis ‘Pfitzeriana’). These are in an expansive and old assemblage of hillside plants, approximately 45-years-old, growing in a sandy loam soil with full sun. Two years ago, needle browning and branch dieback was first observed. Symptoms have since worsened. Two needle blight pathogens (Lophodermium and Pestalotiopsis) and an unidentified needle tip miner were present on blighted plant parts. Additional stresses may also be a factor, such as rodent feeding.

Suspected squirrel damage on a 15-year-old landscape sugar maple (Acer saccharum). The tree is growing in partially shaded setting with drip irrigation. Lower canopy branches were covered with sooty mold fungi but there was no evidence of a scale infestation or bird scaling wounds. Teeth and claw marks were observed on small diameter branches. There were also old cankers that had mostly healed in locations near the recent damage. Sooty mold fungi will often grow on the branches or main stem of sugar maples that have sap flowing from wounds. While bird scaling wounds are often the culprit, any wound that results in a strong flow of sap will stimulate their growth.

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:

• 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.

To date (4/12/2018), winter moth egg hatch has not yet been observed at locations being monitored in Massachusetts. 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. In certain areas, such as Hanson, MA (see Southeast Region reporting above) plant development is delayed and certain phenological indicators for winter moth egg hatch are still behind. Look for expanding buds on apple (McIntosh apple green tip) and Norway maple. Reports from UMass Extension’s Fruit Program indicate that in an orchard in Stowe, MA (for example) as of 4/11/2018, McIntosh apple green tip has not yet been observed. If the predicted warm weather arrives for this weekend, however, the timeline for winter moth egg hatch could advance. 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.

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. (Although reports from Rhode Island indicate that a small percentage, around 5%, of eggs at sites being monitored in their state are beginning to turn blue.) 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).

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 outbreak in 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. 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.

• 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 - 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

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

Plant of the Week

Looking for early spring color? Lindera benzoin is a native shrub with early yellow flower.

https://extension.umass.edu/plant-identification/spice-bush

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

Other Relevant News/Pest Alerts

With spring clean-up comes spring mulching. Need a laugh? See this excellent article by Joe Boggs, Ohio State University Extension, where even in Ohio “Mulch Volcanoes are (still) Erupting”. Don’t let this be you! Full article available here: http://bygl.osu.edu/node/1006

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