UMass Extension’s Landscape Message Update

UMass Extension’s LANDSCAPE MESSAGE is a regular update which includes valuable information on cultural practices and the status of insect, disease, and weed problems of interest to Master Gardeners assisting the public with their gardening questions. Detailed reports from sites throughout Massachusetts include growing degree day accumulations, soil temperature, precipitation amounts, and plant phenology.

Current Update – April 20, 2018

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(link is external) .

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(link is external) .

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/(link is external) 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 brumataThe 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 .

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, visithttp://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report(link is external) .

  • 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(link is external) .

  • 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 AphidNeoceruraphis 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/(link is external) . 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(link is external) . 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(link is external) .

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/(link is external) .
  • 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(link is external) .