UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Green Industry professionals in the management of our collective landscape. Scouts compile and record environmental and phenological data for locations throughout Massachusetts to aid in the monitoring of plant and pest development, the planning of management strategies, and the creation of site-specific records for future reference. Detailed reports from Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. UMass Extension has updated the following issue to provide timely management information and the latest regional news and environmental data.
Welcome to the first Landscape Message of 2016! The Landscape Message will be updated bi-weekly in March, and weekly April through June. The next message will be available on April 1. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.
NEW! To read individual sections of the message, click on the section headings below to expand the content:
Scouting Information by Region
Regional Notes
Cape Cod Region (Barnstable)
General Conditions: The final months of 2015 continued the trend towards above average temperatures, with Growing Degree Days accumulating right until the end of the month. The unusual warmth prompted early flowering species of cherries to bloom in December! ‘Jelena’ witch hazel began to bloom on December 13th, a full month ahead of its usual bloom period. January 2016 cooled off seasonally, but never really got extremely cold. Most precipitation fell in the form of rain, with almost 4” falling over the month. Above average temperatures also occurred in February, and by the end of the month 11.2 GDD had been recorded. February also had some of the coldest weather of the winter, with a low of -10 recorded on Feb. 14th. Mild weather continued into March, with a high of 67º F recorded on March 10th. Plant development is well advanced for the time of year. Cornus mas has begun to bloom. ‘Arnold Promise’ witch hazel has been in bloom since late January. Spring heath and heather are blooming and pussy willow buds are swollen and fuzzy. Crocus have been blooming for a few weeks now, along with snowdrops. Early flowering daffodils are blooming. Hellebores are in full bloom in the perennial garden.
Pests/Problems: There is no plant pest insect activity at this time. Damage from rabbits can be observed on the lower stems of woody plants. Vole “trails” can be seen in perennial beds and under spreading junipers. Due to the frequent high winds over the winter, there are many broken branches littering the ground. Spring clean-up has begun on some landscapes. Deer tick adults are active!
Black knot of Prunus spp. Is quite visible, especially on wild cherries right now.
Southeast Region (Hanson)
General Conditions: What a wonderful difference the winter of 2016 was from the cold, snow-laden winter of 2015! The 2016 winter was one of the warmest on record with no great snow events like last year. Hanson received 15.5 inches of snow and 2.75 inches of rain in January and in February, 16.5 inches of snow and 6.40 inches of rain. Hanson has received 1.75 inches of rain since March 1st and soils are moist.
The warm, mild winter has accelerated plant development. At this time, Hanson has 25 GDD, base 50, we are about 4 weeks ahead of last year (0 GDD) and very similar to the spring of 2012 (28 GDD) which also had an extremely mild, warm winter. Winter Jasmine (Jasminum nudiflorum) started to bloom in December 2015 and was still in bloom at the end of February, 2016. In Hanson, MA, silver maple buds were cracked and ready to open mid-January and were in full bloom March 7th. Hamamelis mollis 'Pallida', Hamamelis x intermedia 'Arnold Promise' & ‘Jelena’ and Lonicera fragrantissima (Winter honeysuckle) were in bloom in January and remain in bloom. Helleborus xhybridus ‘Jacob’ was in full bloom in December and is still flowering. There were also a few flowers on Japanese quince in January with more flowers just about ready to open now! Abeliophyllum distichum (White forsythia), Daphne mezeurem (February Daphne), Helleborus foetidus, Helleborus x hybridus, Helleborus niger, Omphalodes verna (Blue-eyed-Mary; Creeping forget-me-not) Crocus, and snowdrops are in full bloom in Hanson. Cornus mas and Cornus officinalis are beginning bloom and Salix (Pussy Willow) is displaying silver buds. Eranthus hyemalis (Winter aconite) is past bloom. Pieris japonica, Pieris floribunda and Pieris ‘Brower’s Beauty’ are beginning to flower!
In Halifax, MA, in addition to the already mentioned plants in bloom, the following plants are also in bloom: Celandine poppy, Puschkinia, Adonis vernalis, Hepatica sp., Pulmonaria sp., Scilla; early daffodils and Iris verticillata. Honey bees are active and were found in Hellebore flowers and Cornus mas flowers. In many areas, lawns have started to green-up. Peepers started peeping on March 10th and the black-winged blackbirds are back, along with grackles. The site in Hanson is also measuring Growing Degree Days (GDD) at base 40 this year, and there are 139 GDD, base 40.
Pests/Problems: Similar to the 2012 season, UMass Entomologist, Dr. Joe Elkinton is predicting an early winter moth egg hatch, however with the current cooler weather and if cooler weather prevails, hatch may not happen until the latter part of March, early April. If the weather ramps up to the 70’s, hatch could be earlier; if it stays cold, it could be later. It is difficult to predict exactly, and only time will tell. Right now the winter moth eggs are still an orange color and the current cooler weather will probably continue to slow development. With warmer weather, the eggs will turn a light blue then a deep, dark blue just prior to hatch. In areas where winter moth populations were heavy last year, there is a good probability that the numbers will be high again this year. It will be interesting to watch what happens to the winter moth population if eggs hatch early, ahead of leaf bud expansion and if we were to see a deep freeze or frost. So many unknowns; just have to wait and see! If you do have clients that are growing apples or blueberries, they may want to consider protecting the plants and flower buds just as they are swelling and beginning to open, by applying a well-timed dormant oil spray that contains an added insecticide, such as a Spinosad product, which can be useful if applied within a day or so of egg-hatch. Always check to be certain that any two pesticides are compatible for mixing. Also, when applying oil sprays, it is suggested that the temperatures be above 45 degrees F and to avoid applying oil when temperatures may dip below freezing for 24-48 hours after application. Monitor hemlocks for the egg masses of Hemlock Wooly Adelgid. Inspect, especially, the outer branch tips for what look like tiny, white, “cottony balls” lined-up at the base of the needles along the branches. This year may we get lucky and see high mortality of HWA due to the cold weather in February. According to Dr. Joe Elkinton, “the sudden cold snap on the third weekend in February produced temperatures in Amherst at about -20º F. 100% of the adelgids died. We have samples from upstate NY, Buzzards Bay, Hamden CT, and Kingston, RI and there is no HWA survival at any of these places either.” This is great news and hopefully will provide a short respite from HWA, as this insect can rebound later in the season, so continue to monitor hemlocks now and throughout the season.
With this warm winter and enough moisture through snow and rain, it could be a banner season for deer ticks. Be on the lookout for deer ticks any time the weather is above freezing and conduct tick checks frequently and use repellants. For tick information go to: http://ag.umass.edu/services/tick-borne-disease-diagnostics.
Damage to perennial crowns (hosta, sedum, etc) by voles has been observed in the garden. Although we did not have significant lasting amounts of snow, there was enough that when it melted, vole runs were observed on turf and in gardens. Squirrels have been observed chewing through the branch tips on red maples and littering the ground with the chewed-off tips.
Although the winter was mild, the cold days (below 0) in mid-February, especially the low of -9º F on Feb. 14, may have been enough to damage some plants, like the flower buds of Hydrangea macrophylla. Sampling of a few of those plants revealed dead flower buds, although other cultivars appear fine.
Landscape cleanups have begun in many areas. Although this winter was not as storm-ravaged as last year, there were a few storms with high winds and many landscapes are littered with debris and many trees either came down, split or have broken branches.
Although many lawns have started to green up, it is too early to fertilize lawns and too early to apply crabgrass and grub control products. It is not too early to apply limestone to gardens and lawns that need it. For information on UMass soil testing go to: http://soiltest.umass.edu/
Now is a good time to monitor for the black knot disease, a fungal disease, on cherries and plums, and prune out and destroy the “knots” when found.
Winter burn is showing up on broadleaved evergreens like holly, Pieris and rhododendron. Deer are browsing. Cuckoo bittercress (Cardamine pratensis) began blooming in February and remains in full bloom.
North Shore Region (Beverly)
General Conditions: This winter was very mild, snowfall was very minimal and temperatures were above average. Snowfall was experienced only on a few days in January and few days in February. There has been no snow yet in March. Sub zero temperatures were experienced only on three days during the Valentine weekend with lows going down to -11 degrees Fahrenheit. March has been very nice with average temperatures in the 40s and 50s. There was a spike on March 9 and 10 when the temperatures reached high 60s and low 70s. However the temperatures have now gone down to the 40s. April has arrived in the North Shore and some plants have started to bloom. Trees seen in bloom include: Arnold promise witchhazel (Hamamelis x intermedia), Cornelian cherry dogwood (Cornus mas) and Goat willow (Salix caprea). Early spring flowering bulbs seen in bloom include: Winter aconite (Eranthis hyemalis), Snowdrops (Galanthus nivalis), Siberian squill (Scilla siberica) and Puschkinia (Puschkinia libanotica). Hellebores (Helleborus orientalis) are also in bloom.
Pests/Problems: Very little deer browsing has been reported due to lack of snow and relatively warm winter temperatures. Deer had sufficient plants to browse in the woods. Some vole tunnelling was observed on lawns. Ticks are active, so take precautions when working outdoors. This is the best time to prune summer flowering trees and shrubs. Make sure to remove diseased and broken branches. Trees that are susceptible to fire blight such as crabapples, pears and hawthorn should be pruned when dormant to minimize chances of fire blight infection, even though they flower in the spring.
East Region (Boston)
General Conditions: The “growing season” of 2015 ended on December 22 with a total of 3151.5 GDDs. Total precipitation (rain equivalence) was 37.04 inches for 2015. Various weather events throughout January, February and half of March 2016 totaled 11.34” of precipitation – rain equivalent. We received our first GDDs of the year on February 1st. We have a total of 30 GDDs to date. Many Hamamelis sp. (witchhazel) have been in bloom continuously throughout the beginning of the year. Cornus officinalis (Japanese cornelian cherry) and Cornus mas (cornelian cherry) have come into bloom. Rhododendron mucronulatum and close relative Rhododendron dauricum (Dahurian rhododendron) have begun to flower. Various Daphne sp. (daphne) and Erica sp. (heath) are in full bloom. Galanthus sp. (snowdrops) came up in February and continue to bloom despite several cold snaps. Siberian squill (Scilla siberica) and crocus (Crocus sp.) have begun to flower. Skunk cabbage (Symplocarpus foetidus) was observed emerging in late February. The first sign of pollinators were seen visiting witchhazel (Hamamelis sp.) in early March.
Pests/Problems: Many winter annuals appeared in November and December of 2015. Wild garlic (Allium vineale) is prolific in the landscape. Lesser celandine (Ranunculus ficaria) appears to be having a banner year, forming a green mat in moist unmanaged areas. Garlic mustard (Alliaria petiolata) and greater celandine (Chelidonium majus) rosettes are visible. Stinging nettle (Urtica dioica) has emerged. Winter moth egg masses remain orange in color, despite having reached 30 GDDs and have yet to hatch.
Metro West (Acton)
General Conditions: Welcome back! I write and submit this report on March 16th and report that spring is well on its way. Winter treated us well this year. Snowfall was minimal and temperatures were mild for the most part, although there was a string of 4 sub zero temps recorded on February 12th, 13th 14th and 15th with the coldest temp recorded for the year on the 14th with a temp of -14º. But temps were overall above average and the warmest and record-breaking temp of 77º was recorded just last week on March 9th. Much is in bloom, including the following woody plants: Acer rubrum (Red Maple), Acer saccharinum (Silver Maple), Cornus mas (Cornelian Cherry Dogwood), C. officinalis (Japanese Cornelian Cherry), Hamamelis × intermedia 'Arnold Promise'(Arnold Promise Witch hazel), and H. × intermedia 'Diane' (Diane Witch hazel). 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), Narcissus spp. (Daffodil), Petasites japonicus (Japanese Butterbur), and Vinca minor (Periwinkle). Other signs of spring include hearing the sounds of the spring peepers, spying box turtles bathing in the sun on logs in a pond, seeing the sap buckets attached to the maple trees that are tapped for maple syrup production and homeowners outside raking and picking up their yards, and the days are getting longer.
Pests/Problems: Not surprising, there is much woody debris scattered throughout the landscape, particularly white pine branches broken and downed from the wind and snow. Ticks are active. Lamium purpureum (Purple Deadnettle), a winter annual weed was observed in bloom.
Central Region (Boylston)
General Conditions: The first two and a half months of 2016 have been mild and mostly quite tolerable. Very little snow has plagued us. Low temperatures dipped below zero for a few nights in mid-February, the lowest was -15º F. Unusually warm temperatures during the week of March 14th advanced many plants to the state of bud and/or bloom. Spring blooming bulbs are well ahead of schedule with early daffodils (Narcissus ‘Rijnveld’s Early Sensation’) beginning to bloom on March 11th. Winter Aconite (Eranthis hyemalis), Crocus tommasinianus and hybrids, Dwarf Iris (I. reticulata and I. danfordiae), Snowdrops (Galanthus nivalis), February Daphne (D. mezereum), Heath (Erica carnea), Cornelian Cherry (Cornus mas), Witchhazels (Hamamelis xintermedia cultivars, H. vernalis and H. mollis), Speckled Alder (Alnus incana ssp. rugosa), Black Pussywillow (Salix gracilistyla ‘Melanostchys’), Giant Pussy Willow (S. chaenomeloides ‘Mt. Aso’), and American Elm (Ulmus americana) are all in full bloom. Siberian Squill (Scilla siberica) and Glory of the Snow (Chionodoxa forbesii), White Forsythia (Abeliophyllum distichum), low Forsythia (F. ‘Arnold Promise’), Farges Filbert (Corylus fargesii), Winterhazel (Corylopsis spicata) and Fragrant Honeysuckle (Lonicera xpurpusii) are just beginning to bloom. Turf is greening up and peepers and wood frogs were heard last week.
Pests/Problems: Winter annual weeds like Hairy Bittercress (Cardamine hirsuta) and Common Chickweed (Stellaria media) are blooming. Damage from voles is evident and tunnels abundant, skunks have been out on warmer evenings (their pungent perfume and nosing in lawns obvious), and ticks are quite active.
Pioneer Valley Region (Amherst)
General Conditions: Spring has arrived in the Pioneer Valley. Lawn grass is greening more each day, buds are swelling, birds are returning and spring annuals are in bloom. For trees and shrubs, the most conspicuous on the landscape now are silver maple, American elm and hybrid witchhazels. The soil is thawed and tree and shrub planting has begun. We will gain nearly 105 minutes of daylight during the month of March although the majority of this daylight comes at the end of the day thanks (or no thanks) to Daylight Savings. The winter of ′15-′16 was mild in the valley, as expected, due in part to the strong El Niño that developed over the Pacific Ocean in late 2015. According to NOAA, this past winter was record warm throughout the contiguous United States (http://www.noaa.gov/winter-was-record-warm-contiguous-us). In contrast, the bitter arctic air mass that settled over the region during the Valentine’s Day weekend brought in record cold temperatures. Lows in the valley ranged from –10° to –14°F during the two-day cold snap with the wind chill decreasing those values by as much as 20° F. Aside from this anomaly, temperatures were mostly mild (especially in December) and snowfall was minimal. A lack of snow cover can be harmful to shallow rooted trees like hemlock and birch. Persistent snow insulates the roots and protects against major shifts in temperatures that can lead to early thawing of the upper soil horizon. In previous decades, birch decline in New England has been blamed, in part, to root freezing from lack of snow. Early March has been especially nice, with record high temperatures on Wednesday, March 9. Highs in the upper 70s to low 80s were felt across the area. We have since settled into a more seasonable pattern of high 40s to high 50s and scattered rainshowers.
Pests/Problems: Despite the warm weather we recently experienced, most plant pathogens are not yet active. However, disease management strategies at this time should focus on reducing inoculum (diseased plant parts that harbor overwintering populations of the pathogen) at the site. Dead and discarded foliage should be raked and removed or covered with mulch if it is too fine to remove (e.g. spruce needles). Now is the best time to prune trees and shrubs infected with stem and branch cankering fungi like Botryosphaeria, Phomopsis and Cytospora. Many of these fungi are opportunists that invade and spread through the canopies of trees and shrubs predisposed by other stresses. Carefully inspect branches to locate sunken areas of bark, rough cankers or small, black-colored pads of fungal tissue rupturing through the bark. These pads are usually numerous when present. Arborvitae needle blight has been a concern in recent years and high levels of inoculum are present on the landscape. Prune and remove dead needles from interior branches as they harbor the fungal pathogens responsible. If left, they will sporulate and spread during mild weather when new, succulent needles are most susceptible to infection. Spider mites were very abundant in 2015 and large egg masses are abundant on infested trees. Dormant oil applications can help to smother these overwintering eggs. Inspect redcedars and other Juniperus species (trees only) for the presence of brown galls if cedar-apple rust is a concern. Prune and destroy these galls when discovered. Winter injury should be minimal compared to the 2014 and 2015 growing seasons. However, the record cold temperatures during the Valentine’s Day weekend could have caused damage to trees that are semi-hardy in this region (hardy to zone 5) and situated in exposed locations. Mosquitoes have been observed in the Pioneer Valley and precautions should be taken on mild days during the evening hours. Ticks are also active and most abundant where deer and mice populations are high. The lack of a deep snow cover restricted the movement of meadow and pine voles, but damage from these pests is present in many locations. Carefully inspect the base of shrubs and small trees (especially apple) for bark stripping and girdling.
Berkshire Region (Great Barrington)
General Conditions: Even those long in the tooth are short on memory when it comes to recalling a winter as mild as this one has been. In terms of Heating Degree Days, Berkshire County is about 1100 HDD below normal to date (3/16). On the other hand, Growing Degree Days stand at 14 for the year. Usually, GDD is at 0 or slightly above at this time. Precipitation as measured in rainfall equivalent is near normal. However, seasonal snowfall is only 12.6 inches, well below the 66.1 inch average. Among the plants in bloom now are snowdrops (Galanthus), species crocus (Crocus tomassinianus) and some hybrid crocus, winter aconite (Eranthus hyemalis), Iris reticulata, Helleborus niger, and Helleborus orientalis. Flower buds of Cornus mas are just beginning to open and are showing a bit of yellow color. Buds of red maple (Acer rubrum) are swelling but not yet open. Conditions are favorable for outdoor work such as pruning, grubbing out invasive plants. However, this is not a good time for treading on lawns as soil moisture is high and therefore the threat of compaction from foot or vehicle traffic is increased. Likewise, soils are not yet workable due to high moisture content. Otherwise, the weather pattern would allow for early season planting of dormant nursery stock.
Pests/Problems: Despite the relatively mild winter, pest activity is non-existent except for deer ticks, a.k.a. black-legged ticks. These ticks are plentiful and doctors’ offices have had numerous patients with tick bites though I have not heard of any cases of Lyme Disease or any of the other diseases associated with these ticks. Deer are active but there are no reports of serious browsing in managed landscapes. The open winter most likely offered deer plenty of opportunities to find food in the wild. Voles, squirrels, and chipmunks are abundant.
Environmental Data
The following data was collected on or about March 16. Total accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments for the 2016 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.
|
Region/Location |
GDD |
Soil Temp |
Precipitation |
Time/Date of Readings | |||||
| 2015 Total | 2016 Current | Sun | Shade | Since 1/1 | Since 3/1 | ||||
|
Cape Cod |
2997 | 24 | 47 | 42 | 12.01 | 2.58 | 9:15 AM 3/16 | ||
|
Southeast |
2683 | 28 | 46 | 44 | 9.15 (32" snow) |
1.75 | 1:35 PM 3/16 | ||
|
North Shore |
3010 | 25 | 44 | 42 | 7.04 | 1.66 | 9:30 AM 3/16 | ||
|
East |
3151.5 | 30 | 47 | 45 | 10.11 | 2.33 | 3:30 PM 3/16 | ||
|
Metro West |
2669 | 16 | 42 | 39 | 6.34 | 1.98 | 6:30 AM 3/16 | ||
|
Central |
n/a | 28 | 50 | 42 | 11.00 | 1.76 | 1:15 PM 3/16 | ||
|
Pioneer Valley |
3079 | 21 | 47 | 43 | 7.64 | 1.46 | 9:30 AM 3/16 | ||
|
Berkshires |
2397 | 14 | 46 | 43 | 6.53 | 1.13 | 10:00 AM 3/16 | ||
|
AVERAGE |
2855 |
23 |
46 |
43 |
8.73 |
1.83 | - | ||
|
n/a = information not available |
|||||||||
Phenology
Phenological indicators are a visual tool for correlating plant development with pest development. The following are indicator plants and the stages of bloom observed for this period:
| 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. |
| Cornus mas (Corneliancherry Dogwood) | Begin | Begin | Begin | Begin/Full | Begin/Full | Begin | Begin/Full | * |
| Acer rubrum (Red Maple) | Begin | Begin/ Full | Begin | Begin | Begin/ Full | Begin | Begin | * |
| Acer saccharinum (Silver Maple) | Begin/Full | Full | Begin | Full | Full | Full | Full | * |
| Hamamelis mollis (Chinese Witchazel) | * | Full | * | End | * | Full | Full | * |
| Hamamelis x intermedia (Witchhazel hybrids) | Full | Full | Full | End | Full | Full | Full | Full |
- CAPE COD REGION - Roberta Clark, UMass Extension Horticulturist for Barnstable County - Retired, 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, Superintendent of Horticulture, reporting from the 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 pathogens of interest seen in the UMass Extension Plant Diagnostic Lab:
Needle tip blight on eastern white pine (Pinus strobus) caused by Septorioides strobus, Stagonospora and Bifusella linearis. Tree is 75-years-old and growing in a landscape setting with full sun. Subject to strong winds on a hillside but healthy in previous years. 2015 needles were blighted at the tips and upon close inspection were riddled with dark-colored lesions. Septorioides is a newly described pathogen of white pine and much remains unknown about its virulence (aggressiveness).
Dieback of Oriental spruce (Picea orientalis) as a result of stem cankering by Cytospora and needle cast by Rhizosphaera. Tree is approximately 80 to 90-years-old and began showing symptoms of dieback in late summer of 2015. Premature needle shedding and stem dieback was present throughout the canopy but was more prominent in the lower half of the tree. An adjacent Oriental spruce died and was removed in 2014. Tree is growing in a landscape setting where lawn grass is irrigated. It’s possible there was root damage from nearby construction approximately 10 years ago. Other possible predisposing stresses remain unknown at this time.
Canopy dieback of longstalk holly (Ilex pedunculosa) caused by the stem cankering pathogen Botryosphaeria and a secondary leaf blight caused by Pestalotiopsis. Shrub is less than 15-years-old and was planted above a stone wall for screening. Branch dieback and leaf browning is present in the canopy. Botryosphaeria is common and destructive on Ilex, especially I. crenata, usually when plants are weakened by winter injury, transplant or over pruning. In this case, the canopy does not appear excessively pruned and the roots should be well established. Possible soil heating above the stone wall may be a factor.
Aborvitae needle blight on northern white cedar (Thuja occidentalis) caused by Phyllosticta thujae and Pestalotiopsis. Nursery trees, eight to 10-years-old, growing in a protected, sunny location with partial shade and no irrigation. Needle blight and shedding began in summer of 2015 after a freeze in early spring caused sporadic death of canopy shoots. When both of these fungi become established in the canopy, they can cause serious canopy dieback. Many of the trees appear unsalable at this time due to the damage.
For more detailed management information for woody plant diseases in the landscape, refer to UMass Extension's Professional Management Guide for Diseases of Trees and Shrubs.
Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass Amherst.
Insects
Recent woody ornamental insect and non-insect arthropod pests of interest seen in the UMass Extension Plant Diagnostic Lab:
Eastern Spruce Gall Adelgid: Adelges abietis is a pest on spruce, primarily Norway and white spruce. This insect is believed to have been introduced to North America from Europe prior to 1900. The insect causes galls to develop on shoots, which predisposes them to breakage under the weight of snow (although this has not been a problem this year) and other abiotic stresses. Unlike Cooley spruce gall adelgid (Adelges cooleyi), the eastern spruce gall adelgid will have branch growth beyond the gall (the gall is rarely terminal on the twig). This adelgid overwinters as a partially developed female who will lay 100-200 eggs, covered in a woolly material, around bud-break. After egg hatch, nymphs will feed at the base of needles, causing abnormal twig growth and a gall to form. Until the gall breaks open in mid-late summer, the young adelgids are protected from predators, parasites, and most abiotic stresses. Due to the protection this gall offers the insect, a dormant oil application just prior to bud-break is the best strategy for management, allowing the user to catch the eggs and newly emerged nymphs prior to feeding and gall formation. Avoid using dormant oil applications on cloudy and cold days and seek a time period to apply when temperatures will remain above freezing for 24-48 hours after application to avoid plant injury.
Honey Locust Spider Mite: Eotetranychus multidigituli is a pest on honey locust, Gleditsia triacanthos. This particular mite species is interesting in that it overwinters as adult females, shown in the photograph below. Although this image may look more like the surface of Mars, it is actually a close-up view of the adult females hiding in the crevice of the bark on a branch of honey locust. Eggs are laid in the spring. Light feeding can cause white or yellow stippling in the leaves. Heavy feeding can cause honey locust foliage to brown and die. Large overwintering populations can be treated with a dormant horticultural oil spray (Childs et al., 2008). Be sure to get as complete coverage in bark cracks and crevices as possible where these tiny red-colored mites are seen. Again, avoid using dormant oil applications on cloudy and cold days and seek a time period to apply when temperatures will remain above freezing for 24-48 hours after application to avoid plant injury. Especially if populations are low, avoid using other chemical pesticides for management as they may impact populations of beneficial, predatory mites which usually manage honey locust spider mite effectively.
Norway Spruce Gall Midge: Piceacecis abietiperda is a pest on Norway spruce, Picea abies. This pest was first reported in Orange, Connecticut in 1983 and is thought to originate from Europe. It has since been reported in Massachusetts, Vermont, New York, New Jersey, and New Hampshire. This insect is thought to have one generation per year in our area. Adult emergence in the Northeast is thought to occur in April and May. Soon after emergence, the males and females mate and eggs are laid on twigs near the bud or on new shoots. Larvae then hatch in approximately one week and burrow into tissue around bud scales, shoots, and terminal buds causing swelling. The image below is of one such larva, exposed by slicing through tissue swelling near a bud. Past studies have shown larvae to be fully grown in mid-September to October, with pupation occurring in early April. Some samples received at the UMass Plant Diagnostic Lab have shown small overwintering larvae. Norway spruce branches can exhibit browning and needle drop along with bending in the branch with the presence of galls on the inside of the bend. While some samples seen in New York and Connecticut have not shown enough damage to warrant management of this insect, other samples received by the UMass Plant Diagnostic Lab from western Massachusetts have shown significant dieback associated with the presence of this pest. Chemical management of gall midges needs further study and many chemical options in Massachusetts are not yet labeled for this pest. Spinosad is labelled for the management of “gall midges” in ornamental trees as a foliar treatment in both landscape and nursery settings, although exposed life stages would have to be targeted as contact of the pest is required when using spinosad. Other gall midges have been monitored for their emergence as adults with yellow sticky cards, so this technique may be able to be adopted for this pest as well.
Woody ornamental insect pests to consider for the beginning of the 2016 season, a selected few:
Eastern Tent Caterpillar: Malacosoma americanum is native to the United States and has been reported as early as 1646. Large numbers of the caterpillars of this species occur at intervals of approximately 10 years. It is a pest of cherry, apple, and crabapple as well as ash, birch, willow, maple, oak, poplar, and witch-hazel. This insect overwinters as an egg in masses of about 150-350 eggs which can be pruned from the branches of its host trees. 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. Monitoring for and pruning of egg masses should be done immediately, as we are fast approaching the time period where egg hatch will begin. Eggs will hatch as early as 50 Growing Degree Days in Massachusetts (50-400 GDD’s, base 50°F). Once cherry leaves begin to unfold, eggs will hatch and larvae will emerge. These larvae gather together in branch crotches and begin to spin a silken web over themselves. If caught early, these webs can be pruned out of the host trees mechanically and destroyed. DO NOT BURN these webs while they are in the host tree. Not only is this practice dangerous from a fire hazard perspective, but it may cause more damage to the tree than the caterpillars ever would. Large larvae of M. americanum are black with a white stripe down their back with a series of blue spots on either side. Larvae will find tree trunks, fences, and other objects to settle on and pupate in white cocoons. Adults will emerge in late June to early July and there is generally one generation per year. Avoiding damage early by removing egg masses and small webs is best, but for populations that are not prevented this way, caterpillars may be treated on warm days after bud break as they leave their webs to feed on foliage. Some chemical management options for M. americanum in MA include insecticidal soaps, spinosad, and Bacillus thuringiensis ‘Kurstaki’ which should be applied to target young caterpillars.
Elongate Hemlock Scale: Fiorinia externa is an armored scale that can be found on eastern, Carolina, and Japanese hemlock and also on yew, spruce, and Douglas fir and was first discovered in New York in 1908. This non-native pest can be found as adults attached to the underside of host needles. Females can be seen year-round and are covered in a brown, smooth waxy covering whereas males are seen mostly during the growing season and at some stages are covered in bright white, woolly material. Both sexes are less than 1/8 of an inch long. This insect is a serious pest in forested settings, especially when combined with hemlock woolly adelgid, but can also be found in landscape trees and hedges. The insect feeds by inserting long mouthparts into the needles of these plants and removing the liquids inside. Females can live for more than one year and will lay eggs under their waxy covers. Eggs will hatch and young nymphs known as crawlers act as the dispersing stage and will settle out on new needles. Long-range movement of these crawlers may be accomplished by wind. Crawlers can be present in May; however overlap of many developmental stages at any given time has been observed. Management options for this insect, as with all others, can include doing nothing. This may be desirable in a forested setting if the severity of the infestation is too high and the value of the trees too low. This option may also preserve genetic diversity, if any resistance is present. Highly infested landscape trees can be removed and chipped and covered or dried away from healthy trees and replaced, if this is an option. Chemical management options can include foliar applications of insecticidal soaps and horticultural oils, if complete coverage of the insect is able to be achieved (on smaller plants). These applications may be most effective if made while crawler stages are present and exposed (not covered by their waxy scale). Some systemic insecticides are available for the management of this insect on larger landscape specimens where complete coverage cannot be achieved, including dinotefuran which can be effective within weeks of application. Although this chemical is a neonicotinoid which are currently under review, hemlock is wind pollinated and poses a reduced risk to bees and other pollinators for that reason (there is no pollen or nectar that would be attractive to beneficial insects which may have traces of the systemic insecticide). Application can be done as a trunk injection, soil drench, or basal bark spray. Dinotefuran can also protect trees from hemlock woolly adelgid for about 2 years. Please note that imidacloprid does not manage elongate hemlock scale populations. It is also important to observe scales with a hand lens or under a microscope in subsequent years following implementing management strategies as the waxy scale covering can remain for long periods of time without a live insect present, thus not requiring further management. As with all chemical insecticides, use best management practices to reduce drift, avoid applications during times of day when pollinators are most active or when flowers are in bloom, reduce impacts to non-target organisms, and observe all regulations when applying near schools, wetlands, and other sensitive areas or populations.
Forest Tent Caterpillar: Malacosoma disstria is native to North America and is a pest on oak, birch, ash, maple, elm, poplar, and basswood. While referred to as a tent caterpillar, this species does not construct a tent like that of M. americanum. The forest tent caterpillar larvae create a silken mat on the trunk or branches of their host trees and will forage on one branch at a time. Caterpillars of this species are very similar to that of M. americanum, but can be differentiated by the white, “key-hole” shaped spots down their back.Larvae will pupate in pale yellow cocoons spun in folded leaves attached to vegetation or inanimate objects. Adults will emerge around the same time as M. americanum and lay eggs which will overwinter for the next season. There is generally one generation per year. Eggs are laid in masses on host branches and can be distinguished from M. americanum in that they have a squared-off edge. Egg hatch occurs between 192 and 400 GDD’s (base 50°F) in MA. Scouting for these egg masses should also be going on at this time so that masses can be pruned out of trees and destroyed. Because no web is formed with this species, the simplest option for mechanical control is during the egg stage. Chemical management options are similar for the forest tent caterpillar as those listed for the eastern tent caterpillar and include insecticidal soaps, spinosad, and Bacillus thuringiensis ‘Kurstaki’ and should also be applied to target young caterpillars.
Gypsy Moth: Lymantria dispar is an insect native to Europe but very well known to the Northeast. Introduced to 27 Myrtle Street in Medford, Massachusetts accidentally by Mr. Trouvelot while in search of a silk moth that would survive in the United States in the 1870’s, it has been a significant defoliator of forest and landscape trees in Massachusetts ever since. Host plant species include their favorite, the oaks, however this insect will feed on many other species including apple, alder, basswood, hawthorn, poplars, willows, elm, hickories, maple, and sassafras. The Massachusetts Department of Conservation and Recreation reports that gypsy moth was responsible for 38,175 acres of defoliation mapped aerially in Massachusetts in the 2015 season, particularly in the eastern part of the state and areas around the Quabbin Reservoir. Many report seeing increased numbers of egg masses, caterpillars, adults, and pupae of this insect last year. Egg masses are laid in groups of 100-600 or more and are covered in a dense coating of brown hairs from the female moths. Eggs can be laid on host plants, fences, lawn furniture, vehicles, etc. It is this life stage that overwinters and may provide us with a sizeable population of these moths again in the 2016 season. If present in low numbers, they may be mechanically removed at this time. Gypsy moth eggs will hatch around 90-731 GDD’s (base 50°F) in Massachusetts. Larvae will emerge around April to May and can be distinguished by their hairy appearance and five pairs of blue spots directly behind the head followed by six pairs of red spots to the end of the abdomen. Large enough larvae will find a sheltered place to pupate in a dark brown pupal case and adults will emerge around the middle of July. The female is flightless and will attract the male using pheromones. The increase in gypsy moth last year has been attributed to a dry and warm spring, conditions that are not favorable for the fungus, Entomophaga maimaiga which has been a significant factor in decreasing gypsy moth populations. For this reason, we should hope to have a wet spring to allow for the fungus to multiply and perhaps reduce the numbers of young gypsy moth caterpillars. An NPV virus also helps lead to crashes in the Lymantria dispar populations in Massachusetts. If you are living or working in an area that saw an increase in gypsy moth egg masses last year, you may be interested in management options in addition to waiting for the NPV virus and fungus to catch up to the population. Insecticidal soaps can be used on small caterpillars, as well as options such as spinosad and Bacillus thuringiensis ‘Kurstaki’.
Winter Moth: Operophtera brumata has been a significant defoliator, particularly in eastern Massachusetts for over a decade. It is a pest of oaks, maples, cherries, basswood, ash, certain species of elm, crabapples, apple, blueberry, and even some spruce and heathers in other countries. Originally thought to have come to Massachusetts from the population in Nova Scotia, Dr. Joe Elkinton and his lab are in the process of completing a study of the genetics of populations of winter moth from Massachusetts, Canada, and areas across Europe and have reason to believe our winter moth is genetically different from those in Nova Scotia. Winter moth continues to defoliate in eastern Massachusetts and has been observed by the Elkinton lab to be mixing (and even interbreeding!) with a very similar species, Bruce spanworm (Operophtera bruceata), on the western edge of the population. Bruce spanworm is very difficult to distinguish from winter moth using morphological identification techniques. The Massachusetts Department of Conservation and Recreation reports that winter moth was responsible for 61,924 acres of defoliation mapped aerially in Massachusetts in the 2015 season, particularly in the eastern part of the state mainly in counties such as Essex, Norfolk, Bristol, and Plymouth, along with pockets in Barnstable and Middlesex counties. For monitoring and management purposes, knowledge of the lifecycle of this insect (and other insect pests) is very important. Eggs are tiny and laid by female winter moth in the cracks and crevices of host plant bark in groups of 150-350 eggs per female (Faubert, 2016). Eggs should be orange-red in color at this time, but will be very quickly turning the light, powder-blue then dark blue color exhibited just prior to egg hatch. Using a base of 50°F when monitoring Growing Degree Days, winter moth egg hatch should occur around 20-50 GDD. Dr. Elkinton recommends monitoring Growing Degree Days beginning January 1st using a base of 40°F when trying to predict winter moth egg hatch as this threshold of 40°F is closer to the insect’s actual developmental threshold. If you are using the Network for Environment and Weather Applications (NEWA; http://newa.cornell.edu/index.php?page=degree-days) web site to monitor GDD’s with a base 40°F, Dr. Elkinton recommends expecting winter moth egg hatch to begin around 240 GDD accumulated from January 1. He estimates that the majority of winter moth egg hatch will occur early this year, perhaps by the end of March. However, this could happen earlier if we experience prolonged periods of warm temperatures, or be delayed if cooler temperatures prevail. If cool weather continues and egg hatch is delayed until April, Dr. Elkinton reports that fewer GDD’s are required for egg hatch. For example, in 2013 egg hatch occurred around April 15th at a mean GDD accumulation of 177, well below hatch observed at 240 GDD in 2012. As you can see, monitoring winter moth egg hatch this way is incredibly complex. There are reports that a few winter moth eggs are turning blue in Franklin, MA as of 3/16/2016, however the majority are still orange. Knowledge of when to expect egg hatch is important as chemical management options need to be applied at that time.
For information about winter moth management options in blueberry, visit: http://extension.umass.edu/fruitadvisor/sites/fruitadvisor/files/fact-sheets/pdf/Winter%20Moth%20Recommendations%20in%20Blueberry.pdf . For ornamental trees and shrubs, dormant oil can be applied to winter moth eggs just prior to hatch and followed with an application of spinosad at the time of hatch on young caterpillars. The timing of this application is critical as caterpillars must be reached before they wriggle into the buds of their host plants where they will be protected and begin their destructive feeding. Larvae will feed in the bud before it opens, then free-feed after trees leaf out through June. Larvae will then drop to the soil and pupate there. Please be aware that when moving soil from nearby host-plants or transplanting host trees of winter moth, you may be inadvertently moving winter moth pupae to a new location. Look for and remove any pupae in such soils from May through the fall. Adults will emerge in November through January and mate and the flightless females will lay their eggs again. To make monitoring of winter moth eggs easier next season, tree bands can be set up in mid-late October (emptying them throughout the adult flight season) which encourages female winter moths to deposit eggs above and (primarily) below the tree band. These eggs can then be monitored next spring for the color change indicating egg hatch. When managing winter moth, be aware that Dr. Elkinton and his students have released the parasitic fly, Cyzenis albicans, throughout eastern MA. They have had successful establishment of this biological control agent in Wellesley, MA and have been able to collect this fly from overwintering populations. Winter moth populations in Wellesley, MA seem to be decreasing as the numbers of this fly increase. Management of the winter moth should include the preservation and encouragement of beneficial insects, such as Cyzenis albicans.
For More Information About Pesticides and Pollinators:
Clemson University. 2012. How to Protect Honeybees from Pesticides: A Guide for Beekeepers and Applicators. http://www.clemson.edu/public/regulatory/pesticide_regulation/bulletins/bulletin_5_protecting_honeybees.pdf
Cowles. 2016. Neonicotinoids, Bees, and Urban Trees: The Controversy Defined. Urban Forestry Today Noonhour Webcast Series. https://vimeo.com/157623443
Mandy Bayer. 2015. Pollinators in the Landscape I: Importance of Pollinators and Causes of Decline. https://ag.umass.edu/fact-sheets/pollinators-in-landscape-i-importance-of-pollinators-causes-of-decline
Oregon State University. 2006. How to Reduce Bee Poisoning from Pesticides. https://www.cdfa.ca.gov/files/pdf/ReduceBeePesticideEffects.pdf
Report by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program
Management Practices
The first spring plants have begun to bloom and along with them pollinator activity has begun. The first blooming plants visited by pollinators include Acer spp. (maples), Amelanchier spp. (serviceberry), Cornus mas (cornelian cherry dogwood) and Salix spp. (willow).
Keep in mind as spring cleanup begins that pollinators can overwinter in leaf litter, dead twigs and stems, or in patches of soil. It is beneficial to wait until pollinator emergence has been observed before spring cleanup and mulching.
Plant of the Week: Cornus mas
Cornus mas is a large shrub or small tree growing to 20-25’ tall and 15-20’ wide. Ornamental features include yellow flowers in March for around three weeks, bright red fruits in the summer, and exfoliating bark. Dark green leaves in summer; fall color is not showy. Prefers full sun to part shade and prefers a rich well drained soil, but is adaptable to soil types and pH. One of the first plants to flower in spring.
Report by Mandy Bayer, Extension Assistant Professor of Sustainable Landscape Hortulculture, Stockbridge School of Agriculture, UMass Amherst.
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Diagnostic Services
A UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see Plant Diagnostics Laboratory
Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The function of the Soil and Plant Nutrient Testing Laboratory is to provide test results and recommendations that lead to the wise and economical use of soils and soil amendments. For complete information, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. Alternatively, call the lab at (413) 545-2311.
Ticks are active at this time! Remember to take appropriate precautions when working and playing outdoors, and conduct daily tick checks. UMass tests ticks for the presence of Lyme disease and other disease pathogens. Learn more
