Landscape Message: May 13, 2016

May 13, 2016
Issue: 
8

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.

The Landscape Message will be updated weekly April through June. The next message will be available on May 20. 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

Environmental Data

The following growing-degree-day (GDD) and precipitation data was collected for an approximately one week period, May 5 through May 11. Soil temperatures and phenological indicators were observed on or about May 11. Total accumulated growing degree days (GDD) 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
(°F at 4" depth)

Precipitation
(1-Week Gain)

Time/Date of Readings

1-Week Gain

2016 Total

Sun

Shade

Cape Cod

14.5

100

64

54

0.75

6:00 PM 5/11

Southeast

20

110

65

56

1.25

4:45 PM 5/11

North Shore

11

83

51

48

0.20

10:00 AM 5/11

East

14.5

111

62

58

0.82

4:00 PM 5/11

Metro West

13.5

94

54

50

0.62

5:45 AM 5/11

Central

18

144

50

48

0.62

9:00 AM 5/11

Pioneer Valley

25

119

56

51

0.69

10:30 AM 5/11

Berkshires

11

91

54

50

0.43

9:00 AM 5/11

AVERAGE

16

107

57

52

0.67

-

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.
Aesculus hippocastanum (Common Horsechestnut) * * Begin * * * Begin *
Enkianthus campanulatus (Redvein Enkianthus) * * * * * * Begin *
Rhododendron carolinianum (Carolina Rhododendron) * * * Begin * * * *
Elaeagnus umbellata (Autumn-olive) * * Begin/Full * * * Begin/Full *
Syringa vulgaris (Common Lilac) Begin Begin Begin/Full Begin/Full Begin Begin/Full Full Begin/Full
Rhododendron spp. (Early Azaleas) Begin/Full Begin/Full Full Begin/Full Begin Begin/Full Full Begin/Full
Cornus florida (Flowering Dogwood) Begin Full Full Full Begin /Full Begin/Full Full Begin/Full
Malus spp. (Crabapple) Begin Full Full Full Full Full Full/End Full
Cercis canadensis (Redbud) Begin/Full Full Begin/Full Full Full Full Full Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The weather for the start of this reporting period more closely resembled March than May. Cold, damp days, with high temperatures only in the upper 40s, were the norm. Each day had some precipitation, perhaps only in the hundredth of an inch, which made outdoor working conditions miserable. Plant development progressed slowly at best. Monday, May 9th, saw a much needed change in the weather pattern. The sun came out and the constant drizzle ended! Temperatures rebounded back to a more normal range for early May and both plants and people rejoiced. Fringed Bleeding Heart (Dicentra eximia) is beginning to bloom while late flowering cultivars of Daffodils are going by. Pearlbush (Exochorda racemosa) and early Azaleas are brightening the landscape. Fothergilla is also beginning to bloom. Lawns are green and growing.

Pests/Problems: Winter moth caterpillar are in the first and second instar. Emerging leaves of host plants show the characteristic “Swiss cheese” holes. New foliage of Japanese maple that hasn’t yet expanded is, upon closer examination, already consumed by the tiny caterpillars. New leaves of oak are webbed together and the caterpillars are feeding inside. Russ Norton, Extension Specialist with Cape Cod Extension, reports that Gypsy moth caterpillars are hatching. Brewster and Harwich had high populations last year so those areas should be closely monitored. Adult lily leaf beetles continue to feed on foliage of true lilies. No egg laying has been observed as of this report. Hand pick the adults to avoid the more damaging larval stage. Slugs and snails are actively feeding on foliage of perennials. Rabbits are browsing on Hosta and Lily. Monitor Hemlock for Elongate hemlock scale crawlers.

Deer tick nymphs are active. Dog tick adults are active. Seedling Oriental bittersweet has leafed out and can be readily identified; remove it where possible. Dandelions are in full bloom.

Southeast Region (Hanson)

General Conditions: Until Tuesday, May 10, the weather was cool (40’s-50’s), raw and damp contributing to the continued delay of plant development. Many trees, like oaks, have very small leaves and on some oaks we have yet to see leaf expansion; several other species of trees have yet to leaf out. The cool weather has also delayed flower development on plants like lilac which were beginning bloom last week and are at just about the same stage this week. With warmer weather arriving this week, and the recent rain, plant development is starting to pick up; however, this is probably one of the least colorful springs, at this time, due to all the cold damage to flower buds and plants that occurred in previous months. Hanson received 1.25 inches of rain and more is needed. Remind clients to water new plantings and that includes new or renovated lawns. The following plants are in full bloom: Sassafras albidum, Cercis canadensis (Eastern Redbud), late blooming magnolias like Magnolia ‘Elizabeth’, Kwanzan cherry, Crabapples, Cornus florida (Flowering dogwood), Chaenomeles speciosa (Common Floweringquince), Viburnum carlesii (Mayflower Viburnum), Viburnum x burkwoodii ‘Mohawk’, Viburnum ‘Eskimo’, Rhododendron schlippenbachii (Royal Azalea), Prunus serotina (Black Cherry), Amelanchier (shadbush), Halesia sp., Spiraea prunifolia f. simplicifolia (Bridalwreath Spirea), Fothergilla major (large Fothergilla), Fothergilla gardenii (dwarf Fothergilla), Flowering Almond, Kerria, Daphne tangutica, Vaccinium corymbosum (highbush blueberry), Rhododendron ‘Olga Mezitt’, Exochorda racemosa, Epimedium sp., Trillium sp., Tulips, Euphorbia polychroma, Brunnera macrophylla, Asarum canadense, Stylophorum diphyllum (Wood Poppy), Phlox subulata, Phlox divaricata, Arisaema sp.(Jack-in-the-pulpit), Corydalis scouleri, Primula sp., Pulmonaria sp., Ajuga, dwarf bearded Iris, Saruma henryi, Lamiastrum galeobdolon, Lamium sp., Lathyrus vernus, Lunaria annua (honesty or money plant), Mertensia virginica (Virginia bluebells), Glaucidium palmatum, Helleborus foetidus, Violets and Vinca minor. Lilac, Lonicera tatarica (invasive), Corydalis lutea, bleeding heart, Convallaria majalis (Lily-of-the-valley), Phlox stolonifera, Polygonatum sp. (Solomon's Seal), Mazus repens, Tiarella cordifolia (Foam Flower), Galium odoratum (Sweet Woodruff) and Doronicum sp.,arebeginning to bloom. Spiraea thunbergii ‘Ogon’, Azalea ‘April Snow’, and Helleborus x hybridus are ending bloom. Hummingbirds were observed in Hanson, MA on May 7th. Baltimore orioles and a Canadian tiger swallowtail butterfly were observed May 11th. The warm weather has also brought out honeybees which were very active in the crabapples that are now in bloom.

Pests/Problems: In the Hanson, MA area, Winter moth caterpillars were found in the 1st, 2nd and 3rd instars, most were in the mid-late 2nd instar (base 40 growing degree days (GDD) at 470). Winter moth caterpillar development is slow this season but the caterpillars are out there. They were found in the expanding buds of oak, between leaves of various maples, European beech, apples, etc. The cold wet weather has contributed to slowing the caterpillars’ development along with many of the plants they are feeding on; continue to monitor host plants and manage where needed. In last week’s Cape Cod regional landscape report, Roberta Clark reported that deer tick nymphs were active on Cape Cod, so they probably are active, or soon will be, here in Southeastern, MA. Deer tick nymphs are very tiny and it is this stage that is most responsible for the transmission of Lyme disease. Be vigilant, conduct tick checks frequently and take precautions like using repellents when working outdoors; the nymph stage is active for several months. Monitor the undersides of azaleas for azalea whitefly, which is active. Gypsy moth eggs have hatched and small caterpillars were found hunkered down on the egg mass earlier this week. As the warm weather came in the past few days, the caterpillars started moving on and were found in expanding oak leaves. UMass Entomologist, Dr. Elkinton’s staff reports that gypsy moth numbers are very high in Wompatuck State Park in Hingham, MA. Eastern tent caterpillar webs are getting larger and they can be easily removed manually and destroyed at dusk, when the caterpillars retreat back to their tents. Ants are active in lawns and around patios, etc. Mosquitoes, wasps and hornets have started to appear. Continue to monitor for the following insects: Lily leaf beetle adults on true lilies, boxwood psyllid, snowball aphids, Hemlock woolly adelgid and European pine sawfly on Mugo and other pines. Black flies, carpenter bees, and dog ticks continue to be active. The beautiful, bright green, Six spotted tiger beetle (Cicindela sexguttata) is active. This beetle feeds on other insects and spiders and is considered to be beneficial. Barberry, a Massachusetts invasive plant, is in full bloom. Now is a good time to shear or remove and destroy the plant, to reduce seed or eliminate future seed production. The new reddish-green growth of poison ivy is appearing in landscapes. Dandelions are still in bloom but many are setting seed. Ground ivy, garlic mustard, buttercups, veronica, violets, chickweed and wild mustard are in full bloom. Now is a good time to prune, or renovate, spring-flowering shrubs, like Forsythia and PJM rhododendrons, that have already flowered and are starting to put out new growth.

North Shore Region (Beverly)

General Conditions: During the first part of this reporting period we had cooler temperatures and cloudy weather and rain showers on the weekend. Several groups in the area were holding plant sales were very successful despite the cloudy and rainy weekend. Day temperatures were in the low 50s and night temperatures were in mid 40s. During the last few days we have seen temperatures climb up to low the 60s, reaching the low 70s by Tuesday. We gained 11 growing degree days at Long Hill during this reporting period, and approximately 0.20 inches of rainfall was recorded. Woody plants seen in bloom during this reporting period include: Mountain Pieris (Pieris floribunda), Flowering Dogwood (Cornus florida), Redbud (Cercis canadensis), Large Fothergilla (Fothergilla major), Dwarf Fothergilla (Fothergilla gardenii), Royal azalea (Rhododendron schlippenbachii), European elder (Sambucus racemosa), Common Lilac (Syringa vulgaris) Chinese lilac (Syringa x chinensis), Kwanzan Cherry (Prunus serrulata), Crabapple (Malus spp.), Olga Mezitt Rhododendron (Rhododendron ‘Olga Mezitt’), apple trees (Malus spp.) and Highbush blueberry (Vaccinium corymbosum). Non-woody plants seen in bloom include: Daffodil (Narcissus spp.), Forget Me Not (Myosotis sylvatica), Tulips (Tulipa sp.), Bleeding heart (Dicentra spectabilis), Trout lily (Erythronium americanum), Siberian Iris (Iris sibirica), Trillium (Trillium grandiflorum), Rock cress (Aubrieta deltoidea), and Pig squeak (Bergenia cordifolia).

Pests/Problems: Winter moth caterpillars (Operophtera brumata) were feeding on apple and maple leaves. Rabbits and woodchucks were also seen in the landscape. Weeds seen in bloom include: Dandelion (Taraxacum officinale), Lesser celandine (Ranunculus ficaria), Ground Ivy (Glechoma hederacea) and Purple Deadnettle (Lamium purpureum). Ticks are very active. Be careful to protect yourself when working outdoors.

East Region (Boston)

General Conditions: We finally gained some GDDs for the month of May, gaining 14.5 over the last 3 days (May 8th to 10th) bringing us up to 111.0 on the year. For those tracking base 40, GDDs total 577. Over a 12 day period (April 26th to May 7th), we accumulated no GDDs as a cold front lingered over the area bringing cloudy and raining conditions. We have accumulated 1.4 inches of rain so far in the month of May, 0.82 inches in the last 7 days. Low temperatures over the last week have ranged between 40°F and 46°F, averaging 43°F; high temperatures have fluctuated between 46°F and 72°F, averaging 57°F. Once the cold front moved out, highs returned to seasonal, reaching high 60s and low 70s. The warm sunny weather has driven many lilacs into bloom as Syringa vulgaris (common lilac) cultivars are almost at peak flower. Plants currently in bloom include: Aesculus flava (yellow buckeye), Aesculus x bushii (Bush's chestnut), Cornus florida (flowering dogwood), Dicentra spectabilis (bleeding heart), Fothergilla major (large fothergilla), Halesia tetraptera var. monticola (mountain silverbell), Kerria japonica (Japanese kerria), Lonicera sp. (honeysuckle), Rhododendron kaempferi (torch azalea), Rh. minus (Piedmont rhododendron), Rh. schlippenbachii (royal azalea), Rh. vaseyi (pinkshell azalea), Rh. yedoense (Korean azalea), Trillium grandiflorum (trillium), Viburnum lantana (wayfaring tree), and V. lantanoides (hobblebush).

Pests/Problems: Winter moth (Operophtera brumata) can be found in every stage of caterpillar development and free-feeders are on the move; they can be found on almost every deciduous plant throughout the landscape. Weeds in full bloom include garlic mustard (Alliaria petiolata), greater celandine (Chelidonium majus), ground ivy (Glechoma hederacea), and purple deadnettle (Lamium purpureum). Dandelion (Taraxacum sp.) is dispersing seed throughout the landscape. Allergies are particularly bad at this time, mostly due tree pollens including elms and oaks.

Metro West (Acton)

General Conditions: The month of May started with 8 continuous days of cool and damp weather. Finally, there was a break in weather on the 9th with temps in the 60s and in the 70s on the 10th. Much is in bloom for this time of the year, including the following woody plants: Amelanchier spp. (Shadbush, Serviceberry), Aronia arbutifolia (Black Chokecherry), Cercis canadensis (Redbud), Chaenomeles speciosa (Common Flowering Quince), Cornus florida (Dogwood), Daphne x burkwoodii 'Carol Mackie'(Daphne), Fothergilla gardenii (Dwarf Fothergilla), F. major (Large Fothergilla), Halesia tetraptera (Mountain Silverbell), Magnolia ‘Elizabeth’, M. x loebneri 'Merrill', Malus spp. (Crabapples), Pieris japonica (Japanese Pieris), Prunus spp. (Cherry) including Prunus serrulata 'Kwanzan'(Japanese Flowering Cherry), P. japonica (Flowering Almond), P. serotina (Black Cherry), Rhododendron spp. (early flowering Rhododendron), Spirea thunbergii (Thunberg Spirea), Syringa spp.(early blooming Lilac), Syringa vulgaris (Common Lilac), Vaccinium angustifolium (Lowbush Blueberry), V. corymbosum (Highbush Blueberry), Viburnum x burkwoodii (Burkwood Viburnum), and Viburnum × juddii (Judd Viburnum). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Ajuga reptans (Bugleweed), Aquilegia canadensis (Columbine), Arisaema triphyllum (Jack-in-the-Pulpit), Asarum europaeum (European Ginger), A. canadense (Canadian Wild Ginger), Aurinia saxatilis (Basket of Gold), Caltha palustris (Marsh Marigold), Chrysogonum virginianum (Green and Gold), Convallaria majalis (Lily of the Valley), Dicentra canadensis (Squirrel Corn), D. cucullaria (Dutchman's Breeches), D. eximia (Fringed Bleeding Heart), D. spectabilis (Old Fashioned Bleeding Heart), Epimedium x versicolor 'Niveum' (White Flowering Barrenwort), E. x versicolor 'Roseuem' (Pink Flowering Barrenwort), E. versicolor 'Sulphureum' (Yellow Flowering Barrenwort), Gallium odorata (Sweet Woodruff), Helleborus niger (Christmas Rose), Hyacinthus spp. (Hyacinth), Iberis sempervirens (Evergreen Candytuft), Lunaria annua (Money Plant), Mertensia virginica (Virginia Bluebells), Muscari sp. (Grape Hyacinth), Myosotis sylvatica (Forget-me-not), Narcissus spp. (Daffodil), Nepeta spp. (Ornamental Catmint), Omphalodes verna (Blue-eyed Mary), Phlox divaricata (Canadian Phlox), P. x subulata (Moss Phlox), Polygonatum commutatum (Great Solomon Seal), P. odoratum 'Variegatum' (Variegated Solomon Seal), Primula spp. (Primrose), Stylophorum diphyllum (Wood Poppy), Tiarella cordifolia (Foam Flower), Trillium erectum (Red Flowering Trillium), T. grandiflorum (White Flowering Trillium), T. sessile (Toadshade), Tulipa spp. (Tulip), Uvularia sessilifolia (Bellflower), Viola spp. (Violet), and Zizia aptera (Heart-Leaved Alexander).

Pests/Problems: There is significant dieback, if not total death,and needle discoloration on a number of Pinusstrobus (White Pine). There may be two different causes for this. Those impacted trees growing alongside roadways may be stressed by snow and ice winter road treatments, heat and drought. A needle cast/blight may be impacting those trees not growing alongside roadways and in some cases growing in low lying wetter areas that are showing signs of needle discoloration that starts at the needle tips. Winter moth caterpillars are actively feeding and can be seen more easily now on Malus (Crabapple) and Prunus (Cherry) as evidenced by the damage to the leaves and the culprit can be seen by unfurling the leaves on the host trees to reveal the caterpillar upon close inspection. Alliaria petiolata (Garlic Mustard), which is easily seen with its white flowers growing on roadsides and in woodlands, wetlands and gardens continues to flower. Taraxacum officinale (Dandelion) is now going to seed and Polygonum cuspidatum (Japanese Knotweed) has exploded after the recent wet and warm spell and has shot up and is now as tall as a couple of feet in some areas. Be aware of Toxicodendron radicans (Poison Ivy). It is beginning to leaf out so it is fairly easy to detect its shiny red leaves of three.

Central Region (Boylston)

General Conditions: The past week, until Monday, was gray and cool with periodic rain and temperatures in the 40’s and low 50’s. The threat of frost did not materialize Monday night into Tuesday at Tower Hill, but was prevalent nearby. Strong gusty winds affected plants Sunday night and all day Monday. The last two days have been sunny and pleasant with temperatures in a more normal May range - 50’S and 60’S by day, 40’s at night. .

Pests/Problems: Eastern tent caterpillar, black flies, ticks, deer, rabbits and woodchucks.

Pioneer Valley Region (Amherst)

General Conditions: Turbulent spring weather continued this past reporting period as we finally broke free of the low pressure system that ushered in repeated showers and cloudy conditions to the northeast. Aside from a few fleeting moments, the valley was devoid of sun from Sunday, 5/1 to Sunday, 5/8. The unseasonably cool and cloudy weather departed on Mother’s Day after a high pressure system moved into the region, and with it came the winds. Sustained winds of 20–30 mph and gusts up to 40 mph were recorded at Barnes airport in Westfield during the mid-day hours on Sunday, 5/8. Young leaves, especially those of sugar maple, oak and copper beach, littered lawns and roadways as they were ripped from their respective canopies. It was again windy on Monday, 5/9 but both sustained winds and gusts were diminished compared to the previous day. Since then, winds have been calm throughout the valley and we’ve settled into more seasonable weather with highs in the upper 60s to upper 70s and lows in the 30s to low 40s. Frost and freeze warnings were issued for the early morning hours of 5/10 and 5/11. In the Northampton area, low temperatures during the morning of 5/10 dropped to 29° F. It appears only low-lying pockets directly adjacent to the rivers were below freezing as most weather stations reported low 30s at this time. The cool, cloudy start to May suspended development for many trees and shrubs although progress now continues at a rapid rate thanks to full sun and mild temperatures in the 70s. Lawn grass is vibrant green and growing quickly. Soils were moist due to over an inch of rain and dominance of cloudy weather since 5/1. However, the winds on 5/8 and 5/9 and the warm temperatures have quickly dried mulch and the uppermost soil layer so continue to monitor recently transplanted trees, especially conifers. Nearly all landscape conifers are flushing new growth at this time. Budbreak for spruce has been sporadic in the valley. In some locations, Oriental, Norway and blue spruce needles are flushing while at nearby sites, buds are still slowly swelling.

Pests/Problems: According to researchers at the UMass Cold Spring Orchard, conditions have been too cold and too dry for fire blight, so this menacing bacterial disease is not a concern right now on apple, crabapple and pear. Bladder/spindle galls are locally abundant already on the foliage of elms, cherry and maple, among other trees. While highly conspicuous, these insects are a cosmetic pest only. Undersized and distorted leaves were observed on redvein einkanthus and kousa dogwood on the UMass campus and this may represent damage from the 4/5–4/6 arctic blast the region experienced. If Rhizosphaera needlecast is a concern on blue spruce, begin treating new growth when needles are approximately 10-25% elongated and on regular intervals should wet weather persist. Chemical and cultural control is required to control this disease if it has become well established on blue spruce. Norway spruce is highly resistant and does not warrant management. Overall, disease incidence remains low since many trees and shrubs are still flushing new growth. Both oriental bittersweet and Japanese knotweed are actively growing. These two invasive plants should be eradicated by whatever means available, given their ability to dominate forest and landscape settings once they establish.

Berkshire Region (Great Barrington)

General Conditions: After 8 consecutive days of cloudy damp weather, the sun finally poked through on Sunday, May 8. Though day time temperatures rose on the days following, a wide spread frost occurred on the morning of May 10th with a few locations experiencing another frost on the morning of May 11th. The sun and daytime warmth has accelerated plant growth, most notably in lawns, but plant development in general is still lagging that of recent years. The combination of sun, warm temperatures, wind has quickly reduced levels of soil moisture, especially where soils have been tilled. Irrigation may soon be required.

Pests/Problems: There still is not much pest activity but some new pests have been observed this week. Newly added to the list of pests are willow leaf beetle, spruce spider mite, and cutworms. Pests which continue to be active include hemlock eriophyid mites, carpenter bees, pill bugs, millipedes, and lily leaf beetle. Black legged ticks remain a huge problem and many are now in the nymph stage. Skunks have been very active digging up lawns in search of grubs which are now in the upper inch of soil. Skunks have also been digging into patio pots which have been set out. Garlic mustard is in full bloom. Where it has invaded gardens and managed landscapes, garlic mustard plants should be removed before they set seed.

Regional Scouting Credits

  • 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 blight of arborvitae (Thuja occidentalis) caused by Phyllosticta thujae. Several trees that are eight-years-old and have been present at the site for two years. They were planted in a partial sun setting and are not provided with supplemental irrigation. This spring, the foliage became brown throughout the canopy over a three week period. Spider mites were observed last season and drought stress is also a potential predisposing stress.

Infestation of the native hemlock scale (Abgrallaspis ithacae) on eastern hemlock (Tsuga canadensis). No information was provided about the tree, but the scale infestation was significant. Abgrallaspis ithacae is rounded to oval-shaped and predominantly grey-colored. This armored scale pest is native in North America and will also infest spruce and fir on occasion. It is uncommon for the native hemlock scale to establish populations capable of causing significant damage, as was the case here.

Marginal leaf burn of rhododendron (Rhododendron ‘Roseum Elegans’) caused by winter injury and colonization by Phyllosticta and Phomopsis. Shrub is nine-years-old and has been present at the site for nearly as long. This spring, brown and curled leaf margins were observed in the shrub canopy. The injury was apparent in previous years but to a lesser extent. Winter injury is a perennial issue for rhododendrons in New England and there are numerous fungal pathogens that will opportunistically colonized the killed plant parts to further the dieback.

Browning and premature needle shedding of blue spruce (Picea pungens) caused by Cryptomeria scale (Aspidiotus cryptomeriae) and stem cankering by Botryosphaeria. Tree is 50-years-old and has been present at the site for 40 years. Symptoms are present on the lower half of the tree on the north-facing side only. Crusted resin was observed on stems and branches. The setting is full sun with well-drained soils.

Needle browning of eastern white pine (Pinus strobus) caused by Septorioides strobi and pine bark adelgid (Pineus strobi). Tree is 50-years-old and has been present at the site its entire life. Symptoms began to develop two years ago and have since worsened. Septorioides is a recently described pathogen of eastern white pine and was abundant on submitted samples in 2015.

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

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

  • Emerald Ash Borer: Agrilus planipennis has been detected in a new county in Massachusetts. Officials from the MA Department of Conservation and Recreation and the United States Department of Agriculture have confirmed a find in Hampden County in the town of Wilbraham. This invasive insect readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus). For a map of the known locations of emerald ash borer in the state, as well as further information about this insect, please visit: https://ag.umass.edu/fact-sheets/emerald-ash-borer.
  • Azalea Sawfly: Amauronematus azalae is active on deciduous azaleas azaleas in areas where leaf expansion has occurred. Continue to monitor for the feeding damage of this caterpillar. This insect can completely defoliate the plant if present in large numbers. Spinosad based products are effective on this hymenopteran pest, while Bacillus thuringiensis Kurstaki is not.
  • Birch Leafminer: Fenusa pusilla is active at this time. The adult female sawfly wasps are small and dark and can be observed visually on host plant foliage. Eggs are laid within the newly emerging leaves. The use of yellow-sticky cards (1 per tree) works extremely well for monitoring for this pest. Once the adult sawflies have emerged, the tree can then be treated with a chemical insecticide, such as a pyrethroid, to prevent egg-laying within the foliage. Bacillus thuringiensis Kurstaki is not effective against sawflies.
  • Black Vine Weevil: Otiorhynchus sulcatus damage is apparent on rhododendron and taxus, but can also be seen on azalea, mountain laurel, and Euonymus. Adult weevils feed along the leaf/needle margins and create rounded notches. Inspect foliage of these plants for notching from last season’s feeding. Larvae, which dwell in the soil, are conducting their heaviest feeding on plant roots at this time. Pupation will occur by the end of this month. Adults will emerge in June and create new damage to leaves for this season. All individuals are females and reproduce asexually. This insect has developed resistance to many chemical insecticides. Entomopathogenic nematodes such as Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacterio-phora work well against this insect, particularly on containerized plants. Results in the landscape vary. Wetting the soil thoroughly prior to application and keeping it wet for at least 5 days following application can help increase the efficacy of the nematodes. Burlap laid around the base of plants during the time adults are active, by the end of May through August, can be inspected weekly for adult weevils which can be killed before egg laying.
  • Boxwood Psyllid: Psylla buxi will be feeding on newly emerged boxwood foliage with its piercing-sucking mouthparts. This feeding may not cause yellowing or loss of foliage, but will lead to the cupping of new leaves which can be an aesthetic issue for some. If population numbers are low, management of this pest may not be necessary.
  • Cinara spp. Aphids: Aphids in the genus Cinara overwinter as eggs on the needles of conifer species found in New England. Many of these aphids, at maturity, are quite large and have long, almost spider-like legs. The eggs of this group of aphids have hatched at this time and young, tiny insects can be found feeding on small branches or the main stem of smaller trees including pines, fir, and spruce. Usually, management of these insects is not required. However, when populations are large on younger plants, management may need to be considered. Applications of insecticidal soap or horticultural oils at the summer rate can be considered, where appropriate.
  • Eastern Tent Caterpillar: Eastern tent caterpillar eggs have hatched and larvae are active at this time. Young caterpillars are found in small tents in the crotches of branches, which are quickly growing larger. Remove small tents by pruning (when possible, without removing too much foliage) or destroy with a gloved hand. Do not set the tents on fire, as this can do more damage to the plant and surrounding area than the caterpillars ever could. Remove Forest Tent Caterpillar egg masses before we reach 192 GDD, base 50°F, when hatch will occur.
  • Gypsy Moth: Eggs of the gypsy moth have hatched in the towns of Brimfield and Hingham and surrounding areas. Tiny caterpillars can be observed resting on their egg masses and foraging for food. Although the break in the rain has been nice this week, let’s hope for the wet and rainy weather to continue so that the entomopathogenic fungus, Entomophaga maimaiga, can get well established in the gypsy moth population and help reduce the amount of young caterpillars. In areas of the state where multitudes of egg masses have been seen, such as towns around the Quabbin Reservoir and points further east, Bacillus thuringiensis Kurstaki can be used on small caterpillars.
  • 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.
  • Euonymus Caterpillar: Yponomeuta cagnagella will be active soon, in areas above 95 GDD’s, base 50°F. These small yellow caterpillars with black spots feed throughout the host plant and are capable of creating vast amounts of unsightly silk while feeding on the leaves. By early summer, entire viburnum can be covered with silk and leafless. Inspect for the presence of this pest and treat with a product that contains Spinosad if deemed necessary. Handpick and destroy if caterpillars are small in number.
  • European Pine Sawfly: Neodiprion sertifer caterpillar will be active soon. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine, but is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned away and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis Kurstaki is not effective against sawflies.
  • Hemlock Eriophyid Mite: Nalepella tsugifoliae (also known as the hemlock rust mite) is currently active and should be monitored for on eastern hemlock, spruce, fir, and yew.
  • Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will hatch by late May or early June. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary.
  • Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. Infested trees may be treated with a summer rate horticultural oil spray as weather conditions allow.
  • Honeylocust Plantbug: Diaphnocoris chlorionis generally appears at the same time as bud-break of the host plant. It immediately begins to feed on the foliage with its piercing-sucking mouth. If numbers are low and the foliage expands quickly then damage is insignificant. Damage in this case will appear as scattered patches of fine yellow stippling on parts of the leaflets. However, if this pest is present in large numbers or foliage expands slowly, damage caused may warrant management. Monitor for numbers of this pest by gently shaking branches over a white piece of paper. Examine carefully with a hand lens for the tiny pale green nymphs. Young nymphs can be treated with a spray of insecticidal soap.
  • Lily Leaf Beetle: Continue to monitor for Lilioceris lilii. Management can be achieved by hand-picking and removing adults and larvae. Some chemical management options are available for this insect, but if caught early mechanical management may be effective. Pyrethroids can be used against adult beetles, whereas spinosad products are most effective against the larvae.
  • Nantucket Pine Tip Moth: Rhyacionia frustrana larvae feed in the buds, shoots, and base of needles of pitch, Scotch, mugo, and black pines in Massachusetts. The insect overwinters as a pupa in the damaged shoots. Adults will emerge in areas approaching 121 GDD’s, base 50°F. Many parasites, predatory insects, and birds will attack this pest. If chemical management options are deemed necessary, target the young larvae of this insect, which can be found hatching from eggs laid by this spring’s adults 5-10 days after peak adult emergence.
  • Pine Bark Adelgid: Pineus strobi has been observed actively feeding at this time and secreting large amounts of waxy-white wool over their bodies (on white pine). This insect can be found on the trunk, twigs, and branches of white, Scotch, and Austrian pines. These cottony masses can even be seen on the bases of needles. On healthy trees, this insect has not warranted management as they appear unaffected by its feeding. If aesthetically unpleasant, adelgids and wool may be washed off with a strong stream of water from a garden hose on smaller plants.
  • Snowball Aphid: Neoceruraphis viburnicola is very active on certain species of viburnum. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white with a white powdery finish, can be found in curled up and distorted foliage. This pest is mostly aesthetically damaging; however, if chemical management options are deemed necessary, foliar applications of products containing active ingredients such as permethrin can be made as leaves are expanding. Once the aphids are concealed in the curled up foliage, reaching them with an insecticide can be increasingly difficult and efficacy is reduced.
  • Viburnum Leaf Beetle: Pyrrhalta virburni: Inspect newly emerging foliage for spotting caused by the feeding of tiny, pale-yellow larvae skeletonizing the leaves. Larvae may be treated with a product containing spinosad if found. This pest has the potential of completely defoliating the host within 4-5 weeks of larval feeding.
  • White Spotted Pine Sawyer (WSPS): Monochamus scutellatus will be pupating this month and adults can emerge in late May throughout July, depending on local temperatures. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers, however the difference in the color of the scutellum is a key characteristic. 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 captured an Asian longhorned beetle (particularly beginning in July and August) or have seen damage caused by this insect, such as exit holes, 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. 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 .
  • Winter Moth: (Continued monitoring) Operophtera brumata 2nd and 3rd instar caterpillars are being found in host plants such as maple, apple, and blueberry in warmer locations. In certain areas where the cooler weather last week may have stalled development, 1st instar caterpillars are still being found with 2nd and 3rd instars (see Southeast Region report). Hosts whose buds opened earlier this season may be more significantly impacted. Continue to monitor susceptible hosts for the presence of caterpillars. For green industry professionals looking to manage winter moth in the landscape, wait until leaves have finished opening to treat with insecticides. By waiting until the leaf expands, it is easier for the insecticide to reach the caterpillar than when it is protected inside the bud. Products containing active ingredients such as spinosad and pyrethroids are available. Apples, crabapples, and other flowering plants should not be sprayed with these products while in bloom to avoid unintended impacts to pollinators.

A Request for Bruce Spanworm: A graduate student working with Dr. Joseph Elkinton on winter moth is looking for outbreak populations of winter moth’s native counterpart, Bruce spanworm. This insect harbors a microsporidian, a type of parasitic fungus, that is not found in winter moth populations. This may explain why Bruce spanworm very rarely has outbreaks and when they occur, the outbreaks are very short-lived, whereas winter moth is in permanent outbreak phase in Eastern New England. Populations of Bruce spanworm are needed to conduct further research. Bruce spanworm can be found on a wide range of deciduous trees. The caterpillars are bright green inchworms, 3/4-inch-long, and leave behind Swiss cheese patterned holes in the leaves. See this USDA pest alert or this summary by the Maine FS for some photos of the caterpillars and their damage. The defoliation occurs right after bud break and there is only a week to collect before the caterpillars drop down to pupate. If you know of a population of Bruce spanworm, particularly in western Massachusetts, that could be collected for this research, please contact either Dr. Elkinton (elkinton@ent.umass.edu) or Hannah Broadley (hbroadley@cns.umass.edu) as soon as possible.

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.

A note about Deer Tick Awareness: deer ticks (Ixodes scapularis), the American dog tick (Dermacentor variabilis), and the lone star tick (Amblyomma americanum) are all found throughout Massachusetts. Each can carry their own complement of diseases. Adults and nymphs can be active when temperatures are above freezing and anyone working in tick habitats (wood-line areas, forested areas, and landscaped areas with ground cover) should check themselves regularly for ticks while practicing preventative measures. Have a tick and need it tested? Visit the web page of the Laboratory of Medical Zoology (www.tickdiseases.org) and click on the red 'Test a Tick' button for more information.

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

Management Practices

Plant of the Week: Cornus florida

Cornus florida is a native flowering tree growing 20-40’ tall and as wide. Flowering dogwood offers many ornamental features having four seasons of interest. The true flowers are actually the green-yellow centers of the inflorescences with the bracts being the showy part. Flowers can be white or pink, open before leaf emergence in late April–May and are effective for around two weeks. Leaves are dark green through the summer turning red to red-purple in the fall. The red fruits (drupes) ripen in September–October and are eaten by birds. The bark is an ornamental feature in winter having a scaly-blocky appearance. It is important to get plants from northern locations as southern sourced plants often don’t have the bud hardiness in the north. Plants are best grown in a well-drained acid soil with good organic matter. Part shade is best, but flowering dogwood can do well in full sun.

Flowering dogwood can have a number of problems, especially when stressed. Dogwood anthracnose can be a large problem; for this reason it is advisable to plant cultivars with resistance or related species (such as Cornus kousa or the Cornus kousa x C. florida hybrids).

Cornus florida ‘Cherokee Princess’     Cornus florida ‘Cherokee Princess’     Cornus florida

Garden Retailers

Little Paper Pouches in Hanging Baskets and Planters

Some hanging baskets and potted plants purchased for your retail garden center may contain little paper pouches the size of “tea bags”. Wholesale greenhouses using beneficial insects and mites are passing along “good bugs” to you and your customers.

These pouches are called “sachets” and contain very small beneficial predatory mites (commonly called cucumeris) that are used to manage thrips in greenhouses. Thrips feeding on plants cause distorted flowers and leaves. The predatory mites crawl out of the sachets seeking out and killing thrips on the plants. The sachets are a complex breeding system for the beneficial predatory mites that slowly release the mites for 4-6 weeks. Each sachet contains predatory mites, plus food storage mites (for the predatory mites to feed on) and bran (that the food mites feed on). Sachets with predatory mites are usually placed in hanging baskets or in individual pots and can be either, thrown away (if wet and moldy), or left in place to continue releasing mites. The predatory mites will not bite humans and are so small, that an untrained eye would not know they were there.

Reported by Tina Smith, UMass Extension Floriculture Specialist

Additional Resources

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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