Landscape Message: April 21, 2017

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Massachusetts Green Industry professionals in the management of our collective landscape. Detailed reports from scouts and Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. The following issue has been updated to provide timely management information and the latest regional news and environmental data.

To read individual sections of the message, click on the section headings below to expand the content:

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Scouting Information by Region

Environmental Data

The following data was collected on or about April 19. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2017 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	2017 Total	Sun	Shade
Cape Cod	30.5	58.5	61	57	0.00	12:00 PM 4/19
Southeast	35	73	60	49	0.12	3:00 PM 4/19
North Shore	45	101	48	43	0.11	9:30 AM 4/19
East	45.5	112.5	57	52	0.03	4:00 PM 4/19
Metro West	34	87.5	50	46	0.16	5:45 AM 4/19
Central	46	110	53	46	0.09	8:15 AM 4/19
Pioneer Valley	28	77	52	48	0.23	10:30 AM 4/19
Berkshires	28	61	51	48	0.29	8:45 AM 4/19
AVERAGE	37	85	54	49	0.13	-
n/a = information not available

Drought Conditions Update: Very little change from last week, and more rain is in the forecast.  Approximately 48% of Massachusetts is currently under official drought status. For the area under drought status, less than 1% of the Commonwealth is classified as 'Severe Drought'.  For more information see http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?MA.

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.
Cercis canadensis (Redbud)	*	*	*	*	*	*	*	Begin
Amelanchier spp. (Shadbush, Serviceberry)	Begin	*	Begin/Full	Begin/Full	Begin	*	Begin/Full	*
Pyrus calleryana (Callery Pear)	Begin	Begin/Full	Begin/Full	*	Begin	*	Begin/Full	*
Chaenomeles speciosa (Common Flowering quince)	Begin	Begin	*	*	*	*	*	*
Magnolia soulangiana (Saucer Magnolia)	Begin	Begin	Begin	Begin	Begin	*	Begin	*
Rhododendron 'P. J. M.'	Full	Full	Begin/Full	Begin/Full	Begin/Full	*	Begin/Full	*
Prunus serrulata (Japanese Flowering Cherry)	Begin/Full	Begin/Full	Begin/Full	Full	Begin/Full	*	Begin/Full	Begin
Forsythia x intermedia (Border Forsythia)	Full	Full	Full	Full	Full	Full	Full	Full
Rhododendron mucronulatum (Korean Rhododendron)	Full/end	*	Full	Full	Full	Full	Full	Begin/Full
Magnolia stellata (Star Magnolia)	Full	Full	Begin/Full	Full	Full	*	Full	Begin
Pieris japonica (Japanese Pieris)	Full/End	Full	Full	Full	Full	Full	Full	Begin/Full
Cornus mas (Corneliancherry Dogwood)	End	End	End	End	End	End	Full/End	Full
Acer rubrum (Red Maple)	Full/End	End	Full/End	Full/End	End	Full/End	Full/End	Full/End
n/a = information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature over the last week was 52° F, with a low of 31° F on April 19 and a high of 77° F on April 17. No precipitation occurred during the week. Most days were sunny or mostly sunny making for seven days of favorable outside working conditions. Lawns continue strong green up. Soil moisture is adequate however worked soils are drying out fast.

Pests/Problems: Winter moth hatch is probably close if not over. Winter moth caterpillars can be found in buds of oak, maple, apple and blueberry. Azalea lacebug adults were found on ‘PJM’ Rhododendron. Many calls regarding rhododendron damage as a result of drought. Shrubs should be pruned to remove dead material, in many cases this means removal of all stems back to 9-12 inch stumps and keeping fingers crossed that shoots will develop from dormant buds, no guarantees. Weeds in bloom include Whitlow grass (Draba verna), Mouse-ear cress (Arabadopsis thaliana), Bittercress (Caradamine hirsuta), Dandelion (Taraxacum officinale), Henbit (Lamium spp), Speedwell (Veronica spp), Fig buttercup (Ficaria verna), Chickweed (Stellaria media), Mouse-ear chickweed (Cerastium vulgatum). Larry Dapsis, Cape Cod Cooperative Extension Tick Project Coordinator/Entomologist reports; no nymph stage ticks but adults are still active. Take precautions. Permethrin-treated clothing and footwear is the most effective tool in the box.

Southeast Region (Hanson)

General Conditions: Warm weather over Easter weekend pushed plant development and the landscapes are starting to color up! Easter Sunday saw a high of 83 degrees followed on Monday by a high of 76! Tuesday cooled a bit to 53 degrees with an overnight temperature on early Wednesday morning of 33 degrees, followed by 55 degrees daytime. The cooler weather was welcome to extend the flowering time of Magnolias and other plants in bloom; too warm and the flowers go by too quickly, especially as the soils are starting to dry out. Hanson received only a trace of rain of last week.

Sugar maple, Norway maple, Magnolia 'Wada's Memory’, Magnolia stellata, Magnolia kobus var. loebneri 'Leonard Messel, Lonicera fragrantissima (winter honeysuckle), Corylopsis sp., Stachyurus praecox, Prunus sp. (cherries), Lindera benzoin (Common Spicebush), Salix sp. (pussy willow), PJM Rhododendron, Forsythia, Pieris japonica, Pieris floribunda, Pieris 'Brouwer's Beauty', Spiraea thunbergii 'Ogon', Anemones, Omphalodes verna, Primula sp., daffodils, Sanguinaria canadensis (Bloodroot), Scilla sibirica, Petasites japonicus (Japanese butterbur), Jeffersonia diphylla, hyacinths, Muscari botryoides (Grape Hyacinth), Tulipa sp. (early flowering tulips), daffodils, Brunnera macrophylla, Hepatica, Chionodoxa luciliae, Dicentra cucullaria (Dutchman's Breeches), Pachysandra terminalis, Pachysandra procumbens, Helleborus foetidus, H. x hybridus, Corydalis solida, Trillium, Phlox subulata, Pulmonaria sp., and Vinca minor are in full bloom. Chaenomeles speciosa (Common Floweringquince), Vaccinium corymbosum (highbush blueberry), Glaucidium palmatum, Dicentra spectabilis, Epimedium sp., and Lamium are beginning to bloom. Cornus officinalis, Cornus mas (Corneliancherry Dogwood) and Abeliophyllum distichum (White Forsythia) are ending bloom. Flowering dogwood bracts are expanding.

Lawns continue to green up and some look in need to be mowed. Hanson has recorded 326 GDD, at Base 40.

Pests/Problems: Winter moth caterpillars began to hatch in Hanson on April 14th and with the warm weather over the weekend, hatch continues and should probably be complete around April 22-23, depending on weather. There are no orange eggs and the blue eggs are hatching on the west side of the tree that is being monitored; the north side has not yet started hatch. It is difficult to predict numbers right now as hatch is not complete, but initial observations at the monitoring site in Hanson, indicate fewer winter moth caterpillars at this time compared to previous years. Of course, these observations may change when we report next week after hatch is complete. Oak buds are still tight, wild blueberries are beginning to bloom and a cultivated blueberry is just breaking bud. After sampling several flower buds, one winter moth caterpillar was found on the calyx of one Norway maple bud and one caterpillar was found on the developing foliage of the wild blueberry. It is early yet and so continue to monitor the expanding buds of susceptible plants (maples, oaks, blueberry, crabapple, apple, birch, etc.) for the tiny blackish winter moth caterpillars and manage early if found. (See Tawny Simisky’s Insect Section of the Landscape Message).

Continue to monitor hemlocks for the white cottony egg masses of Hemlock Wooly Adelgid (HWA) and manage as needed. Hemlock woolly adelgid still poses a significant threat to eastern and Canadian hemlocks. https://www.na.fs.fed.us/spfo/pubs/pest_al/hemlock/hwa05.htm

Also monitor hemlocks for elongate hemlock scale (Fiorinia externa), which may also cause significant damage to hemlocks and is difficult to manage. https://www.na.fs.fed.us/spfo/pubs/pest_al/ehscale/ehscale.htm

Aphids were observed on the expanding foliage of Japanese maples and Snowball aphids were observed on the expanding foliage of Viburnum. Feeding by the snowball aphid may cause foliar distortion but does not cause significant damage. The foliage of true lilies (Lilium sp.) has emerged but no sign yet of the bright red lily leaf beetle. Continue to monitor lilies for this beetle and manage when seen. Monitor for eastern tent caterpillar on crabapples, apples and wild cherry and monitor for spruce spider mite on spruce, fir, hemlock, arborvitae, etc.

Unfortunately, black flies are active. Reports have come in of deer and dog ticks being found on people; no surprise as it will probably be a good season for ticks. So, plan accordingly and use repellents and conduct tick checks frequently.

Ants, carpenter bees, bumblebees, honeybees, and solitary bees are active. Bittercress continues to bloom and to form seed heads. Dandelions, Ranunculus ficaria, violets, and ground ivy are in full bloom. Deer continue to browse as do rabbits, which are eating Hosta, Scilla and tulips, etc. and turkeys continue to browse. Chipmunks are also active and were observed eating/devouring newly planted Swiss chard in a four foot high raised planting box.

North Shore Region (Beverly)

General Conditions: We experienced warmer unseasonable temperatures over the previous 6 days adding 45 Growing Degree Days for a total of 101 GDDs since the beginning of the year. Temperatures have returned to a more seasonable range starting yesterday 4/18/17. We received minimal precipitation during this reporting period. Long Hill received approximately 0.11 inches of rain during this reporting period. The combination of warm weather and rains in the last few weeks has drastically changed the appearance of the landscape. Many early spring flowering bulbs are in full bloom, grass is greening up and other landscape plants are coming into bloom. Spring flowering herbaceous plants seen in full bloom include: Daffodils (Narcissus spp.), Bloodroot (Sanguianaria canadensis), Glory of the Snow (Chionodoxa luciliae), Crocus (Crocus spp.), Puschkinia (Puschkinia libanotica), Siberian Squill (Scilla Siberica) and Japanese wood poppy (Glaucidium palmatum). There is a lot of yellow color in the landscape from different forsythias in bloom including: Border Forsythia (Forsythia intermedia), Weeping Forsythia (Forsythia suspensa) and Giraldi Forsythia (Forsythia giraldiana). Other woody plants in bloom include: Winter honeysuckle (Lonicera fragrantissima), Fly Honeysuckle (Lonicera canadensis), Serviceberry (Amelanchier arborea), Weeping Higan Cherry (Prunus subhirtella), Japanese Pieris (Pieris japonica), Mountain Pieris (Pieris floribunda), Sargent Cherry (Prunus sargentii), Red Maple (Acer rubrum), Cornelian Cherry Dogwood (Cornus mas), Anise Magnolia (Magnolia salicifolia), Star Magnolia (Magnolia stellata), Winter hazel (Corylopsis winterthur), Korean Rhododendron (Rhododendron mucronulatum), Callery Pear (Pyrus calleryana), Daphne (Daphne spp.) andLeatherwood (Dirca palustris).

Pests/Problems: Annual weed seeds continue to germinate. Yellow buttercup weed (Ranunculus ficaria) has formed masses of green carpets and is in full bloom with yellow flowers. Winter moth eggs will have hatched. Scout for the young larvea and apply a registered insecticide. Ticks are becoming more and more active so be careful and check yourself for ticks after working outdoors. Apply a repellent before going out into the landscape.

East Region (Boston)

We began the week with seasonal temperatures before the weekend warm up. We hit 70° F on the 15^th, 86° F on the 16^th and 75° F on the 17^th. This warm weather lead to an accumulation of 45.5 GDDs over the last week spurring plant development. Trees are beginning to leaf out, turf is greening up and early flowering plants are coming into bloom. Temperatures returned to seasonal on the 18^th.

Bulbs. Crocus sp. (crocus) and Puschkinia scilloides (striped squill) continue to put on a show. Chionodoxa forbesii (Forbes' glory-of-the-snow) and Scilla siberica (Siberian squill) are starting to fade. Hyacinthus sp. (hyacinth), Muscari armeniacum (grape hyacinth), and Narcissus sp. (daffodil) are coming into full bloom.

Herbaceous. Anemone ranunculoides (yellow wood anemone), Corydalis solida (spring corydalis), Pachysandra procumbens (Allegheny spurge), Pachysandra terminalis (Japanese spurge), Petasites hybridus (butterbur), Petasites japonicus (fuki), Vinca minor (common periwinkle), and Viola sororia (common blue violet) are in full flower.

Trees and Shrubs. Alnus maximowiczii (montane alder), Amelanchier arborea (downy serviceberry), Corylopsis glabrescens (fragrant winterhazel), Corylopsis sinensis (Chinese winterhazel), Dirca palustris (eastern leatherwood), Lindera benzoin (northern spicebush), many magnolia [M. cylindrica (cylindrical magnolia), M. x loebneri (Loebner's magnolia), cultivars M. 'Elizabeth', M. 'Galaxy', M. 'Waterlily', and M. ‘White Pearl’], Mahonia aquifolium (Oregon grape), Mahonia japonica (Japanese mahonia), many Prunus sp. [P. apetala (petalless cherry), P. cerasifera (Myrobalan plum), P. cyclamina (Cyclamen cherry), P. nipponica (Japanese alpine cherry), P. sargentii (Sargent cherry), P. serrulata ‘Washi-no-o’ (Oriental cherry) and P. x yedoensis ‘Shidare Yoshino’ (cultivar of Yoshino cherry)], Rhododendron dauricum (Dahurian rhododendron), Rhus aromatica (fragrant sumac), Ribes fasciculatum var. chinense (Chinese winterberry currant), Spiraea prunifolia (bridalwreath spirea), early blooming lilacs [Syringa oblata (early lilac), S. oblata ssp. dilatata (Korean early lilac), S. x diversifolia (varileaf lilac), and S. x hyacinthiflora (hyacinth lilac)], Viburnum furcatum (forked viburnum), Viburnum lantanoides (hobblebush), and Xanthorhiza simplicissima (yellowroot).

The snapping turtles are coming out of brumation (hibernation-like state) and have been observed making their way to the ponds. The northern spring peepers (Pseudacris crucifer crucifer) can be heard around the ponds as their calls welcome in spring.

Pests/Problems: The invasive spring ephemeral Ficaria verna (pilewort) is in full bloom throughout the landscape. Alliaria petiolata (garlic mustard) is thriving, the germinated seedlings are getting larger while the rosettes continue to push out and form buds. The biennial Chelidonium majus (greater celandine) seems to be growing exponentially, as buds are visible. Perennial weeds coming into bloom include: Glechoma hederacea (ground ivy), Lamium amplexicaule (henbit), Lamium purpureum (red dead-nettle), and Taraxacum sp. (dandelion). Annual weeds in full bloom and beginning to go to seed: Cardamine hirsuta (hairy bittercress), Draba verna (shadflower), and Stellaria media (common chickweed). Difficult to control biennials and perennials leafing out include: Arctium minus (common burdock), Cynanchum louiseae (black swallow-wort), Rumex obtusifolius (bitter dock), and Urtica dioica (stinging nettle). The annual Impatiens capensis (jewelweed) is germinating. Tree pollens affecting spring allergies include: Acer sp. (maple), Alnus sp. (alder), Celtis sp. (hackberry, nettle tree), Populus sp. (cottonwood, poplar, aspen), and Ulmus sp. (elm).

Metro West (Acton)

General Conditions: Happy Earth Day! Spring is exploding with the recent spell of summer like temperatures. This past week, I saw my first garter snake and turtles bathing in the sun. Little precipitation has been recorded for this area in the past seven days, but nonetheless, it is closing the gap as we creep our way to reaching the monthly average. Average rainfall total for the month of April is 4.16” and I have recorded 3.85” for this month so far. Since, the last report, one week ago, there has been a gain of 34 growing degree-days. We picked up much of that with 21.5 GDD gained on the 16^th with a high of 87° and a low of 56°. The landscape is lit up with color and in some stage of bloom at this time are the following woody plants:

Amelanchier spp. (Shadbush, Serviceberry), Cercis canadensis (Redbud), Chaenomeles speciosa (Common Flowering Quince), Forsythia spp., Lindera benzoin (Common Spicebush), Magnolia stellata (Star Magnolia), Magnolia x loebneri 'Merrill', (Merrill Magnolia), M. x soulangeana (Saucer Magnolia), Pieris japonica (Japanese Pieris), Prunus spp. (Cherry), Pyrus spp. (Pear), and Rhododendron 'P. J. M.' (PJM Rhododendron). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Anemone nemorosa (Wood Anemone), Asarum europaeum (European Ginger), Caltha palustris (Marsh Marigold), Chionodoxa luciliae (Glory of the Snow), Claytonia virginica (Virginia Spring Beauty), Dicentra cucullaria (Dutchman's Breeches), Epimedium versicolor 'Sulphureum' (Yellow Flowering Barrenwort), Helleborus niger (Christmas Rose), Hepatica spp. (Liver Leaf), Hyacinthus spp. (Hyacinth), Mertensia virginica (Virginia Bluebells), Muscari sp. (Grape Hyacinth), Narcissus spp. (Daffodil), Omphalodes verna (Blue-eyed Mary), Pachysandra procumbens (Allegheny Spurge), P. terminalis (Japanese Pachysandra), Petasites japonicus (Japanese Butterbur), Primula spp. (Primrose), Pulmonaria longifolia (Lungwort), P. rubra (Salmon colored Lungwort), Puschkinia libanotica (Striped Squill), Sanguinaria canadensis (Bloodroot), S. canadensis 'Multiplex' (Double Bloodroot), Scilla siberica (Siberian Squill), Tulipa spp. (Tulip), Vinca minor (Periwinkle) and Viola spp. (Violet).

Pests/Problems: As of April 1^st, the Drought Management Task Force had not downgraded this areas’ drought status from a drought advisory to normal. We remain in a rain defecit. Acer platanoides (Norway Maple) is in full bloom. This invasive tree is hard to miss now that it is in bloom and its flowers are a bright yellowish-green and are easily seen on a tree found growing most everywhere. Ticks are active so continue to monitor yourself and others for these parasites. Wear light color clothes to make the job easier on you. Also, seen flourishing everywhere is the basal foliage of Alliaria petiolata (Garlic Mustard). Other weeds seen in bloom but without the invasive tendency of the previous two mentioned are: Draba verna (Spring Whitlow Grass), Glechoma hederacea (Ground Ivy) and Lamium purpureum (Purple Deadnettle), Stellaria media (Common Chickweed), and Taraxacum officinale(Dandelion).

Central Region (Boylston)

General Conditions: Temperatures have returned to a more normal range after several days of exceptionally warm weather, including Sunday, April 16th when the daytime temperatures were in the upper 80’s. Many plants sprang into growth with leaves emerging on apples and crabapples (Malus cultivars); Seven Sons Flower (Heptacodium miconioides), Cherry (Prunus sp.), Korean Abelia (Abelia mosanensis) and others. Minor bulbs like Glory of the Snow (Chionodoxa forbesii), Siberian Squill (Scilla sibirica), Pushkinia libanotica, Grape Hyacinth (Muscari sp.) and early Daffodils (Narcissus ‘Rijnveld’s Early Sensation’, N. ‘Jetfire’, N. ‘Ice Follies’) are now in full bloom. Also in bloom in the landscape are Rhododendron dauricum, Corylopsis pauciflora and C. picata, Lonicera x purpusii, Prunus cerasifera ‘Thundercloud’, Pieris floribunda and P. x ’Brouwer’s Beauty’, Lindera benzoin and L. benzoin ‘Rubra’, Prunus subhirtella ‘Pendula Rosea’, Acer saccharum. Herbaceous plants in full bloom or showing color include Helleborus x hybridus cultivars, Bergenia cordifolia cultivars, Mukdenia rossii, Sanguinaria canadensis, Pachysandra procumbens, Phlox subulata, Erythronium americanum, and Epigaea repens.

Pests/Problems: Eastern Tent Caterpillars were spotted on Sunday, April 16th in cherry trees. Tick activity remains high. Voles and chipmunks continue to feed on Tulips and Crocus especially. Canada Geese are scouting ponds looking for nesting sites.

Pioneer Valley Region (Amherst)

General Conditions: Shifting temperatures and strong, gusty winds encapsulate this past reporting period in the Pioneer Valley where spring is taking hold. Aside from Easter Sunday, when high temperatures spiked to the upper 80s, highs have mostly hovered in the upper 50s to upper 60s with low temperatures staying above freezing. Two minor rain events occurred over the past week with the first on 4/12 and the second on 4/16. Accumulations from both storms were limited, with a combined total of 0.2–0.25″ at many weather stations. At Barnes airport in Westfield, wind gusts up to 37 mph were recorded on Saturday, 4/15 and Sunday, 4/16. The warm spring sun and driving winds are drying exposed surface soils and whipping newly emerging leaves and shoots. However, most soils remain moist thanks to the heavy precipitation in late March and early April. Because soils are no longer saturated, they are in prime condition for new plantings. A significant amount of new root development can take place before mid-May, making this an ideal time to establish trees and shrubs. In addition, the long-term forecast calls for cloudy skies, scattered showers and highs in the 50s to 60s, which will help to lessen the shock of transplant. Crabapple, sugar, red and Norway maple, camperdown elm, serviceberry, and cornelian cherry dogwood are all flushing new foliage at this time. Spring colors are abundant, with flowering annuals, perennials, shrubs and trees ablaze with yellow, white, pink and purple. Lawn grass is bright green in the valley bottom and in some locations requires the first mowing of the season.

Pests/Problems: Overall, disease pressure is very low right now. The cool nights in the 30s and day time highs in the 50s and 60s are not ideal for sporulation and growth of many fungal and bacterial pathogens. Reports from the UMass Cold Spring Orchard are calling for an upcoming apple scab infection period with young foliage developing and forecasted rain. The combined effects of drought and winter injury have injured many evergreen trees and shrubs like hemlock, rhododendron, azalea, mountain laurel and arborvitae, among others. On arborvitae, injured shoots and needles appear pale green to light tan and contrast sharply with the increasingly green foliage of health shoots. Cedar-quince rust, caused by Gymnosporangium clavipes, was widespread in 2016 despite the dry conditions. This fungus can girdle shoots and stems on serviceberry (Amelanchier) and hawthorn (Crataegus), in addition to juniper (Juniperus). The orange-colored, gelatinous spore masses will be developing on juniper and redcedar soon. Deer and rabbit feeding is waning and new turfgrass growth is hiding mole and vole tunneling. Continue to locate and prune dead stems and branches from deciduous and evergreen trees and shrubs.

Berkshire Region (Great Barrington)

General Conditions: The weather roller coaster continued over the past week with a high of 87° F observed on Sunday, April 16, at this Great Barrington reporting site. A strong wind and brief shower that night brought temperatures back to seasonal levels. Though some rain occurred, there were enough sunny days and subsequent soil moisture evaporation that soils are now workable on just about all sites, as witnessed by the sight of farmers plowing fields in preparation for planting. After the dramatic rise in temperature on the 16^th, many plants burst into bloom literally overnight. Ornamental cherries were the most obvious of these plants. Many early blooming perennials, e.g. Pulmonaria officinalis and Brunnera macrophylla. Lawns are rapidly greening and grass growth is advancing but not to the level where mowing has yet been necessary.

Pests/Problems: Despite the warm up and a return to seasonal temperatures, pest pressures remain very low. However, wasps and bees were observed. Eastern tent caterpillars have not yet been found but there hatching should be imminent. Browsing by deer and rabbits is still a problem but the level of activity has diminished, most likely due to the presence of food in their natural habitats. Deer tick population and frequency of tick bites remains high. With warming temperatures, winter desiccation damage on broadleaf evergreens is becoming more apparent.

Regional Scouting Credits

• CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
• SOUTHEAST REGION - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, reporting from Hanson.
• NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
• EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.
• METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
• CENTRAL REGION  -  Joann Vieira, 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 pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab:

Needle tip blight of white fir (Abies concolor) caused by Rhizosphaera. Tree is approximately 15-years-old and has been present at the site for six years. Needles on the submitted sample were gray to brown at the tips with visible sporulation by the fungus. Rhizosphaera invades through the stomata, causes disease and then produces black-colored fruiting bodies that exit through stomata and release large volumes of spores. White fir is the only host that exhibits the gray-colored needle tip blight as a result of infection.

Foliar blight caused by the anthracnose pathogen Colletotrichum on Oregon grapeholly (Mahonia aquifolium). Plant is three-years-old and resides in a shaded setting with drip irrigation. The foliage exhibits a marginal leaf blight and scattered spotting on interior sections. Colletotrichum has an extremely broad host range and mostly causes a foliar blight, but can also attack shoots, small branches and fruit.

Botrytis blight, caused by Botrytis cinerea, of red drift rose (Rosa ′Meigalpio′). Two-year-old plants in a greenhouse setting that developed a foliar and shoot tip blight. The roots were healthy and there was no evidence of root disease or lower stem decay. Botrytis is often a secondary pathogen on many trees and shrubs but can be an important pathogen on rose in shaded landscape settings. Botrytis thrives under cool temperatures and high humidity and as a result, is most abundant in spring and autumn. Overhead watering helped to facilitate disease development and spread.

Stem cankering caused by Botryosphaeria on inkberry (Ilex glabra). Plant is five-years-old and has been present at the site for only 18 months. Leaves have blackened spots and blotches and blackened stems. Transplant shock was a likely predisposing factor that facilitated disease development. Botryosphaeria and Phomopsis are common on recently transplanted Ilex, especially those with dense canopies of thin stems, that exhibit a general decline.

Volutella leaf and stem blight and a severe infestation of the boxwood spider mite on boxwood (Buxus sempervirens). Several plants, approximately five-years-old and present at the site for three years, planted in a formal garden against a short wall. Last fall, a few of the plants became symptomatic and have since died. Lawn irrigation is provided and the subsequent wetting of the canopy often facilitates infection and spread by Volutella. In a formal setting, where the plants are sheared, potential infection sites are innumerable. Boxwood spider mite is very common in these settings as well, creating the characteristic flecking symptom on the upper leaf surface.

Infestation of the Norway spruce gall midge (Piceacecis abietiperda) on Norway spruce (Picea abies). Very limited information was provided about the tree, only that stem dieback with yellowing and browning needles was observed. A neighboring spruce, species unknown, has died. The spruce gall midge was locally abundant in 2015 and in some cases, caused significant damage on large, landscape Norway spruces. Since then, reports and submitted samples have been much less common. Infestation leads to distorted shoot tips, shoot tip dieback and premature needle shedding.

Diplodia blight, caused by Shaeropsis sapinea, on eastern white pine (Pinus strobus). Tree is over 10-years-old but has been present at the site for only one year. It was planted in a partially shaded site on the edge of a forest and hand-watered throughout the growing season in 2016. Submitted stems were desiccated and a large number of Sphaeropsis fruiting bodies emerged after a brief incubation. Transplant shock and light stress may have predisposed the tree to infection.

Figure 1 (click to enlarge): Assessment of internal decay using sonic and electrical resistance tomography: The American elm pictured on top (A: dbh of 35″ and sampled on 4/18/17) has a very large trunk canker that has killed a significant percentage of sapwood and phloem tissue at the base. Additional target-shaped cankers were present on the upper trunk as well. The two tomograms on the right, however, indicate that decay is not yet present in the lower trunk. The sonic tomogram (top) shows sound wood throughout the sampled cross section (brown) while the electrical resistance tomogram (bottom) shows high relative conductivity (blue) throughout much of the interior. The high conductivity could be the result of wetwood bacteria or the early actions of a wood-decaying fungus. The American elm pictured below (B: dbh of 40″ and sampled on 4/17/17) has no visible symptoms of internal decay and a healthy canopy. Yet, the sonic tomogram (top) shows a high level of damage is present in the lower trunk (magenta and blue area) and the electrical resistance tomogram (bottom) indicates a cavity is developing within the decaying section of the heartwood (red areas in the center of the cross section). The results illustrate the difficulty in assessing internal decay of landscape trees based only on external symptoms.

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

Insects

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

• Winter Moth: Operophtera brumata. For more information about the life cycle and management of winter moth, please visit this newly updated (March, 2017) fact sheet: Winter Moth Identification and Management (https://ag.umass.edu/landscape/fact-sheets/winter-moth-identification-management).

Over the holiday weekend, winter moth eggs were very actively hatching in certain locations where this insect is problematic in eastern Massachusetts. Many scouting the activity of this pest provided the following information: winter moth egg hatch has been observed this season in Massachusetts since 4/6/2017 at a site in Franklin. A winter moth larvae was found within a single bud at a site in Dennis, MA on 4/11/17 out of 100 buds that were inspected. A couple of winter moth larvae were found within apple buds on 4/12/17 in Falmouth. In addition, most recently, on 4/14/17, winter moth egg hatch was observed in Hanson, MA. Winter moth eggs being observed by the Elkinton Lab in semi-natural conditions in Falmouth and Hanson are now 50%-95% hatched as of 4/19/17; however, these particular eggs tend to hatch a little in advance of what is observed for completely “wild” winter moth eggs according to the Elkinton Laboratory. Overall, sites on Cape Cod typically have delayed egg hatch due to cooler temperatures in comparison to sites being monitored at more inland locations. More “inland sites” may complete their winter moth egg hatch by this weekend (see the Southeast Region Report above) and reports from the Cape Cod Region indicate winter moth egg hatch is probably “close if not over” in Barnstable (see Cape Cod Region Report above).

Blueberry and apple growers looking to manage winter moth caterpillars early before damage to the buds can occur may consider an application of dormant oil just prior to egg hatch, when temperatures are above 40°F for at least 48 hours following application, which can help suffocate overwintering winter moth eggs if good coverage is achieved. Observe all precautions on the label regarding phytotoxicity and the environmental conditions required for increased effectiveness of the product. Once egg hatch occurs, before the tiny winter moth caterpillars wriggle their way into the expanding blueberry or apple buds (where they will be protected from insecticide applications until the buds open fully), a follow-up application of a product containing the active ingredient spinosad (which is effective by contact) can aid in protecting these crops.

For individuals managing winter moth in ornamental plants, depending on the active ingredient being used, waiting until host plant leaves open completely may be important for management, particularly if Bacillus thuringiensis Kurstaki (Btk) is the active ingredient of choice. Btk must be ingested by actively feeding, young caterpillars to be effective. Applying Btk to closed buds for winter moth management will not have the desired effect. Spinosad is also effective through contact on winter moth (including older caterpillars) once ornamental plant leaves have fully expanded, however it should not be applied to flowering plants as it is toxic to pollinators until it has dried (which can take 1-3 hours depending upon local environmental conditions). The Elkinton Lab has reported that the number of pupating winter moth in 2016 (at their study sites) was much lower than what has been observed in previous years. Reports from Hanson, MA indicate fewer winter moth eggs are present on monitored trees than in previous years. Hopefully this will translate into fewer caterpillars at least for some areas in Massachusetts this year, however one should not expect them (or the damage they cause) to completely disappear in 2017.

Winter moth is a non-native insect that was identified in Massachusetts for the first time in 2003 following persistent reports of defoliation in eastern areas of the state such as Cape Anne and on the North Shore near Cohasset, Hingham, and Rockland on the South Shore in the late 1990’s. For more detailed information about the history of this insect pest in North America and Massachusetts, please visit the newly updated (March, 2017) fact sheet: Winter Moth in Massachusetts: History and Biological Control (https://ag.umass.edu/landscape/fact-sheets/winter-moth-in-massachusetts-history-biological-control).

This fact sheet also includes updates regarding the progress of the work of Dr. Joseph Elkinton’s laboratory group at the University of Massachusetts and their efforts towards the biological control of winter moth using Cyzenis albicans, a tachinid fly. The fly parasitizes the caterpillars of winter moth specifically. In other areas, such as Nova Scotia where winter moth was also problematic, this fly used for biological control has been successful in reducing winter moth to a non-pest. C. albicans has been released across 41 sites in Massachusetts and has been established in at least 17 of those sites as evidenced through the recovery of flies in winter moth in subsequent years. In one site in Wellesley, these flies have been observed to be spreading from the initial release location and their populations have increased alongside an observed decrease in the winter moth population there. For more information, please visit the above mentioned fact sheet.

• Gypsy Moth: Lymantria dispar egg masses laid by female moths in 2016 can be seen at this time. This is the stage of the insect that overwinters. Egg masses are “fuzzy” or hairy and brownish-tan in color. Each egg mass can hold up to 500-1000 eggs. Gypsy moth egg hatch typically occurs between 90-100 growing degree days, using a base of 50°F, average temperatures, and a March 1^st start date. This is usually around the first week in May in Massachusetts, but variations in temperature may lead to early egg hatch in the last week in April. This can also coincide with serviceberry (Amelanchier) bloom. That being said, it may be easily noticed in this message that 101, 112.5, and 110 growing degree days have accumulated in the North Shore, East, and Central Regions respectively, as reported in the Environmental Data above. Amelanchier or serviceberry bloom has begun or is in full activity in certain portions of the state. Therefore, one would expect gypsy moth eggs to begin hatching very soon. As of 4/19/2017, gypsy moth egg masses observed in Belchertown and Monson, MA have not yet begun to hatch (see photos). However, in certain areas, they are present in very large numbers.

These masses may be found on host plant trunks and branches such as oak (favored), maple, birch, poplar, and many others, but are also laid on inanimate objects including the surfaces of homes, outdoor furniture, camping equipment, firewood piles, etc. This may make the accidental movement of gypsy moth egg masses possible. (Note: winter moth and gypsy moth share some common host plants. Therefore, where populations of these two insects overlap in Massachusetts, the same tree may be defoliated by winter moth and then again by gypsy moth following in the same season.) After egg hatch occurs, groups of tiny gypsy moth caterpillars may remain on their egg mass just before crawling to the canopy of their host plant, where they can disperse using a technique known as “ballooning”. Ballooning occurs when very young caterpillars spin a silken thread and catch the wind to blow onto a new host plant once the thread breaks. This method of dispersal can lead to host plants becoming defoliated that previously did not have egg masses directly on them, however egg masses may be present on nearby oaks, for example, and provide a local population of caterpillars.

Patchy areas across mostly central and eastern Massachusetts experienced elevated populations of gypsy moth and significant amounts of defoliation in 2016 (see the Insects section of the archived 2016 Landscape Messages between April 29 and July 29). The Massachusetts Department of Conservation and Recreation aerially mapped approximately 350,000 acres of defoliation across Massachusetts last year, attributed to gypsy moth. State officials warn the public about another year of defoliation from gypsy moth as predicted for 2017: http://www.mass.gov/eea/agencies/dcr/pr-2017/another-year-of-defoliation-from-gypsy-moth-in-2017.html. That web page also links to a map of the 2016 defoliation from gypsy moth, which may provide a reference regarding areas that may be impacted by this insect again in 2017. To prepare for this insect, now (and before the last week in April) is a great time to scout the landscape and count the number of gypsy moth egg masses present not only on valuable landscape specimens that are hosts for this insect, but on nearby forested hosts such as oak which might provide sources of ballooning caterpillars. Egg mass counts can help us make decisions regarding whether or not to manage for this insect. Some individuals also use this opportunity to scrape egg masses into a container of soapy water, although this is time consuming and some egg masses will be missed.

We can hope for elevated rainfall in the months of May and June, which helps facilitate the successful infection of younger gypsy moth caterpillars with the insect-killing fungus Entomophaga maimaiga. This fungus is currently overwintering in the soil litter in tough, protected asexual resting spores, which can survive in this state for years. Having lacked much precipitation most recently during the springs of 2015 and 2016, it is thought that our current expanding populations of gypsy moth are at least in part a result of a lack of infection in the caterpillar population by this fungus. Hopefully Massachusetts will see more normal rainfall amounts this season. Only time will tell.

We can also hope areas in Massachusetts that do not have large numbers of gypsy moth egg masses present at this time and did not experience much gypsy moth defoliation last year (areas such as most of Berkshire County) will be mostly spared in 2017 in comparison to those areas who suffered last year in central and eastern Massachusetts. At this time, monitoring susceptible hosts for gypsy moth egg masses and educating and reminding ourselves about this invasive insect that has a long history in the state is the best way to plan for management this season. For more information about gypsy moth, please visit: http://ag.umass.edu/landscape/fact-sheets/gypsy-moth and return to the Landscape Message for timely updates about this pest and others throughout the season.

• Balsam Twig Aphid: Mindarus abietinus is active between 30-120 GDD’s, base 50°F. Inspect the needles of fir for “stem mothers” that will soon be reproducing. Young aphid feeding will lead to distorted foliage. Excessive amounts of honeydew are produced and cause needles to stick together. Monitor for the presence of reproducing females and treat with an oil application as weather permits.

• Cooley Spruce Gall Adelgid: Adelges cooleyi is active between 20-91 GDD’s, base 50°F. This insect can be found in the crevices of bark on terminal twigs and bases of buds of blue spruce, Norway spruce, and Douglas fir. Control overwintering nymphs prior to gall formation on spruce (roughly 22-81 GDD). Oil applications on Douglas fir should be made before bud break to avoid phytotoxicity (roughly 120-190 GDD). Do not plant spruce and Douglas fir close together. Do not fertilize either host (spruce or Douglas fir) if it is infested with this insect.

• Eastern Tent Caterpillar: Malacosoma americanum eggs have begun to hatch in areas of the state that are above 50 GDD’s, base 50°F. Reports of eastern tent caterpillar egg hatch have come from Acton and Barre, MA at this time. Other areas that have reached the needed GDD accumulations will have tiny, newly hatched caterpillars starting to form their tents as well. Egg masses of Malacosoma americanum vary from those of Malacosoma disstria, the forest tent caterpillar, as they have a rounded edge whereas M. disstria egg masses have square edges. Scout for, remove, and destroy the small, newly forming eastern tent caterpillar tents in the crotches of branches on susceptible hosts such as cherry and crabapple. If the tents and the tiny caterpillars within are found early enough, this is a great way of removing these insects without the use of chemicals. Other host plants impacted by this native insect can include apple, ash, birch, willow, maple, oak, poplar, and witch-hazel.

• Forest Tent Caterpillar: Malacosoma disstria egg hatch will occur between 192-400 GDD’s, base 50°F. Scout for and prune out or otherwise remove any reachable forest tent caterpillar egg masses, which can hold 100’s of eggs, on susceptible hosts such as oak, birch, ash, maple, elm, poplar, and basswood at this time. Once these egg masses hatch, these native caterpillars can defoliate their host plants.

• Lily Leaf Beetle: Lilioceris lilii should be monitored for at this time. 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.

The University of Rhode Island Biological Control Lab is researching ways to find a natural method to combat these beetles. Small parasitic insects have been established in lily plots in Cumberland, RI and Wellesley, MA in hopes that these insects will disperse naturally to reduce the effects of the lily leaf beetle. If you have larvae in your yard (or a customer’s yard), please send to URI, following the instructions on the URI Biocontrol Lab website: http://web.uri.edu/biocontrol/home/lily-leaf-beetle-larval-collections-2016-mailing-instructions/

• Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. This beetle feeds exclusively on many different species of viburnum. This insect is now overwintering in the twigs of the host plant as eggs, which will hatch soon after bud break. Now is the time to inspect susceptible plants (including but not limited to viburnum such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum) for over-wintering eggs on stems toward branch tips. Inspect branches for egg laying sites created by female viburnum leaf beetles last season. These will appear as small holes approximately 1 mm. in diameter that have been capped with a lid made of chewed bark and excrement, which may appear raised above the surface of the twig. Removal and destruction of infested stems, if small in number, can help reduce populations of this insect pest. If management this way is not possible, larvae may be treated with a product containing spinosad once they appear soon after bud break. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found at http://www.hort.cornell.edu/vlb/.

• Chilli Thrips: *A non-native insect has been confirmed in Massachusetts for the first time.* The non-native, exotic chilli thrips (Scirtothrips dorsalis) has been recently confirmed from two samples of damaged Hydrangea spp. foliage from two residential landscapes located in Barnstable County, MA submitted to the UMass Plant Diagnostics Laboratory. At this time, this pest has not been confirmed in nurseries or greenhouses in Massachusetts or on any other host plants. Due to the limited number of samples, the significance of chilli thrips in Massachusetts is not yet known. This species of thrips is a significant global pest of economically important ornamental, vegetable, and fruit crops in southern and eastern Asia, Oceania, and parts of Africa. It was first determined to be established in the United States in 2005 in Florida, although previous interceptions of this pest were detected. It is reportedly a pest of over 100 host plants belonging to over 40 plant families, including, but not limited to, pepper, strawberry, blueberry, cotton, rose, peanut, Japanese privet, Rhododendron spp., Viburnum spp., eggplant, grapes, melon, tobacco, and tomato. For more information, please visit this Chilli Thrips Fact Sheet (https://ag.umass.edu/landscape/fact-sheets/chilli-thrips) available on the UMass Extension Landscape, Nursery, and Urban Forestry Program web page.

• Asian Longhorned Beetle, Anoplophora glabripennis, ALB: Look for signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches. These particular signs of damage from the beetle may be more visible at this time of year, when host trees such as maples are leafless. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity.

The regulated area for Asian longhorned beetle is 110 miles² encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn. If you believe you have seen damage caused by this insect, such as exit holes or egg sites, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938. Adult insects of this species will not be present at this time of year.

To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: http://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report.

• Emerald Ash Borer (EAB): Agrilus planipennis readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus). Adult insects of this species will not be present at this time of year. Signs of an EAB infested tree may include (at this time) D-shaped exit holes in the bark (from adult emergence in previous years), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in the bark, from larval feeding beneath. Positive identification of an EAB-infested tree may not be possible with these signs individually on their own.

For 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. If you believe you have located EAB-infested ash trees, particularly in an area of Massachusetts not identified on the map provided, please follow the instructions below.

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 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. 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 UMass 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: Rhododendron mucronulatum; Korean Rhododendron

Rhododendron mucronulatum is a 4-8’ tall, deciduous rhododendron with an upright to rounded habit. Korean rhododendron has light rosy purple 1.5” diameter flowers that grow in clusters of 3-6. ‘Cornell Pink’ is a common cultivar with clear pink flowers. Flowers emerge in April and can be damaged by frost or freeze events. Leaves are medium green, 1-4” long, 0.5-1” wide, and are aromatic when crushed. Fall color is a mix of yellow, orange, and red. Rhododendron mucronulatum are best grown in an acidic, well-drained but moist soil in dappled shade. Plants should not be sited in areas with southern exposure which may lead to early bloom and increased risk of frost damage. Phytopthora root rot can be a problem in heavy, wet soils. Chlorosis can occur in high pH soils. Rhododendron can suffer from various disease and insect problems including borers and lacebugs. Plants that are sited correctly suffer from fewer problems. Korean rhododendron is a good choice for shrub borders, naturalistic areas, woodland gardens, or as a foundation plant offering early spring color.

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

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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 whenever temperatures are above freezing! 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