Landscape Message: May 12, 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 May 10. 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	23	140	53	64	1.40	5:00 PM 5/10
Southeast	16	149	57	51	1.10	4:14 PM 5/10
North Shore	14	167	50	46	0.63	9:30 AM 5/10
East	19	205	58	53	0.90	4:00 PM 5/10
Metro West	21	178.5	51	48	1.09	6:45 AM 5/10
Central	17	200	51	48	1.26	10:00 AM 5/10
Pioneer Valley	11.5	166	55	49	1.94	12:00 PM 5/10
Berkshires	7	147	50	47	2.02	8:45 AM 5/10
AVERAGE	16	169	55	49	1.29	-
n/a = information not available

Drought Conditions Update: Virtually all of Massachusetts (99.99%) is not under official drought status at this time!  For more information see http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?MA.

Phenology

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT NAME (Botanic/ Common)	CAPE	S.E.	N.S.	EAST	METRO W.	CENT.	P.V.	BERK.
Rhododendron catawbiense (Catawba Rhododendron)	*	*	Full	*	*	*	*	*
Spiraea x vanhouttei (Vanhoutte Spirea)	Begin	*	*	*	*	*	Begin	*
Aesculus hippocastanum (Common Horsechestnut)	Begin	Begin	*	Begin	Begin	*	Begin	*
Elaeagnus umbellata (Autumn-olive)	Begin	Begin	Begin/Full	Begin/Full	Begin/Full	Begin	Full	*
Syringa vulgaris (Common Lilac)	Begin/Full	Full	Full	Full	Full	Full	Full	Full
Rhododendron spp. (Early Azaleas)	Full	Full	Begin/Full	Begin/Full	Begin	Begin	End	Full/End
Cornus florida (Flowering Dogwood)	Full	Full	Full	Full	Full	Full	Full	Full
Malus spp. (Crabapple)	Full	Full	Full	Full	Full	Full	End	Full
Cercis canadensis (Redbud)	Full	Full	Full	Full	Full	Full	Full/End	Full
* = no activity to report/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 35° on 5/9, some low lying areas likely had a light frost, and a high of 66° F on 5/3. A total of 1.4 inches of rain fell primarily on 5/5 but remained cloudy with occasional mist/showers on 5.6 and into 5/7. Soil moisture is adequate and in many cases too moist for landscape constructions projects.

Pests/Problems: Gypsy moth caterpillars are ballooning and finding appropriate hosts. Winter moth continue to feed on susceptible hosts, larvae are about 6-7mm in length and primarily found in buds or developing leaves. Boxwood psyllid, Psylla buxi can be found feeding on new growth of boxwood resulting in cupped leaves. Rose slug sawfly larvae have hatched and are beginning to feed on leaves causing window pane like damage. Lily leaf beetle is active on susceptible lilies. Slugs have been enjoying the wet conditions causing damage to Iris and Hosta. Anthracnose damage to Cornus florida is rampant on non-resistant cultivars. Cedar apple rust teliohorns were active during periods of high humidity. Red thread has been active in lawns causing some browning. Weeds in bloom include garlic mustard (Alliaria petiolata), Dandelion (Taraxacum officinale), Henbit (Lamium spp.), Speedwell (Veronica spp.), Mouse-ear chickweed (Cerastium vulgatum), Common violet (Viola papilionacea), Shepard's purse (Capsella bursa-pastoris), and Yellow rocket (Barbarea vulgaris).

Southeast Region (Hanson)

General Conditions: This 2017 spring continues to be one of the most colorful springs in near and distant memory. Cooler temperatures and sufficient rain continue to hold bloom this past week. Daytime temperatures started out on May 4^th and 5^th in the low 60’s, but the fell to the 40’s-50’s, with 37 degrees noted on the early morning of May 9^th. Hanson received 1.1 inches of rain this past week and soils remain moist. The following plants are, or remain, in full bloom:

Cercis canadensis (Eastern Redbud), late blooming magnolias like Magnolia ‘Elizabeth’, Kwanzan cherry, Malus sp. (apples, crabapples), Cornus florida (Flowering dogwood), Daphne x burkwoodii 'Carol Mackie', Daphne tangutica, Chaenomeles speciosa (Common Floweringquince), Viburnum ‘Eskimo’ and other viburnums, Syringa vulgaris (Common Lilac), Halesia sp., Pieris floribunda (Mountain Pieris), Spiraea prunifolia f. simplicifolia (Bridalwreath Spirea), Fothergilla major (large Fothergilla), Fothergilla gardenii (dwarf Fothergilla), Flowering Almond, Kerria, Vaccinium corymbosum (highbush blueberry), Rhododendron ‘Olga Mezitt’, Lonicera tatarica (invasive), Exochorda racemosa, Cytisus scoparius (Scotch broom) and Ilex x meserveae. Epimedium sp., Trillium sp., Galium odoratum (Sweet Woodruff), Brunnera macrophylla, Asarum canadense, Polygonatum sp. (Solomon's Seal), Stylophorum diphyllum (Wood Poppy), Phlox subulata, Aurinia saxatilis (Basket of Gold), Phlox divaricata, Arisaema sp.(Jack-in-the-pulpit), Primula sp., Pulmonaria sp., Ajuga, dwarf bearded Iris, Saruma henryi, Lamiastrum galeobdolon, Lamium sp., Dicentra spectabilis, Lunaria annua (honesty or money plant), Mertensia virginica (Virginia bluebells), Glaucidium palmatum, Helleborus foetidus, Violets and Vinca minor . The following plants are beginning bloom: Magnolia fraseri, Rutgers hybrid dogwoods (Stellar series), Weigela florida ‘Versicolor’, Wisteria floribunda (Japanese Wisteria), Calycanthus floridus (Common Sweetshrub), Geranium sp., Camassia sp., Persicaria bistorta ‘Superbum’, Corydalis lutea, Tiarella cordifolia (Foam Flower) and Convallaria majalis (Lily-of-the-valley).

The following plants are ending bloom: Viburnum carlesii (Mayflower Viburnum), Viburnum x burkwoodii ‘Mohawk’, Rhododendron ‘PJM’, Rhododendron schlippenbachii (Royal Azalea), Spiraea thunbergii ‘Ogon’, Azalea ‘April Snow’, Helleborus x hybridus, daffodils and tulips.

The wet weather has delayed mowing and landscape operations. Once again, if using a preventative grub management product that contains Chlorantraniliprole (Acelepryn^TM, GrubEx^TM), it is best applied before the end of May; follow the directions on the label before applying.

Pests/Problems: In the Hanson, MA area, winter moth caterpillars are actively feeding, often found at the leaf tips between webbed leaves and most winter moth caterpillars are at 3^rd instar, although a few 2^nd instars were observed. (540 growing degree days (GDD) at Base 40). Many maples have leafed out and damage by winter moth is dramatically reduced from previous years, HOWEVER, gypsy moth caterpillars in high numbers were present on Norway, Japanese, sugar and red maples, feeding alongside the winter moth caterpillars. Both caterpillars were also found feeding on: oak, rose, crabapple, apple, blueberry, beech, etc., so even though winter moth caterpillar numbers are down, gypsy moth caterpillar numbers are high and damage is beginning to show. Continue to monitor host plants and manage these caterpillars when they are small. (See Tawny Simisky’s Insect Section of the Landscape Message).

Gypsy moth hatch was completed and the small (about the size of a thick eyelash), black caterpillars have been ballooning and landing everywhere. Three people in Hanson reported and displayed skin rashes on necks and arms from gypsy moth caterpillars landing on them while they were outside gardening. The recent and continued rain and drizzle, hopefully will contribute to activating the Entomophaga maimaiga fungus which could help reduce the gypsy moth caterpillar population.

Deer tick nymphs usually become active in May and are active for several months; so be on the lookout! Deer tick nymphs are very tiny and it is this stage that is usually most responsible for the transmission of Lyme disease. Recent news has also highlighted the other diseases that may be carried and transmitted by deer ticks. Be vigilant, conduct tick checks frequently and take precautions like using repellents when working outdoors.

http://www.cnn.com/2017/05/03/health/powassan-tick-virus/

http://www.mass.gov/eohhs/docs/dph/cdc/factsheets/powassan.pdf

Lily leaf beetle adults remain active on true lilies and egg-laying has begun. Hand-pick and destroy the adults when possible, or manage with a labeled insecticide. Check beneath the foliage for the tan-red-dark-colored eggs and prune out and destroy. Monitor the undersides of azaleas for azalea whitefly, and manage if found. Eastern tent caterpillar remains active and webs are noticeable, mostly on wild cherry; although numbers, as in past years, appear to be down in many areas of Plymouth County. Snowball Aphid remains active and aesthetic damage is apparent as curled foliage. The White-spotted Pine Sawyer (native insect) may soon, if not already be active. This large insect is often mistaken for the Asian longhorned beetle, which emerges later in the season.

Continue to monitor for European pine sawfly; boxwood psyllid; hemlock woolly adelgid, spruce spider mite and Elongate hemlock scale. The following insects are also active: black flies, carpenter bees, ants, wasps, slugs and dog ticks. Beneficial insects like, the beautiful, bright green, six-spotted tiger beetle (Cicindela sexguttata) are active.

With the recent rain, the bright, orange, jelly-like galls of cedar-apple rust (Gymnosporangium) continue to be seen on Eastern red cedar and other junipers.

Dogwood anthracnose disease, (often characterized by lower branch dieback) is a fungal disease of flowering dogwoods and Pacific dogwoods which are susceptible to infection during wet springs, as new leaves and shoots are emerging. Consider managing high value trees and protect new growth with a labeled fungicide, according to label directions.

https://www.na.fs.fed.us/spfo/pubs/howtos/ht_dogwd/ht_dog.htm

https://ag.umass.edu/landscape/fact-sheets/dogwood-anthracnose

Dandelion remains in flower although a few plants have started to set seed. Veronica, garlic mustard, ground ivy, violet, and chickweed remain in bloom. The Massachusetts invasive plants Euonymus alatus (burning bush) and barberry are also in bloom. To prevent seed formation and subsequent future dispersal of these invasive plants, prune or sheer back now to remove the flowers.

Immediately after bloom is a good time to prune, or renovate, spring-flowering trees and shrubs, like Spirea, lilac, Forsythia, azaleas and rhododendrons before flower buds are set for next year.

North Shore Region (Beverly)

General Conditions: This reporting period we experienced cloudy weather and cooler than normal spring temperatures most of the days. Day temperatures were in the 50s most days except on Saturday and Sunday when temperatures went up to the low 60s. Night temperatures were mostly in the 40s going to low 30s on Tuesday May 9. We gained 14 growing degree days and 0.63 inches of rainfall at Long Hill during this period. Due to the continued rains soils are moist, lawns are green and turf is thriving. Many groups in the area are busy organizing spring plant sales for the week. Many plant species continue to be in full bloom and others are beginning to bloom. Woody plants in full bloom include: Mountain Pieris (Pieris floribunda), Flowering Dogwood (Cornus florida), Redbud (Cercis canadensis), Large Fothergilla (Fothergilla major), Dwarf Fothergilla (Fothergilla gardenii), Royal azalea (Rhododendron schlippenbachii), Catawba Rhododendron (Rhododendron catawbiense), Common Lilac (Syringa vulgaris), Chinese lilac (Syringa x chinensis), Kwanzan Cherry (Prunus serrulata), Silverbells (Halesia carolina), Cucumber tree (Magnolia acuminata), Hardy orange ( Poncirus trifoliata), 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), Pachysandra(Pachysandra procumbens), Vinca vine (Vinca minor), Trout lily (Erythronium americanum), Trillium (Trillium grandiflorum) and grape hyacinth (Muscari armeniacum).

Pests/Problems: Eastern spruce gall adelgid (Adelges abietis) was observed on spruce. Winter moth caterpillars (Operophtera brumata) observed feeding on apple and maple leaves last week are done feeding and only the damage was observed and no caterpillars. Rabbits and woodchucks were 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 active. Be careful to protect yourself when working outdoors.

East Region (Boston)

General Conditions: We continue to experience unseasonably cool temperatures for early May. We had lows in the 30’s on three occasions reaching down to 34° F on the morning of the 9^th. Daytime temperatures averaged 59° F, ranging from 51° F to 68° F. Conditions have been cool, windy, and overcast for the week; we received precipitation on two days accounting for 0.90 inches of rain. We have gained 19 GDDs bringing us to 205 GDDs on the year. Last year at this time, we had reached 105 GDDs, and we are well ahead of 2016 despite these recent cool temperatures. The landscape is decorated with many flowering trees and shrubs. The cooler weather has helped to hold plants in bloom, especially the lilacs which are approaching peak bloom.

Woody plants in bloom include: Aesculus glabra (Ohio buckeye), Amelanchier sp. (shadbush), Aronia arbutifolia (red chokecherry), Aronia melanocarpa (black chokecherry), Aronia x prunifolia (purple chockecherry), Berberis sp. (barberry), Chaenomeles speciosa (common flowering quince), Cydonia oblonga (quince), Daphne genkwa (lilac daphne), Daphne x burkwoodii 'Carol Mackie'(daphne), Davidia involucrata (ghost tree), Fothergilla gardenii (dwarf fothergilla), Fothergilla major (large fothergilla), Halesia tetraptera (Carolina silverbell), Kerria japonica (Japanese kerria), Prunus laurocerasus (cherry laurel), Prunus serrulata 'Kwanzan'(kwanzan cherry), Prunus serotina (black cherry), Prunus virginiana (chokecherry), Rhododendron schlippenbachii (royal azalea), Rhododendron vaseyi (pinkshell azalea), Rhodotypos scandens (jetbead), Sorbus commixta (Japanese rowan), Sorbus yuana, Syringa vulgaris (common lilac), Vaccinium angustifolium (lowbush blueberry), Vaccinium corymbosum (highbush blueberry), Viburnum x burkwoodii (Burkwood viburnum), and Weigela subsessilis (weigela).

Herbaceous plants in bloom include: Arisaema triphyllum (Jack-in-the-pulpit), Aristolochia manshuriensis (Manchurian pipevine), Convallaria majalis (lily-of-the-valley), Dicentra cucullaria (Dutchman's breeches), Dicentra spectabilis (bleeding heart), Epimedium cultivars (barrenwort), Galium odorata (sweetscented bedstraw), Iberis sempervirens (evergreen candytuft), Phlox subulata (creeping phlox), Polygonatum biflorum (Great Solomon’s seal), Trillium erectum (red trillium), and Viola sp. (violet).

Due to inclement weather, the Arnold Arboretum’s annual Lilac Sunday will be held on Saturday, May 13th instead of on Mother’s Day.

Pests/Problems: Temperatures have remained consistently cool. Unwanted vegetation continues to flourish throughout the landscape: Chelidonium majus (greater celandine), Glechoma hederacea (ground ivy), Iris pseudacorus (yellow flag iris), Lamium amplexicaule (henbit), Lamium purpureum (red dead-nettle), Taraxacum sp. (dandelion), and Urtica dioica (stinging nettle). Garlic mustard (Alliaria petiolata) is just past peak flower and has started to form fruit. Japanese hops (Humulus japonicus) has germinated; seedlings are approximately four inches in size. Winter moth (Operophtera brumata) continues to feed and is gaining in size every day. Ticks are highly active at this time.

Metro West (Acton)

General Conditions: We’ve been experiencing typical spring like temperatures with daytime temps ranging between 50 and 60 degrees and evening temps dropping down into the 30s and 40s. There’s also been some rain and a fair amount of wind. 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), M. 'Butterflies' (Magnolia Butterflies), Malus spp. (Apple, Crabapple), 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) including R. vaseyii (Pink shell Azalea), Spirea thunbergii (Thunberg Spirea), Syringa vulgaris (Common Lilac),Vaccinium angustifolium (Lowbush Blueberry), V. corymbosum (Highbush Blueberry), Viburnum x burkwoodii (Burkwood Viburnum), V. x burkwoodii 'Mohawk' (Mohawk Burkwood Viburnum) and V.× 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), Aurinia saxatilis (Basket of Gold), Caltha palustris (Marsh Marigold), Chrysogonum virginianum (Green and Gold), Claytonia virginica (Virginia Spring Beauty), 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), Hyacinthus spp. (Hyacinth), Iberis sempervirens (Evergreen Candytuft), Iris germanica (Bearded Iris), Linaria annua (Money Plant), Mertensia virginica (Virginia Bluebells), Muscari sp. (Grape Hyacinth), Myosotis sylvatica (Forget-me-not), Narcissus spp. (Daffodil), Phlox 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 and Waldsteinia ternata (Barren Strawberry).

Pests/Problems: Snowball Aphid and the distorted leaves it causes are evident on Viburnums and caterpillars are visible to the naked eye and are actively feeding on the foliage of Acer (Maple), Malus (Crabapple), and Tilia (Linden). Ticks and black flies are feeding and active. Many weeds are in flower including one of the most invasive of all time, Alliaria petiolata (Garlic Mustard), which is in full bloom and can easily be seen because of its white flowers and it is growing everywhere including on roadsides and in woodlands, wetlands and gardens. Other weeds seen in bloom now are Glechoma hederacea (Ground Ivy), Lamium purpureum (Purple Dead Nettle) and Taraxacum officinale (Dandelion). Weeds emerging but not in bloom include: Arctium minus (Lesser Burdock), Impatiens capensis (Touch-me-not) and Polygonum cuspidatum (Japanese Knotweed). 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 cool temperatures over the reporting period have extended the bloom season on early ephemerals, Apples and Crabapples (Malus cvs.), Flowering Dogwood (Cornus florida), Magnolia ‘Elizabeth’ and M. ‘Alexandrina’, Grape Hyacinth (Muscari armeniacum) and Tulips. It seems that every bud on every flowering tree and shrub survived the winter and all seem to be blooming more prolifically than ever before. Daffodils and minor bulbs are now finishing. Early blooming perennials like Bleeding Heart (Dicentra spectabile), Disporum maculatum, Hydrastis canadensis, Virginia Bluebells (Mertensia virginica), Umbrella Plant (Darmera peltata), Windlflower (Pulsatilla vulgaris), Moss Phlox (Phlox subulata), Hellebores (Helleborus x hybridus), Mukdenia rossii, Primula denticulata, Trillium erectum, T. grandiflorum, Bergenia cordifolia cultivars, Aurinia saxatilis are all in full bloom. Also in full bloom are Fothergilla ‘Mt. Airy’, Fothergilla gardenii, Viburnum carlesii, Cercis canadensis, Prunus ‘Kwanzan’, Chaenomeles speciosa ‘Nivalis’, Acer japonicum ‘Vitifolium’, Flowering Almond (Prunus glandulosa ‘Flore Plena’), Mountain Andromeda (Pieris floribunda), Bearberry (Arctostaphylos uva-ursi) and Fragrant Sumac (Rhus aromatica ‘Gro-Low’). Trollius europaeus ‘Lemon Supreme’ is beginning to bloom. The plentiful rain and cool conditions has turf growing vigorously.

Pests/Problems: Ticks and blackflies are pestering humans while Gypsy Moth Caterpillars and Eastern Tent Caterpillars are plaguing trees and shrubs. Soils are very wet and cold, excessive foot traffic over soils in these conditions will result in compaction.

Pioneer Valley Region (Amherst)

General Conditions: Cooler spring temperatures below the historical averages have extended the bloom season on early ephemerals and tulips, while daffodils are now finishing. Low temperatures hovered in the 30s, and a high temperature of 71.8° F on Thursday 5/4 lead into a beautiful weekend, with temperatures dipping back down for the week. Despite the lack of rainfall this week, soils are still saturated, perennials and turf are growing quickly, and most woody species have begun to leaf out. Perennials including Dicentra eximia (bleeding heart), Mertensia virginica (Virginia bluebells), Phlox subulata (creeping phlox), Helleborus x hybridus (hellebore), Mukdenia rossii, Primula denticulata (drumstick primrose), Trillium erectum (red trillium), T. grandiflorum (white trillium), Convallaria majalis (lily of the valley), and Aurinia saxatilis (basket-of-gold) are in full bloom. Spring-flowering woody plants blooming now include Chaenomeles sp. (quince), Halesia carolina (Carolina silverbell), Prunus maritima (beach plum), Viburnum carlesii (Koreanspice viburnum), and it has been a spectacular year for Syringa spp. (lilacs), Malus spp. (flowering crabapples) and Cercis canadensis (Eastern redbud) in the landscape, which are beginning to come to an end of peak bloom.

Pests/Problems: Gypsy moth caterpillars are crawling about, and Eastern tent caterpillar is abundantly-colonizing rosaceous trees this year. Characteristic leaf curl symptoms caused by aphid feeding on Viburnum and Ribes spp. has been observed, as well as cupping of new Buxus sempervirens (boxwood) foliage caused by boxwood psyllid feeding. Tsuga canadensis (Eastern hemlock) needles are yellowing due to elongate hemlock scale damage, and monitoring for the crawler stage should ensure timely control treatment. Continue to monitor conifer growth if needlecast diseases have been present in the past; if needed, preventative treatments should be applied during the early stages of new growth. Black flies are active in the warmer part of the days. Problem weeds Alliaria petiolata (garlic mustard), Ranunculus ficaria (lesser celandine), and Taraxacum officinale (dandelion) are in full bloom.

Berkshire Region (Great Barrington)

General Conditions: Cold, cloudy, and wet describes the weather since the last LM report. Scattered frost occurred in many locales in the county on the morning of May 4^th. Some precipitation fell on every day from May 3^rd through May 8^th with the heaviest rain occurring on May 4^th when 1.6 inches of rain fell. Snow flurries were reported in Lanesboro, Lenox, and parts of Great Barrington on Monday, May 8^th. It is very likely that the flurries were not limited to just those areas. Despite the flurries, there was no accumulation. Cold air and precipitation were not the only issues as strong winds blew in over the weekend leaving behind numerous fallen limbs and some toppled trees. Gusts to 40 mph were reported on May 6^th. Most of the fallen trees showed signs of decay. Soils at this time are saturated or nearly so. Only a slight warmup is expected over the next week and temperatures will remain below normal. The very chilly air has slowed plant development and therefore has extended the bloom period for many flowering trees and shrubs. Many magnolias, e.g. Magnolia ‘Butterflies’ and Magnolia × soulangeana , are still in full bloom as is Japanese andromeda (Pieris japonica) and shadbush (Amelanchier canadensis). Turfgrass is growing rapidly in response to the moist conditions and mowing is in full swing.

Pests/Problems: Woolly beech aphid (Phyllaphis fagi) was found on the undersides of a copper beech (Fagus sylvatica ‘'Atropurpurea'). The infestation on this particular tree has been an annual occurrence, yet the tree shows no deterioration. The insect is not considered to be an economic pest but when large populations of the aphid occur, the resulting honeydew deposited on the tree foliage attracts yellow jackets, ants, and wasps. Also, sooty mold growing in the honeydew blackens the tree leaves. Eastern tent caterpillars were finally found this past week, but on a black cherry growing at the edge of a woodlot. However, no tent caterpillars have been found this spring in managed landscapes. Boxwood leafminers are in the pupal stage. Viburnum leaf beetle larvae continue to feed. Spruce spider mites, deer ticks, carpenter bees, and wasps continue to be active. The first of the season evidence of apple scab and cedar apple rust were observed on a crabapple. Some frost injury to newly emerging leaves of several shrub species was also observed. Dandelions dot most lawns. Two invasive plants now in full bloom are garlic mustard (Alliaria petiolate) and lesser celandine (Ranunculus ficaria).

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 - Kelly Allen for 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

As covered previously in this space, a topic that has been of interest to many involved in landscaping, arboriculture, and forestry within the past few years is the widespread and ongoing decline of white pines in New England.  The following report recently compiled at the University of New Hampshire details current research into the role of pathogens and nutrient cycling in this troubling issue.

White Pine Needle Damage Report

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:

*New Pollinator Protection Resource Online: The Massachusetts Department of Agricultural Resources has developed a Massachusetts Pollinator Protection Plan. It is a set of voluntary guidelines that discuss best management practices for stakeholders seeking to promote the health of the European honeybee and other pollinators. This document includes information for beekeepers, pesticide applicators, land managers and farmers, nurseries and landscapers, and homeowners and gardeners. Please locate the MA Pollinator Protection Plan for more information here: http://www.mass.gov/eea/docs/agr/farmproducts/apiary/pollinator-plan.pdf.

• Gypsy Moth: Lymantria dispar caterpillar dispersal (ballooning) is well under way in most locations where this insect has been recently problematic in Massachusetts. Tiny caterpillars have been observed to be settled on young oak foliage and actively feeding in certain locations. Dispersing caterpillars were observed in Hanson, MA on 4/29/17, crawling away from their egg masses and suspected ballooning was reported in that location on 5/2/17. Dispersed caterpillars were observed on newly opened oak leaves on 5/3/17 at a site in Belchertown, MA. Ballooning caterpillars were observed in Monson, MA at a specific location in very high numbers, as reported with photographic evidence from a homeowner on 5/4/2017. Gypsy moth egg hatch was confirmed in Milton, MA on 5/6/17 and ballooning caterpillars were reported on that date in Ware, MA. Previous locations where gypsy moth egg hatch has been reported during the past 2-3 weeks include (but are not limited to) Belchertown, Dennis, Hanson, Hingham, Petersham, Randolph, Sandwich, Sturbridge, and near the Wachusett Reservoir. At a site in Belchertown where egg hatch was first observed on 4/26/2017, egg masses observed hatching on that date were devoid of newly hatched caterpillars (on top of the masses) by the time they were re-visited on 5/3/17. Egg masses observed with hatched caterpillars resting on top of them on 5/3 were devoid of caterpillars when they were re-visited on 5/10/17. It would appear, at least at the site being monitored in Belchertown, that the egg masses have hatched over an extended period of time and that ballooning has occurred throughout that period as caterpillars were observed to be feeding on oak and maple in that area. It would appear that hatch and dispersal is mostly over and that by the next Landscape Message, most of the young gypsy moth caterpillars, in the areas of the state where they are problematic, will have settled to feed. (Many are actively feeding at this time. If you find a host plant leaf with small, tattered holes in it, flip the leaf over and you may find a small, roughly ¼ -inch long gypsy moth caterpillar feeding on the leaf underside. The size of the caterpillars in your area depend on when hatch began. These caterpillars are dark in color, hairy, but at this time the blue and red raised “wart-like” spots on the back are not yet as apparent as they will be in the older caterpillars.) For more information about gypsy moth egg hatch, please visit: https://ag.umass.edu/landscape/news/gypsy-moth-egg-hatch-has-begun-in-massachusetts.

To treat individual, landscape ornamental and shade trees using the active ingredient Btk (Bacillus thuringiensis Kurstaki) for gypsy moth, be sure that the newly hatched caterpillars have settled to feed on fully expanded foliage and are roughly between ¼ - ¾ inch in length. Larger caterpillars are less susceptible to Btk. These applications should be made when very young caterpillars are actively feeding on host plant leaves, as it must be ingested to be effective.

Gypsy moth host plants include but are not limited to oak (favored), maple, birch, poplar, and many others. Caterpillars will feed on conifers (such as eastern white pine, hemlock, and spruce) when favored resources have been exhausted. (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.) Caterpillar dispersal occurs by crawling to the canopy of their host plant, where they can scatter 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.

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. However, at this time, it is too early to know what impact this fungus will have on the 2017 gypsy moth population. It is also important to note that even with fungal infection in the caterpillars, we may still see significant defoliation in certain areas of Massachusetts this year due to this insect. This fungus overwinters 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. So far, according to reports from the Northeast Regional Climate Center, last month (April) showed most (not all) of Massachusetts at or above normal precipitation amounts for that month. As a region, they report from the U.S. Drought Monitor that the Northeast became free of severe drought for the first time since late June 2016 (reported on 4/27/17). Although the rain might impede our outdoor recreational plans in some ways, let us hope this trend continues! See: http://www.nrcc.cornell.edu/regional/drought/drought.html.

We can also hope areas in Massachusetts that 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 southern central and eastern Massachusetts. 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. An excellent article written by Dr. Joseph Elkinton and Jeff Boettner of the University of Massachusetts about the 2016 outbreak and the history of this insect in Massachusetts may be found here: http://www.mass.gov/eea/agencies/dfg/dfw/publications/gypsy-moth-outbreak-of-2016.html.

• 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).

Reports continue to indicate that in certain areas this year, winter moth caterpillar numbers are reduced. Reports from Hanson, MA indicate that most winter moth caterpillars are in the 3rd instar at this time. (See Regional Reports.) Dr. Joseph Elkinton and his lab team at the University of Massachusetts report that when sampling for winter moth this season in host plant buds, at most of their research sites they are observing greatly reduced winter moth numbers this year. Dr. Elkinton reports that in past similar surveys, it was not uncommon to find 20+ winter moth caterpillars per host plant bud sampled. In the 2017 season, at most of their research sites, the Elkinton lab reports finding roughly 1-2 caterpillars every other bud or so that is sampled. At this time, this information is still largely anecdotal, but more information about winter moth will become available as the season progresses. Please see the Regional Reports above for local information regarding this insect.

For individuals managing winter moth in ornamental plants, spinosad is effective through ingestion and contact on winter moth (including older caterpillars) once ornamental plant leaves have fully expanded, however it should not be applied to plants in flower as it is toxic to pollinators until it has dried (which can take 1-3 hours depending upon local environmental conditions). For more in-depth information regarding winter moth management, see the Identification and Management Fact Sheet above.

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.

• 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 is 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. Nymphs of this insect may be managed between 290-440 GDD’s.

• Eastern Tent Caterpillar: Malacosoma americanum (ETC) young, but growing, caterpillars are expanding their tents as they feed on tender, new plant foliageand are quite visible at this time. Scout for, remove, and destroy any small eastern tent caterpillar tents in the crotches of branches on susceptible hosts such as cherry and crabapple. If the tents and the growing 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. For a photo demonstration on how to mechanically manage ETC, please visit the following Buckeye Yard & Garden onLine report from Joe Boggs of the Ohio State University Extension. Warning, reader discretion is advised: http://bygl.osu.edu/node/733.

• 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.

• European Pine Sawfly: Neodiprion sertifer caterpillars or sawflies are active. Reports of this insect on Mugo pine were made on 4/27/17 in Framingham. At that time, the tiny, newly hatched sawflies were still located on the very needles from which they emerged. For other locations, see the Regional Reports above. 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.

• Forest Tent Caterpillar: Malacosoma disstria (FTC) eggs have hatched as observed in Belchertown, MA on 5/3/17 on young maple leaves. Observations at that same site on 5/10/17 indicate FTC caterpillars are actively feeding (observed on maple and oak, removing larger portions of the foliage than the much smaller gypsy moth caterpillars at this time) and that FTC caterpillars are approximately ½-inch in length at that particular site. Other susceptible hosts such as birch, ash, elm, poplar, and basswood may also be fed upon by these caterpillars. These native caterpillars can defoliate their host plants, but are not currently in large populations in all areas in the state. In 2016, certain forested locations in Berkshire County supported ample numbers of these caterpillars. Neighboring states also reported some increased activity by this native insect such as in Vermont (http://bit.ly/2qAoxkR) and New Hampshire (https://nhbugs.org/forest-tent-caterpillar). It will be interesting to keep an eye on the Massachusetts population.

• 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.

• Lily Leaf Beetle: Lilioceris lilii should be monitored for at this time. See Regional Reports for local activity of this insect. 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/

• Snowball Aphid: Neoceruraphis viburnicola has been observed on certain species of viburnum. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. See Regional Reports. 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 at this time.

• Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. See the Regional Reports regarding areas where this insect has been noted to be active thus far this season. This beetle feeds exclusively on many different species of viburnum including but not limited to susceptible plants such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum. Larvae may be treated with a product containing spinosad. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found at http://www.hort.cornell.edu/vlb/.

• White 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. See the Asian longhorned beetle entry below for more information about that non-native insect.

• 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. 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.

For information about managing ticks in landscapes, among other topics, please visit the following publication from the Connecticut Agricultural Experiment Station: “Tick Management Handbook”: http://www.ct.gov/caes/lib/caes/documents/publications/bulletins/b1010.pdf.

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

Management Practices

Plant of the week: Fothergilla gardenii, dwarf fothergilla

Looking for a great dwarf plant with multi-season interest? Fothergilla gardenii is a slow growing, dense and compact shrub; generally growing 2-3’ but sometimes reaching 5-6’. The ornamental appeal begins in May with the 1-2” long white, lightly fragrant bottlebrush flowers that last around 2 weeks. Flowers usually emerge before leaves but sometimes with. Leaves are green to blue-green with a pale green underside. Leaves are obovate with rounded lobes on the upper half towards the tip. Fall color is a beautiful mix of yellow, orange, red, and purple. Dwarf fothergilla prefers a cool, acidic, well-drained soil in part shade to full sun. Plants can spread by root suckers. Fothergilla gardenii has no serious insect or disease problems. This versatile plant is a good choice for shrub borders, foundation plantings, or woodland gardens with the ornamental impact best in groupings. ‘Blue Mist’ is a cultivar offering more reliable blue-green leaf color but tends to be less cold hardy and with less showy fall color. Fothergilla major is very similar to F. gardenii but growing larger and with larger leaves and flowers.

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

Landscape Turf

Insects

White grubs on the 'rise': I have received a few phone calls and e-mails this week from people asking about white grubs, which are starting to make their presence known in some parts of southern New England. Soil temperatures are still a little on the cool side, thanks to the cool and cloudy weather, so grub damage has not been showing up as quickly as it sometimes does. The steady rains have been masking grub damage in some locations, and eventually the skunks and raccoons will figure out where the grubs are!

The main question seems to be whether there is anything that can work at this point to control the grubs?

The only curative product we have that might have an impact on the grubs is trichlorfon - but it probably will not kill more than 40 to 50% of the grubs that are present right now. That is partly because the grubs are larger than they were in the fall, and partly because their physiology is already beginning to change in anticipation of pupation in a few weeks. Many people find that such a low mortality rate makes it difficult to justify the cost of the application.

Remember that trichlorfon cannot be used on school grounds in Massachusetts and has similar restrictions in several other northeastern states. It works very quickly (usually within three days) and breaks down very quickly. However, it is very soluble in water so it would be more likely to run-off or leach than other products. Note that trichlorfon is also very sensitive to high pH, so if the water in your sprayer is higher than 7.2, you need to use one of the additives to buffer the reaction or lower the pH.

Dr. Dave Shetlar, my colleague at Ohio State University, has claimed in the past that chlothianidin could provide some curative effect on white grubs in as little as seven days. I don't know whether he has tested chlothianidin in a spring application. But when we conducted a trial in September a few years ago with chlothianidin, we did not see a significant reduction in grub numbers 10 days after application. (We did see a reduction 30 days after application.) Dr. Shetlar's trials were looking at Japanese beetles and masked chafers, which are much more susceptible to insecticides than the European chafer and oriental beetle, which are our primary species. So personally I doubt that chlothianidin would provide any better relief than trichlorfon for a spring "rescue" treatment.

If you are experiencing major grub damage now or you begin to see activity in the next week or two, as soils finally begin to warm up, you might want to apply a preventive insecticide. One option would be chlorantraniliprole, which is outstanding against all the white grub species we see in New England and has no activity against bees, ants, or wasps. (It is also virtually non-toxic to vertebrates.) It should be applied any time from now until the first week of June. It will not affect the grubs that are present now, but it will control the grubs that emerge later in the summer.

The second option would be to apply a neonicotinoid (e.g., chlothianidin, imidacloprid, or thiamethoxam) between mid June and early August. These products can be very effective against European chafers, oriental beetles, masked chafers, and Japanese beetles, but have no effect on asiatic garden beetles. Remember that neonicotinoids are toxic to honey bees and other pollinators, and must not be used when bees are foraging (for comprehensive information on minimizing the impact of neonicotinoid insecticides on pollinators, see our Neonicotinoid Turf Insecticides and Pollinators fact sheet: http://ag.umass.edu/turf/fact-sheets/neonicotinoid-turf-insecticides-pollinators).

Whatever approach you use, remember that the product needs to be watered in to enhance its effectiveness. And remember that thick or dense thatch often makes it harder for the insecticide to get to the root zone, so thatch management might be the first step to take.

Report by Dr. Pat Vittum, Professor Emeritus and Extension Turf Entomologist, UMass Amherst 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 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