Landscape Message: September 8, 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 September 6. 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 (2-Week Gain)	Time/Date of Readings
	2-Week Gain	2017 Total	Sun	Shade
Cape Cod	195	2060	68	64	1.61	8:00 AM 9/6
Southeast	148	1830	73	68	0.78	4:25 PM 9/6
North Shore	209	2102	68	63	0.55	9:30 AM 9/6
East	200.5	2318.5	70	68	0.46	3:30 PM 9/6
Metro West	154	2074	66	n/a	0.66	5:45 AM 9/6
Central	168	2100	n/a	n/a	0.50	3:50 PM 9/6
Pioneer Valley	166	2146	68	66	2.52	5:00 PM 9/6
Berkshires	185	1846	64	61	0.95	8:00 AM 9/6
AVERAGE	178	2060	68	65	1.00	-
n/a = information not available

Drought Status: Approximately 80% of Massachusetts is not under official drought status at this time.  The 20% classified as 'Abnormally Dry' includes the northernmost portions of Essex county, virtually all of Plymouth and Bristol counties, and the southern 2/3rds of Norfolk county.  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.
Heptacodium miconioides (Seven-Son Flower)	Begin	Begin	Begin	Begin/Full	Begin	Begin	Begin/Full	*
Clematis paniculata (Sweet Autumn Clematis)	Begin/Full	Begin	Full	*	Begin	*	Full	Begin
Styphnolobium  japonicum (Japanese Pagodatree)	Full/End	*	End	End	Full	Full	Full	Full
Polygonum cuspidatum (Japanese Knotweed)	Full/End	Full	Full	Full	Full	Full	Full	Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature from August 23 - September 6 was 64° F with a high of 83° F on August 23 and a low of 47° F on September 2.  Temperatures have primarily been in the 50s at night and the 60s to low 70s during the day.  1.61 inches of precipitation was recorded in Barnstable from two events, one on August 30 and the other on September 2.  Topsoil and subsoil moisture are adequate at this time.  There is little need for supplemental irrigation on established lawns or established landscape plantings at this time because of the shorter days, cooler temperatures, and adequate rainfall.  Compared to last year at this time, lawns are in excellent condition and conditions are great for renovation or installation.

Pests/Problems: Insect pests or damage seen during the period include viburnum leaf beetle on V. dentatum, two spotted spider mite on many ornamentals, chilli thrips on hydrangea, azalea lace bug on ‘PJM’ rhododendron, andromeda lacebug on andromeda, leaf hopper damage on numerous plants including dahlia, hibiscus sawfly on hibiscus, magnolia scale on magnolia, bronze birch borer damage on birch, turpentine beetle damage on pitch pine,  and powdery mildew on lilac, monarda, rose, coreopsis, phlox, dogwood, white oak and sycamore. Tar spot is prevalent on maple.  Weeds in bloom include yellow woodsorrel (Oxalis stricta), purslane (Portulaca oleracea), prostrate spurge (Euphorbia maculata), Pennsylvania smartweed (Polygonum lanceolata), spotted knapweed (Centaurea maculosa), Japanese knotweed (Polygonum cuspidatum), redroot pigweed (Amaranthus retroflexus), ragweed (Ambrosia artemisiifolia), crabgrass (Digitaria spp.), and horseweed (Conyza canadensis).

Southeast Region (Hanson)

General Conditions: Dry weather continued over much of the past two weeks. Fall-like days, 70’s and some 80’s and cool nights, with one night showing a low of 46 degrees, were the norm as we edge into the late summer season.  Remnants from Hurricane Harvey did not produce much rain (0.2 inches) here in Hanson which only received 0.78 inches of rain for a total over the past two weeks. The total rainfall for Hanson for the past 10 weeks is 4.53 inches and un-irrigated trees, shrubs, perennials and lawns are showing the effects of low soil moisture with leaf drop, marginal leaf browning, wilting, leaf scorch, etc. Many lawns are brown, although crabgrass, purslane, ground ivy and other lawn weeds are unfortunately thriving.  

Albizia julibrissin, Rose-of-Sharon, roses, Campsis radicans, Hydrangea paniculata, Hydrangea quercifolia, Rubus odoratus, Butterflybush, Rudbeckia trilobum, Rudbeckia ‘Herbstonne', Rudbeckia subtomentosa ‘Henry Eilers’,  Rudbeckia ‘Goldsturm’, Caryopteris divaricata, Lobelia cardinalis, Lobelia syphilitica, Lobelia hybrids, Heliopsis ‘Summer Sun’, Helianthus 'Lemon Queen', Persicaria amplexicaulis, Sedum spp., Eupatorium spp., perennial Hibiscus like Hibiscus 'Summer Storm’ and Hibiscus ‘Old Yella’, Corydalis lutea, Ligularia dentata ‘Desdemona’, Goldenrod,  Hosta spp., ornamental grasses, Coreopsis ‘Harvest Moon‘ and Phlox paniculata remain in bloom.

New England asters and Japanese anemone are beginning to bloom. The fruits of many plants like Kousa dogwood, Cornus controversa, crabapples, hollies, Staghorn sumac and Viburnums are beginning to add color to the landscape. The fruits of many invasive plants, like Berberis sp. (barberry), Euonymus, autumn olive, and Oriental bittersweet, are also showing color and are easy to see and eradicate, where possible.

Monarch, painted ladies, cabbage, and swallowtail butterflies continue to be seen, along with hummingbirds.  Hanson has 3,378 GDD (Growing Degree Days) Base 40.

Pests/Problems: Continue to remind clients to irrigate high value plants that may be experiencing some drought stress, especially those trees defoliated by caterpillars. Many defoliated trees in the Hanson area still have not fully recovered from defoliation by gypsy moth caterpillars.

The following insects and pests remain active: Andromeda, rhododendron and  azalea lacebugs; Asiatic garden beetles; redheaded pine sawfly larvae; introduced pine sawfly larvae; leafhoppers; slugs; snails; hibiscus sawfly larvae; spider mites; elongate hemlock scale; lily leaf beetle larvae; wasps, boxelder beetles, stinkbugs, ticks, mosquitoes, biting flies, sunflower moth caterpillars and aphids. Oriental beetles have finished for the season. Hickory tussock moth caterpillars and milkweed tussock moth caterpillars are also active.

Continue to monitor lawns for sod webworm larvae and for chinch bug activity; not all brown lawns are caused by drought stress.

Continue to monitor for Asian Longhorned Beetle (ALB), dogwood sawfly larvae; and viburnum leaf beetle. (See the Insect section of the Landscape Message below). 

The usual late season diseases continue to show up: anthracnose on maples, dogwoods, etc; powdery mildew on susceptible plants like: lilac, dogwoods, witchhazel, Beebalm, Helianthus, and garden phlox; Tarspot is visible on the foliage of silver and Norway maples.

Deer continue to browse and chipmunks continue to be pests.

North Shore (Beverly)

General Conditions: Temperatures during this reporting period were in the low to high 70s during the day and the low to high 50s during the night. Temperatures of 80 degrees and above were recorded for only two days, and there were no temperatures of 90 degrees and above reported. Rainfall occurred only on one day (September 3^rd) during this period. However a storm is expected through later today (Wednesday, September 6). The total amount of precipitation during this reporting period was 0.55 inches. Woody plants seen in bloom include Silk tree or Mimosa (Albizia julibrissin), Oakleaf hydrangea (Hydrangea quercifolia), Butterfly bush (Buddleia davidii), Blue mist shrub (Caryopteris x clandonensis) and Seven Son Flower (Heptacodium miconioides). Herbaceous plants seen in bloom include: Bush clover (Lespedeza thunbergii), Garden phlox (Phlox paniculata), hostas (Hosta spp.), Autumn joy sedum (Sedum spp.), Joe pye weed (Eutrochium purpureum), Sweet autumn clematis (Clematis paniculata), Rudbeckia (Rudbeckia hirta), Japanese anemone (Anemone x hybrida), Yellow wax bells (Kirengeshoma palmata) and Water lily (Nymphaea odorata). Different kinds of annuals are also contributing more color in landscapes.

Pests/Problems: Powdery mildew is prevalent on some lilac varieties and on garden phlox. Tar spot and anthracnose are prevalent on maple trees.  Crabgrass and other weeds such as prostrate spurge (Euphorbia maculata), horseweed (Conyza canadensis), ragweed (Ambrosia artemisiifolia) and Japanese knotweed (Polygonum cuspidatum) are thriving in the landscape. Goldenrod (Solidago canadensis) is in full bloom and providing a lot of color on roadsides. Mosquitoes have slowed down but they are still active at dawn and dusk. Ticks are still very active.

East Region (Boston)

General Conditions: Weather conditions have been varied over the last two weeks, highs have ranged from 63° F to 87° F averaging 75° F, while lows have ranged from 43°F to 64°F averaging 53°F. We’ve experienced 4 days with temperatures in the 80’s, reaching at 87° F on September 5^th. Meteorological autumn began September 1st, as opposed to astronomical autumn that begins on September 22nd. Remnants of hurricane Harvey arrived on September 3rd delivering 0.31” of precipitation for a total of 0.46” over the last two weeks.  We accumulated 200.5 GDDs for a total of 2318.5 this growing season.  Many perennials and late blooming plants continue to attract pollinators. Heptacodium miconioides (seven-son-flower) and Rhus chinensis (Chinese sumac or nutgall tree) are in full bloom. Colorful fruit is abundant throughout the landscape including: Chaenomeles sp. (flowering quince), Cydonia oblonga (common quince), Malus sp. (crabapple), Prunus sp. (cherry), Rosa sp. (rose), Sorbus sp. (mountain ash), and Viburnum sp. (viburnum), among others. Fall color and early leaf drop has begun on Acer sp. (maple), Amelanchier sp. (serviceberry), Betula sp. (birch), Cornus florida (flowering dogwood), Salix sp. (willow), and others.

Pests/Problems: Despite the 0.46” of precipitation we have received soil conditions remain dry. Supplemental irrigation is ongoing for mature specimens as well as recently planted trees and shrubs. Unwanted vegetation is going to seed including Arctium minus (lesser burdock), Cynanchum louiseae (black swallowwort), Solanum dulcamara (bittersweet nightshade) and many others. Japanese knotweed is flowering. Powdery mildew is prevalent on lilacs. Lacebug continues to feed and multiply. Japanese Beetles (Popillia japonica) have been observed feeding on the leaves of Arctium minus (burdock), Fallopia japonica (Japaneese knotweed), and Petasites sp. (butterbur).

Metro West (Acton)

General Conditions: There was little rain recorded during this past two-week reporting period, however the total recorded for the month of August was 4.03” and the month’s historical monthly average rainfall is 3.72”, so again, the monthly total has been exceeded.  However, 3.4”of that rain fell fast and furious on August 2^nd so our soils are dry, requiring supplemental irrigation for some plants. September’s average rainfall is 3.77” and a total of 0.51” has been recorded for the month so far. Woody plants seen in bloom this past week are: Albizia julibrissin (Silk Tree), Buddleia spp. (Butterfly Bush), Clethra alnifolia (Summersweet), Heptacodium miconioides (Seven-Son Flower), Hibiscus syriacus (Rose-of-Sharon), Hydrangea paniculata (Panicle Hydrangea), and its many cultivars including 'Tardiva', and Potentilla fruiticosa (Potentilla). A woody vine in bloom is Clematis paniculata (Sweet Autumn Clematis). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Alcea rosea (Hollyhocks), Asclepias tuberosa (Butterfly Weed), Aster spp. (New England Aster, New York Aster, Smoother Aster, White Wood Aster), Boltonia asteroides (Bolton’s Aster), Daucus carota (Queen Anne's Lace), Echinacea purpurea (Coneflower), Eutrochium purpureum (Joe Pye Weed), Hosta spp. (Plantain Lily), Kirengeshoma palmata (Yellow Wax Bells), Patrinia gibbosa (Patrinia), Perovskia atriplicifolia (Russian Sage), Phlox carolina (Carolina Phlox), P. paniculata (Garden Phlox), Platycodon grandiflorus (Balloon Flower), Rudbeckia fulgida var. sullivantii 'Goldsturm' (Black-eyed Susan), Sedum ‘Autumn Joy’, S. ‘Rosy Glow’ (Stonecrops), and Solidago spp. (Goldenrod).

Pests/Problems: Let’s hope that we receive more rain now that the fall planting season is upon us.  We’ve been in a dry spell for several weeks now.  Observed in the landscape this past two weeks were browning and leaf drop on Acer platanoides (Norway Maple) due to tar spot and/or anthracnose, leaf blotch on Aesculus sp. (Horsechestnut), powdery mildew on Hamamelis (Witch Hazel), Monarda (Bee Balm), Phlox, and Syringa (Lilac), and Cedar Apple Rust on Amelanchier spp. (Serviceberry).

Central Region (Boylston)

General Conditions: Lack of rainfall during the past few weeks has impacted lawns and planting beds, necessitating irrigation. Conditions have been surprisingly cool with nighttime temperatures dipping into the low to mid 40’s in the area on a few nights. The foliage on trees under stress is beginning to take on autumn hues. Many herbaceous plants continue to bloom in gardens and fields and meadows. Goldenrod (Solidago sp.), joe-pye-weed (Eupatorium sp.), boneset (Eupatorium perfoliatum) are among the colorful natives in fields and meadows. In cultivated areas many annuals and tender perennials continue to be lush and showy. Among the herbaceous perennials in bloom are Russian sage (Perovskia atriplicifolia), late blooming daylilies (Hemerocallis), Japanese anemones (Anemone hupehensis, A. tomentosa ‘Robustissima’), Phlox paniculata, Rudbeckia fulgida var. sullivantii ‘Goldsturm’, Rudbeckia triloba, Rudbeckia nitida ‘Herbstsonne’, Autumn Crocus (Colchicum sp) are beginning to bloom.  The last of the Clethra alnifolia blooms are perfuming the air. Now in full bloom is Clerodendron trichotomum, Callicarpa dichotoma, Hydrangea paniculata cultivars, Seven Son Flower (Heptacodium miconioides), and Rose of Sharon (Hibiscus syriacus).

Pests/Problems: Insects like Blister Beetle, Squash Bugs, Fall Webworm, Cross Hatched Cabbage Worm, and Tobacco Hornworms continue to flourish. Powdery mildew is appearing on Phlox paniculata, Syringa vulgaris and Cucurbita.

Pioneer Valley Region (Amherst)

General Conditions: As the growing season winds down in the Pioneer Valley, the weather has sharply transitioned towards autumn. In recent years, we have gradually observed the change of season, but this year we can point to a particular day when fall arrived. After the scorcher on 8/22, when the heat index was at or close to 100° F, temperatures completely bottomed out on 8/23. Since that day, highs have mostly hovered in the upper 70s with lows in the upper 40s to mid 50s. The cooler temperatures, coupled with dry and sunny weather, created some ideal outdoor working conditions. We really got a taste of autumn during the morning hours of Saturday, 9/2 when lows along the Connecticut River plunged to the upper 30s (38° F in Easthampton). The cooler weather continues the trend we saw in August when, according to the Northeast Regional Climate Center, temperatures were 1–3° F cooler than average across the Pioneer Valley. We had a brief return to summer-like conditions as the fall semester started at UMass, with highs in the upper-80s and rising dew points. We’ve also seen a return of the rain after a fairly dry August, when accumulations were only 50–75% normal for the month. The remnants of hurricane Harvey dropped over an inch throughout the valley on Sunday, 9/3. Additional rain, some heavy at times, took place between 9/5 through 9/7, with further accumulations around 0.5”. Since 9/1, Hampshire and Hampden Counties have accumulated over 2” of rainfall, while Franklin County has seen over 3”, and hopefully this trend continues. The rainfall and cooler temperatures have allowed turfgrasses to break summer dormancy and green up dramatically. Soil temperatures dropped >5°F since our last report, owing to the cool nights. Conditions are currently ideal for transplanting woody ornamentals and establishing or rehabilitating turfgrasses. For recently transplanted conifers, continue regular watering through October. For deciduous ornamentals, continue until leaf drop. Supplemental water during the first year of establishment is critical to lessen the shock of transplant and help plants reestablish a robust root system.

Pests/Problems: Fall colors are starting to appear on sugar and red maple. Rosaceous hosts continue to shed large volumes of foliage, especially large, old apple trees. Regular, nearly annual, pruning of crabapples and apples can help protect these trees from major foliar disease outbreaks. Removal of interior branch suckers improves airflow and can help reduce inoculum on heavily shaded leaves deep in the canopy. Katsura and Stewartia are developing their typical marginal burn and are shedding leaves. With the mild temperatures and recent rainfall, which has been heavy at times, many different stem cankering and foliar blight pathogens are sporulating at this time. Now is the time to treat susceptible conifers for the spruce spider mite. After a mid-summer lull, populations will be increasing once again. Scout for flecking symptoms and white webbing (won’t be present after rainfall) to detect infestations. Use of insecticidal soap or a registered miticide can significantly reduce infestations. However, the damaged needles will persist, so it may take several years for the tree to grow out of the damage. Fall treatments for needle cast should also take place now as these fungi are sporulating and initiating new infection centers. Needle cast pathogens of spruce are of particular concern, and include Rhizosphaera and Stigmina. Utilize fungicides that are locally systemic and rotate to avoid development of fungicide resistance.

Berkshire Region (Great Barrington)

General Conditions: The first frost of the season occurred on the morning of September 2^nd in some areas of the County.  Frost damage was observed on certain vegetable crops (sweet potato, squash, beans, cucumbers, and beans) in West Stockbridge with reports of similar damage in the Stockbridge area.  No frost damage observed nor reported on ornamental plants.  The frost occurred despite an official low temperature of 36° F being reported.  It is not unusual to see a coating of frost on plants at some point in September, but in this area that is usually in late September.  The frost observed, despite air temperatures above freezing, is termed “radiative frost.”  During the day, the sun’s radiation heats the surfaces of plants and earth; at night, that heat radiates back toward the sky. On a clear, windless night, heat lost from the plants can occur quite rapidly, resulting in intense cooling of the surfaces of plants and other objects.  On such a night, these surfaces can be as much as 5 degrees colder than the air temperature.   As such, temperature of the vegetable plant leaves was actually at or below freezing.  This resulted in some damage to plant tissue as represented by a darkening of the leaves, mostly the top or outermost leaves. The vegetables which showed any damage were species of tropical or sub-tropical origin.  Plants which can tolerate light frosts were unaffected.  There has been a cooling trend in recent weeks.  Mean daily temperatures for the month of August were 2 degrees below normal.  The month was also drier than normal with 3.36 inches of rain compared to the normal of 4.20 inches. However, rainfall of the past few days and possible remnants of Atlantic hurricanes should result in ample rains.  September is a critical month for plants in terms of moisture uptake as studies have shown that ample rainfall and water uptake by plant roots this month reduces the chances of winter desiccation for woody species.  

Pests/Problems: Pest pressures remain low but diseases, particularly foliar diseases, are prominent.  High humidity has favored development of powdery mildew on many plants, especially lilacs, phlox, beebalm (Monarda) and dahlias.  Premature leaf drop continues on crabapples due to heavy infections of apple scab and cedar apple rust. Tar spot on silver maple, Norway maple, and boxelder are common occurrences. Some premature fall color is occurring on trees and shrubs, especially on those woody plants along roadsides and on sites with impoverished soils.  Leaves on Enkianthus are now red. Tussock moth caterpillars, particularly hickory tussock moth and American dagger moth, are common.  Deer browsing on tender landscape plants has picked up as vegetation in the wild hardens.  Other pests are slugs, snails, ants, and aphids.  Nuisance pests include wasps and hornets, mosquitoes, earwigs, and ticks.

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

Recent pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab:

Verticillium wilt, caused by either Verticillium dahliae or V. albo-atrum, on east Asian stripe maple (Acer tegmentosum ʹJoe Wittʹ). Tree is approximately eight to ten-years-old and was planted three years ago. In early August, leaves throughout the canopy began to wilt and turned pale green. Approximately 30 to 40% of the foliage was symptomatic. Submitted stems had pitting in the vascular tissue, a symptom often associated with Verticillium wilt. The tree was one of three stripe maples transplanted in 2014. While the setting offered significant shade, the trees were not regularly watered following transplanting. The tree that became diseased received the least amount of water, while the other two appeared healthy at the time of sample submission.

Fabrella needle blight, caused by Fabrella tsugae, on a weeping eastern hemlock (Tsuga canadensis ʹPendulaʹ). Large weeping hemlock, approximately 70-years-old in a full sun, landscape setting. Wounds from the hemlock borer lead to resin flow and stained bark on many of the branches. Needles on scattered shoots in the canopy became yellowish-brown and Fabrella was found sporulating from the underside of the symptomatic needles. Fabrella is believed to be an uncommon needle blight pathogen of eastern hemlock in New England, attacking trees weakened by other stresses.

Needle blight of weeping eastern white pine (Pinus strobus ʹPendulaʹ) caused by Septorioides strobi and Hendersonia pinicola. Tree is approximately 10-years-old and has been present at the site for roughly six years. This season, ¾ of the canopy has browning needles. More specifically, needle tips are browning while the base of the needles remains green in most cases. This is a typical pattern of symptom development for white pines infected by these two fungal pathogens. Septorioides is a newly described fungal pathogen of white pine and Hendersonia is believed to a weak colonizer of stressed needles. They often co-occur on samples submitted to the diagnostic lab. The tree resides in full sun but does not receive supplemental water. However, the tree is fertilized and mulched.

Premature leaf shedding of sugar maple (Acer saccharum) caused by maple anthracnose (Discula campestris) and transplant shock. Tree is 10- to 12-years-old (8” dbh and ~30’ tall) and was transplanted one year ago. In mid-August of this year, leaves began to senesce and fall from the canopy. The tree is in full sun with drip irrigation and well-drained, loamy soils. Maple anthracnose has been abundant this season a variety of maples, including sugar maple.

Severe infestation of the cryptomeria scale (Aspidiotus cryptomeriae) on Fraser fir (Abies fraseri). Tree is nine-years-old and was planted in a Christmas tree farm seven years ago. Scattered yellowing of the needles, especially lower in the canopy, has been worsening in recent years. Like nearly all Christmas trees, this tree resides in full sun without irrigation but weed control maintains surrounding vegetation. The cryptomeria scale is a destructive, non-native insect pest from Asia, just like the elongate hemlock scale. However, unlike the latter, the cryptomeria scale is still an uncommon pest of true fir in New England.  

Infestation of the arborvitae leafminer (Argyresthia thuiella) and needle blight caused by Pestalotiopsis on arborvitae (Thuja occidentalis ′Nigra′). Mature row of trees along a paved driveway, approximately 30-years-old and present at the site for 20 years. Needle browning and crown thinning has been steadily worsening in recent years. Numerous brown shoot tips with exit holes indicated an infestation of leafminer. These blighted tissues likely served as a point of infection for Pestalotiopsis, a common and sometimes destructive pathogen of Thuja.

Leaf browning and premature shedding on apple (Malus domestica). Large and old landscape apple, approximately 24” dbh. Leaf yellowing, browning and shedding originated in the lower canopy and then spread throughout the crown. By mid-August, the tree was almost completely defoliated. The submitted foliage had a severe case of cedar-apple rust (Gymnosporangium juniper-virginianae) along with foliar anthracnose, caused by Colletotrichum. The anthracnose pathogen appeared to colonize the cedar-apple rust leaf spots and continues a trend observed on other samples submitted to the lab, such as Norway maple. The trend being a conspicuous foliar pathogen, like cedar-apple rust or tar spot, coupled with a foliar anthracnose pathogen that is likely more damaging than its conspicuous counterpart. Tree resides in full sun with surrounding turf grasses with other apple trees. 

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

Insects

Amazing Ant Nuptial Flights: On 9/5/2017, ant mating flights were witnessed in a residential landscape in Hampshire County. These spectacular events can be commonplace in not only the early spring, but also the late summer for certain species of ants. To the average observer, such activity might be frightening: especially when, seemingly, as far as the eye can see, thousands upon thousands of these individuals are on the move. Groups of hundreds of ants – wingless workers (all female) and winged sexual forms (the ones doing the mating) – seemed to be pouring out of the ground in clusters on a warm, humid evening, just following a light rain. The glinting reflection of hundreds of flying ants could be seen in the early evening light as they lift from these groups, winged males and females swarming to meet each other to mate. For the males, this is the beginning and the end – they live only long enough to reproduce. The females then disperse, shed their wings, lay their eggs, and shortly thereafter they feed their first generation of larvae. Ants are Hymenopterans – closely related to bees, wasps, and sawflies. Ant colonies will continue to survive the winter in the soil, decayed wood, or other protected areas. When these mating swarms are observed, one might fear that the individuals involved are termites, particularly when witnessing the abundant activity right next to a home. Termites are in a different order, the Isoptera. “Iso” meaning equal and “ptera” meaning wings. This refers to one key morphological difference between alate (winged) termites and ants. Both will have two pairs of wings. However, the wings of a termite, if present, are equal in size and length. The wings of an ant, if present, will be unequal in size – with the front wings being larger than the rear wings. Ants will also have a constricted or “pinched” waist, whereas the waist of a termite is broad and not pinched. If you have magnification available, the antennae of a winged ant may be elbowed, whereas those of a winged termite will be straight and beadlike. For more information about ants found in lawns, visit: https://ag.umass.edu/turf/fact-sheets/ants-in-lawns.  

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

• 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, or have captured an adult beetle that you believe to be ALB, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938.

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

• Aspen Petiole Gall Moth:  a moth (Lepidoptera) in the family Nepticulidae (the pygmy moths) is known to create round galls (swelling) on leaf petioles adjacent to the base of the leaves of aspens such as Populus tremuloides (quaking aspen) and P. grandidentata (bigtooth aspen). The species of moth most likely responsible for this is Ectoedemia populella, referred to by some as the aspen petiole gall moth. This insect was recently seen in sample material submitted to the UMass Plant Diagnostics Laboratory. Adult moths of this species are tiny, with approximately 6 mm. wingspans. It is suspected that the adult moth emerges sometime in May and begins to lay eggs after the host plant leaves have fully expanded. Larvae emerge from their galls and pupate in October. Pupae overwinter in the soil. Because of this, they are not found in the leaf litter and are not easy to culturally remove by raking and removing leaves. This species is suspected to have only 1 generation per year and is not typically considered a serious pest, as it does not typically have a severe impact on the overall health of the host plant.  
  
   
• Azalea Leafminer: The azalea leafminer (Caloptilia azaleella) was recently seen in sample material submitted to the UMass Plant Diagnostics Laboratory. Leaf mines, rolled leaf tips, frass, and larval C. azaleella were present. The azalea leafminer is a tiny moth (Lepidoptera) as an adult. This species is from the Gracillariidae family of moths, often referred to as the leaf blotch miner moths. This insect is interesting in its feeding habits in that it creates two distinct types of damage: upon hatching from its egg, the young larva feeds initially as a leafminer. Once large enough, the larva emerges, folds the tip or edge of the leaf over itself, secures it with silk, and feeds within this protected area by chewing holes in the leaf. Therefore, upon inspection of the browned leaves, blotch/lineal mines and leaf rolling may both be present. The larvae of this insect rarely destroy entire leaves, but they do significantly disfigure them. The eggs of this insect are white and laid singly on the underside of host plant leaves. After hatching, the larva begins mining the leaf, creating either lineal or blotch-like mines. The mined area will fill with frass (excrement) and brown in color. Once this is complete, the larva will roll the end of the leaf, or the leaf edges, secured with silk, and feed within. Once mature, the larva may find an undamaged leaf to roll and pupate inside. In approximately 1 week, a small moth will emerge, find a mate, and start the cycle over again. Host plants impacted are the azaleas. Moths are tiny, approximately 10 mm in length, yellow/gold in color. In New York, two generations of these insects have been observed. Further south in the United States, such as in Georgia or Alabama, 3-4 generations per year have been observed. In areas such as Florida, "breeding is continuous". Depending on geographic location and temperatures, this insect may overwinter in differing developmental stages. This insect is considered a destructive pest for evergreen azaleas. Injured leaves can turn brown and yellow and drop. If plant health is maintained, it is possible to reduce the impact of this insect. It appears that this species was originally endemic to Japan, but has been introduced throughout the world. Mechanical management can include pruning out and destroying infested branches, as long as this itself does not severely impact the health/aesthetics of the plant. Rake and destroy fallen leaves. Maintaining plant vigor through proper fertilization and watering can also aid in the azalea's ability to tolerate or outgrow the activity of this pest. At least 3 species of parasitoids have been found associated with the azalea leafminer, so if chemical management options are employed, this should be considered when selecting active ingredients.
• Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. Crawlers will be present throughout the growing season and the overlap of many developmental stages at any given time can be observed.
• Emerald Ash Borer (EAB): A new county detection of Agrilus planipennis (EAB) was made using green panel traps and a combination of a host plant volatile chemical and pheromone (sexual attractant) lures placed in Brookline, MA. This is unfortunately a new county detection (Norfolk County) in Massachusetts for 2017. (However, it is in very close proximity to a prior detection made in Suffolk County.) EAB has previously been detected in Berkshire County (2012), Essex County (2013), Suffolk County (2014), Worcester County (2015), and Hampden County (2016). In this case, two green panel traps, hung in close proximity to one another, captured 6 adult beetles between them, which were collected on 7/14/17 and sent to the UMass Plant Diagnostics Laboratory for confirmation. This identification was also confirmed by the USDA Animal and Plant Health Inspection Service (APHIS).

EAB readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and most recently, cultivated olive (Olea europaea). (See: https://academic.oup.com/jee/article-lookup/doi/10.1093/jee/tox139.) Signs of an EAB infested tree may include D-shaped exit holes in the bark, “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/upon peeling 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 report it at the Massachusetts Introduced Pests Outreach Project: http://massnrc.org/pests/pestreports.htm.

• Fall Home-Invading Insects: Various insects, such as ladybugs, boxelder bugs, seedbugs, and stink bugs will begin to seek overwintering shelters in warm places, such as homes, throughout the next couple of months. While such invaders do not cause any measurable structural damage, they can become a nuisance especially when they are present in large numbers. If you are not willing to share your home with such insects, now should be the time to repair torn window screens, repair gaps around windows and doors, and sure up any other gaps through which they might enter the home.
• Fall Webworm: Hyphantria cunea is native to North America and Mexico. It is now considered a world-wide pest, as it has spread throughout much of Europe and Asia. (For example, it was introduced accidentally into Hungary from North America in the 1940’s.) Hosts include nearly all shade, fruit, and ornamental trees except conifers. In the USA, at least 88 species of trees are hosts for these insects, while in Europe at least 230 species are impacted. In the past history of this pest, it was once thought that the fall webworm was actually two species. It is now thought that H. cunea has two color morphs – one black headed and one red headed. These two color forms differ not only in the coloration of the caterpillars and the adults, but also in their behaviors. Caterpillars may go through at least 11 molts, each stage occurring within a silken web they produce over the host. When alarmed, all caterpillars in the group will move in unison in jerking motions that may be a mechanism for self-defense. Depending upon the location and climate, 1-4 generations of fall webworm can occur per year. Fall webworm adult moths lay eggs on the underside of the leaves of host plants in the spring. These eggs hatch in late June or July depending on climate. Young larvae feed together in groups on the undersides of leaves, first skeletonizing the leaf and then enveloping other leaves and eventually entire branches within their webs. Webs are typically found on the terminal ends of branches. All caterpillar activity occurs within this tent, which becomes filled with leaf fragments, cast skins, and frass. Fully grown larvae then wander from the webs and pupate in protected areas such as the leaf litter where they will remain for the winter. Adult fall webworm moths emerge the following spring/early summer to start the cycle over again. 50+ species of parasites and 36+ species of predators are known to attack fall webworm in North America. Fall webworms typically do not cause extensive damage to their hosts. Nests may be an aesthetic issue for some. If in reach, small fall webworm webs may be pruned out of trees and shrubs and destroyed. Do not set fire to H. cunea webs when they are still attached to the host plant.
• Gypsy Moth: Although the activity of Lymantria dispar is through for the 2017 season, we have been revisiting this year’s outbreak frequently in the Landscape Message to keep track of the extent of the activity that occurred this year. Thankfully, the insect killing fungus (Entomophaga maimaiga) kicked in (although later this season that perhaps we wished for), causing widespread mortality during the caterpillar stage of this insect.

Before the fungus caused caterpillar death, however, these insects defoliated much of Massachusetts forests and landscapes. As previously mentioned in prior Messages, the MA Department of Conservation and Recreation estimates that approximately 922,460 acres were defoliated by gypsy moth in 2017. Valerie Pasquarella, a postdoctoral fellow with the University of Massachusetts Amherst’s Northeast Climate Science Center used Landsat images to generate maps that quantify the activity of gypsy moth during an outbreak. For more information, and to see these maps, visit: http://www.umass.edu/newsoffice/article/using-landsat-images-postdoctoral-fellow.

• Hickory Tussock Moth: Lophocampa caryae is native to southern Canada and the northeastern United States. There is one generation per year. Overwintering occurs as a pupa inside a fuzzy, oval shaped cocoon. Adult moths emerge approximately in May and their presence can continue into July. Females will lay clusters of 100+ eggs together on the underside of leaves. Females of this species can fly, however they have been called weak fliers due to their large size. When first hatched from their eggs, the young caterpillars will feed gregariously in a group, eventually dispersing and heading out on their own to forage. Caterpillar maturity can take up to three months and color changes occur during this time. These caterpillars are essentially white with some black markings and a black head capsule. They are very hairy, and should not be handled with bare hands as many can have skin irritations or rashes (dermitis) as a result of interacting with hickory tussock moth hairs. By late September, the caterpillars will create their oval, fuzzy cocoons hidden in the leaf litter where they will again overwinter. Hosts whose leaves are fed upon by these caterpillars include but are not limited to hickory, walnut, butternut, linden, apple, basswood, birch, elm, black locust, and aspen. Maple and oak have also been reportedly fed upon by this insect. Several wasp species are parasitoids of hickory tussock moth caterpillars.
• Lace Bugs: Stephanitis spp. lacebugs such as S. pyriodes can cause severe injury to azalea foliage. S. rhododendri can be common on rhododendron and mountain laurel. S. takeyai has been found developing on Japanese andromeda, leucothoe, styrax, and willow. Stephanitis spp. lace bugs should be monitored through September. Before populations become too large, treat with a summer rate horticultural oil spray as needed. Be sure to target the undersides of the foliage in order to get proper coverage of the insects. Fall or early spring soil treatment with imidacloprid has been effective, but be aware of the implications this may have on pollinators attracted to these flowering plants when making management decisions. Certain azalea and andromeda cultivars may be less preferred by lace bugs.

• Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. Adult beetles are expected to be active roughly through October, or when the first frost hits. Adult beetles will create their own feeding damage, but will also mate and females will lay eggs in the stems of the viburnums, typically beginning in late-June to mid-July until October. 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. 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: The non-native, exotic chilli thrips (Scirtothrips dorsalis) has been 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.

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.

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.

Management Practices

Plant of the Week: Rhus typhina ‘Bailtiger’, Tiger Eyes staghorn sumac

Rhus typhina ‘Bailtiger’ is a dwarf cultivar of R. typhina growing 3-6’ tall and wide. It is commonly planted for its foliage color - leaves emerge chartreuse and mature to yellow. The foliage appeal continues into fall with a mix of yellow, orange and red fall color. The pinnately compound leaves are large (1-2’ long) and leaflets are dissected adding to the foliar appeal. Young stems are fuzzy due to being covered in hairs. Stems and branches are purple in color providing a striking contrast to the yellow foliage. Flowers are terminal panicles of small green-yellow flowers. On female plants the flowers are followed by pyramidal clusters of hairy, bright red drupes in fall. Fruit is attractive to wildlife. Plants are best grown in dry to medium, well-drained soil in full sun to part shade. Tiger Eyes staghorn sumac is tolerant of drought and urban conditions. R. tyhpina is known for spreading by suckering and self-seeding; however, Rhus typhina ‘Bailtiger’ will spread more slowly and is not as aggressive as the species. Rhus typhina ‘Bailtiger’ has no serious insect or disease problems but can be susceptible to leaf spot, rust, blisters, cankers, powdery mildew, scale insects, or caterpillars.

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 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