Landscape Message: July 28, 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 July 26. 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	301	1299	72	66	0.44	5:00 PM 7/26
Southeast	144	1185	68	63	1.10	8:00 PM 7/26
North Shore	273	1339	62	60	1.02	9:00 AM 7/26
East	313.5	1508.5	72	66	1.78	3:30 PM 7/26
Metro West	285	1386	62	59	3.27	5:45 AM 7/26
Central	n/a	n/a	n/a	n/a	n/a	n/a
Pioneer Valley	350	1453	70	63	2.40	1:10 PM 7/26
Berkshires	264	1193	65	60	2.34	8:45 AM 7/26
AVERAGE	102	1338	67	62	1.76	-
n/a = information not available

Drought Status: Nearly all of Massachusetts (99.3%+) 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.
Clethra alnifolia (Summersweet Clethra)	Begin	Begin/Full	Full/End	Begin	Full	*	Full	*
Hibiscus syriacus (Rose-of-Sharon)	Begin	Begin/Full	Full	Begin/Full	Full	*	Full	Begin
Buddleia davidii (Butterfly Bush)	Begin/Full	Begin/Full	Begin/Full	Full	Full	*	Begin/Full	Begin/Full
Oxydendron arboreum (Sourwood)	Full	Full	Full/End	End	Full/End	*	Full	*
Campsis radicans (Trumpet Vine)	Full	Full	Full	Full	Full/End	*	Full/End	Full
Hydrangea paniculata (Panicle Hydrangea)	Begin/Full	Begin/Full	Full	Full	Full	*	Begin/Full	Begin/Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature from July 12 - July 26 was 71° F with a high of 90° F on July 20 and a low of 55° F on July 26. Overall the period has been dominated by days reaching the lower 80s and nights in the upper 60s/lower 70s. The relative humidity was very high from July 12-20… generally 90-100%. July 23-25 had cooler conditions with temperatures barely reaching the 70s. Just under a half inch of precipitation fell over two minor rain events on July 13 and 24. Topsoil moisture is short, subsoil moisture remains adequate. In most cases even unirrigated lawns still remain green.

Pests/Problems: Insect pests or damage seen during the period include, Japanese beetle, oriental beetle and asiatic beetle, viburnum leaf beetle, two spotted spider mite, andromeda lace bug, leaf hoppers, chilli thrips, ambrosia beetle, and chinch bugs. Powdery mildew is extremely active and can be found on all the usuals; lilac, monarda, rose, coreopsis, phlox, and dogwood. Rabbit complaints have been numerous as there seems to be a very large population this year. Deer tick nymphs are still active. Make sure you do a tick check and use permethrin treating clothing to protect yourself. Weeds in bloom include; white clover (Trifolium repens), red sorrel (Rumex acetosella), yellow woodsorrel (Oxalis stricta), purslane (Portulaca oleracea), plantain (Plantago lanceolata), prostrate spurge (Euphorbia maculata), Pennsylvania smartweed (Polygonum pennsylvanicum) yellow toad flax (Linaria vulgaris), annual toadflax (Linaria canadensis), Canadian thistle (Cirsium arvense), queen anne's lace (Daucus carota), common milkweed (Asclepias syriaca), and spotted knapweed (Centaurea maculosa).

Southeast Region (Hanson)

General Conditions: The past two weeks found many areas of the state, including Hanson, to have experienced muggy, hot, weather in the 80’s and 90’s with little rain. This past Monday and Tuesday, July 24 and 25^th, saw some changes where the temperatures dropped to the mid to high 50’s and low 60’s. Much needed rain came in on those days and Hanson received 1.10 inches of rain over the past two weeks. Last year at this time, much of Massachusetts was in a drought watch and although it has been warm this season, we are fortunate to have had sufficient rain to keep us out of a drought watch, thus far. We need more rain, as trees and other plants damaged by gypsy moth feeding are slow to recover, and although much of the area around Hanson was spared from massive defoliation, there are many areas where trees were defoliated and they are struggling. Remind clients to water defoliated trees and those that were planted this year and last year.

The following plants are in full bloom. Oxydendrum arboreum (Sourwood Tree), Albizia julibrissin, Clethra barbinervis, Weston hybrid azaleas, Hydrangea macrophylla (mostly lacecaps), Hydrangea quercifolia (Oakleaf Hydrangea), Hydrangea arborescens (Smooth Hydrangea), Hydrangea paniculata (Panicle Hydrangea), roses, Rose-of-Sharon, Rubus odoratus, Echinacea sp., Persicaria polymorpha, Persicaria amplexicaulis ‘Firetail’, Liatris spicata, Lysimachia clethroides, Lysimachia ciliata, Actaea (formerly Cimicifuga) racemosa, Perovskia atriplicifolia, Acanthus mollis, Asclepias tuberosa, Acanthus spinosus, daylilies, Ligularia dentata ‘Desdemona’, Hosta, Veronicastrum virginicum, Corydalis lutea, Hemerocallis (daylily), Filipendula sp., Phlox paniculata (Garden Phlox), Platycodon grandiflorus, Spigelia marilandica, Coreopsis verticillata, Shasta daisy, Nepeta sp., Macleaya cordata (Plume poppy), Echinops ritro (Globe Thistle), Alcea rugosa (Russian Hollyhock), Heliopsis ‘Summer Sun’, Helianthus sp., Monarda didyma (Beebalm), Silphium sp., Lavender, Rudbeckia sp. (including R. fulgida and R. ‘Herbstonne’), Oriental lilies, Coreopsis verticillata, Astrantia major and Campanula sp. Aesculus parviflora (bottlebrush buckeye) and Clerodendrum trichotomum are beginning bloom. Stewartia pseudocamellia is ending bloom. There are still a few Kousa dogwoods in flower around the area.

Hanson has 2,328 GDD (Growing Degree Days) base 40).

Pests/Problems: Most gypsy moth caterpillars stopped feeding at the end of June and began to pupate; however, there were still some caterpillars found feeding the first few days of July. The end of June and the first of July also saw massive caterpillar death by the fungus Entomophaga maimaiga. Male gypsy moths started to emerge in early July, followed by the females and continued into late July and Gypsy moth females were still found laying tan masses of eggs on tree trunks and branches, rocks, etc. at the end of July. As of right now, gypsy moth season appears to be over and although there are many areas, where there was massive caterpillar die-off due to the fungus, there were still plenty of gypsy moth caterpillars that survived to pupate and emerge as male and female moths to mate and lay significant numbers of eggs for next year. Stay tuned.

Sunflower moth caterpillars (Homoeosoma electellum) were found in the flowers of Rudbeckia fulgida. This caterpillar has many hosts in the composite family: Echinacea sp., Bidens sp., Heliopsis, marigolds, Rudbeckia, Helianthus, etc. The sunflower moth lays eggs at the base of the florets in the cone, which then hatch into small caterpillars that feed on the true flowers in the cone causing the flowers to appear messy-looking. https://negreenhouseupdate.info/photos/sunflower-moth-caterpillar

Monitor Phlox paniculata. If the flowers or buds are turning brown and not opening, or if the flowers appear “blasted’, dissect and examine the buds for very small, orange-gold colored maggots. I do not know what this insect pest is, but it causes the flowers not to open and the damage may be incorrectly attributed to drought. The insect may be some type of blossom midge, but that is only a wild guess on my part. If and when this pest is found, cut back, clean up and remove the damaged flower buds from the garden.

Oriental beetles and Asiatic beetles are feeding at night on a wide variety of plants and causing foliar and floral damage. Snails are numerous and feeding on a variety of plants, especially hosta. Japanese beetles are also active and were again founding feeding on perennial hibiscus, but in general, Japanese beetle numbers appear to be low. Monitor perennial Hibiscus for foliar feeding of the larvae of the hibiscus sawfly and manage if found; Bt (Bacillus thuringiensis) will not manage sawfly).

Continue to monitor susceptible deciduous host trees (maple, ash, birch, horsechestnut, etc.) for Asian longhorned beetles: https://ag.umass.edu/landscape/fact-sheets/asian-longhorned-beetle

This is usually a slow time of the season for insect pests, however, continue to monitor pines for introduced pine sawfly and redheaded pine sawfly, which are often active late into the season and may cause considerable damage to unmanaged pines. Also continue to monitor Pieris japonica, Rhododendron and Azaleas for lacebug, which also may cause considerable damage if left untreated.

The following insects also remain active: mosquitoes, aphids, stinkbugs; spider mites; earwigs; slugs; four-lined plant bug; leafhoppers; dog ticks; Taxus mealybug; Asian longhorned beetle look-alikes, like the White-spotted Pine Sawyer and Graphisurus fasciatus (Longhorned Beetle); Sharpshooter leafhopper (red-banded leafhopper), wasps and hornets. Continue to take precautions while working outdoors as deer tick nymphs remain active and it is this stage that is most often responsible for transmitting disease: https://ag.umass.edu/tick-borne-disease-diagnostics/tick-borne-diseases

Giant tar spot is showing up on Norway maples; other leafspots and anthracnose were observed on various susceptible plants, including blackspot on susceptible roses. Rabbits are plentiful and deer continue to browse plants. It continues to be a very good year for butterflies with more monarchs being observed this year than in previous years, along with eastern swallowtail, pipevine swallowtail, American copper, red admiral, painted lady, and fritillary butterflies. Pipevine swallowtail butterfly larvae were observed feeding on (Aristolochia durior (Dutchman's pipe).

North Shore (Beverly)

General Conditions: The first one and a half weeks of this reporting period were dry, hot and humid. Temperatures at Long Hill during this reporting period were in the mid 80s to low 90s during the day and in the high 60s during the night. Temperatures 90 degrees and above were recorded on July 19th and 20th. There were big changes during the last half of the second week, when rain showers moved into the area and cloudy weather lowered the temperatures into the mid-60s. During the last two weeks of this reporting period, Long Hill gained 273 growing degree days (GDD) bringing the total degree day accumulation for the year to 1339. Approximately 1.02 inches of rainfall was received.

Woody plants seen in bloom include; Sourwood (Oxydendrum arboreum), Oakleaf hydrangea (Hydrangea quercifolia), Panicle hydrangea (Hydrangea paniculata), Mountain Stewartia (Stewartia ovata var. grandiflora), False tree spirea (Sorbaria arborea), Chinese chaste tree (Vitex sinensis), Lemon drop Weston azalea (Rhododendron ‘Lemon Drop’), Butterfly Bush (Buddleia davidii), Rose-of-Sharon (Hibiscus syriacus) andTrumpet vine (Campsis radicans). Herbaceous plants seen in bloom include: Bee balm (Monarda didyma), Shasta daisy (Leucanthemum x superbum), Yarrow (Achillea millefolium), Garden phlox (Phlox paniculata), Hostas (Hosta spp.), Sedums (Sedum spp.), Stachys (Stachys officinalis), Meadow rue (Thalictrum rochebrunianum), Astilbe (Astilbe spp.), Summer flowering roses (Rosa sp.), Clematis vines (Clematis paniculata), Spiderwort (Tradescantia sp.), Persicaria (Persicaria polymorpha) and Water lily (Nymphaea odorata). Adding even more color in the landscapes are an assortment of annuals.

Pests/Problems: Japanese beetles were observed in the landscape and are starting to cause damage on some plants. Also observed was powdery mildew on susceptible lilac varieties, and cedar hawthorn rust on single seed hawthorn. Cottony taxus scale was also observed on some yew shrubs. Weeds are thriving due to moist soil and warm temperatures. Ticks and mosquitoes continue to be active.

East Region (Boston)

General Conditions: Over the past two weeks we received 1.78 inches of precipitation, the majority occurring on the 24^th into the morning of the 25^th when a cold front came through dropping temperatures into the mid 60’s on both days. Conditions over the last two weeks have been quite variable, we reached only 65° F on the 14^th before hot and humid weather returned; we reached temperatures in the low 90s from the 19^th through to the 21^st. The cold front brought low temperatures dipping down to 53° F. We gained 313.5 GDDs bringing us up to 1508.5 so far this year. Plants in bloom include: Albizia julibrissin (silktree), Aralia californica (elk clover), Asclepias incarnata (swamp milkweed), Buddleja davidii (summer lilac, butterfly-bush), Centaurea montana (perennial cornflower), Clerodendrum trichotomum (Harlequin glory bower), Echinacea purpurea (Eastern purple coneflower), Echinacea sp. cultivars, Echinops ritro (globe thistle), Eutrochium purpureum (sweet Joe-Pye weed), Gaillardia sp. (blanket flower), Helianthus tuberosus (Jerusalem artichoke, sunchoke), Heuchera sp. (alumroot) and cultivars, Hibiscus moscheutos (swamp rosemallow), Hibiscus syriacus (rose of Sharon), Hosta sp. (hosta, plantain lily), Hydrangea paniculata (panicled hydrangea), Kalopanax septemlobus (tree aralia), Lavandula angustifolia (English lavender), Liatris spicata (dense blazing star, prairie gay feather), Liriope muscari var communis 'Peter's Pick' (lilyturf), Monarda sp. (bee balm), Phlox paniculata (garden phlox), Platycodon grandifloras (balloon flower), Pontederia cordata (pickerelweed), Rudbeckia fulgida 'Goldsturm' (black-eyed Susan), Rudbeckia hirta (black-eyed-Susan), Sedum sp. (stonecrop), Silphium perfoliatum (cup plant), and Tanacetum vulgare (common tansy). Platanus × acerifolia (London plane) has been shedding its bark, exposing the yellow bark beneath.

Pests/Problems: The recent weather conditions have contributed to the spread of many fungal diseases. Black spot and black knot are prevalent on many rosaceous plants. Powdery mildew on Syringa sp. (lilac) is common as is Guignardia Blotch on Aesculus sp. (horse chestnut). Unwanted vegetation is thriving. Currently in bloom: Cichorium intybus (common chicory), Daucus carota (Queen Anne's lace, wild carrot), Linaria vulgaris (toadflax), Persicaria sp. (smartweed), and Phytolacca americana (American pokeweed). Purple loosestrife is flowering in areas where purple loosestrife beetle populations are low. Weeds seeds continue to develop on: Circaea lutetiana (enchanter's nightshade), Cynanchum louiseae (black swallow-wort), Lepidium virginicum (Virginia pepperweed), Rhamnus cathartica (common buckthorn), Rumex acetosella (common sheep sorrel), and Solanum dulcamara (bittersweet). Late season weeds Digitaria spp. (crabgrass), Euphorbia maculata (spotted sandmat), and Portulaca oleracea (common purslane) have germinated and are steadily gaining in size. Over the last two weeks, cicadas have emerged and can now be heard singing throughout the landscape.

Metro West (Acton)

General Conditions: What a growing season! The warm and hot days are followed by brief periods of rain; enough so that the grass is still green and gardens require little if no watering but do keep in mind that this rain is most likely not sufficient for new plantings. The historical monthly average rainfall for the month of July is 4.07” and 4.05” of rain has been recorded so far this month, with 2 significant rain events with over 1” of rain recorded both times. The area experienced its second heat wave of the summer with one occurring on July 19^th, 20^th and 21^st with temperatures recorded at 90°, 91° and 90° respectively and then some cool temps on the 24^th and 25^th with a high of 61° and a low of 48°. Overall, there has been 10 days this summer with temperatures recorded in the 90’s. Woody plants seen in bloom this past week are: Aesculus parviflora (Bottlebrush Buckeye), Buddleia spp. (Butterfly Bush), Castanea mollissima (Chinese chestnut), Clethra alnifolia (Summersweet), Hibiscus syriacus (Rose-of-Sharon), Hydrangea arborescens (Smooth Hydrangea), H. paniculata (Panicle Hydrangea), H. quercifolia (Oakleaf Hydrangea), Oxydendron arboreum (Sourwood), Potentilla fruiticosa (Potentilla), Rosa rugosa (Rugosa Rose), R. 'Knockout' (The Knockout family of Roses), and Rosa spp. (Rose). Woody vines in bloom are: Campsis radicans (Trumpet Vine) and Clematis spp. (Clematis). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Achillea millefolium (Yarrow), Alcea rosea (Hollyhocks), Asclepias syriaca (Common Milkweed), A. tuberosa (Butterfly Weed), Astilbe spp. (False spirea), Boltonia asteroides (Bolton’s Aster), Campanula takesimana ‘Elizabeth’ (Bell Flower), C. spp. (Bell Flower), Cichorium intybus (Chicory), Coreopsis spp. (Tickseed), C. verticillata (Threadleaf Coreopsis), Daucus carota (Queen Anne's Lace), Echinacea purpurea (Coneflower), Gaillardia aristata (Indian Blanket Flower), Hemerocallis 'Stella D'Oro' (Daylily), H. fulva (Orange Daylily), H. spp. (Daylily), Hosta spp. (Plantain Lily), Lamium maculatum (Dead Nettle), Lavandula angustifolia (Lavender), Leucanthemum sp. (Shasta Daisy), Liatris spicata (Spike Gayfeather), Lilium spp. (Lily), Lysimachia clethroides (Gooseneck Loosestrife), Monarda didyma (Bee-Balm), Nepeta spp. (Ornamental Catmint), Perovskia atriplicifolia (Russian Sage), Phlox carolina (Carolina Phlox), P. paniculata (Garden Phlox), Platycodon grandiflorus (Balloon Flower), Rudbeckia fulgida var. sullivantii 'Goldsturm' (Black-eyed Susan), Senna marilandica (Wild Senna), Solidago spp. (Goldenrod), Tradescantia sp. (Spiderwort), Verbena hastata (American Blue Vervain), and Veronicastrum virginicum (Culver's Root).

Pests/Problems: Observed in the landscape this past two weeks were leaf blotch on Aesculus sp. (Horsechestnut) and Cedar Apple Rust on Amelanchier sp. (Serviceberry). Not only has this been a great growing season for our landscape plants but our herbaceous weeds and woody weedy vines are thriving as well. Setting seed and quite visible is Ailanthus altissima (Tree of Heaven). Look for it growing along roadsides and in parking lots and medians.

Central Region (Boylston)

No reprt available this week.

Pioneer Valley Region (Amherst)

General Conditions: The dog days of summer roll on in the Pioneer Valley. This past reporting period was mostly hot, muggy and dry (or wet), with high temperatures holding steady in the upper 80s to low 90s for roughly a week, accompanied by uncomfortable dew points. A cool front finally cleared out the humid air mass on Monday, 7/24 and brought some meaningful precipitation. Most weather stations in the valley recorded >.80″ of rainfall from the latest storm, the first significant rain event in Franklin and Hampshire County since 7/12. While there have been a number of thunderstorms in the region since the last Landscape Message, the largest have either tracked north into Vermont and New Hampshire or south into Connecticut. A northwest to southeast tracking storm did bring significant rain to Hampden County on 7/18, with over 1.5″ recorded in Springfield. Surface soils were dry before the rainfall earlier this week but subsurface soils still remain fairly moist, especially in shaded settings. An ever growing number of trees and shrubs are developing scorch, branch dieback and death. Early senescence has been observed on a few scattered and very unthrifty trees in the landscape. Turfgrasses have browned and gone dormant in many locations. But overall, it’s been a season of strong growth for many trees and shrubs in the landscape. Newly planted trees and shrubs need regular watering now more than at any time this season. Continue to soak the root ball on these new transplants once weekly to minimize the impacts of transplant shock.

Pests/Problems: Japanese beetle populations seem to be a smaller this season, based on scouting in Amherst and Easthampton. Asiatic and Oriental beetle populations are also a bit suppressed compared to previous years. Mosquito populations have resurged after a brief lull in early July. The wood-rotting fungus Bondarzewia (Berkeley’s polypore) is starting to appear on oaks, based on sightings and photos from arborists. Several clusters of fruiting bodies emerged at the base of a 61″ dbh red oak in Northampton this past week. Subsequent testing for internal decay using sonic and electrical resistance tomography revealed significant decay in the base of the tree. There have been limited sightings and reports of Laetiporus to date, but continue to scout for the orange-colored shelves of this destructive root and butt rot pathogen. The cream-colored, overlapping shelves of the northern tooth fungus (Climacodon septentrionalis) are starting to appear on sugar maple. Dutch elm disease continues its rampage on landscape elms. It’s been a banner year for this disease despite a high level of awareness and management. The anthracnose pathogen Colletotrichum continues to be isolated from a wide array of trees and shrubs in the landscape. Marginal leaf scorch, leaf spots/blotches and shoot tip dieback are the most common symptoms observed. Prune and discard blighted stems and branches as the season wears on to avoid the continued development and spread of this fungus, if suspected to be present. Tubakia leaf blotch on oak is becoming more and more apparent. The spots are growing and coalescing to create large, necrotic blotches.

Berkshire Region (Great Barrington)

General Conditions: It was an up and down weather picture over the past two week period in terms of temperature. For much of the time, temperatures were above normal with some very cool days in between. July 14, 24, and 25 were the coolest, largely due to cold fronts accompanied by rain. Currently, soil moisture levels are high though not saturated except for poorly drained sites. Precipitation continues to be a little more than one inch above normal but almost 7 inches above last year’s total at this time. In general, the landscape is lush and turfgrass growth has been rapid, necessitating more frequent mowing than is typical during what is about the hottest time of the year.

Pests/Problems: Asiatic garden beetle, and Japanese beetles are the dominant plant pests at the moment. Aphid and scale pests are also active but not overwhelming, though foliage of some trees, notably Liriodendron tulipifera and magnolias, have some sooty mold. Spider mites, earwigs, wasps, deer tick, mosquitoes, and slugs and snails are active. As might be expected, given frequent rains, the slug population is high and damage to herbaceous ornamentals and vegetables is extensive. Galls on leaves of many tree species are common and may cause undue concern as they cause no economic harm to their hosts.

Botrytis blight can be seen on many peonies. This is the most common disease of garden peonies and is not unusual during rainy summers. Likewise, powdery mildew is a common occurrence, especially on its usual hosts. One report had it on cosmos. Other diseases observed include tar spot on both silver and Norway maple, black spot on roses, and pear leaf blight (Fabraea leaf spot). Pre-mature leaf drop is prevalent on many crabapple cultivars due to apple scab and cedar apple rust. The fruiting bodies (called aecia) of cedar apple rust can be seen on the undersides of apple and crabapple leaves and are now releasing their spores which in turn infect juniper species, including eastern red cedar.

The chipmunk population seems to be unusually high this year. Not only is their browsing on plants an issue but their burrowing in gardens and lawns is leaving holes and piles of soil in their wake.

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:

Foliar and shoot tip blight of American holly (Ilex opaca 'Jersey Knight' & 'Jersey Princess') caused by Phyllosticta and Colletotrichum. Several plants at a site that are roughly six-years-old and were planted in the spring of 2016. In May and June of this year, shoot tip dieback and premature leaf shedding developed on many of the shrubs. Phyllosticta was present on the margins of the blackened foliage, where it produces numerous black-colored pads of tissue that release spores. Colletotrichum was abundant at the base the foliage, the petioles and on blackened shoot tips.

Stem cankering of elm (Ulmus sp.) caused by Botryodiplodia ulmicola. Tree is approximately 30-years-old and is exhibiting a general wilt throughout the canopy. The symptoms were not consistent with Dutch elm disease, but vascular staining was observed on cut stems. The Dutch elm disease pathogen was not present on the submitted sample, but Botryodiplodia was abundant. This stem cankering pathogen is common on stressed elms and the symptoms can mimic those caused by DED. Tree resides in full sun in moderately well-drained soils near a septic field. There have been no recent disturbances the arborist was aware of.

Canopy dieback of Japanese stewartia (Stewartia pseudocamellia) caused by the anthracnose pathogen Colletotrichum. Small tree that was planted four years ago, approximately nine-years-old. Leaf margins were scorched and shoot tips blackened on the submitted sample. The tree has flowered only sparsely, leaves are prematurely shedding and branches are dying back. Symptoms developed soon after planting. Tree was planted in an ornamental bed with shrubs that appear to be healthy. The site is near the ocean with persistent winds and clay soils that hold moisture. Colletotrichum was abundant on the submitted tissues and has been observed on other stewartia trees this season with similar symptoms.

Leaf spot and stem cankers caused by Alternaria on privet (Ligustrum sp.). Plants are approximately five-years-old and have been present at the site for two years. Zonate leaf spots and stem dieback was observed this year. Alternaria mostly behaves as a secondary pathogen on trees and shrubs but on privet the pathogen can be quite destructive. There were several longitudinally splitting stem cankers that were primarily responsible for the symptoms. Transplant shock likely contributed to the development of the disease.

Needle and shoot blight on Japanese cryptomeria (Cryptomeria japonica) caused by Pestalotiopsis. Tree is 15-years-old and has been present at the site for only two years. Browning branches were present in the canopy and after a brief incubation of the material, numerous black-colored, tendrils of spores were produced by the fungal pathogen. Pestalotiopsis is common on arborvitae, falsecypress, juniper and cryptomeria in the landscape. The tree resides in full sun with drip irrigation.

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:

• 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. Adults of this insect are (historically) active at this time in the regulated area in Massachusetts.

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.

• White Spotted Pine Sawyer (WSPS): Monochamus scutellatus adults will continue to be active through July. 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 emerge in Massachusetts in July and August. Now is the time to 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 (ALB’s is black). See the Asian longhorned beetle entry above for more information about that non-native insect.

• Asiatic Garden Beetle: Maladera castanea adults are active and are typically most abundant in July and August. These rusty-red colored beetles are bullet-shaped and active at night. They are often attracted to porch lights. They feed on a number of ornamental plants, defoliating leaves by giving the edges a ragged appearance and also feeding on blossoms. Butterfly bush, rose, dahlia, aster, and chrysanthemum can be favored hosts. When levels of damage reach a management threshold, pyrethroid- based insecticides may be necessary. Read and follow label instructions and avoid harming non-target organisms. Certain neem oil products are also labelled for use against adult beetles. Observe label instructions to minimize the potential for leaf injury.
• 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. Adults emerged 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, through August, can be inspected weekly for adult weevils which can be killed before egg laying.

• 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): 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) and most recently, cultivated olive (Olea europaea). (See: https://academic.oup.com/jee/article-lookup/doi/10.1093/jee/tox139.) Adult insects of this species are active. 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 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: Lymantia dispar most (if not all) adult activity should be at an end by the time this Landscape Message is posted. Management at this time is typically not effective. The young, feeding caterpillars that hatch from these egg masses next spring are the life stage to be targeted for management.

That being said, some have asked about what can be done for the gypsy moth egg masses currently found in the landscape. Some homeowners take action by scraping egg masses into a can of soapy water (without damaging the bark of the tree). That activity is laborious, time consuming, and limited in its effectiveness mainly because other egg masses (particularly in the surrounding forests or high in the tree canopy and out of reach) are bound to be missed. Do not apply products (such as WD40) to the gypsy moth egg masses that are not specifically labelled for that purpose. (WD40 is not intended nor labelled for that purpose.) Other ideas for management that have been posed to UMass Extension include “what if I burn them off with a blow torch?” UMass Extension does not recommend this for obvious safety reasons, risks to the health of the tree, and again (perhaps least important when compared to the previous two reasons) because of the limits to its effectiveness.

For more information about gypsy moth and its management next season: http://ag.umass.edu/landscape/fact-sheets/gypsy-moth and for an overview of the 2017 season and gypsy moth activity, please visit: http://ag.umass.edu/landscape/news/gypsy-moth-caterpillars-dying-across-massachusetts.

• Japanese Beetles: Popillia japonica adult beetles were first reported as active in Massachusetts the week of June 23^rd this year and continue to be spotted across the landscape. Adult female beetles will lay their eggs primarily by early August, however eggs may be laid into September. Females lay these eggs in groups in soil cavities they excavate 2-4 inches down. Japanese beetles overwinter as nearly grown grubs in the soil which are capable of evading freezing behaviorally by moving below the frost line. As soils warm in the spring, larvae become active and feed on the roots of grasses. Pupation occurs 1-3 feet below the soil surface. Adults emerge from these lawn areas and disperse to feed on foliage, mate, and return to turf-type locations for females to lay their eggs. Japanese beetle adults use aggregation pheromones (chemicals that signal between individuals) to call in others of the same species. These pheromones and volatile chemicals from host plants being fed upon are thought to be the reason why large numbers of these beetles can be found feeding together. Adult beetles feed on foliage and flowers, often skeletonizing leaves until they appear lace-like. Larvae are highly damaging turf pests. Tree and shrub hosts are comprised of more than 300 species including but not limited to rose, mountain-ash, willow, linden, elm, Japanese and Norway maples, birch, sycamore, rose of Sharon, ornamental apple, and many others. Adult beetles are often attracted to feeding on sunny areas of the plant. Pheromone traps for this insect have not been found to be effective at lowering populations, and research suggests they may draw in more beetles to any host plants within the vicinity of the trap. Many organisms are parasitoids of Japanese beetles, such as two wasps that attack overwintered grubs in the spring, and a tachinid fly (winsome fly: Isocheta aldrichi) which parasitizes newly emerged adult beetles. Other organisms act as generalist predators with Japanese beetles on their menus, including but not limited to ants, certain other beetles, small mammals, and birds.
• Lace Bugs: Corythucha spp. and Stephanitis spp. lace bugs are active. Corythucha spp. utilize many hosts such as: hawthorn, cotoneaster, amelanchier, quince, pyracantha, various oaks, birch, maple, mountain ash, sycamore, hackberry, elm, walnut, butternut, basswood, etc. By the time we reach 1266-1544 GDD’s, management of Corythuca spp. may be necessary again if these insects were problematic earlier this season. 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.
• Lily Leaf Beetle: Lilioceris lilii adult beetles were nowhere to be seen on 7/12/17 at a location in Amherst, MA where observations have been made all season. On this same date, only a single frass-covered larva was found feeding on the plants in question. Larvae can feed for 16-24 days and then drop to the soil to pupate. Adults will emerge 16-22 days later and are then seen feeding throughout the remainder of the growing season. Adults will overwinter. 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. (Although when many plants are involved, mechanical management may not be practical.)

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/

• Oriental Beetle: Exomala (Anomala) orientalis is another introduced species (first detected in CT in 1920 from Japan) in the scarab beetle family (Scarabaeidae) that is typically smaller than the Japanese beetle as an adult. Adults are typically 4/10 of an inch, with the stout (broad) body typical of scarabs. Adult coloration can be variable, ranging from a black color to mottled gray with black patches/patterned markings. Oriental beetles can feed on flowers such as daisy, roses, phlox, and petunia as adults; although typically, the feeding by the adults is not severe. Larvae often coexist with those of the Japanese beetle and can be very difficult to distinguish from them. Larvae can damage the roots of turf grasses as well as the roots of many nursery plants and small fruits, including containerized plants. Common ornamental hosts include hemlock, holly, rhododendron, azalea, juniper, and andromeda. Adults are seen typically in mid-June and can be found through at least early August in MA. By late July, the larvae can cause serious damage to turfgrass and ornamental plants. Management of the larvae may be most critical. Hand-pick adults when appropriate.

• Roseslugs: These small, caterpillar-like sawfly larvae will skeletonize the upper leaf surface and leave a “window-pane” like pattern behind. When present in large numbers, these insects are capable of defoliating their entire host. Management options include an insecticidal soap spray or a product containing spinosad. One species, Allantus cinctus, may require management again in mid-August; otherwise the window for management passes typically by mid-June.
• Two-marked Tree Hopper: The Enchenopa binotata species complex is now thought to be made up of very closely related Enchenopa spp. that are morphologically very similar but separated by the different host plants that they are found on. These particular treehoppers are found on black walnut, wafer ash (Ptelea trifoliata), and viburnum. These insects will feed on the host plants with piercing-sucking mouthparts and drink plant juices from the leaves and petioles. Leaves will become shiny and sticky with their excrement. Some nymphs are still present, but mostly adults of this insect were observed on wafer ash in Amherst on 7/12/17. Eggs will be laid by adult females using saw-like ovipositors to insert them into plant stems. (This has not yet been observed at this location.) Eggs are then covered with a vivid white, sticky, frothy material that protects them but can easily be mistaken for a scale insect. These treehoppers, whether by their feeding activity or egg laying behavior into plant stems, are not considered to be damaging pests (even when high in numbers) and therefore management is generally not required.
• 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 this season. Adult beetles have been spotted by scouts in the Cape Cod Region and 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.

Weeds

Summer annual weeds are very apparent in many landscape beds.  Directed spot treatment of glyphosate can be used at this time.  If a preemergence herbicide was not applied to mulches in the spring, consider a tank mix of glyphosate and another preemergence herbicide product labelled for landscape beds.  Additional mulch can be added in areas where mulch is thin or nonexistent.

Many landscape trees commonly produce vegetative suckers at their trunk base.  Suckers are commonly seen on crabapple, pear, plum, linden, maple and sometimes oak.  Honeylocust will also produce vegetative sprouts along the entire length of their trunk.  It these suckers or sprouts are not controlled the landscape will be a contender for the “shabby landscape award”.  Pruning is effective but very time consuming.  Another option would be to use the product Scythe^TM that contains pelargonic acid to remove these vegetative suckers and sprouts when they are very small.  Very small means one inch in length or less.  Pelargonic acid is a contact herbicide. If Scythe is applied to small suckesr and sprouts the product will desiccate them and physical removal will not be required.  Larger growth will first need to be physically removed and then Scythe can be used as a maintenance program.  Products that contain glyphosate should not be used as glyphosate is a translocated herbicide.

Inspect areas of the landscape where new trees or shrubs, especially those that were field grown, have been planted early this season or last year.  Look for perennial weeds that may be growing from the root ball.  Canada thistle, mugwort, quackgrass, bindweed and horsenettle are some of the possible culprits.  These weeds can be spot treated with glyphosate.

Poison ivy can be treated now.  Use a broadleaf brush herbicide or glyphosate based material.  Remember that even after the plant is dead the oil that causes the rash will be active in leaves, stems and roots.

Still too early for attempting to control Japanese knotweed, Polygonum cuspidatum.  Plan for applications of glyphosate to begin when Japanese knotweed begins to flower in a few weeks.

Report by Randall Prostak, Weed Specialist, UMass Extension Agriculture & Commercial Horticulture Program

Management Practices

Plant of the week: Monarda didyma, bee balm

Monarda didyma is a great late summer bloomer for pollinators! It is a North American native, herbaceous perennial growing 2-4’ tall and 2-3’ wide. The globular flowerheads consist of tubular, two-lipped, bright red flowers. The flowers rise above the foliage on square stems, occurring in mid to late summer. Leaves are opposite, ovate, and medium to deep green growing 3-6” long. Bee balm is part of the mint family so leaves have a minty scent when crushed. Plants are best grown in medium to wet soil in full sun to part shade. Clumps should be divided every 3-4 years. Good air circulation helps to deal with powdery mildew, which can be a problem. Plants should not dry out to avoid stress and disease. Deadheading helps to prevent self-seeding. Monarda didyma attracts butterflies, bees, and hummingbirds making it a great choice for pollinator gardens, butterfly gardens, and bird gardens. It is also a good choice for perennial borders, cottage gardens, native or naturalized areas, and rain gardens. Cultivars offer smaller sizes and pink or purple flowers.

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

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Additional Resources

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Diagnostic Services

A UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see Plant Diagnostics Laboratory

Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The function of the Soil and Plant Nutrient Testing Laboratory is to provide test results and recommendations that lead to the wise and economical use of soils and soil amendments. For complete information, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. Alternatively, call the lab at (413) 545-2311.

Ticks are active at this time! Remember to take appropriate precautions when working and playing outdoors, and conduct daily tick checks. UMass tests ticks for the presence of Lyme disease and other disease pathogens. Learn more