Landscape Message: June 3, 2016

June 3, 2016
Issue: 
11

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Green Industry professionals in the management of our collective landscape. Scouts compile and record environmental and phenological data for locations throughout Massachusetts to aid in the monitoring of plant and pest development, the planning of management strategies, and the creation of site-specific records for future reference.  Detailed reports from Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. UMass Extension has updated the following issue to provide timely management information and the latest regional news and environmental data.

The Landscape Message will be updated weekly April through June. The next message will be available on June 10. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.

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

Scouting Information by Region

Environmental Data

The following growing-degree-day (GDD) and precipitation data was collected for an approximately one week period, May 26 through June 1. Soil temperatures and phenological indicators were observed on or about June 1. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2016 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

Region/Location

GDD

Soil Temp
(°F at 4" depth)

Precipitation
(1-Week Gain)

Time/Date of Readings

1-Week Gain

2016 Total

Sun

Shade

Cape Cod

34

231

74

65

0.52

4:30 PM 6/1

Southeast

118

335

74

65

1.53

3:50 PM 6/1

North Shore

116

307

63

60

0.61

10:00 AM 6/1

East

147

376.5

71

65

1.35

4:30 PM 6/1

Metro West

138

342.5

64

62

0.35

5:45 AM 6/1

Central

148

429

63

60

0.26

6:45 AM 6/2

Pioneer Valley

208

404

70

66

0.59

12:00 PM 6/1

Berkshires

149

335

72

65

0.77

10:15 AM 6/1

AVERAGE

132

345

69

63

0.75

-

n/a = information not available

Phenology

Phenological indicators are a visual tool for correlating plant development with pest development. The following are indicator plants and the stages of bloom observed for this period:

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT NAME (Botanic/ Common) CAPE S.E. N.S. EAST METRO W. CENT. P.V. BERK.
Cornus sericea (Red Osier Dogwood) * * Full End Full Full End *
Cotinus coggygria (Common Smokebush) * Full Begin Begin Begin Begin Full Begin
Kalmia latifolia (Mountain-laurel) * * Begin * Begin Begin Full *
Hydrangea anomala petiolaris (Climbing Hydrangea) * Begin * * * * Begin Begin
Robinia pseudoacacia (Black Locust) * Full Full Full Full Full Full *
Kolkwitzia amabilis (Beautybush) Begin/Full Full Full Full Full Full Full Full
Weigela florida (Old Fashioned Weigela) Full Full Begin Begin/Full Full Full Full Begin
Deutzia spp. (Deutzia species) Full Full Full * * Full Full Begin
Syringa meyeri (Meyer Lilac) Full Full Full Full/End Full Full Full Full
Rhododendron catawbiense (Catawba Rhododendron) Begin/Full Full Full Begin Full Full Full Begin/Full
Spiraea x vanhouttei (Vanhoutte Spirea) Full End Full/ End End Full/ End Full End Full
Aesculus hippocastanum (Common Horsechestnut) Full/end End Full Full/End Full Full/End End Full
Enkianthus campanulatus (Redvein Enkianthus) Full Full Full End * End End Full
Rhododendron carolinianum (Carolina Rhododendron) Full/End Full Full * Full * Full *
Elaeagnus umbellata (Autumn-olive) Full End Full/ End End Full/ End End End Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General conditions: This reporting period saw mostly sunny and warm weather. Bright skies and temperatures in the 70s made for a mostly delightful Memorial Day weekend. However, a backdoor cool front came through on Sunday evening and the remnants of Tropical Storm Bonnie came through on Memorial Day, bringing cooler temperatures with high humidity but not all that much in the way of needed rainfall. In Marstons Mills, precipitation only measured 0.46” on Monday, with another 0.06” accumulations on Tuesday morning. Soils are somewhat dry. Many spring perennials are in bloom. Both Bearded and Siberian Iris are in bloom, along with Bleeding Heart (Dicentra spectabile) and Fringed Bleeding Heart (Dicentra eximia). Doublefile viburnum (V. plicatum tomentosum), Seibold viburnum (V. seiboldii), and Cranberrybush viburnum (V. trilobum) are in bloom. Kousa dogwood bracts are beginning to expand.

Pests/Problems: Winter moth caterpillars are beginning to pupate and feeding, for the most part, is over (894 Growing Degree Days, base 40). Scattered pockets of defoliation are present on the Cape but overall, this hasn’t been a huge year for defoliation. There are also scattered pockets of gypsy moth caterpillars which will continue to feed for another two to three weeks. Azalea sawfly larvae are feeding on the edges of deciduous azalea foliage. Boxwood psyllids are active on boxwood. Rose slug sawfly is getting larger and damage is quite visible. Leafhoppers and aphids are active on a variety of shrubs and perennials. Holly leafminer is still in the pupal stage within the mines on last year’s leaves of American holly (Ilex opaca) but will be emerging soon. Monitor adult emergence with yellow sticky cards. June beetle adults are flying at night, crashing into screens of windows near lights. Lily leaf beetle adults and larvae are actively feeding on true lilies.

Mosquitoes are active! Deer tick nymphs are active.

Azalea gall can be seen on azaleas. Prune out before it begins to sporulate.

Southeast Region (Hanson)

General Conditions: The warm weather (mid-80’s) from Wed. May 25th - May 28th certainly accelerated plant growth, however with the extremely dry soils, it also stressed unirrigated landscape plants and plants that had just started to flower were wilting. Relief from the heat came on Sunday, May 29 when temperatures dropped to the 50’s -60’s followed by rain on May 30th. Hanson received 1.5 inches of much-needed rain. The following plants are in full bloom:

Styrax obassia, Rutgers hybrid dogwoods (Stellar series), Prunus serotina (black cherry), Aesculus x carnea (Red Horsechestnut), Liriodendron tulipifera (Tuliptree), Cornus kousa, Cornus controversa, Cornus alternifolia, Laburnum watereri (Goldenchain Tree),Wisteria floribunda (Japanese Wisteria), Robinia hispida, Calycanthus floridus (Carolina allspice), Kerria, Weigela florida, Aristolochia durior (Dutchman's pipe), numerous viburnums (including Viburnum opulus, V. plicatum var. tomentosum (Doublefile viburnum), V. sargentii), Beautybush, Indigofera sp., Abelia mosanensis, Chionanthus virginicus, Cytisus scoparius (Scottish broom), Rhododendron, late lilacs like Syringa x prestoniae ‘James Macfarlane’ and Syringa ‘Miss Kim’, Clematis, Paeonia (Peony), Allium, Salvia ‘May Night’, Baptisia australis and Baptisia hybrids, Tradescantia , Anemone canadensis, Amsonia sp., Thalictrum aquilegifolium, Oriental poppies, Lupine, Columbine, Geranium sp., Buglossoides purpurocaerulea, Doronicum sp., Lamiastrum galeobdolon, Lamium, Dianthus sp., Dicentra spectabilis (Bleeding heart), Saruma henryi, Arisaema (Jack-in-the-pulpit), Cypripedium sp.,(Lady’s Slipper), Polygonum bistorta ‘Superbum’, Corydalis lutea, Siberian Iris, bearded iris, Phlox subulata, Phlox divaricata, Phlox stolonifera, Valeriana officinalis, Myosotis sylvatica and Centaurea montana.

Cotinus obovatus and Cotinus coggyria are also in full bloom with their small, rather insignificant flowers, to be followed by the interesting ‘smoke’ they produce following full bloom. Multiflora rose has started to bloom and Oriental bittersweet and burning bush are in full bloom. Now is a good time to remove these Massachusetts invasive plants along with barberry and autumn olive which just completed bloom. The yellow pollen of eastern white pines has been steadily falling, filling the air and covering everything in sight.

Pests/Problems: According to staff at UMass Entomologist Dr. Elkinton’s lab, winter moth caterpillars are just about done feeding for the season and have pupated, except for a few spots on the north shore. Scouting here in Plymouth County, I did not find one winter moth caterpillar. Foliar damage is present, yet sporadic, but by no means as extensive as in previous years. The early winter moth egg hatch April 1, followed by the freezing snow and then the extended winter moth egg over several weeks, combined with delayed foliar emergence, may have played a part in reducing the number of caterpillars. The upper canopies of some trees are thin but overall most trees look good. However, gypsy moth caterpillars may become problematic and cause further damage, especially in those areas where they were in high densities last year. There are many gypsy moth caterpillars in the landscape and most are in 3rd instar and a few in 2nd and 4th instars. They will continue to feed for a few more weeks and the bigger they get the more they eat, so monitor now and manage if needed. Gypsy moth caterpillars were found in high numbers on oak and were also in lower numbers on maples, blueberry, Fothergilla, etc. At this time they are mostly found feeding on the underside of the leaf. Cottony camellia scale (also known as Cottony Taxus Scale) is active on Taxus and Meserve hollies; monitor and manage as needed. We should soon, if not already, be seeing the emergence of the White-spotted pine sawyer, a native beetle that does not damage trees like the ALB. The White-spotted pine sawyer is often confused with the Asian Longhorned Beetle (ALB) but is merely one of the “ALB look-alikes”. http://massnrc.org/pests/albdocs/ALBLookalikes_Massachusetts.pdf

The small white maggot of the Orthacheta Bud Fly, sometimes referred to as the Iris bud fly, has been found in the developing buds and flowers of Siberian iris, Iris pseudacorus and bearded Iris. The maggots feed in the developing buds, and the emerging flowers are tattered and look terrible. The maggots will go down into base of the flower then into the stem. Not much can be done to prevent this pest, but removing and destroying the newly damaged flowers and stems, may help manage it. Lily leaf beetle adults, as well as the red eggs and disgusting, feces-covered larvae, are active on true lilies. If not managed, the beetles and larvae will destroy the lilies. Roseslug sawfly is still active and will skeletonize rose plant foliage if not managed. Azalea sawfly is almost done feeding for the year; not as much damage to plants at the Hanson site, as in previous years. Euonymus caterpillars (cream colored with black spots) remain active, feeding on the new foliage of euonymus and expanding their webs as they feed.

Mosquitoes are numerous this year; empty containers of water to help prevent breeding and consider using Bti (Bacillus thuringiensis israelensis) in birdbaths, plant saucers, etc.

The following insects remain active: elongate hemlock scale, hemlock woolly adelgid, spider mites, spittlebugs, aphids, deer tick nymphs, dog ticks, biting flies, carpenter ants, azalea whitefly, snails, woolly beech aphid, ants, wasps, hornets, carpenter bees, and bumblebees.

Monitor the foliage of ‘Arnold Promise’ witchhazel for Phyllosticta hamamelidis (Witchhazel blight); look for irregular shaped brown splotches. http://extension.illinois.edu/hortanswers/detailproblem.cfm?PathogenID=54

Several people have observed that numerous Eastern white pines are turning brown and these pines are not near roadways where roadway salt may be a factor. (See Nick Brazee’s Disease Section of the Landscape Message).

The shiny green Azalea leaf gall (Exobasidium vaccinii) continues to show up on deciduous azaleas; hand-pick and destroy the galls before they turn white. The following weeds are in bloom: ground ivy, oxeye daisy, cinquefoil, narrowleaf plantain, buttercups and veronica. Wild turkeys, chipmunks and rabbits are numerous in the landscape.

North Shore Region (Beverly)

General Conditions: The weather during this reporting period was very comfortable for outdoor work except on Saturday May 28 when the temperature rose up to 90 degrees Fahrenheit. Most of the other days the day temperatures were in mid to high 70s with sunny or partially cloudy weather. We also had comfortable sleeping weather with night temperatures in the mid to high 50s on most nights. Approximately 0.61 inches of rain was recorded at Long Hill during this reporting period. The month of May was unusually dry this year with less than 2 inches of rainfall recorded at Long Hill. We gained 116 growing degree days during this reporting period. Woody plants seen in bloom include: Horse Chestnut (Aesculus hippocastanum), Sapphireberry (Symplocos paniculata), Large leaf dogwood (Cornus macrophylla), Fragrant snowbell tree (Styrax obassia), Chinese Neillia (Neillia sinensis), Sweet bells (Leucothoe racemosa), Slender Deutzia (Deutzia gracilis), Fringe tree (Chionanthus virginicus), American cranberrybush viburnum (Viburnum trilobum), Doublefile viburnum (Viburnum plicatum var. tomentosum), Constellation Rutgers dogwood (Cornus x rutgersensis), Unique azalea (Rhododendron ‘Unique’), Tree peony (Paeonia suffruticosa), Hardy orange (Poncirus trifoliata),Umbrella tree (Magnolia tripetala), Redvein enkianthus (Enkianthus campanulatus), Vanhoutte spirea (Spirea vanhouttei), Little leaf lilac (Syringa microphylla), Mock orange (Philadelphus spp.), Beautybush (Kolkwitzia amabilis), Japanese wisteria (Wisteria floribunda), Toucan Azalea (Rhododendron “toucan”) Kyushu Azalea (Rhododendron kusianum), Flame azalea (Rhododendron calendulaceum), Nova Zembla Rhododendron (Rhododendron ‘Nova Zembla’, and Carolina Rhododendron (Rhododendron carolinianum). Non-woody plants seen in bloom include: Fetterbush (Leucothoe fontanesiana), Scotch rose (Rosa spinosissima), Peony (Paeonia sp.), Cranesbill (Geranium sp.), Bleeding heart (Dicentra spectabilis) and several annuals.

Pests/Problems: Woolly beech aphid (Phyllaphis fagi) was observed on European beech (Fagus sylvatica). Also observed were Azalea bark scale (Eriococcus azaleae) on Pieris (Pieris japonica). Winter moth caterpillars continue to enlarge and they continue to cause damage on several trees such as maples, crabapples and apples. Cedar quince rust (Gymnosporangium clavipes) was observed on twigs of Eastern red cedar trees (Juniperus virginiana). Galls of azalea leaf and flower gall (Exobasidium vaccinii) continue to be observed on some azaleas. . Viburnum leaf beetles continue to enlarge and to continue to cause serious damage on viburnums. They were observed skeletonizing leaves of American cranberrybush viburnum and Arrowwood viburnum. Doublefile viburnum doesn’t seem to be affected by the viburnum leaf beetle. Eastern tent caterpillars were also observed causing damage on crabapples and apple trees. Mosquitoes are very active. Protect yourself with a repellent when working outdoors. Ticks are also very active.

East Region (Boston)

General Conditions: Temperatures have been all over the place this week, Memorial Day weekend started off with sizzling conditions reaching 95° F on the 28th before dropping 20 degrees, returning to the mid 70’s on the 29th and 30th. Highs fluctuated between 75° F and 95° F while lows ranged from 53° F to 69° F. We received 1.35 inches of much needed steady precipitation during the early hours and into the morning of the 30th. For the month of May, high temperatures averaged 67.8° F and lows averaged 48.9° F; we received a total of 3.09 inches of precipitation. Plants in bloom include: Ajuga reptans (bugleweed), Catalpa bungei (Manchurian catalpa), Catalpa fargesii (Farges catalpa), Chionanthus virginicus (white fringetree), Cornus kousa (Rutgers hybrid dogwood), Cotinus obovatus (American smoke tree), Iris versicolor (blue flag), Kerria japonica (Japanese kerria), Leucanthemum vulgare (oxeye daisy), Liriodendron tulipifera (tulip tree), Lonicera sempirvirens (trumpet honeysuckle), Lupinus sp. (blue lupine), Paeonia suffruticosa (tree peony), Philadelphus coronarius (sweet mock orange), Philadelphus inodorus (scentless mock orange), Potentilla fruticosa (bush cinquefoil), Rhododendron spp. (Ghent hybrid azaleas), cultivars of Rhododendron spp. (rhododendron), species roses including R. rugosa (beach rose), R. villosa (apple rose), and R. woodsii (Woods' rose), Symplocos paniculata (Asiatic sweetleaf), Viburnum plicatum ‘Mary Milton’ (Japanese snowball bush), and Zabelia biflora (zabelia).

Pests/Problems: Swallowwort (Cynanchum ssp.) are popping up and quickly growing. Invasive plants in flower include: Iris pseudacorus (yellow flag), Lonicera maackii (Amur Honeysuckle), Lonicera tatarica (Tatarian honeysuckle), and Phellodendron amurense (Amur corktree). Poison ivy (Toxicodendron radicans) is leafing out and is visible in wooded areas. Aphids can be found throughout the landscape, especially on the buds of rose bushes. Early instars of Eastern tent caterpillars (Malacosoma americanum) are active. Pine sawfly is active as the adults are readily feeding on the needles of pines. Lacebug damage is visible on Pieris sp. (fetterbush) planted in sunny locations. Azalea apple gall (Exobasidium vaccinii) is growing, becoming larger and more visible. Leaf galls of all sorts are visible on many trees.

Metro West (Acton)

General Conditions: Nothing like kicking off the Memorial Holiday weekend with summer like temperatures! A high of 93° was recorded on Saturday the 28th followed by more seasonable temperatures in the 70’s. The holiday weekend also brought some much-needed rain but not enough. Despite the eight consecutive days of rain that we experienced at the beginning of the month, the average monthly precipitation total for May is 4.04" and only 2.25” of rain was recorded this year for the entire month. Woody plants seen in bloom this past week are Aesculus hippocastanum (Horsechestnut), Cladrastis kentukea (Yellowwood), Cornus kousa (Kousa Dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers Hybrid Dogwood), Cornus sericea (Redosier Dogwood), Cotinus coggygria (Common Smokebush), Kalmia latifolia (Mountain Laurel), Kerria japonica (Japanese Kerria), Kolkwitzia amabilis (Beautybush), Leucothoe axillaris (Coast Leucothoe), Liriodendron tulipifera (Tulip Tree), Philadelphus coronarius (Sweet Mock Orange), Potentilla fruiticosa (Potentilla), P. tridentata (Cinquefoil), Physocarpus opulifolius (Common Ninebark), P. opulifolius 'Summer Wine'(Summer Wine Ninebark), Prunus serotina (Black Cherry), Rhododendron spp. (Rhododendron and Azalea), Robinia pseudoacacia (Black Locust), Rosa rugosa (Rugosa Rose), Rubus spp. (Blackberry, Bramble, Raspberry), Spirea spp.(Spirea), Syringa spp. (mid-late blooming Lilac), Viburnum cassinoides (Witherod Viburnum), V. plicatum var. tomentosum (Doublefile Viburnum), V. sargentii (Sargent Viburnum), and Weigela florida (Old Fashioned Weigela). Woody vines in bloom are: Clematis spp. (Clematis) and Lonicera sempirvirens (Trumpet Honeysuckle). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Achillea millefolium (Yarrow), Actaea pachypoda (White Baneberry), Ajuga reptans (Bugleweed), Alchemilla mollis (Lady's Mantle), Allium giganteum (Giant Onion), A. schoenoprasum (Chives), Amsonia hubrichtii (Arkansas Blue Star), Aquilegia spp.(Columbine), A. vulgaris (Columbine), Arisaema triphyllum (Jack-in-the-Pulpit), Baptisia australis (False Blue Indigo), Centaurea montana (Cornflower), Chrysogonum virginianum (Green and Gold), Convallaria majalis (Lily of the Valley), Dianthus deltoides (Maiden Pink), Dicentra eximia (Fringed Bleeding Heart), D. spectabilis (Old Fashioned Bleeding Heart), D. spectabilis alba (White flowering Old Fashioned Bleeding Heart), Dictamnus albus (Gas Plant), Fragaria sp.(Strawberry), Gallium odorata (Sweet Woodruff), Geranium cantabrigiense 'Biokovo' and 'Cambridge'(Hardy Cranesbill), G. maculatum (Wild Geranium), G. macrorrhizum (Bigroot Geranium), G. sanguineum (Cranesbill Geranium), Heuchera spp.(Coral Bells), Hyacinthoides hispanica (Wood Hyacinth), Iris germanica (Bearded Iris), I. sibirica (Siberian Iris), Lunaria annua (Money Plant), Lupinus 'Russell Woodfield Hybrids' (Lupine), Maianthemum dilatatum (False Lily of the Valley), Myosotis sylvatica (Forget-me-not), Nepeta spp. (Ornamental Catmint), Paeonia spp. (Peony), Papaver orientale (Poppy), Phlox divaricata (Canadian Phlox), P. stolonifera (Creeping Phlox), P. x subulata (Moss Phlox), Podophyllum peltatum (Mayapple), Polemonium reptans (Jacob’s Ladder), Polygonatum commutatum (Great Solomon's Seal), P. odoratum 'Variegatum' (Variegated Solomon's Seal), Primula spp. (Primrose), Salvia nemerosa (Salvia), Saponaria ocymoides (Rock Soapwort), Stylophorum diphyllum (Wood Poppy), Thymus praecox (Thyme), Tiarella cordifolia (Foam Flower), Tradescantia sp. (Spiderwort), Veronica repens (Speedwell), V. umbrosa 'Georgia Blue' (Speedwell), Vinca minor (Periwinkle), Viola spp. (Violet), and Zizia aptera (Heart-Leaved Alexander).

Pests/Problems: Lack of significant rainfall is a concern, particularly this early in the growing season. Many weeds are in flower or are just passing including some of the most invasive ones such as Alliaria petiolata (Garlic Mustard), Celastrus orbiculatus (Oriental Bittersweet), Elaeagnus umbellata (Autumn-olive), Euonymous alatus (Burning Bush), Lonicera maackii (Amur Honeysuckle), and Rhamnus cathartica (Common Buckthorn).

Central Region (Boylston)

General Conditions: Warm sunny weather was the norm for most of this reporting period, though hot, steamy weather made for uncomfortable conditions on Saturday, May 28th when temperatures soared into the 90’s. The remainder of the weekend was cooler, with wet weather on Memorial Day. A mere 0.26” of rain fell for this rain event, leaving soils dry beneath the surface. Rhododendrons, Azaleas, Manchurian Lilacs, Doublefile Viburnum (V. plicatum var. tomentosum) and many early perennials like Lemon Lily (Hemerocallis lilioasphodelus), Bearded Iris, Iceland Poppies, Woodland Phlox, Columbine, early Peonies, Salvia, Pinks (Dianthus cvs.), Wild Geranium (G. maculatum), Bigroot Geranium (G. macrorrhizum) are colorful now.

Pests/Problems: Brilliant red Lily leaf beetles are active, many Gypsy Moth caterpillars have been spotted on oaks in particular, leafminers have been abundant on Swiss Chard. Deer, rabbits and woodchucks are helping themselves to the tender growth of plants, and chipmunks are particularly abundant this year.

Pioneer Valley Region (Amherst)

General Conditions: Mid-summer heat ruled this past reporting period in the Pioneer Valley as unseasonably warm temperatures settled into the region over the Memorial Day weekend. A high temperature of 91° F was recorded on Saturday 5/28 at Barnes Airport in Westfield, making conditions feel more like mid-July than late May. We ended the month of May with below-average precipitation. Across the valley, precipitation averaged 2.47″, with a range of 1.26″ (Northampton) to 4.00″ (Ashfield). As is typical, Franklin County received more rain than Hampshire and Hampden Counties with the exception of the eastern foothills of the Berkshires. The steady rainfall on Sunday 5/30 was welcome but the remnants of tropical storm Bonnie was mostly a disappointment given what was predicted. The original forecast called for >1″ of rain on Memorial Day, which would have represented the much needed soaking we have lacked this growing season. However, as the storm approached forecasted accumulations were cut in half. Western Franklin and Hampshire Counties fared well, receiving >0.75″ but the final tally in Amherst–Northampton was a measly 0.25″. The Springfield area did slightly better with accumulations around 0.4″. The rain cleared out by mid-morning and lawns and mulch beds were already dry by the afternoon. The heat and subsequent increase in soil temperatures resulted in an explosion of growth for turfgrass and lawn weeds. Clover, crabgrass, nutsedge, cinquefoil and other lawn weeds are lush and growing vigorously. Clover flowers are a good source of pollen for bees so consider delaying your mowing schedule, if at all possible, to allow bees to utilize this food source. Baldfaced hornet queens and other wasps are now actively building nests. These grey-colored, papery, cone-shaped nests are often created on interior branches of shrubs and small trees. Scout for these nests and remove them (safely) around patios, decks and swing sets to avoid a troublesome population as the season progresses. A sting from the baldfaced hornet is described by University of Arizona entomologist Justin Schmidt as: “Rich, hearty, slightly crunchy. Similar to getting your hand mashed in a revolving door.” The Schmidt Sting Pain Index is a great read for those who have suffered the stings of various landscape insects.

Pests/Problems: Lack of significant rainfall will become a problem soon if temperatures remain in the 80s and we fail to receive any soaking rainfall. Soils are still fairly moist overall but are drying at the surface. Patches of dead turfgrass and weeds have been observed on south-facing slopes with well-drained soils. Continue to irrigate recently transplanted trees and shrubs as drought is one of the primary predisposing stresses that weaken a plant's ability to defend against pests and pathogens. Rose slug sawfly larvae continue to enlarge and feed on roses. Infestations result in browning of the foliage, mostly on interior sections of the leaves. Various types of small caterpillars have been observed on oak, chewing succulent leaves. Thankfully we don’t have to deal with the winter moth epidemic in the Pioneer Valley but there are scattered pockets of gypsy moth populations. Forest tent caterpillar is actively feeding so scout for damage on deciduous hardwoods like sugar maple. Aphids are abundant on a number of landscape trees, shrubs and herbaceous plants. This issue has been reported throughout the region. Woolly aphids have been spotted on conifers such as larch and fir and severe infestations on nursery grown green ash and viburnum have also been observed. Black spot of rose is developing and is quite conspicuous on susceptible cultivars. Stem cankering pathogens like Phomopsis, Botryosphaeria and Fusarium are growing and sporulating whenever conditions allow (mild and wet). Prune and discard dead stems and branches, especially on trees with dense canopies and thick bark, like kousa dogwood and Japanese maple.

Berkshire Region (Great Barrington)

General Conditions: What a difference a week makes. Plant growth – and pest appearance – exploded with record-setting heat over the weekend. Temperatures on Saturday, May 28, reached 92° F at 2 PM as recorded at this monitoring station in Great Barrington. With that kind of heat, coupled with high humidity, thunderstorms are common. However, these storms can be very local, not to mention violent at times. Such an event occurred on the following day, i.e. May 29. A thunderstorm dumped almost 5 inches of rain in parts of the towns of Stockbridge and Lee, and caused considerable street flooding and washed out driveways. High winds accompanying the storm brought down some trees and many large branches. Interestingly, just a few miles to the south in Great Barrington and a few miles to the west in West Stockbridge, either no rain or just a trace was measured. At least for the two affected towns, the rainfall wiped out the rainfall deficit for the year. A rainfall deficit of 4 to 5 inches remains in the rest of the area. On May 30, rain did fall on a much wider scale and 0.77 inches was recorded in Great Barrington. Still, soils are quite dry and crops, gardens, and landscapes are in need of irrigation. Many azaleas and lilacs are still in bloom.

Pests/Problems: Pest activity accelerated during the week. Aphids and leafhoppers are more prominent and feeding on a wide variety of woody and herbaceous plant material. Azalea sawfly larvae are feeding on the leaf margins and inward, leaving only midribs of the leaves of azaleas. The eggs of the imported willow leaf beetle which was observed last week have since hatched and the larvae are feeding on the surfaces of willow leaves, leaving the leaves skeletonized. Viburnum leaf beetle larvae, spruce spider mites, boxwood psyllids, wooly beech aphid, and four-lined plant bug remain active. Boxwood leaf miners are mostly in the adult stage at this time and are laying eggs in new leaves of boxwood. Mottled tortoise beetle adults were found feeding on leaves of tomatoes but these beetles are also known to feed on morning glories. The heat and humidity has brought about an upsurge in mosquito population. Ticks, wasps, carpenter bees, millipedes, and pill bugs are plentiful. Leaf galls of various sorts are prominent on tree foliage, notably maples and poplars. They are mainly curiosities and cause no economic damage to the plants. Ladybugs and predatory mites are common and should help reduce numbers of certain pests. Spots of apple scab and cedar-apple rust are expanding on the foliage of crabapples. Powdery mildew has covered the leaves of certain eastern ninebark (Physocarpus opulifolius). Coppertina ninebark (Physocarpus opulifolius ‘Mindia’) is particularly susceptible to powdery mildew, an observation consistent with results of studies at the University of Connecticut. With the prominence of limestone bedrock here in the Berkshires, soil pH is routinely at or above pH 7. For this reason, ericaceous species, e.g. rhododendrons, can frequently be seen to be suffering from iron chlorosis (yellowing of plant leaves caused by iron deficiency, usually in high pH soils). This is also true in other regions for ericaceous plants growing near concrete foundations and walkways. Applications of soil acidifying materials i.e. elemental sulfur and/or ferrous sulfate may help alleviate the problem.

Regional Scouting Credits

  • CAPE COD REGION - Roberta Clark, UMass Extension Horticulturist for Barnstable County - Retired, reporting from Barnstable.
  • SOUTHEAST REGION - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, reporting from Hanson.
  • NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
  • EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.
  • METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
  • CENTRAL REGION  -  Joann Vieira, Superintendent of Horticulture, reporting from the Tower Hill Botanic Garden, Boylston.
  • PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
  • BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals

Diseases

A special report from the UMass Extension Plant Diagnostic Lab on needle browing and canopy dieback of Eastern white pine this spring:

Dramatic needle browning and canopy dieback of eastern white pine (Pinus strobus) in southern New England

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

Insects

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

  • Winter Moth: The Elkinton Lab is reporting that winter moth caterpillar activity is near its end in most areas. Pupation is nearly complete, with the exception of some locations on the North Shore. The window to make chemical treatments for this insect is closed when all caterpillars are pupating, as that stage occurs while protected in the soil. For further localized information, see the Cape Cod, Southeast, and North Shore Region reports.
  • Gypsy Moth: Caterpillars are actively feeding. In areas of the state where multitudes of egg masses have been seen, such as towns around the Quabbin Reservoir and points further east, Bacillus thuringiensis Kurstaki can be used on small caterpillars. However, gypsy moth larvae are rapidly becoming larger and will soon be conducting some of their more damaging feeding and will be more difficult to manage with chemical options as caterpillars enlarge and become more robust.
  • Andromeda Lacebug: Stephanitis takeyaiwill be active soon on Japanese Andromeda in areas above 250 GDD’s. Overwintering eggs buried in the underside of leaves will hatch and nymphs will begin to feed. Inspect plants known to have S. takeyai in the past (or exhibiting yellow stippling on the upper leaf surface) and inspect undersides of leaves for this season’s lacebugs. Before populations become too large, treat with a summer rate horticultural oil spray as needed.
  • Azalea Sawfly: Amauronematus azalae is active on deciduous azaleas. Continue to monitor for the feeding damage of this caterpillar. This insect can completely defoliate the plant if present in large numbers. Spinosad based products are effective on this hymenopteran pest, while Bacillus thuringiensis Kurstaki is not.
  • Birch Leafminer: Fenusa pusilla is active at this time. The adult female sawfly wasps are small and dark and can be observed visually on host plant foliage. Eggs are laid within leaves. The use of yellow-sticky cards (1 per tree) works well for monitoring for this pest. Once the adult sawflies have emerged, the tree can then be treated with a chemical insecticide, such as a pyrethroid, to prevent egg-laying within the foliage. Bacillus thuringiensis Kurstaki is not effective against sawflies.
  • Black Vine Weevil: Otiorhynchus sulcatus damage is apparent on rhododendron and taxus, but can also be seen on azalea, mountain laurel, and Euonymus. Adult weevils feed along the leaf/needle margins and create rounded notches. Inspect foliage of these plants for notching from last season’s feeding. Adults will begin to emerge soon 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, now through August, can be inspected weekly for adult weevils which can be killed before egg laying.
  • Boxwood Psyllid: Psylla buxi will be feeding on newly emerged boxwood foliage with its piercing-sucking mouthparts. This feeding may not cause yellowing or loss of foliage, but will lead to the cupping of new leaves which can be an aesthetic issue for some. If population numbers are low, management of this pest may not be necessary.
  • Eastern Tent Caterpillar: Eastern tent caterpillar larvae are active at this time and growing ever larger. Pupation will begin soon and last for few weeks. Forest Tent Caterpillars are active and also growing rather large. These caterpillars do not make tents likes those of the eastern tent caterpillar, but rather web foliage together. Caterpillars are hairy, with blue lines and white, key-hole shaped spots down the center of their dorsal side, distinguishing them from eastern tent caterpillars where a white line is present dorsally.
  • 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: 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). Adults will be emerging soon. 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 .
  • Euonymus Caterpillar: Yponomeuta cagnagella is currently active. These small yellow caterpillars with black spots feed throughout the host plant and are capable of creating vast amounts of unsightly silk while feeding on the leaves. By early summer, entire viburnum can be covered with silk and leafless. Inspect for the presence of this pest and treat with a product that contains Spinosad if deemed necessary. Handpick and destroy if caterpillars are small in number.
  • European Pine Sawfly: Neodiprion sertifer caterpillar is active. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine, but is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned away and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding and still small. Bacillus thuringiensis Kurstaki is not effective against sawflies.
  • Fall/Spring Cankerworm: These two species of geometrid moth caterpillars have hatched. Both species may be found feeding together on hosts such as oak, cherry, elm, apple, and maple. Initial feeding may cause foliage to become tattered in appearance. Caterpillars will be present until approximately the end of this month. Fall cankerworm caterpillars look quite similar to winter moth caterpillars, however winter moth has 2 pairs of prolegs whereas fall cankerworm has 2 full pairs of prolegs and a 3rd, half-sized pair. Spring cankerworm has 2 pairs of prolegs but may have darker caterpillars than winter moth (otherwise, they can be very difficult to differentiate in the field). Young cankerworm larvae can be managed with horticultural oils applied to the trunk and branches of hosts when deemed necessary.
  • Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will be hatching soon. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary.
  • Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. Infested trees may be treated with a summer rate horticultural oil spray as weather conditions allow. Be cautious when pruning or removing infested hemlocks as to avoid accidentally transporting eggs and nymphs that are present at this time.
  • Imported Willow Leaf Beetle: Plagiodera versicolora overwintered adults are present and active at this time and will chew holes and notches in the leaves of willow. Egg laying will finish shortly and larvae are already hatching. These immatures are slug-like and bluish-green in color. They will feed in clusters and skeletonize the leaves. Most plants can tolerate the feeding from this insect, and foliage will appear brown. Repeated yearly feeding can be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water.
  • Lily Leaf Beetle: Continue to monitor for Lilioceris lilii. Management can be achieved by hand-picking and removing adults and larvae. Bright red adults are seen mating on host plants and females are laying their reddish-orange eggs in lines on the undersides of leaves. Some chemical management options are available for this insect, but if caught early mechanical management may be effective. Pyrethroids can be used against adult beetles, whereas spinosad products are most effective against the larvae.
  • Nantucket Pine Tip Moth: Rhyacionia frustrana larvae feed in the buds, shoots, and base of needles of pitch, Scotch, mugo, and black pines in Massachusetts. The insect overwinters as a pupa in the damaged shoots. Adults will emerge in areas over 121 GDD’s, base 50°F. Many parasites, predatory insects, and birds will attack this pest. If chemical management options are deemed necessary, target the young larvae of this insect, which can be found hatching from eggs laid by this spring’s adults 5-10 days after peak adult emergence.
  • Roseslugs: Two species of sawfly can be found on the leaves of roses at this time. These small, caterpillar-like 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.
  • Viburnum Leaf Beetle: Pyrrhalta virburni: Inspect newly emerging foliage for spotting caused by the feeding of tiny, pale-yellow and green colored larvae skeletonizing the leaves. Larvae may be treated with a product containing spinosad if found. Larvae are actively feeding at this time. This pest has the potential of completely defoliating the host within 4-5 weeks of larval feeding. Planting species of viburnum that are most resistant to the viburnum leaf beetle can help solve this issue. Resistant varieties include V. bodnantense (dawn viburnum), V. carlesii (Koreanspice viburnum), V. davidii (David viburnum), V. sieboldii (Siebold viburnum), and others. Highly susceptible species of viburnum frequently attacked by this beetle can include V. dentatum (arrowwood viburnums), V. opulus (European cranberrybush viburnum), and V. rafinesquianum (Rafinesque viburnum).
  • White Spotted Pine Sawyer (WSPS): Adults are emerging and will do so throughout July, depending on local temperatures. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers, however the difference in the color of the scutellum is a key characteristic. The regulated area for Asian longhorned beetle is 110 miles2 encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn. If you believe you have captured an Asian longhorned beetle (particularly beginning in July and August) or have seen damage caused by this insect, such as exit holes, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938. To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: http://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report.

Concerned that you may have found an invasive insect or suspicious damage caused by one? Need to report a pest sighting? If so, please visit the Massachusetts Introduced Pests Outreach Project: http://massnrc.org/pests/pestreports.htm.

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

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

Management Practices

Plant of the Week: Chionanthus virginicus

Chionanthus virginicus is a large shrub to small tree growing 12-20’ tall and wide. Plants do not leaf out until mid-May. Leaves are medium to dark green in the summer and yellow to golden in the fall. Plants are dioecious meaning that there are male and female plants, both of which have flowers but the male flowers are usually showier due to longer petals. Flowers are slightly fragrant and emerge in mid-May to early June as leaves have almost finished expanding. Very showy in bloom, flowers are on the previous year’s wood. Petals are very fine and fleecy leading to the common names of white fringetree and Grancy gray-beard. The fruit is a deep blue egg-shaped drupe that is effective in August-September. Chionanthus virginicus prefers full to part shade and a moist, fertile, acid soil, but is adaptable. C. virginicus is native to the United States with its native range running from the mid-Atlantic to Florida.

Chionanthus virginicus    Chionanthus virginicus    Chionanthus virginicus

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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