Landscape Message: June 30, 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:

Scouting Information by Region

Environmental Data

The following data was collected on or about June 28. 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.

Drought Conditions Update: Nearly all of Massachusetts (98%) is not under official drought status at this time.  For more information see http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?MA

Phenology

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature from June 21 - June 28 was 70° F with a high of 85° F on June 24 and a low of 53° on June 28. Overall temperatures have been primarily in the 70s with a good amount of sun and relatively high humidity but far less than the previous week. Only 0.32 inches of precipitation was recorded in Barnstable which occurred on June 24. Other locations on the Cape received a little bit more with up to about 0.75 inches. Topsoil moisture is short, subsoil moisture is adequate.

Pests/Problems: The primary insect news for the past week is the massive die off of gypsy moth that began being seen on June 21 and 22 on the Cape. Really an amazing sight to see the thousands of caterpillars per tree dead on the lower trunk in many locations the lower 10 feet on white oaks were completely covered. This is great news ending the several year buildup in gypsy moth populations. It will be interesting to see if there is much survival. However, before the mass die off considerable defoliation did occur in many parts of the Cape and the health of these trees is still a concern. Oriental and asiatic beetles have begun emerging and have been seen in minimal numbers. Other insects seen over the past week include elongate hemlock scale on hemlock, chilli thrips on hydrangea, andromeda lacebug on japanese andromeda, turpentine beetle on pitch pine, boxwood mite on boxwood, honeylocust plant bug on honeylocust, lilly leaf beetle on lily, plant hoppers on several species, earwigs and slugs also remain abundant. Mosquitos, deer flies, dog ticks are all active. Rabbits are abundant. Sycamores are still recovering from heavy anthracnose damage and still have not completely leafed out. Maple anthracnose and dogwood anthracnose are also being seen. Powdery mildews are starting to be seen on phlox and beebalm. Weeds in bloom include; black medic (Medicago lupulina), black swallow-wort (Cynanchum louiseae), white clover (Trifolium repens), purple clover (Trifolium pratense), rabbitfoot clover (Trifolium arvense), sulfur cinquefoil (Potentilla recta), hawkweed (Hieracium pratense), red sorrel (Rumex acetosella), curly dock (Rumex crispus), goutweed (Aegopodium podagraria), yellow woodsorrel (Oxalis stricta), purslane (Portulaca oleracea), and plantain (Plantago lanceolata).

Southeast Region (Hanson)

General Conditions: Terrific summer weather continued this past week and Hanson received 0.75 inches of rain. Soils are beginning to dry out, so continue to remind clients to water newly planted or transplanted plants and those plants defoliated by caterpillars.

The following plants are in bloom: Northern Catalpa, Stewartia pseudocamellia, Stewartia rostrata, Sinocalycanthus chinensis, Cornus kousa, Magnolia virginiana (Sweetbay magnolia), Hypericum androsaemum ‘Mrs. Gladys Brabazon’,Weston hybrid azaleas, Hydrangea anomala petiolaris, Itea virginica, Spiraea sp., Rhododendron maximum, Kalmia, Calycanthus floridus (Common Sweetshrub), Indigofera sp., landscape roses, Rosa rugosa, Clematis sp., Lonicera sempervirens, Lonicera ‘John Clayton’, Thermopsis, Lysimachia punctata, Aruncus dioicus, early daylilies, Alchemilla mollis, Salvia sp., Geranium sp., Astilbe, Asclepias syriaca (common milkweed), Campanula sp., Anemone canadensis, Persicaria polymorpha, Lamium, Allium, Nepeta sp., Dianthus sp., Tradescantia, Corydalis lutea, and Foxgloves. Baptisia ‘Cherries Jubilee’ is pushing out a second bloom…. nice. Hydrangea quercifolia is beginning bloom.

Rhus typhina (Staghorn sumac) has ended flowering and is producing its’ showy, red fruiting clusters. Cotinus obovatus (American Smoketree) and Cotinus coggygria (European Smokebush) continue to display their colorful “smoke”. Although mentioned last week, it is worth mentioning again in case clients are asking why their “blue hydrangeas” are not blooming: this is the third year in a row, in many areas, that the overwintering stems of most Hydrangea macrophylla were winter-killed and or bud-killed. Clients who are looking for hardier hydrangea macrophylla, may want to check out the more cold-hardyhybrids like Hydrangea macrophylla ‘Blue Billow’ or H. ‘Lady-in-red’ or the remontant, or repeat-blooming, Hydrangea macrophylla, which produce flowers on new wood. Weston hybrid azaleas not only produce great early-mid-summer color, but they are also fragrant! Summer annuals are looking great with all the recent heat.

Hanson is at 1,518 GDD - Growing Degree days, Base 40.

Pests/Problems: Gypsy moth caterpillars are about done for the season. There are still some large, mostly 6^th instar, females feeding but their numbers are dwindling and feeding should be done by July 1. Some caterpillars have started to pupate, but a great number are dying in masses and may be found hanging head-down on the bottom trunks of trees. Most of these dead caterpillars were killed by the Entomophaga maimaiga fungus. The fungus needs moisture to infect the caterpillars and luckily, this spring has been a very wet one. Some areas of Massachusetts show massive defoliation but in other areas, it is sporadic. Based on the number of gypsy moth eggs laid last June 2016, damage could have been considerably more severe in many more areas. At the site in Hanson, MA, several large oaks were defoliated this past week and when the oaks were stripped, the caterpillars defoliated the leaves of a large Katsura and two Rutgers hybrid dogwoods. I have never seen gypsy moth caterpillars defoliate Katsura or dogwood! Next, the gypsy moth caterpillars will soon pupate and moths will appear. The brown male moths fly and will mate with the larger whitish female moths, which do not fly, and she will produce the tan, fuzzy egg masses that will hatch next April 2018. (For a complete gypsy moth update, please see the Insect section of this Landscape Message).

The following insects remain active: Deer ticks, dog ticks, European chafer beetles; Asiatic garden beetles, lacebugs on Japanese Andromeda (Pieris japonica), Rhododendron and azaleas; White pine sawyer beetle (Asian longhorned beetle look-alike); Hemlock woolly adelgid; elongate hemlock scale; cottony camellia scale on Meserve hollies and Taxus; Fletcher scale on Taxus; Taxus mealybug, earwigs; planthoppers; leafhoppers; stink bugs; mosquitoes; aphids; four-lined plant bugs; lily leaf beetle (adults, larvae, eggs); slugs; snails; wasps. Damage to foliage from the four-lined plantbug is evident on a wide variety of plant material. Roseslug sawfly has finished for the season.

Beneficial insects remain active including large Ichneumon wasps. The wet spring provided good conditions for the caterpillar killing fungus, Entomophaga maimaiga, and it also produced moist conditions that enhanced foliar disease which continue to show up: sycamore anthracnose; maple anthracnose; dogwood anthracnose; blackspot on roses; apple scab on crabapples and apples;foliar leafspots and powdery mildew on dogwood; Phyllosticta hamamelidis (Witchhazel blight) on ‘Arnold Promise’ witchhazel; Monilinia (brown rot) on Kwanzan cherry. Remove the white, spore-coveredAzalea leaf galls (Exobasidium vaccinii) from deciduous Azaleas and place them in the trash.

The following weeds are in full bloom: Achillea, grasses, hawkweed, fleabane, oxeye daisy, and red and white clover. Oriental bittersweet seedlings are growing by leaps and bounds and now is a good time to pull them out and remove them, along with Multiflora rose, barberry, burning, and autumn olive.

Deer were observed browsing perennials (hosta, phlox, etc.) Consider using repellents, fencing, etc. to deter deer before too much damage occurs.

North Shore (Beverly)

General Conditions: Temperatures were more consistent this reporting period compared to the last several weeks. Day temperatures were in the low to mid 80s and night temperatures were in the 50s to low 60s. We accumulated 145 growing degrees days at Long Hill during this period bringing us to a total of 772 GDD since the beginning of the year. There were spotty quick rain storms in the area on some days during this reporting period, and approximately 0.55 inches of rain were recorded at Long Hill. Most the rainfall came on Tuesday June 27 with 0.41 inches recorded for the day. Turf on lawns is green and the landscapes are looking lush and fresh due the rains during this growing season.

Woody plants seen in bloom include: Japanese tree lilac (Syringa reticulata), Peking tree lilac (Syringa pekinensis), Stewartia (Stewartia rostrata), Privet (Ligustrum spp.), Kousa Dogwood (Cornus Kousa), Sweet azalea (Rhododendron arborescens), Virginia sweetspire (Itea virginica), Tall stewartia (Stewartia Monadelpha), Smooth Witherod (Viburnum nudum), Oakleaf Hydrangea (Hydrangea quercifolia), Climbing Hydrangea (Hydrangea anomala), Carolina allspice (Calycanthus floridus) and Mountain Laurel (Kalmia latifolia). Herbaceous plants in bloom include: Black eyed susan (Rudbeckia hirta), Milkweed (Asclepias syriaca), Virginia rose (Rosa virginiana), Spiderwort (Tradescantia spp.), Leopard’s bane (Doronicum spp.), meadowsweet (Filipendula ulmaria), Geranium (Pelargonium spp.), Aruncus (Aruncus dioicus), Allium (Allium sp.), Ox-eye daisy (Leucanthemum vulgare) and various annual plants.

Pests/Problems: Leaf blotch was observed on Peony. Leaf tip necrosis continues to be observed on a Japanese stewartia. Phyllosticta leaf blotch also continues to be observed on Witchhazel (Hamamelis intermedia). If you observe these in the landscape, consider sending a sample to the UMass Extension Plant Diagnostic Lab for correct diagnosis of the problem. Goutweed (Aegopodium podagraria), an invasive weed, is in full bloom and is flourishing in the landscape. Oriental bittersweet (Celastrus orbiculatus), another invasive plant, is also growing vigorously in the landscape. Learn how to identify poison ivy to prevent exposure as you walk in the woods. Many other weeds in the landscape continue to flourish. Take measures to control weeds before they set seed. Mosquitoes and ticks are still very active. Protect yourself with insect repellent when working outdoors especially at dawn and at dusk.

East Region (Boston)

General Conditions: Summer officially began on June 21^st. Temperatures have been seasonal with lows ranging from 55° F to 68° F, averaging 61° F and highs ranging from 77° F to 90° F, averaging 83° F. We received 157 GDDs over the past week for a total of 876.5 so far this year. Precipitation has been welcome throughout the month. This past week, we received a total of 0.41 inches over three rain events. A thunderstorm on the evening of the 27^th brought high winds and short heavy downpours, with minimal damage to the grounds. A cold front moved in following the storm, we experienced cool temperatures in the low 50’s on the morning of the 28^th. Summer flowering plants in bloom include: Asclepias syriaca (common milkweed), Calycanthus floridus (Carolina allspice), Cotinus coggygria (European smokebush), Cotinus obovatus (American smoketree), Diervilla lonicera (northern bush honeysuckle), Hemerocallis fulva (tawny daylily), Houttuynia cordata (chameleon plant), Hosta spp. (plantain lily), Hydrangea quercifolia (oakleaf hydrangea), Lavandula angustifolia (English lavender), Leucanthemum × superbum (Shasta daisy), Lysimachia punctata (yellow loosestrife), Magnolia grandiflora (southern magnolia), Magnolia grandiflora 'Bracken's Brown Beauty' (Bracken's Brown Beauty magnolia), Magnolia virginiana (sweetbay), Rubus x fraseri (thornless bramble), Scabiosa ‘Butterfly Blue' (pincushion flower), Sorbaria sorbifolia (false spiraea), Stewartia pseudocamellia (Japanese stewartia). The unusual shrub-vine Tripterygium wilfordii (thunder god vine) and the ericaceous Zenobia pulverulenta (honeycup) are in full bloom. The fruit of Morus alba (white mulberry) is ripe.

Pests/Problems: Recent precipitation and sunny conditions have been conducive to growth of unwanted vegetation. New weeds in bloom include Cichorium intybus (common chicory), Conium maculatum (poison hemlock), Erigeron annuus (daisy fleabane), Linaria vulgaris (butter-and-eggs toadflax), and Medicago lupulina (black medick). Portulaca oleracea (common purslane) has been putting on significant growth. The invasive Aegopodium podagraria (goutweed) is in full bloom. Cedar-apple rust spores are being released from fruit of the host plant Amelanchier spicata (dwarf serviceberry) while fruiting bodies are just beginning to develop on fruit of Amelanchier laevis (Allegheny serviceberry). Lace bugs and their damage are highly visible on azaleas (Rhododendron spp.) and andromeda (Pieris spp.). Guignardia leaf blotch (Guignardia aesculi) continues to cause browning of foliage on Aesculus spp. (horsechestnut). Adult lily leaf beetles (Lilioceris lilii) are actively feeding on true lilies (Lilium spp.). Mosquitos are prevalent around bodies of water. Ticks carrying Anaplasmosis have been found in the area.

Metro West (Acton)

General Conditions: The first week of summer brought with it a low temp of 53° on Thursday, a high temp of 91° on Friday, wind gusts of 18 mph on Saturday, and a downpour and hail on Tuesday afternoon. As with the past two months, the precipitation measured has exceeded the historical monthly average rainfall. For June, the average is 3.93” and 4.55” of rain has been recorded for this month so far and it’s not over yet! Woody plants seen in bloom this past week are Catalpa speciosa (Northern Catalpa), Hydrangea arborescens (Smooth Hydrangea), H. quercifolia (Oakleaf Hydrangea), Ilex glabra (Inkberry), I. pendunculosa (Longstalk Holly), Ligustrum spp. (Privet), Liriodendron tulipifera (Tulip Tree), Oxydendron arboreum (Sourwood),

Potentilla fruiticosa (Potentilla), Rhus typhina (Staghorn Sumac), Rosa rugosa (Rugosa Rose), R. 'Knockout' (The Knockout family of Roses), Rosa spp. (Rose), Sambucus canadensis (American Elderberry), Spirea japonica 'Alpina' (Daphne Spirea), Syringa reticulata (Japanese Tree Lilac), Stewartia psuedocamellia (Japanese Stewartia), Tilia cordata (Littleleaf Linden), and Weigela florida (Old Fashioned Weigela). Woody vines in bloom are: Campsis radicans (Trumpet Vine), 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), Aruncus aethusifolius (Dwarf Goat's Beard), A. dioicus (Goat's Beard), Astilbe spp. (False spirea), Campanula takesimana ‘Elizabeth’ (Bell Flower), C. spp. (Bell Flower), Chrysogonum virginianum (Green and Gold), Clematis recta 'Purpurea' (Clematis), Coreopsis spp. (Tickseed), Daucus carota (Queen Anne's Lace), Dianthus deltoides (Maiden Pink), Dicentra eximia (Fringed Bleeding Heart), Digitalis purpurea (Foxglove), Filipendula sp. (Meadow Sweet), Gaillardia aristata (Indian Blanket Flower), Geranium sanguineum (Cranesbill Geranium), Hemerocallis 'Stella D'Oro' (Daylily), H. fulva (Orange Daylily), H. spp. (Daylily), Heuchera spp. (Coral Bells), Hosta spp. (Plantain Lily), Lamium maculatum (Dead Nettle), Leucanthemum sp. (Shasta Daisy), Lilium spp. (Lily), Lychnis coronaria(Rose Campion), Oenothera macrocarpa (Ozark Sundrops), Nepeta spp. (Ornamental Catmint), Paeonia spp. (Peony), Penstemon digitalis 'Husker Red' (Beardtongue), Perovskia atriplicifolia (Russian Sage), Salvia nemerosa (Salvia), Sedum kamschaticum (Stonecrop), Silene latifolia (White Campion), Stachys byzantina (Lamb’s Ear), Thermopsis caroliniana (Southern Lupine), Thymus praecox (Thyme), Tradescantia sp. (Spiderwort), and Veronica umbrosa 'Georgia Blue' (Speedwell).

Pests/Problems: Be careful for what you wish for! The rain that we were hoping for to help control the gypsy moth caterpillar with the Entomophaga maimaiga fungus is also responsible for the anthracnose on Platanus (Sycamore) and canker on Pinus strobus (White Pine) observed in the landscape this past week.

Central Region (Boylston)

General Conditions: In full bloom: Stewartia pseudocamellia, Ligustrum, Syringa reticulata, Sambucus, Catalpa bignonioides, Cornus kousa, Knockout roses, Itea virginica, no Campsis yet. Beginning to bloom : Hydrangea paniculata, H. quercifolia and H. arborescens.

Pests/Problems: Gypsum moth defoliation is ending due to fungus & virus, while hibiscus sawfly is ramping up. Powdery mildew is starting on phlox.

Pioneer Valley Region (Amherst)

General Conditions: Scattered rain showers and thunderstorms have been a near daily occurrence over this past reporting period in the Connecticut River Valley. From Friday, 6/23 through Tuesday, 6/27 we experienced a mixture of sun, light showers and heavy rainfall with frequent thunder and lightning. Conditions have ranged from hot and humid to cool and wet, continuing the trend of oscillating weather patterns as we approach mid-summer. The recent cool nights, when temperatures dropped into the lower 50s, have decreased soil temperatures in both sun and shade settings. Rainfall totals throughout the tri-county region are varied, owing to the highly scattered occurrence of rain showers over the past week. Totals in Springfield were <0.4″ while the Cold Spring Orchard in Belchertown recorded well over 1″. Even in cases where totals were modest, the rainfall accumulated so quickly from some thunderstorms that turfgrasses, perennials and some woody plants may have received a sufficient volume of water. For recently transplanted trees and shrubs, especially conifers with dense canopies over the root ball, continue to water once-weekly. Oaks unaffected by gypsy moth defoliation are flushing new growth at this time. Even trees with determinate growth rates (otherwise known as preformed) can produce a second flush of leaves provided environmental conditions are ideal. Another example is Douglas-fir. Trees with indeterminate growth rates flushing new foliage at this time include silver maple, red maple, katsura, redbud, hornbeam and American elm. Growth of turfgrasses is slowing down a bit with the increased heat, but overall lawns are still green and vibrant, especially in shaded settings. Crabgrasses are abundant and thriving too, along with many other landscape weeds and invasive plants like oriental bittersweet.

Pests/Problems: The recent reports of mass gypsy moth caterpillar mortality in Massachusetts and Rhode Island are very welcome news. Nevertheless, for trees and shrubs severely defoliated by this non-native pest over the past two years, the worst may be yet to come. Most trees in good health can readily tolerate one year of defoliation. Woody plants can utilize stored root starch reserves to compensate for the lost resources due to defoliation. However, a second year of defoliation is often the tipping point; if additional stresses are not a factor, trees can often survive. Of course, secondary stresses are almost always present and many pests and pathogens have evolved to aggressively attack weakened trees. A third year of defoliation is usually intolerable, as resources are so depleted that even basic maintenance of existing tissues cannot be met and attack by pests and pathogens delivers the coup de gras. We can only hope that trees defoliated in 2016 and 2017 can survive for another year, given the ample soil moisture this growing season and the impending decline in gypsy moth numbers going forward.

Trees and shrubs exhibiting leaf yellowing at this time are unlikely to be suffering from drought stress. The issue may be nutrient related or the result of waterlogging in poorly-drained soils. For smaller and recently transplanted trees and shrubs with yellowing foliage, fertilization during the next watering can dramatically improve vigor in some cases.

We are entering the period when fruiting bodies of chicken of the wood (Laetiporus species) will become visible at the base of infected trees, especially large oaks. Regularly scout and train your clients to identify this destructive wood-rotting pathogen, as symptoms of root and butt rot are often cryptic.

Because of the good conditions this season, many trees and shrubs have put on significant growth. Don’t let deer and rabbits erase this progress with their harmful browsing. High-quality repellents work, so utilize them if these pests are causing damage. There have been reports and sightings of squirrel damage in the landscape. Bark on the trunk and main scaffold branches of a Japanese maple was stripped (quite dramatically) by squirrels, presumably interested in the sap. If you’re finding 6–12″ shoot tips scattered around the base of a mature tree, this can also be the result of squirrel damage. Once again, these small rodents snip the ends of shoots to drink the flowing sap.

Anthracnose reports and sightings continue to be the biggest issue for deciduous hardwoods this season. The overcast skies and frequent rain have led to widespread outbreaks. If the alternative is another drought year, anthracnose is tolerable in most cases. Continue to scout for and treat mature American elms for Dutch elm disease. Once a mature American elm is lost in a landscape, it can never be replaced. Treatment of Dutch elm disease is worth the time and money to help preserve these important and increasingly threatened trees.

Berkshire Region (Great Barrington)

General Conditions: The past week has given us some of the best weather one could ask for. It was neither too hot during the day nor too cool at night, though the early morning of June 28 dipped to 48° F. There was just enough rain to keep soil moisture levels at adequate levels to sustain plant growth without need for additional irrigation. The only disturbance in weather occurred late afternoon of Tuesday, June 27, when a very brief but fierce thunderstorm roared through part of the county. At this reporting station in Great Barrington, the storm lasted all of 5 minutes but the wind brought down numerous twigs and branches. For a moment, the roar of the wind reminded this landscape scout of the 1995 Memorial Day tornado. Fortunately, such was not the case this time. Some hail was reported in West Stockbridge but was brief enough that little damage occurred except for a few tiny holes in the foliage of hostas. Cool temperatures, plenty of sunshine, and good soil moisture has kept turfgrass growing at a rapid rate. With early flowering perennials having completed their bloom period, this is a good time to fill in the gaps in color in perennial borders with flowering annuals.

Pests/Problems: The prolonged cool and damp weather of April, May, and early June as expected to encourage development of foliar diseases. That prediction has come to fruition as many, many trees and shrubs are showing symptoms of various diseases. Most prominent is anthracnose which was observed this week infecting oaks, American hornbeam, maples, dogwoods, and azaleas. Particularly hard hit is American sycamore (Platanus occidentalis), many of which are almost completely defoliated. Powdery mildew of ninebark (Physocarpus), black spot and mosaic virus on roses, and canker on dogwood were observed.

New to this week’s insect observations is the oak skeletonizer, the larvae of which were feeding on leaves of bur oak.

The large helmet-shaped scales of magnolia scale are prominent on various species of magnolia. However, one such infested magnolia was seen to have numerous white larvae of lady beetles crawling about among the scales. These larvae feed on magnolia scale.

Ongoing plant pest infestations include; spruce spider mite, oak leaf lace bug (eggs), imported willow leaf beetle (adults and larvae), and euonymus scale (crawlers and settled crawlers), Asiatic garden beetles, four-lined plant bugs (adults), aphids, woolly aphids, slugs, and cutworms. Other pests include: deer ticks (population still quite large), wasps, mosquitoes, earwigs, millipedes, centipedes, and ants.

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:

Black spot of elm (elm anthracnose), caused by Gnomonia ulmea (formerly Stegophora) and Dutch elm disease, caused by Ophiostoma novo-ulmi, on slippery elm (Ulmus rubra). The tree is 29-years-old and was planted at an arboretum 25 years ago. A large portion of the canopy is exhibiting flagging symptoms and dieback. Tree resides in a grassland setting that is mowed monthly with half-sun and no supplemental irrigation. Elm anthracnose can resemble DED at times, making confirmation of the latter important before treatment takes place. Case in point, a nearby Ulmus × hollandica was also suspected of harboring DED but was found to be infected by anthracnose only.

Needle browning and stem deformation on Norway spruce (Picea abies) caused by an infestation of the eastern spruce gall adelgid (ESGA; Adelges abietis) and stem cankering by Phomopsis. The tree is 15-years-old and has been present at the site for eight years. This spring, needles began to brown and upon closer inspection highly deformed stems in the canopy were observed. A severe infestation of the ESGA caused the stem deformation and Phomopsis invaded at the site of the galls to kill the stem. The ESGA galls were only partially formed and appeared aborted, allowing the stem to continue to grow in a distorted pattern. While often a secondary pest on Norway spruce, the insect was clearly causing major problems for this particular tree.

Foliar anthracnose, caused by Colletotrichum, on Japanese stewartia (Stewartia pseudocamellia). The tree is approximately 35-years-old and has been present at the site for nearly as long. The tree resides in a mostly shaded setting with wet, but well-drained, soils. Foliage in the upper two-thirds of the canopy appears thin and foliage in the lower canopy exhibited a marginal scorch. Just the outer 1 cm of the foliage was blighted, but the anthracnose pathogen Colletotrichum was abundant on the submitted sample.

Needle and shoot blight, caused by a species of Kabatina, on Siberian cypress (Microbiota decussata). Plants reside in a large, hillside bed with full sun exposure with drip irrigation provided. Patches of the mass planting are dying off with browning needles and shoot death. Symptoms have been present in previous years. Symptoms of Kabatina can resemble winter injury, with pale green to yellow/brown shoot tips that appear desiccated. But, black-colored lesions are visible at the base of one-year-old shoots. It is from these sites that masses of clear-colored spores are produced.

Needle yellowing, browning and dieback of Chinese juniper (Juniperus chinensis) caused by the juniper scale (Carulaspis juniperi) and Lophodermium needlecast (Lophodermium juniperinum). Mature shrub, approximately 20″ wide, of unknown age located at the edge of a driveway, shaded by an eastern larch. The juniper scale infestation was severe and the primary agent driving decline. Lophodermium was a secondary pathogen and the football-shaped fruiting bodies were readily visible on blighted needle tips.

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:

•   Gypsy Moth: Lymantria dispar caterpillars are dying across Massachusetts! Reports had been trickling in throughout most of June, and from earlier Landscape Message’s you know that Dr. Joseph Elkinton’s Lab at the University of Massachusetts has been documenting fungal (Entomophaga maimaiga) activity for a couple of weeks now. E. maimaiga is of course an insect-killing fungus that is quite specific to gypsy moths. Any gypsy moth caterpillars that have not become diseased are mostly 6^th instar females at this point, and others have begun to pupate. The feeding period for gypsy moth is nearly over for 2017, so management at this time is not necessary.

Particularly at the end of last week and through the weekend (6/24 and 6/25), reports of caterpillar mortality (with photographic evidence) have flooded in to UMass Extension from various locations. This includes but is not limited to the following areas of Massachusetts: Amherst, Belchertown, Bernardston, Boylston, Brewster, Brookfield, Cotuit, Eastham, Falmouth, Hanson, Hingham, Marlborough, Marstons Mills (Barnstable), Milford, Monson, North Attleborough, Pelham, Plymouth, Sturbridge, Wellfleet, West Bridgewater, West Brookfield, Yarmouth, and much of Cape Cod and the South Shore. The spores of the fungus (Entomophaga maimaiga) have been confirmed from samples taken from many of those areas and the NPV virus was confirmed active in Hanson, MA and is likely active in other areas as well.

For example, a population of gypsy moth caterpillars was observed to be “otherwise healthy” and feeding on a crabapple at a location in Amherst, MA on Sunday, 6/18/2017. (They had already done a number on nearby oaks in the area.) By Friday, 6/23/17, the caterpillars were either shriveled up and hanging vertically from the trunk and branches of the tree (may be indicative of Entomophaga maimaiga) or juicy and drooping in this location in an inverted-V shape, which may be mortality caused by the NPV virus that kills gypsy moth. (The only way to truly tell which pathogen is responsible is to look at samples from the dead caterpillars under a microscope.) If you have gypsy moth caterpillars hanging off of your trees in this manner, there is no need to "clean them off" in any way. They will eventually be washed off by rains, etc. Leave them where they are so that the fungal spores or NPV viral particles can disperse in a natural manner.
 

Unfortunately, gypsy moth caterpillars are still responsible for some widespread defoliation in certain areas of the state this year, as seen in these photos from Ware, MA (taken on 6/24/17). Many caterpillars survived long enough to reach the size where they are able to partially or completely strip the leaves from their host trees. Partial or complete defoliation of trees due to gypsy moth can be seen on either sides of the MA Turnpike (I-90), particularly from Wilbraham to the Charlton Plaza. More updates about estimated total acreage defoliated by gypsy moth in 2017 will become available once the Massachusetts Department of Conservation and Recreation is able to complete their aerial survey of the state. This survey began only recently, in order to most accurately capture the defoliation caused by these caterpillars (those not killed by the fungus are still feeding, particularly the female caterpillars who undergo an additional instar (6^th), or developmental stage, than the males (5^th)). Some are still reporting caterpillar feeding activity in areas such as Brimfield, Southborough, and Westborough, MA. The Elkinton Lab reports that many have successfully pupated in the Hopkinton, MA area. This should be noted, as although the mortality of these caterpillars has been very impressive in many areas, we should remind ourselves that it is not occurring in 100% of the population.

Residents in Massachusetts, particularly in southern central MA and the southeastern portions of Franklin, Hampshire, and Hampden counties still experienced high populations of this insect in 2017, many dealing with caterpillars dropping in driveways along with shredded leaves. Caterpillar frass (excrement) could be heard raining down from tree canopies at various locations, often covering patios and lawn furniture. The recent wave of mortality sweeping gypsy moth caterpillars is a welcome sight for many.

Just as we may be able to credit (mostly) the drought conditions experienced in 2015 and 2016 with the recent increase in the gypsy moth population (through the impediment of Entomophaga maimaiga activity), we can credit the rainfall events seen in May and June of 2017 for the success of the fungus this year. Although we have been waiting for this with much anticipation and wish the caterpillar collapse occurred sooner, it is certainly better than the alternative. Hopefully, this outbreak of these pathogens in this year’s gypsy moth population will mean a reprieve for many from this insect in 2018. The Elkinton Lab reports that fungal activity was particularly pronounced on Cape Cod and the South Shore, and it seems that in many other areas across the state, the fungus has kicked in just in time.

Gypsy moth caterpillars (those that survived), as mentioned previously, have begun to pupate in many locations. (The pupae, or “resting stage”, do not feed and neither do the adults, so management is no longer necessary this season.) Those that successfully pupate will become adults, which will mate (particularly in July) and the females will lay their fuzzy, tannish-brown egg masses, which will overwinter and provide caterpillars for 2018. Our hope is that we will see fewer males (brown moths that fly) and perhaps most importantly fewer females (white colored moths that, although they have wings, do not fly) which will lead to fewer egg masses to hatch in 2018. Fewer: that is not to say that these insects will 100% disappear from the landscape next year. However, the hope is that the population will drop below nuisance levels at least in some locations. The Elkinton Lab reports as of 6/28/17, with the exception of one of their research sites in Massachusetts, 80-90% of their sampled caterpillars have perished. This is certainly excellent news; however, we should keep this in perspective, given that each female moth can potentially lay, according to Dr. Elkinton, approximately 300 female eggs. Even if 298 of those individuals die before maturity in 2018, the population could still theoretically increase.

Therefore, we rejoice in the fact that the fungus and virus are finally active in the gypsy moth population this year as compared to recent years, but remain cautious. We will continue to watch the number of caterpillars that make it to pupation in the next week, and keep an eye on the adults and the number of egg masses the females lay. Overall, having these grotesque caterpillars stuck to the sides of our trees is a great thing. In many areas, they are full of the hardy, long-lived resting spores of Entomophaga maimaiga, which are capable of overwintering and providing continued infection of this insect’s population for many years to come.

• 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. By the time the next Landscape Message is released, adults of this insect could be active 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, 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 have been previously reported from Middlesex, Plymouth, and Worcester counties in MA. (One was also observed in Jaffrey, NH while hiking in Monadnock State Park on Saturday, June 3.) 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 do not emerge in Massachusetts until 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.

• Azalea Bark Scale: Eriococcus azaleae was discovered in CT in 1917 and has since been reported in other states. It is found on the bark of twigs and stems and commonly settles in branch crotches. It has been reported on azalea, rhododendron, andromeda, and others. Female scales are approximately 2-3 mm. in length and covered in a white, waxy coating. The females are purple in color and may resemble a mealybug, although they are a soft or felt scale. These females have overwintered and are going to lay eggs which will hatch into crawlers toward the end of June through mid-July. Crawlers will settle into branch crotches, bark crevices, or on the axils of leaves. There is a parasitic wasp that will attack these insects. When high in number, these scales can cause yellowing of the foliage and their sugary excrement can lead to the promotion of sooty mold. Because these are soft scales, they may be targeted with horticultural oils or insecticidal soaps while observing label instructions to prevent phytotoxicity.

• 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 emerge in June and create new damage to leaves for this season. All individuals are females and reproduce asexually. This insect has developed resistance to many chemical insecticides. Entomopathogenic nematodes such as Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacterio-phora work well against this insect, particularly on containerized plants. Results in the landscape vary. Wetting the soil thoroughly prior to application and keeping it wet for at least 5 days following application can help increase the efficacy of the nematodes. Burlap laid around the base of plants during the time adults are active, through August, can be inspected weekly for adult weevils which can be killed before egg laying.

• Cottony Taxus Scale: Chloropulvinaria floccifera, also referred to as the cottony camellia scale, utilizes such hosts as taxus, camellia, holly, hydrangea, Japanese maple, euonymus, magnolia, jasmine, and Callicarpa americana. This insect was observed on taxus in Amherst on 5/31/17. Females are laying the long, narrow, white colored egg sac that makes them much more noticeable. This was observed again on 6/8/17 and 6/14/17. Eggs will hatch over an extended period of 6 weeks and crawlers may be treated between 802-1388 GDD’s. This insect can cause the host to appear off-color. They also produce honeydew which promotes sooty mold growth. Target the underside of the foliage. Horticultural oil, neem oil, and insecticidal soaps may be used to manage these soft scales. They may also be washed from plants with a strong jet of water.

• 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.

• European Elm Scale: Gossyparia spuria is a type of felt scale and was observed on an elm on 6/7/17, 6/14/17, and 6/28/17 in Amherst. First noted in New York in 1884, this non-native scale is now widespread in North America and is found on native and European elms, but also rarely on hackberry and Zelkova. This insect can cause yellowing of foliage, premature leaf drop, and eventually dieback on its host. Honeydew and thus sooty mold are produced. The females observed in Amherst have produced a ring of white fibers around their black, oval bodies. By the end of June, these females lay eggs that hatch into bright yellow crawlers, which will disperse to the midrib and leaf veins on the underside of elm leaves where they will remain to feed. Crawlers are tiny and magnification is necessary to observe. Crawlers were observed on a small sample of elm leaves at a location being monitored in Amherst on 6/28/17. Natural enemies such as parasitic wasps and predatory insects have been reported as successful in managing this insect.

• Fletcher Scale: Parthenolecanium fletcheri (soft scale) was observed on taxus (yew) in Amherst on 6/8/17 and 6/14/17. Several effective parasites will impact these scale populations and any management decisions should seek to preserve them. Dead, desiccated female scales appear at this time as covers (test) that one might expect from an armored scale and should not be confused for one. When removed, it is easy to find hundreds of tiny, white colored eggs beneath the female (you will need a hand lens to observe). This scale is commonly found on yew and arborvitae (but has also been reported on juniper and hemlock). It may be confused with the European fruit lecanium (P. corni), which has a much broader host range. Depending upon the host plant, crawlers of the fletcher scale will hatch by the end of June and management may be targeted between 1029-1388 GDD’s, base 50°F. Crawlers were observed beneath a single desiccated female sampled on 6/29/17 from Taxus in Amherst, MA. Large populations of this scale may lead to host plant yellowing, premature needle drop, and production of honeydew giving way for sooty mold. Each female produces on average 500-600 eggs. The degree of impact this insect may have depends on the host. Some hosts, such as yew, are reportedly more heavily impacted by this scale as when compared to arborvitae, where visible damage may be seldom. Horticultural oil, insecticidal soap, or neem oil may be used according to label instructions in order to preserve natural enemies.

• 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 hatched in early June. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary. Anecdotal reports of increasing hemlock looper populations in certain areas of western Massachusetts (Berkshire County) have been made this season.

• 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 still present and mating when observed on 6/28/17. Frass-covered larvae were difficult to find on this particular scouting mission to a location that has been continuously monitored in Amherst this season. See Regional Reports for local activity of this insect. Management can be achieved by hand-picking and removing adults and larvae. Some chemical management options are available for this insect, but if caught early mechanical management may be effective. (Although when many plants are involved, mechanical management may not be practical.) 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.

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/

• 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.

• Taxus Mealybug: Dysmicoccus wistariae was spotted on taxus in Amherst on 5/31/17, 6/8/17, 6/14/17, and 6/29/17. This insect will produce honeydew and lead to sooty mold growth, yellowing of needles, and sparsely foliated plants. Eventual dieback may be possible. This species is commonly associated with taxus in New England, but can be occasionally found on dogwood, rhododendron, Prunus spp., maple, andromeda, and crabapple. These mealybugs are found on stems and branches and particularly like to congregate at branch crotches. Management may be targeted between 246-618 GDD’s. Horticultural oil and neem oil may be used.

• 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. What a difference a week can make! Much larger nymphs and adults have now been observed on wafer ash in Amherst on 6/28/17. 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. At this time, larvae have dropped to the soil to pupate and adult beetles will soon be present in most locations where they exist in late-June through roughly 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: *A non-native insect has been confirmed in Massachusetts for the first time.* 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.

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

Management Practices

Plant of the Week: Liatris spicata, blazing star

Liatris spicata is an upright, clumping, herbaceous perennial native to much of the eastern and central US. Plants grow 2-4’ tall and 0.75-1.5’ wide. The 6-12” long terminal flower spikes occur in summer from late June to August. The spikes consist of multi flowerheads of 4-10 pink to purple disk florets and bloom from the top down. Flower spikes rise above the tufts of narrow-grass like leaves. The medium green leaves are alternate and up to 10” long, becoming smaller as they go up the stems. Liatris spicata is best grown in well-drained soil in full sun but is tolerant of both dry and wet soils (tolerant of wet soil in summer but not in winter). Its tolerance to wet soil makes blazing star a good choice for rain gardens. Liatris spicata attracts bees and butterflies which also makes it a great choice for a pollinator garden. It is also a good selection for mixed perennial borders, prairies, native gardens, cut flower gardens, and cottage gardens. Taller plants can become floppy and require staking. ‘Kobold’ is a popular cultivar that grows to 2-2.5’ tall.

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

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