Landscape Message: May 20, 2016

May 20, 2016
Issue: 
9

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 May 20. 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 12 through May 18. Soil temperatures and phenological indicators were observed on or about May 18. 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

56

156

67

54

0.26

4:40 PM 5/18

Southeast

54

164

65

58

0.28

4:41 PM 5/18

North Shore

51

134

54

50

0.18

10:00 AM 5/18

East

62

173

64

60

0.16

4:00 PM 5/18

Metro West

55

149

54

50

0.01

5:45 AM 5/18

Central

65

209

68

54

0.11

8:45 AM 5/18

Pioneer Valley

47

166

61

53

0.42

2:00 PM 5/18

Berkshires

31

122

56

50

0.47

10:15 AM 5/18

AVERAGE

53

159

61

54

0.24

-

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.
Syringa meyeri (Meyer Lilac) * * * * Begin * * *
Rhododendron catawbiense (Catawba Rhododendron) Begin * * * * * * *
Spiraea x vanhouttei (Vanhoutte Spirea) Begin Full * Begin * Begin * *
Aesculus hippocastanum (Common Horsechestnut) Begin Begin/full Begin/Full Begin Begin * Begin/Full Begin
Enkianthus campanulatus (Redvein Enkianthus) * * * Full * Full Begin/Full *
Rhododendron carolinianum (Carolina Rhododendron) Begin Begin Begin * Begin * Begin *
Elaeagnus umbellata (Autumn-olive) Begin Begin Begin/Full Begin Begin Full Full *
Syringa vulgaris (Common Lilac) Begin/Full Full Full Full Full Full Full Full
Rhododendron spp. (Early Azaleas) Full Full Full Full Full Full Full Full
Cornus florida (Flowering Dogwood) Begin/Full Full Full Full/End Full Full Full Full
Malus spp. (Crabapple) Begin/Full Full/End Full/ End Full/End Full/ End Full/End End Full
Cercis canadensis (Redbud) Full Full Full End Full/ End Full End Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: It has been another week of up and down temperatures on the Cape. High temperatures ranged from 73° F on May 12th to only the upper 40s on May 15th. Gusty winds in the 20-30 MPH range made working outdoors quite chilly on the 15th and 16th! Rainfall was scarce this week and soils are drying fast. Lawns are growing rapidly and weekly mowing is the norm. Tulips are in full bloom as are Kwanzan cherries. Mayflower viburnums are just starting to go by but are still perfuming the air. Soils are drying out as there has been little in the way of precipitation coupled with fairly windy weather.

Pests/Problems: Winter moth is in the free-feeding stage and can be found on both deciduous trees and shrubs, as well as on roses. Small third and fourth instar caterpillars, generally ¼” to ½” long, are folding and webbing leaves together. Spinosad sprays can be applied to expanding foliage. Lily leaf beetle adults are still feeding and the first egg mass was observed on Asiatic lilies. Rose slug sawfly larvae have hatched and the tiny green slug-like larvae have begun to skeletonize rose foliage. At this point, most of the damage to rose foliage is due to winter moth caterpillar. Gypsy moth caterpillar hatch is pretty much completed and, in those areas of the Cape where they will be active, they are “ballooning” into the canopies of host trees, mainly oaks. Eastern tent caterpillar nests are quite visible and can easily be removed. Deer tick nymphs are active. Thorough tick checks throughout the day are important. Sprays of permethrin labeled for application to clothing are available in many local garden centers and are a good way to prevent a tick bite.

White grubs are right up in the turf root zone. Rabbits continue to browse on emerging hosta and other perennials. In the vegetable garden, the Imported cabbage butterfly is active and laying eggs. Advise your clients with gardens to use row covers.

Crabgrass has begun to germinate.

Southeast Region (Hanson)

General Conditions: Sunny weather, variable, on the cool side, with some high winds, prevailed this past week.Not much rain asHanson received only 0.28 inches of rain and soils are beginning to dry out. Remind clients to water water newly planted trees and shrubs. Looking at the plants in Hanson, MA, the cold damage continues to show up with the buds blasted on some of the more tender rhododendrons along with Asian Arisaema like Arisaema ringens and Arisaema sikokianum and outright death of Corydalis ‘Canary Feathers’. There is no sign of growth on Cercis chinensis. This was a tough winter and spring for many plants. The following plants are in full bloom: Halesia sp. (Silverbell), Magnolia fraseri, Magnolia macrophylla, otherlate blooming magnolia hybrids, Cercis canadensis, Cornus florida, Chaenomeles speciosa (Common Floweringquince, Viburnum ‘Eskimo, Viburnum setigerum, Calycanthus floridus (Carolina allspice), Ilex x meserveae (Meserve hybrid Hollies), Rhododendron schlippenbachii (Royal azalea), Fothergilla sp., Syringa sp., Loniceratatarica (invasive),Kerria, Daphne x burkwoodii 'Carol Mackie', Daphne tangutica, Weigela florida 'Versicolor', Iberis sempervirens,Aristolochia durior (Dutchman's pipe), Pulmonaria, Trillium, Convallaria majalis (Lily-of-the-valley), Euphorbia polychroma, Lamium sp., Primula sp., Brunnera macrophylla, Ajuga, Saruma henryi, Phlox subulata, Phlox divaricata, Phlox stolonifera, Myosotis sylvatica (Forget-me-not), Lunaria annua (honesty or money plant), Violets, Dicentra spectabilis (Bleeding heart), Corydalis scouleri, Tiarella cordifolia (Foam Flower), Mertensia virginica (Virginia bluebells), Vinca minor, Galium odoratum (Sweet Woodruff), Hyacinthoides hispanica, Pulmonaria sp., Arisaema dracontium (Jack-in-the-pulpit), Polygonatum sp. (Solomon's Seal), Epimedium sp., Asarum canadense, Stylophorum diphyllum (Wood Poppy), Lamiastrum galeobdolon, Glaucidium palmatum, Corydalis lutea, Mazus reptans and Doronicum sp. The following plants are ending bloom: Sassafras albidum, Kwanzan cherry, Viburnum carlesii (Mayflower Viburnum), Viburnum ‘Mohawk’ and Exochorda racemosa (Pearlbush. Aesculus hippocastanum (Common Horsechestnut), Cypripedium parviflorum (Yellow Lady’s Slipper) and Persicaria bistorta ‘Superbum’ are beginning to bloom and the flowering bracts of the Rutgers hybrid dogwoods (Stellar series) are beginning to open and show color. Lilacs have finally opened and fertilized lawns are green and looking good. Ilex opaca, American holly, has started to shed its older leaves. The yellow leaves falling on the ground often bring questions of concern from clients but this is an annual event for these hollies.

Pests/Problems: Caterpillars are the theme of the season right now. Winter moth caterpillars are mostly at 3rd instar with some 1st and 4th instars observed. It is still too early to predict what the damage might be: some Norway maples have leaves resembling Swiss cheese; other trees show little damage. Many Japanese maples and sugar maples show very little damage, of course this may change as winter moth caterpillars continue to grow and feed on susceptible plants. Continue to monitor and manage as needed. 2nd instar gypsy moth caterpillars were reported ‘ballooning’ or floating through the air this past week in several southeastern communities including: Raynham, Plymouth, Kingston, Carver and Hanson. At this 2nd instar stage, the caterpillars are small, black and covered with tiny hairs which are capable, for some people, of causing an allergic skin reaction (rash). There were 2 reported instances where people developed skin rashes from the caterpillars. Monitoring oaks in Hanson revealed numerous 2nd instar gypsy moth caterpillars feeding on the young oak leaves. Occasionally, winter moth caterpillars were found feeding in the oak foliage along with the gypsy moth caterpillars. However, the gypsy moth caterpillars outnumbered the winter moth caterpillars. (See Tawny Simisky’s Insect Section of the Landscape Message.) Continue to monitor landscape plants for gypsy moth caterpillars and manage as needed. It looks like it will be a big season for gypsy moth unless we get some well-timed rain and the Entomophaga maimaiga fungus kicks in. Roseslug sawfly is active on roses. Monitor the undersides of rose foliage for the small, slug-like larvae, if left untreated, the sawfly larvae will skeletonize the rose foliage. Bacillus thuringiensis (Bt) does not work on sawflies. Elongate hemlock scale was found on Abies koreana 'Horstmanns Silberlocke’, a heretofore uncommon host. This scale is difficult to manage. Fletcher scale is active on Taxus. Monitor pines for European pine sawfly larvae which can decimate the new growth if not managed. The following insects remain active: lily leaf beetle, eastern tent caterpillar, snowball aphid on viburnum, hemlock woolly adelgid, spruce spider mites, snails, slugs, aphids, ants, wasps, hornets, azalea whitefly on azalea, black flies, mosquitoes, honeybees, mason bees, carpenter bees, bumblebees, deer tick nymphs and dog ticks. Remember, the deer tick nymph stage is often thought to be most responsible for transmitting Lyme disease.

North Shore Region (Beverly)

General Conditions: Temperatures during this reporting period have been variable with day temperatures ranging from high the 50s to low the 70s on some days. The highest temperature of 77 degrees during this reporting period was recorded on May 14. Night temperatures were mostly in the low to mid 40s. Due to very low relative humidity and very windy conditions especially on May 15 and 16, fire danger warnings were posted throughout the area during this reporting period. We gained 51 growing degree days at Long Hill during this reporting period, and approximately 0.18 inches of rainfall was recorded. Woody plants seen in bloom include: Silver bell (Halesia carolina), Wright Viburnum (Viburnum wrightii), Pinkshell Azalea and White find azalea (Rhododendron vaseyi), Unique azalea (Rhododendron ‘Unique’), Blue princess holly (Ilex x meserveae), Sweet bells (Leucothoe racemosa), Beach plum (Prunus maritima), Hardy orange (Poncirus trifoliata), Molten lava crabapple (Malus molazah), Flowering Dogwood (Cornus florida), Redbud (Cercis canadensis), Large Fothergilla (Fothergilla major), Dwarf Fothergilla (Fothergilla gardenii), Royal azalea (Rhododendron schlippenbachii), Little leaf lilac (Syringa microphylla), Common Lilac (Syringa vulgaris), Crabapple (Malus spp.), Olga Mezitt Rhododendron (Rhododendron ‘Olga Mezitt’), apple trees (Malus spp.) and Highbush blueberry (Vaccinium corymbosum). Non-woody plants seen in bloom include: Forget Me Not (Myosotis sylvatica), Tulips (Tulipa sp.), Bleeding heart (Dicentra spectabilis), Trout lily (Erythronium americanum), Siberian Iris (Iris sibirica), Trillium (Trillium grandiflorum), Rock cress (Aubrieta deltoidea), and Pig Squeak (Bergenia cordifolia).

Pests/Problems: Damage by winter moth caterpillars (Operophtera brumata) was observed on crabapple, apple, horsechestnut and maple leaves. Hemlock woolly adelgid was also observed on some hemlock trees in the area. Problems of leafing out and flowering was observed on Wisteria. The plants were probably affected by the sub-zero temperatures that were experienced in early April. Rabbits and woodchucks were also observed in the landscape. Weeds seen in bloom include: Dandelion (Taraxacum officinale), Lesser celandine (Ranunculus ficaria), Ground Ivy (Glechoma hederacea) and Purple Deadnettle (Lamium purpureum). Ticks are very active. Be careful to protect yourself when working outdoors.

East Region (Boston)

General Conditions: Temperatures have been seasonal this week, with highs averaging 71° F and lows averaging 47° F. Windy conditions have persisted for most of the week. We have gained 62 GDDs bringing us up to 173 on the year. Plants in bloom include: Abelia mosanensis (fragrant abelia), Ajuga reptans (carpet bugleweed), ornamental Allium sp. (flowering onion, Aronia arbutifolia (red chokeberry), A. melanocarpa (black chokeberry), A. prunifolia (purple chokeberry), Berberis gilgiana (wildfire barberry), Calycanthus floridus 'Michael Lindsey' (sweetshrub), Convallaria majalis (lily of the valley), Cornus controversa (giant dogwood), early Cotoneaster sp. (cotoneaster), Cydonia oblonga (quince), Daphne × burkwoodii 'Carol Mackie' (Carol Mackie daphne), Daphne genkwa (lilac daphne), Euonymus alatus (burning bush), Galium odoratum (sweet woodruff), Genista sp. (broom), Hyacinthoides hispanica (Spanish bluebell), Ilex opaca (American holly), Iris sp. (iris), Lavandula stoechas (French lavender), Ledum palustre (wild rosemary), Leucothoe fontanesiana 'Nana' (dwarf fetterbush), Magnolia fraseri (Fraser magnolia), Morus sp. (mulberry), Orixa japonica (Japanese orixa), Ornithogalum umbellatum (star-of-Bethlehem), early Paeonia sp. (peony), Photinia villosa (Oriental photinia), Polygonatum biflorum (Solomon seal), Rhododendron vaseyi (pinkshell azalea), R. ‘Crete’, ‘Duke of York’, and ‘Pink Parasol’, Rhodotypos scandens (jetbead), Rosa primula (primrose rose), Sorbus latifolia (whitebeam), Sorbus yuana, Spiraea pubescens (spirea), Staphylea pinnata (European bladdernut), Vaccinium corymbosum (highbush blueberry), and Xanthoceras sorbifolium (yellowhorn).

Pests/Problems: The effects of the early spring temperature fluctuations combined with the April cold snap can be spotted throughout the landscape as plants are delayed in their leaf out, many with dead buds, including almost all Corylopsis sp. (winterhazel), some Lindera sp. (spicebush), Sassafras albidum (sassafras), and Tilia japonica (Japanese linden). We have only received 0.16 inches of precipitation over the last week and soils are dry. Buttercups (Ranunculus sp.) and violets (Viola sp.) are flowering in turf. Garlic mustard (Alliaria petiolata) continues to flower and form seed pods. Japanese knotweed (Fallopia japonica) continues to grow, reaching heights of up to 4 feet. Winter moth (Operophtera brumata) continues to feed on deciduous plants throughout the landscape. Viburnum leaf beetle (Pyrrhalta viburni) has hatched and is actively feeding on the underside of viburnum leaves; browning, skeletonized leaves are becoming visible on infested plants.

Metro West (Acton)

General Conditions: This one week reporting period started off with unseasonable temperatures with a high recorded on the 12th at 82° F, followed by 79° F recorded on the 11th and 78° F on the14th and 75° F on the 13th. Temperatures have moderated since and are more “spring-like” but have brought with them some breezy days with wind gusts up to 24mph recorded on the 15th. Woody plants seen in bloom this past week are Aesculus hippocastanum (Horsechestnut), Amelanchier spp. (Shadbush, Serviceberry), Aronia arbutifolia (Black Chokecherry), Cercis canadensis (Redbud), Cornus florida (Dogwood), C. x rutgersensis 'Ruth Ellen' (Rutgers Hybrid Dogwood), Crataegus spp. (Hawthorn), Daphne x burkwoodii 'Carol Mackie' (Daphne), Fothergilla gardenii (Dwarf Fothergilla), F. major (Large Fothergilla), Halesia tetraptera (Mountain Silverbell), Ilex aquifolium (English Holly), Leucothoe axillaris (Coast Leucothoe), Magnolia ‘Elizabeth’, M. x loebneri 'Merrill', Malus spp. (Crabapple) including M. sargentii (Sargent Crabapple), Prunus japonica (Flowering Almond), P. serotina (Black Cherry), Rhododendron spp. (early flowering Rhododendron), R. vaseyi (Pinkshell Azalea), Spirea spp.(Bridalwreath), Syringa spp.( Lilac), Syringa vulgaris (Common Lilac), Vaccinium angustifolium (Lowbush Blueberry), V. corymbosum (Highbush Blueberry), Viburnum plicatum var. tomentosum (Doublefile Viburnum), Viburnum x burkwoodii (Burkwood Viburnum), and V. x burkwoodii 'Mohawk' (Mohawk Burkwood Viburnum). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Actaea pachypoda (White Baneberry), Ajuga reptans (Bugleweed), Allium spp. (Ornamental Flowering Onion), A. schoenoprasum (chives), Amsonia hubrichtii (Arkansas Blue Star), Aquilegia canadensis (Columbine), Arisaema triphyllum (Jack-in-the-Pulpit), Asarum europaeum (European Ginger), A. canadense (Canadian Wild Ginger), A. vulgaris (Columbine), Aurinia saxatilis (Basket of Gold), Camassia scilloides ‘Blue Danube’ (Wild Hyacinth), Chrysogonum virginianum (Green and Gold), Convallaria majalis (Lily of the Valley), Cypripedium parviflorum (Yellow Lady's Slipper), Dicentra eximia (Fringed Bleeding Heart), D. spectabilis (Old Fashioned Bleeding Heart), Epimedium x versicolor 'Niveum' (White Flowering Barrenwort), E. x versicolor 'Roseuem' (Pink Flowering Barrenwort), E. versicolor 'Sulphureum' (Yellow Flowering Barrenwort), Gallium odorata (Sweet Woodruff), Geranium maculatum (Wild Geranium), G. sanguineum (Bloody Cranesbill), Hyacinthoides hispanica (Wood Hyacinth), Iris germanica (Bearded Iris), Lunaria annua (Money Plant), Myosotis sylvatica (Forget-me-not), Nepeta spp. (Ornamental Catmint), 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), Stylophorum diphyllum (Wood Poppy), Tiarella cordifolia (Foam Flower), Trillium erectum (Red Flowering Trillium), Trillium grandiflorum (White Trillium), Uvularia sessilifolia (Bellflower), Veronica Repens (Speedwell),Vinca minor (Periwinkle), Viola spp. (Violet), and Zizia aptera (Heart-Leaved Alexander).

Pests/Problems: Caterpillars are actively feeding on the foliage of Acer (Maple), Corylus (Filbert), Fagus (Beech), Malus (Crabapple), and Prunus (Cherry) and are easy to detect this week with the naked eye. Imported Willow Leaf Beetles are feeding on willow foliage and Snowball Aphid is evident on Viburnums. Ticks, mosquitoes and black flies are feeding and active. Many weeds are in flower including a few of the nastiest invasives of all time, Alliaria petiolata (Garlic Mustard) which is easily seen with its white flowers growing on roadsides and in woodlands, wetlands and gardens, Elaeagnus umbellata (Autumn-olive), and Lonicera maackii (Amur Honeysuckle). Other weeds seen in bloom now are Glechoma hederacea (Ground Ivy), Lamium purpureum (Purple Dead Nettle) and Taraxacum officinale (Dandelion). Be aware of Toxicodendron radicans (Poison Ivy). It is leafing out and it is fairly easy to detect its shiny red leaves of three.

Central Region (Boylston)

General Conditions: The past week featured temperatures ranging from the mid 30’s at night to low 80’s by day. Though we did not experience frost, we protected tender plants on Saturday and Sunday evenings. Windy conditions on Sunday and Monday took a toll on plants leaving the ground littered with small branched and tender leaves. Soils are dry and irrigating turf and planting beds has begun. Among the many things in bloom are Tulips (Tulipa cvs.), Lungwort (Pulmonaria species & cultivars), Columbine (Aquilegia vulgaris), Rhododendron yakushimanum cultivars, Tea Viburnum (V. setigerum), Veronica peduncularis ‘Georgia Blue’, Leucothoe axillaris, Viburnum carlesii & V. carlcephalum (ending), Lilacs (Syringa vulgaris, S. laciniata) Birdsfoot Violet (Viola pedata), Aronia melanocarpa, Pieris floribunda, Enkianthus campanulatus ‘Showy Lantern’, Bergenia cordifolia, Dicentra spectabilis, Phlox stolonifera, Phlox subulata, Phlox divaricata, Stylophorum diphyllum, Trillium grandiflorum, Fothergilla gardenii and F. major. Aesculus carnea ‘Briotii’ and Viburnum plicatum tomentosum are beginning to bloom.

Pests/Problems: Rabbits, deer, woodchucks are feeding on unprotected plants. Ticks, blackflies, and mosquitoes are feeding on unprotected people. Eastern Tent caterpillar webs continue to expand. Conditions are quite dry and supplemental watering is necessary for new transplants and turf.

Pioneer Valley Region (Amherst)

General Conditions: The Pioneer Valley continues to experience erratic spring weather. We passed the midway point of May and the days continue to grow longer on each end. This past reporting period started off with beautiful spring conditions; full sun and temperatures in the upper 70s to low 80s on 5/11 and 5/12. Temperatures dropped slightly over the next two days before yet another cold front swept into the region with high temperatures that barely budged out of the mid-50s by Sunday 5/15. In addition to the cool temperatures, this front brought strong winds on Sunday 5/15 and Monday 5/16 with sustained speeds of 28 mph and gusts up to 43 mph recorded at Barnes airport in Westfield. Once again, succulent leaves and small stems littered lawns and roadways as a result of the brutal winds. Overnight low temperatures dropped to the middle 30s during the early morning of Monday 5/16, but since then have gradually inched upwards in the lower to middle 40s. Despite all this, leaves and shoots continue to expand and the landscape grows greener every day. Lawn grass is still bright green and growing rapidly. Mulch and exposed surface soils are dry as a result of the winds but overall, soils remain moist at this time of new root development, which is very encouraging. Scattered rain showers are predicted in the long-term forecast with a chance for soaking rainfall next week. We can only hope we will receive the ≥1″ soaking we have lacked so far this growing season.

Pests/Problems: Spruce spider mites are now active and were observed feeding on both Norway and white spruce on the UMass campus. Populations of this pest can build up rapidly and if damage on spruce, fir, hemlock and arborvitae has been significant in previous years, begin treatment now. Scout for mottled yellow to pale green needles, especially on protected, inner shoots and branches. Spider mites are easily dislodged from infested needles by rain which is why populations build up during extended dry periods. A strong stream of hose water can reduce populations on infested trees. If chemical treatment is desired, use a registered miticide and not a broad-spectrum insecticide to limit non-target effects. Spruce needle rust pustules are mature and disseminating spores at this time. Newly developing needles are susceptible to infection and may not exhibit symptoms of the disease until late winter or early spring of 2017. As such, the diseased needles we are observing now were infected in May of 2015. Weather conditions at this time in 2015 were not conducive to spore germination, as the region experienced a prolonged dry stretch that lasted from the last week of April through almost the entire month of May. Despite the dry weather, infections did take place but are mostly confined to lower canopy shoots on the north side of trees. Avoid situations where lawn sprinklers are wetting the foliage on blue, Serbian and Oriental spruce. While highly conspicuous, spruce needle rust is not a particularly damaging disease and needles harboring rust pustules may not be killed. This disease warrants chemical management only in very extreme cases. A much greater threat to the health of blue spruce is needle cast caused by Rhizosphaera and Stigmina. The treatment window to protect newly developing needles from these fungal pathogens is now upon us. Fungicide application should take place when needles are ¼ elongated and on regular intervals should wet weather occur. Lower canopy branches that are badly diseased and have healthy needles on the branch tips only should be pruned out. Cultural management alone will not be sufficient to break the cycle of infection on large, mature trees. In what appears to be the case for many diseased blue spruces, there is so much inoculum within the canopy, that even cultural and chemical treatment does little to slow the progression of dieback. In those situations, time and resources may be better allocated on other tree pathogen/pest issues. Newly developing needles that become infected may show symptoms of the disease this autumn if the tree is stressed. Typically, however, infected needles will not show symptoms until the following year, up to 15 months after infection. Rose slug sawfly larvae and aphids have been observed feeding on rose. Winter injury is widespread on a number of evergreen shrubs and conifers. Prune these plants part as soon as possible to avoid colonization by secondary pathogens.

Berkshire Region (Great Barrington)

General Conditions: Many plants’ people estimate about a two week lag in plant development in the Berkshires. Deciduous trees including oaks, ash, honeylocust, birch, and hickory remain naked, are just beginning to leaf out, or have minimal foliar development. Sub-normal temperatures on most days continue to hold back plant development, though growth of turfgrass has not been much affected by cool temperatures. Hail was reported to have occurred in some areas of the county on Sunday (5/15) evening and snow squalls were observed on Monday (5/16) morning with no accumulation. High winds through the weekend and Monday brought down large tree limbs and caused some power outages. Precipitation was scant and the rainfall deficit at this time is near 3 inches. However, soil moisture is good except for gravelly soils. Garlic mustard remains in bloom and is pervasive. Invasive honeysuckle shrubs are in bloom.

Pests/Problems: One of the new pests observed this week include woolly beech aphid which can be found on the undersides of leaves beech, including copper beech. Though not considered to be a serious pest, it is a messy one in that the aphids produce large amounts of honeydew. The honeydew not only attracts wasps, ants, and yellow jackets but functions as a medium for sooty mold which distracts from the aesthetics of a beech tree and can reduce photosynthetic productivity. Boxwood leaf miner is currently in the larval stage. Infestation of the leaf miner can be detected by the appearance of blisters on leaves of boxwood. Dissection of a blister will expose the tiny yellow larvae. Pruning boxwood now and disposing of the clippings will help reduce the population of leaf miner. Presence of pearleaf blister mite (Phytoptus pyri) infestation was detected by the small greenish pimples on leaves of pears. Other pests observed on plants are willow leaf beetle adults and spruce spider mites. Ticks, carpenter bees, wasps, and gnats remain active. Plant browsing critters including rabbits, voles, and chipmunks are quite numerous this spring.

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

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

Severe winter burn of yew (Taxus cuspidata). Sheared hedgerow consisting of several plants estimated at 30 to 40-years-old. In early April, after the arctic blast the region experienced, the majority of the canopy needles turned yellow to brown. A minor infestation of the cottony taxus scale was detected along with some secondary twig cankering caused by Pestalotiopsis.

Needle and shoot blight of Leyland cypress (×Cupressocyparis leylandii) caused by Phomopsis and Phyllosticta. Trees are 25-years-old and have been present at the site for 15 years. In the spring, needles on the shoot tips became yellow to brown and the symptoms were present in previous years. The trees are growing along a driveway in full shade. Because Leyland cypress prefers full sun, the lack of light should be considered a predisposing stress. Winter injury may also be a factor, as Leyland cypress are considered marginally hardy in Massachusetts.

Needle tip blight of white fir (Abies concolor) caused by Rhizosphaera. Tree is approximately 25-years-old and has been present at the site for roughly 20 years. It has a full sun setting with drip irrigation and well-drained, loamy soil. Needle tips on scattered branches have turned brown to grey for multiple years. This symptom of infection by Rhizosphaera is unique to white fir alone and does not develop on spruce.

Needle browning and decline of Hinoki falsecypress (Chamaecyparis obtusa) caused by environmental stress. Trees are 10-years-old and have been present at the site for eight years. While the trees are growing in full sun and provided with supplemental irrigation, they were planted in large containers on a roof deck and are exposed to strong winds. Container trees in urban settings often suffer from stress due to very high soil temperatures in the summer and freezing temperatures in the winter that they would not experience if they were established in the soil. No pests or pathogens were detected from the submitted sample.

Ruptured spruce needle rust (Chrysomyxa weirii) pustules on blue spruce (Picea pungens). The masses of spores are in close contact to the newly developing needles, setting the stage for infection. The infected needles are on the north-facing side of this tree where shade is more abundant and moisture lingers longer in the day.     Armored scale infestation of umbrella pine (Sciadopitys verticillata) caused by a species of Lepidosaphes. The scales cluster at the base of the needle, partially obscured by the sheath.    Close-up view of the spruce spider mite (Oligonychus ununguis) on a needle of white spruce (Picea glauca).    Mottled yellowing of white spruce needles as a result of spruce spider mite infestation.

For more detailed management information for woody plant diseases in the landscape, refer to UMass Extension's Professional Management Guide for Diseases of Trees and Shrubs.

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 and gypsy moth caterpillars feeding on the same oak in Hanson, MA (photo by Deborah Swanson). Cater-PALOOZA: A suite of caterpillars has been out for a while now, but are really picking up their pace as host plant foliage has expanded and we’ve experienced some warm weather and degree day accumulation. Multiple species can be found on shared hosts, such as these gypsy moth and winter moth caterpillars found on the same oak. Eastern tent caterpillar has been feeding now for some time and the cankerworms and forest tent caterpillar have joined us. Gypsy moth numbers are up this season and caterpillars are seen feeding on oak and other hosts. They are ballooning onto other hosts as competition rises and some folks have experienced dermatitis due to the insect’s urticating (irritating) hairs (see notes below). The Elkinton Lab has found 4th instar winter moth in Seekonk and Wellesley, but 2nd and 3rd instars are still out there. See section below for management.

  • Eastern Tent Caterpillar: Eastern tent caterpillar eggs have hatched and larvae are active at this time. Young caterpillars are found in tents in the crotches of branches, which are quickly growing larger. Remove small tents by pruning (when possible, without removing too much foliage) or destroy with a gloved hand. Do not set the tents on fire, as this can do more damage to the plant and surrounding area than the caterpillars ever could. Forest Tent Caterpillar eggs have hatched and small caterpillars are seen. 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. Bacillus thuringiensis Kurstaki is effective on young caterpillars.
  • Fall/Spring Cankerworm: These two species of geometrid moth caterpillars have hatched in areas above 148 GDD’s, base 50°F. 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 June. 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.
  • Gypsy Moth: Eggs of the gypsy moth have hatched. Tiny caterpillars can be observed dispersing in search of food. 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. At this time, as small caterpillars are dispersing, some individuals may experience skin rashes or dermatitis (particularly on exposed areas like the arms, neck, and legs) from the urticating hairs from these caterpillars. Children may be more sensitive to this problem than adults, although sensitivities may vary between individuals. Anti-itch creams may help provide some relief, but concerned individuals experiencing a rash due to gypsy moth should contact their physician or a dermatologist as necessary.
  • Winter Moth: (Continued monitoring) Operophtera brumata 2nd and 3rd instar caterpillars are being found in host plants such as maple, apple, willow, and blueberry in most locations. Wellesley and Seekonk are seeing 4th instars. Hosts whose buds opened earlier this season may be more significantly impacted. Continue to monitor susceptible hosts for the presence of caterpillars, feeding on foliage making it look like Swiss cheese, frass, and silken webbing holding leaves together. For green industry professionals looking to manage winter moth in the landscape, products containing active ingredients such as spinosad and pyrethroids are available. Apples, crabapples, and other flowering plants should not be sprayed with these products while in bloom to avoid unintended impacts to pollinators.
  • Azalea Sawfly: Amauronematus azalae is active on deciduous azaleas in areas where leaf expansion has occurred. Continue to monitor for the feeding damage of this caterpillar. Tiny sawfly caterpillars have been seen in areas like Boston, feeding on the edge of foliage and will wave their abdomen over their head when disturbed. 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 the newly emerging leaves. The use of yellow-sticky cards (1 per tree) works extremely 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. Larvae, which dwell in the soil, are conducting their heaviest feeding on plant roots at this time. Pupation will occur by the end of this month. Adults will emerge in June and create new damage to leaves for this season. All individuals are females and reproduce asexually. This insect has developed resistance to many chemical insecticides. Entomopathogenic nematodes such as Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacterio-phora work well against this insect, particularly on containerized plants. Results in the landscape vary. Wetting the soil thoroughly prior to application and keeping it wet for at least 5 days following application can help increase the efficacy of the nematodes. Burlap laid around the base of plants during the time adults are active, by the end of May through August, can be inspected weekly for adult weevils which can be killed before egg laying.
  • Boxwood Psyllid: Psylla buxi 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.
  • Cinara spp. Aphids: Aphids in the genus Cinara overwinter as eggs on the needles of conifer species found in New England. Many of these aphids, at maturity, are quite large and have long, almost spider-like legs. The eggs of this group of aphids have hatched at this time and young insects can be found feeding on small branches or the main stem of smaller trees including pines, fir, and spruce. Usually, management of these insects is not required. However, when populations are large on younger plants, management may need to be considered. Applications of insecticidal soap or horticultural oils at the summer rate can be considered, where appropriate.
  • Clover Mite: Bryobia praetiosa may be found on the underside of honeysuckle and elm foliage in areas reaching 192 GDD’s, 50°F. May cause bronzed or silvery appearance to foliage. When management is deemed necessary, insecticidal soap or neem oil may be used particularly in mid-late May when mites are most active. Observe product labels and avoid phytotoxicity.
  • Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. Crawlers will be present this month and throughout the growing season and the overlap of many developmental stages at any given time can be observed.
  • Emerald Ash Borer: Agrilus planipennis has been detected in a new county in Massachusetts. Officials from the MA Department of Conservation and Recreation and the United States Department of Agriculture have confirmed a find in Hampden County in the town of Wilbraham. This invasive insect readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus). 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 will be active in areas above 95 GDD’s, base 50°F. 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 will be active in areas above 78 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine, but is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned away and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis Kurstaki is not effective against sawflies.
  • Hemlock Eriophyid Mite: Nalepella tsugifoliae (also known as the hemlock rust mite) is currently active and should be monitored for on eastern hemlock, spruce, fir, and yew.
  • Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will hatch by late May or early June. Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary.
  • 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.
  • Honeylocust Plantbug: Diaphnocoris chlorionis generally appears at the same time as bud-break of the host plant. It immediately begins to feed on the foliage with its piercing-sucking mouth. If numbers are low and the foliage expands quickly then damage is insignificant. Damage in this case will appear as scattered patches of fine yellow stippling on parts of the leaflets. However, if this pest is present in large numbers or foliage expands slowly, damage caused may warrant management. Monitor for numbers of this pest by gently shaking branches over a white piece of paper. Examine carefully with a hand lens for the tiny pale green nymphs. Young nymphs can be treated with a spray of insecticidal soap.
  • 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 now 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.
  • Snowball Aphid: Neoceruraphis viburnicola is very active on certain species of viburnum and may be reaching the end of its activity on viburnum in warmer areas soon. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white with a white powdery finish, can be found in curled up and distorted foliage. Nymphs and alates (or winged dispersing adults) may also be found in distorted foliage. This pest is mostly aesthetically damaging; however, if chemical management options are deemed necessary, foliar applications of products containing active ingredients such as permethrin can be made as leaves are expanding. Once the aphids are concealed in the curled up foliage, reaching them with an insecticide can be increasingly difficult and efficacy is reduced.
  • Viburnum Leaf Beetle: Pyrrhalta virburni: Inspect newly emerging foliage for spotting caused by the feeding of tiny, pale-yellow larvae skeletonizing the leaves. Larvae may be treated with a product containing spinosad if found. Larvae are actively feeding in the Boston area. This pest has the potential of completely defoliating the host within 4-5 weeks of larval feeding.
  • White Spotted Pine Sawyer (WSPS): Monochamus scutellatus will be pupating this month and adults can emerge in late May throughout July, depending on local temperatures. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers, however the difference in the color of the scutellum is a key characteristic. 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: Aesculus x carnea

Aesculus x carnea is a hybrid from a cross between A. pavia and A. hippocastanum. It is a medium sized rounded tree growing 30-40’ tall and slightly less wide. It is quite showy in bloom with 6-8” high and 3-4” wide red panicle flowers. The large palmate compound leaves have 5 (sometimes 7) dark green leaflets and are 6-10” long. The fruit are rounded capsules that are slightly prickly. Red horsechestnut does best in full sun to part shade and prefers a moist, well-drained, fertile soil. Foliage can be scorched and declines during dry conditions. Once established they are difficult to transplant because of a tap root. Leaf blotch can be a problem along with powdery mildew and leaf spots. Aesculus x carnea is also susceptible to a fungal blight that can cause browning of leaves.

Aesculus x carnea    Aesculus x carnea

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Diagnostic Services

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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