Landscape Message: May 6, 2016

May 6, 2016
Issue: 
7

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 13. 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, April 28 through May 4. Soil temperatures and phenological indicators were observed on or about May 4. 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

4.5

85.5

52

48

0.87

3:45 PM 5/4

Southeast

4

90

54

50

0.75

4:10 PM 5/4

North Shore

0

72

48

45

0.45

10:00 AM 5/4

East

0

96.5

53

50

0.58

3:30 PM 5/4

Metro West

3

80.5

48

46

0.62

5:45 AM 5/4

Central

11

126

48

47

0.81

4:00 PM 5/4

Pioneer Valley

7

94

53

48

0.77

12:00 PM 5/4

Berkshires

6

80

53

49

0.87

11:00 AM 5/4

AVERAGE

4

91

51

48

0.72

-

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.
Spiraea x vanhouttei (Vanhoutte Spirea) * * * * * Begin * *
Syringa vulgaris (Common Lilac) * Begin Begin Begin Begin Begin Full *
Rhododendron spp. (Early Azaleas) Begin Begin Begin/ Full Begin Begin Begin Begin *
Cornus florida (Flowering Dogwood) * Begin Begin/ Full Begin Begin Begin Full *
Malus spp. (Crabapple) Begin Begin/Full Begin/Full Begin Begin/Full Begin/Full Full *
Cercis canadensis (Redbud) Begin Begin Begin Begin Begin Begin Full Begin
Amelanchier spp. (Shadbush, Serviceberry) Begin Full Full/End Full/End Full Full Full/End Full
Pyrus calleryana (Callery Pear) Begin/Full Full/End Full/End * Full/End Full/End Full/End Full/End
Chaenomeles speciosa (Common Flowering quince) Full Full Full/End Full Full Full Full/End Full
Magnolia soulangeana (Saucer Magnolia) Full/End Full Full/End Full Full Full Full/End *
Rhododendron 'P. J. M.' Full Full Full/End * Full Full Full *
Prunus serrulata (Japanese Flowering Cherry) End End End * End * Full Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The weather for this reporting period has felt more like March than May. Daytime temperatures rarely rose above 50° F, staying mostly in the upper 40s. Night time temperatures stayed in the low 40s. The sun rarely made an appearance, last being seen on Saturday the 30th of April. The jet stream has dipped and kept most of New England on the chilly, damp side. Every day has seen some precipitation, although generally not accumulating much more that 1/10th of an inch at a time. The exception was Tuesday, May 3rd, when the Cape received just shy of half an inch of rain. Plant development is progressing slowly due to the chilly weather. One benefit of the coolness is that those plants that are in bloom seem to have an extended period of looking good! Pearlbush (Exochorda racemosa) is beginning to bloom and tulips and creeping phlox are providing some bright color in the landscape.

Pests/Problems: Winter moth caterpillars are actively feeding on emerging foliage of maple and other host plants. In the Falmouth area, which appears to have plant development somewhat ahead of the rest of the Cape, Oak buds are breaking. Look for webbing and small holes in the new foliage. Tiny caterpillars can be observed if you look very closely. For those areas of the Cape particularly hit by Gypsy moth caterpillar last year, including the areas of Nickerson State Park and the Brewster/Harwich border, start monitoring for egg hatch as it should occur within the next week or so depending on temperatures. Lily leaf beetle adults are active. Hand pick before egg laying begins. Eastern tent caterpillar is getting a bit larger and can be seen in the webs.

Cedar-apple rust and Cedar-quince rust can be observed on eastern red cedar at this time.

Larry Dapsis, entomologist with the Cape Cod Extension, reports that deer tick nymphs are now active. This is the life stage most associated with transmission of Lyme and other pathogens. Take all precautions when working outdoors.

Rabbits continue to browse on emerging perennials.

Southeast Region (Hanson)

General Conditions: Overall, this past week has been cooler than usual with cold (many days in the 40’s) raw weather to start the month of May. The weather is very similar to the previous week of late April. Although it rained May 1, 2, 3, there was not very much of it. Hanson received only 0.75 inches of rain in that period and could use more. Sounding like a broken record, the cool weather continues to delay plant development. Magnolia x loebneri ‘Leonard Messel’ and Magnolia ‘Wada’s Memory’ have ended bloom but there are still a few star magnolias, along with Forsythia still in flower and the following plants are in full bloom: Magnolia soulangeana (Saucer Magnolia), Magnolia ‘Elizabeth’, Amelanchier (shadbush), Halesia sp., Prunus serotina (Black Cherry), Rhododendron ‘Olga Mezitt’, PJM Rhododendron, Chaenomeles speciosa (Common Floweringquince), Vaccinium corymbosum (highbush blueberry), Spiraea prunifolia f. simplicifolia (Bridlewreath Spirea), Spiraea thunbergii ‘Ogon’, Exochorda racemosa (Pearlbush), Epimedium sp., Rhododendron schlippenbachii (Royal Azalea), Kerria, Viburnum 'Mohawk', Mayflower viburnum, Flowering Almond, Saruma henryi, Helleborus foetidus, Glaucidium palmatum, Vinca, Pulmonaria, Trillium, Anemones, Lamiastrum sp., Lamium, Primula, Corydalis scouleri, Brunnera macrophylla, Ajuga, Lunaria, Sanguinaria canadensis ‘Multiplex’ (Double Bloodroot), Stylophorum diphyllum (Wood Poppy), Phlox subulata, Dicentra cucullaria (Dutchman’s Breeches), Lathyrus vernus, Dwarf Bearded Iris, Violets and Tulips. Kwanzan cherry and Saucer magnolia, while in full bloom, also suffered cold damage and flowers are few. The ground beneath several Saucer magnolias is littered with dead fallen buds. Cercis canadensis, Corydalis lutea, Lonicera tatarica (invasive), Phlox divaricata and bleeding heart are beginning bloom. Cherry 'Holly Jolivette', Pieris 'Brouwer's Beauty', Pieris floribunda (Mountain Pieris), Pieris japonica, Forsythia, Star magnolia, Helleborus x hybridus, Muscari botryoides Grape Hyacinth), Pachysandra terminalis and Erythronium americanum (Trout Lily) are ending bloom. All the wet weather has put a damper on lawn mowing.

Pests/Problems: Winter moth egg hatch progressed over 3 weeks In April and we are now seeing winter moth caterpillars at first, second and a few at third instar. The cool weather is very likely slowing winter moth caterpillar development along with plant development (405 Growing Degree Days, base 40). The caterpillars are small and green and in this cool weather, where foliage is slow to expand, the caterpillars can often be found feeding between the leaves which they have webbed together. Damage is not yet that noticeable but continue to monitor plants as foliage expands and caterpillars increase in size and continue to feed. Damage was noticed on some Japanese maples and rose foliage. Many oaks are just leafing out now and some oak foliage has yet to expand. Continue to monitor the following plants for winter moth and manage as needed: oaks, maples (Norway, sugar, red, Japanese), birch, roses, viburnums, crabapple, etc. Reports came in that Gypsy moth hatched last week in Foxborough and Hingham. Although the rain may slow green industry operations, it is beneficial for the Entomophaga maimaiga fungus that inoculates gypsy moth caterpillars. Hopefully, the rain will do just that and knock back the potential gypsy moth population. The following insects are active: red lily leaf beetle, ants, Eastern tent caterpillars, aphids, deer ticks, dog ticks, honeybees, wasps, carpenter bees, bumblebees, and solitary bees. Continue to use tick repellents and conduct tick checks frequently, especially now, as May is the month that we typically begin to see the very tiny Deer tick nymphs emerge and this is the stage most responsible for transmitting Lyme disease. Continue to monitor hemlocks for hemlock woolly adelgid and Mugo and other pines for European pine sawfly. Dandelions are still in full bloom but many some are setting seed. Bittercress is also setting seed. Violets, ground ivy, and chickweed are in bloom. The invasive plant, barberry is in bloom. Squirrels and rabbits continue to browse. With the rain, the orange, jelly-like galls of cedar-apple rust (Gymnosporangium) continue to be found on Eastern red cedar.

North Shore Region (Beverly)

General Conditions: Cooler temperatures have persisted during this reporting period. Day temperatures have been in the low 50s and night temperatures have been in high 30s and low 40s. There were no gains for growing degree days at Long Hill during this reporting period. Cloudy weather and rain showers were reported most of the days during this reporting period. At Long Hill we recorded a total of 0.45 inches of rainfall during this period. Woody plants still in bloom since the last reporting period include: Star magnolia (Magnolia stellata), Shadblow serviceberry (Amelanchier canadensis), Callery Pear (Pyrus calleryana), Burkwood viburnum (Viburnum x burkwoodii), Mountain andromeda (Pieris floribunda) and yellow root (Xanthorhiza simplicissima). New woody plants seen in bloom include: Flowering Dogwood (Cornus florida), Redbud (Cercis canadensis), Witch-alder (Fothergilla major), Royal azalea (Rhododendron schlippenbachii) and Highbush blueberry (Vaccinium corymbosum). (Non-woody plants seen in bloom include: Bloodroot (Sanguinaria canadensis), Vinca vine (Vinca minor), Daffodil (Narcissus spp.) Japanese wood poppy (Glaucidium palmatum), forget me not (Myosotis sylvatica) and tulips (Tulipa sp.), Bleeding heart (Dicentra spectabilis) and Trout lily (Erythronium americanum).

Pests/Problems: Ticks are still active and people should be careful to protect themselves when working outdoors. Young caterpillars of Eastern tent caterpillars have been seen in the tents. Some weeds seen in bloom include: Dandelion (Taraxacum officinale), Fig buttercup (Ranunculus ficaria), Ground Ivy (Glechoma hederacea) and Purple Deadnettle (Lamium purpureum).

East Region (Boston)

General Conditions: We experienced cool temperatures over the last week, lows ranging from 32° F to 45° F, averaging 39° F and high temperatures ranging from 50° F to 63° F, averaging 56°F. Temperatures have been consistently cooler than average, at this time of year, we should be experiencing highs in the low 60s. We gained zero GDDs over the last week and remain at 96.5 GDDs. (For those tracking GDDs base 40, we gained 50 GDDs over the last week, bringing us to 505 GDDs). Light frost was visible on turf on the morning of the 27th. May has been cold, wet and dreary thus far: overcast conditions, cool temperatures and on-and-off rain delivered 0.58 inches of precipitation. Despite cool conditions, trees continue to slowly leaf out. Turf has greened up and mowing has commenced. Many plants are adding color to the landscape: Acer henryi (Henry maple), Betula lenta (sweet birch), Corylus sp. (hazel), Enkianthus perulatus (white enkianthus), Exochorda x macrantha ‘The Bride’ (pearlbush), Fothergilla major (mountain witch alder), Magnolia (magnolia) cultivars ‘Elizabeth’ and ‘Galaxy’, early flowering Malus sp. (apple and crabapples), Malus mandshurica (Manchurian crabapple), late Prunus sp. (cherry), Rhododendron ‘Caronella’ (rhododendron), Rhododendron schlippenbachii (royal azalea),Trillium sp. (trillium),Vaccinium corymbosum (highbush blueberry), and Viburnum carlesii (Koreanspice viburnum). Early blooming lilacs (Syringa x diversifolia, S. x hyacinthiflora, and S. oblata) are in flower and some common lilac (S. vulgaris) cultivars are starting to blossom. A green heron (Butorides virescens) was observed feeding from the ponds; orioles are busy building nests. Despite the high quantities of pollen distributed by trees in bloom, allergy levels are low due to the recent precipitation.

Pests/Problems: Black swallowwort (Cynanchum louiseae) Japanese knotweed (Fallopia japonica) are emerging, garlic mustard (Alliaria petiolata) and white morning glory (Ipomea sp.) have germinated. Catchweed bedstraw (Galium mollugo) and mouseear chickweed (Cerastium vulgatum) are growing well and getting larger. Weeds in seed include: garlic mustard (Alliaria petiolata), hairy bittercress (Cardamine hirsuta), and shephard’s purse (Capsella bursa-pastoris). Weeds in flower include: dandelion (Taraxacum officinale), greater celandine (Chelidonium majus), ground ivy (Glechoma hederacea), lesser celandine (Ficaria verna), and purple deadnettle (Lamium purpureum). Hydrangea leaf tier (Olethreutes ferriferana) has hatched and is visible on hydrangeas [Hydrangea arborescens ‘Dardom’ (smooth hydrangea) and H. radiata (silverleaf hydrangea) as they have sown terminal leaves together creating a protective “leaf tier” in which they are feeding. Cooler temperatures have been favorable for winter moth (Operophtera brumata) as trees have been slow to leaf out, allowing larvae protection to continue feeding within the slow opening bud. There was some damage to the lilacs that occurred on the evening of the 26th/morning of the 27th as temperatures dipped to 32° F.

Metro West (Acton)

General Conditions: The month of May has started out with some cool and damp weather. There has been precipitation recorded every day and the forecast for the next several days calls for even more moisture. Much is in bloom for this time of the year, including the following woody plants: Amelanchier spp. (Shadbush, Serviceberry), Cercis canadensis (Redbud), Chaenomeles speciosa (Common Flowering Quince), Cornus florida (Dogwood), Daphne x burkwoodii 'Carol Mackie'(Daphne), Forsythia spp. (Forsythia), Fothergilla gardenii (Dwarf Fothergilla), F. major (Large Fothergilla), Halesia tetraptera (Mountain Silverbell), Magnolia ‘Elizabeth’, M. x loebneri 'Merrill', M. x soulangeana (Saucer Magnolia), Malus spp. (Crabapples), Pieris japonica (Japanese Pieris), Prunus spp. (Cherry) including Prunus serrulata 'Kwanzan' (Japanese Flowering Cherry), P. japonica (Flowering Almond), P. serotina (Black Cherry), Rhododendron 'P. J. M.'(PJM Rhododendron), R. spp. (early flowering Rhododendron), Spirea thunbergii (Thunberg Spirea), Syringa spp.(early blooming Lilac), Vaccinium angustifolium (Lowbush Blueberry), V. corymbosum (Highbush Blueberry), Viburnum x burkwoodii (Burkwood Viburnum), and Viburnum × juddii (Judd Viburnum). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Ajuga reptans (Bugleweed), Aquilegia canadensis (Columbine), Anemone nemorosa (Wood Anemone), Arisaema triphyllum (Jack-in-the-Pulpit), Asarum europaeum (European Ginger), A. canadense (Canadian Wild Ginger), Aurinia saxatilis (Basket of Gold), Caltha palustris (Marsh Marigold), Chrysogonum virginianum (Green and Gold), Dicentra canadensis (Squirrel Corn), D. cucullaria (Dutchman's Breeches), D. 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), Helleborus niger (Christmas Rose), Hyacinthus spp. (Hyacinth), Iberis sempervirens (Evergreen Candytuft), Lunaria annua (Money Plant), Mertensia virginica (Virginia Bluebells), Muscari sp. (Grape Hyacinth), Narcissus spp. (Daffodil), Nepeta spp. (Ornamental Catmint), Omphalodes verna (Blue-eyed Mary), Phlox divaricata (Canadian Phlox), P. x subulata (Moss Phlox), Polygonatum commutatum (Great Solomon Seal), P. odoratum 'Variegatum' (Variegated Solomon Seal), Primula spp. (Primrose), Sanguinaria canadensis (Bloodroot), S. canadensis 'Multiplex' (Double Bloodroot), Stylophorum diphyllum (Wood Poppy), Tiarella cordifolia (Foam Flower), Trillium erectum (Red Flowering Trillium), T. grandiflorum (White Flowering Trillium), T. sessile (Toadshade), Tulipa spp. (Tulip), Uvularia sessilifolia (Bellflower), Vinca minor (Periwinkle), Viola spp. (Violet), Waldsteinia ternata (Barren Strawberry) and Zizia aptera (Heart-Leaved Alexander).

Pests/Problems: There is significant dieback, if not total death,and needle discoloration on a number of Pinusstrobus (White Pine). There may be two different causes for this. Those impacted trees growing alongside roadways may be stressed by snow and ice winter road treatments, heat and drought. A needle cast/blight may be impacting those trees not growing alongside roadways and in some cases growing in low lying wetter areas that are showing signs of needle discoloration that starts at the needle tips. Winter moth caterpillars are actively feeding and were seen on Malus (Crabapple) and Prunus (Cherry) as evidenced by the damage to the leaves and the culprit can be seen by unfurling the leaves on the host trees to reveal the caterpillar upon close inspection. Alliaria petiolata (Garlic Mustard), which is easily seen with its white flowers growing on roadsides and in woodlands, wetlands and gardens continues to flower.

Central Region (Boylston)

General Conditions: Cooler conditions have kept many early blooming plants looking fine - Narcissus continues to bloom, tulips are in full swing, Pulmonaria, Muscari armeniacum, Pieris floribunda, Pieris ‘Brouwer’s Beauty’, Corylopsis pauciflora, Arctostaphylos uva-ursi, Bergenia cordifolia, Phlox subulata, Dicentra spectabile, Mertensia virginica, Glaucidium palmatum, Magnolia ‘Elizabeth’, Viburnum carlesii, Vinca minor, and Aurinia saxatilis are among the plants providing color this week. Vaccinium angustifolium and V. corymbosum, Fothergilla gardenii and F. major, and Phlox stolonifera are beginning to bloom.

Pests/Problems: Eastern Tent Caterpillar webs are expanding. Dandelions (Taraxacum officinale), Garlic Mustard (Allaria petiolata) and Gill-over-the-Ground (Glechoma hederacea) are blooming.

Pioneer Valley Region (Amherst)

General Conditions: Cool and cloudy weather with scattered rain has been the dominant pattern this reporting period. The clouds rolled in during the early morning hours of Sunday 5/1 and aren’t expected to break up until Friday, 5/6. There has been a regular light rain during this overcast stretch that doesn’t even appear on weather radar systems. Badly needed rainfall has accumulated less than 1″ throughout the valley, with the brunt of that total occurring on the morning of Monday, 5/2 when roughly 0.5″ was recorded at most weather stations. The long-term forecast, aside from clear conditions on Monday, 5/9, calls for continued cloudy and rainy weather. This first week of May has been lacking sun with below-average temperatures and without significant rainfall accumulations. High temperatures this period have ranged from the low 50s to the upper 60s while low temperatures have ranged from the low 30s to the upper 40s. Soil temperatures continue to hover in the upper 40s to low 50s, turfgrass is vibrant green and growing strong and many trees and shrubs are slowly developing new growth. The spring winds have noticeably calmed as of late and hopefully the wet, cool and overcast weather has eliminated the fire danger that was so prevalent throughout the region in April. Dwarf white spruce, dawn redwood and hemlock have joined larch, balsam fir and yews as conifers flushing new needles. Pine candles continue to elongate but are not yet flushing. Norway spruce and Douglas-fir buds are very swollen and some have broken but overall appear to be waiting for warmer weather to continue flushing. Blue spruce buds are slowly swelling but won’t be flushing over the next 7–10 days.

Pests/Problems: The cloudy weather and gentle rain has been ideal for planting of tender perennials and has also taken some of the stress off transplanted trees and shrubs, especially those with less-than-ideal root systems. We still have not received the soaking rain that we need to thoroughly wet the upper soil horizon so continue to monitor and irrigate accordingly. Cedar-apple and quince rust continue to sporulate and orange-colored gelatinous masses are very abundant right now on Juniperus. Apple scab spores are also abundant right now and are establishing on succulent foliage of crabapple and apple. The below-average temperatures will hopefully limit the growth of anthracnose fungi on dogwood, maple and sycamore but the persistent cloud cover and light rain is ideal for sporulation and spread of these pervasive tree and shrub pathogens. Pruning of blighted shoots on flowering dogwoods should quite easy now as the trees are in full bloom and dead parts are easy to recognize. Winter injury on rhododendron and azalea is also obvious by this point. These dead plant parts should be pruned and discarded to discourage colonization by opportunistic pathogens. Mosquitoes were not much of an issue in late April and the cool weather has kept their populations suppressed. But with the recent rain they will emerge once temperatures warm. Scout properties for standing water where egg masses will be laid.

Berkshire Region (Great Barrington)

General Conditions: It’s been another cool week with daily temperatures below normal. This is reflected in the small gain in GDD. Frosts occurred in most areas of the county on the mornings of April 27th and 28th. Only on April 30th did temperatures reach the 60° F mark. Daytime high temperatures were in the low to mid-50s. Coupled with cloudy, breezy, and wet weather, working outdoors was not very comfortable. As expected with such cool conditions, plant development during the period was slow. The sparsely flowering star magnolias (Magnolia stellata) still hang on to the few blossoms which survived the frigid temperatures on the mornings of April 5 and 6. Flowering of Japanese Andromeda (Pieris japonica) is at its peak and showiest stage. In most of the state, these have already completed their flowering. May 1st began a procession of rainy days and the prospect ahead is that this pattern will continue for a while. At the end of April, rainfall deficits were near 3 inches. As such, the rain was welcomed. Interestingly, the rain has been persistent but light to moderate, that is, without any heavy downpours. On the plus side, this means that the rain has soaked in rather than run off soil surfaces or eroded soil as is the case during heavy rains. Soil moisture levels in the upper 4-6 inches of soil are good. On the down side, persistent wetness of emerging leaves on plants facilitates infection by plant pathogens. This will become more of an issue as temperatures increase to above 60° F as is expected in the week ahead. Persistent moisture and warm temperatures favor development of foliar diseases.

Pests/Problems: Pest development continues to be slow due to cool conditions. Still no sightings or reports of Eastern tent caterpillars. Blacklegged ticks, eriophyid mites (on Hemlock), lily leaf beetle, and carpenter bees remain active. Biting midges, commonly referred to as no-see-ums, have been anuisance on the few warm days of the past week. They’ll become more of a nuisance in the coming week when temperatures are expected to reach into the 60s and low 70s. The usual plant browsers, i.e. deer, rabbits, and voles, continue to dine on emerging plants and developing foliage. The orange blisters of spruce needle rust (Chrysomyxa weirii) were found on one specimen. Marginal necrosis or death of entire leaves on several trees and shrubs continue to appear on many species of trees and shrubs with crabapple, lilacs, and viburnums being some of the most severely affected. Considerable browning of foliage on boxwood and rhododendrons is becoming apparent. Flower buds on PJM rhododendrons are extremely slow to open though inspection of a few buds indicated that they were still alive. That is not the case with many magnolia hybrids including Magnolia ‘Butterflies’ and ‘Elizabeth’. Dissection of flower buds on these as well as Magnolia soulangeana has found the flower buds to be dead.

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

Severe stem cankering of rose (Rosa sp.) caused by Phomopsis and Colletotrichum. 10-year-old shrub, present at the site for eight years, growing in a foundation bed with full sun and drip-irrigated on regular intervals. This spring, it was determined that all vegetative growth was dead. Submitted canes had sunken lesions and a dark discoloration of the bark that is consistent with cankering. Fruiting bodies of both fungi were prolific from most of the canes but symptoms of cankering were not observed last year. The plant was likely infected in 2015, possibly predisposed by cold injury from the record cold temperatures during the winter of ′14–′15.

Armored scale (Lepidosaphes sp.) infestation of umbrella pine (Sciadopitys verticillata). Tree is approximately 10-years-old, has been present at the site for six years, and is growing in full sun in a landscape setting with no supplemental irrigation. Over this past winter, needles throughout the canopy turned brown. Scales were abundant at the base of the needles, partially obscured by the sheath. This is the second sample from umbrella pine this season harboring the pest.

Needle browning of eastern white pine (Pinus strobus). There have been several reports to the diagnostic lab of widespread needle browning of white pine in the metro west and northeast regions of Mass. Multiple samples have also been submitted where no pest or pathogen can be detected. While needle cast of white pine continues to be a major issue in the region, needle browning can result from a multitude of stresses that may include: root disease, drought, mechanical root damage and insect infestation.

Canopy dieback of boxwood (Buxus sp.) caused by Volutella buxi and Macrophoma candollei. Shrub is 20-years-old and has been present at the site for over 15 years. Significant yellowing and spotting was observed on the foliage this spring, along with blighted shoots. Dark-colored stem and foliar lesions, similar to those caused by the boxwood blight pathogen Calonectria, were also observed. At times Volutella can create these dark lesions and the pathogen was abundant on the submitted sample. Overhead irrigation likely aided in disease development and spread.

Sunscald injury on the southwest side of the trunk of Japanese Flowering Cherry (Prunus serrulata). Ornamental cherry and plum are particularly susceptible to sunscald injury.

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:

  • Azalea Sawfly: Amauronematus azalae is active on deciduous azaleas as soon as new foliage emerges. Monitor for the feeding damage of this caterpillar as soon as new foliage appears and continue monitoring for 3-4 weeks after. In that amount of time, this insect could completely defoliate the plant if present in large numbers. Spinosad based products are effective on this hymenopteran pest, while Bacillus thuringiensis Kurstaki is not.
  • Balsam Twig Aphid: Mindarus abietinus is active at this time. Inspect the needles of fir for “stem mothers” that will soon be reproducing. Young aphid feeding will lead to distorted foliage. Excessive amounts of honeydew are produced and cause needles to stick together. Monitor for the presence of reproducing females and treat with an oil application as weather permits.
  • Birch Leafminer: Fenusa pusilla will be active in areas approaching 100 GDD’s, base 50°F, or when newly emerged leaves are approximately the size of a dime. 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.
  • Hatched Cinara spp. aphid eggs observed on Japanese black pine needles in Amherst. 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, tiny 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.
  • Cooley Spruce Gall Adelgid: Adelges cooleyi is active at this time. This insect can be found in the crevices of bark on terminal twigs and bases of buds of blue spruce, Norway spruce, and Douglas fir.
  • Eastern Tent Caterpillar: Eastern tent caterpillar eggs have hatched and larvae are active at this time. Young caterpillars are found in small tents in the crotches of branches. Remove small tents by pruning (when possible, without removing too much foliage) or destroy with a stick or other object. Do not set the tents on fire, as this can do more damage to the plant and surrounding area than the caterpillars ever could. Remove Forest Tent Caterpillar egg masses before we reach 192 GDD, base 50°F, when hatch will occur.
  • Hatched gypsy moth caterpillars on top of their egg mass, seen on 5/2/2016 in Hingham. (Photo courtesy of the MA Department of Conservation and Recreation.) Gypsy Moth: Eggs of the gypsy moth have begun to hatch in the towns of Brimfield and Hingham. Tiny caterpillars can be observed resting on their egg masses. Serviceberry (shadbush) is blooming and is the phenological indicator for egg hatch of this insect. Let’s hope for the wet and rainy weather to continue so that the entomopathogenic fungus, Entomophaga maimaiga, can get well established in the gypsy moth population and help reduce the amount of young caterpillars. 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.
  • Elongate hemlock scale (Fiorinia externa) on fir. (Photo courtesy of Nicholas Brazee.) 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. Management options can be seen in the Landscape Message: Mar. 18, 2016.
  • Euonymus Caterpillar: Yponomeuta cagnagella will be active soon, 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 soon. 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 Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. Infested trees may be treated with a summer rate horticultural oil spray once weather conditions allow. For other management options, see the Landscape Message: April 1, 2016.
  • 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: Lilioceris lilii should be monitored for at this time. 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. Pyrethroids can be used against adult beetles, whereas spinosad products are most effective against the larvae.
  • Pine Bark Adelgid: Pineus strobi has been observed in the Amherst area actively feeding at this time and secreting large amounts of waxy-white wool over their bodies (on white pine). This insect can be found on the trunk, twigs, and branches of white, Scotch, and Austrian pines. These cottony masses can even be seen on the bases of needles. On healthy trees, this insect has not warranted management as they appear unaffected by its feeding. If aesthetically unpleasant, adelgids and wool may be washed off with a strong stream of water from a garden hose on smaller plants.
  • Snowball Aphid: Neoceruraphis viburnicola is now being seen on certain species of viburnum. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage and have been observed to be active in Amherst, MA. 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 at this time.
  • 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. This pest has the potential of completely defoliating the host within 4-5 weeks of larval feeding.
  • Winter Moth: (Continued monitoring) Operophtera brumata egg hatch has been complete for the past few weeks and 1st and 2nd instar caterpillars are being found in host plants such as maple, apple, and blueberry. A few 3rd instar caterpillars may also be present (see Southeast Region update). Hosts whose buds opened earlier this season may be more significantly impacted, however as we are seeing oak buds open the caterpillars are quickly taking advantage of the newly available real estate. The Elkinton Lab has observed oak buds in Falmouth and Yarmouth to be further along in development than those on the south shore in some cases (the Cape is usually a week behind but perhaps this is not the case in all areas on the Cape this season). Silk and frass (excrement) may be seen on newly emerged leaves of hosts and tiny caterpillars seen with a hand lens. Continue to monitor susceptible hosts for the presence of caterpillars. For green industry professionals looking to manage winter moth in the landscape, wait until leaves have opened to treat with insecticides. By waiting until the leaf expands, it is easier for the insecticide to reach the caterpillar than when it is protected inside the bud. 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.

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: Viburnum x juddii

Viburnum x juddii is a hybrid of V. carlesii and V. bitchiuense propagated by William H. Judd and introduced at the Arnold Arboretum in 1920. It is a rounded deciduous shrub growing 6-8’ tall and wide. The wonderfully fragrant, semi-rounded flower cymes emerge in spring and are in bloom for around 2 weeks. Flower buds are pink opening to white. The ovate leaves are green in spring and summer turning red in the fall. Viburnum x juddii has better resistance to bacterial leaf spot than either parent. It is best grown in full sun to part shade and can be planted as a specimen or can make a great addition to a mixed border.

Viburnum x juddii     Viburnum x juddii     Viburnum x juddii

Landscape Turf

Mowing and Wet Weather

This weekend is Commencement Weekend at UMass Amherst, and the grounds staff have been working hard to get the lawns and landscapes on campus into fine shape ahead of the festivities. One of the big challenges in this regard has undoubtedly been the persistent rain that has characterized this week. While the rain is welcome in terms of replenishing soil moisture, it certainly puts a damper on outdoor work at a time when things are really beginning to ramp up.

For turf care, prolonged wet weather can really play havoc with maintenance demands, especially mowing schedules.  The detrimental effects are similar for everyone, from lawn care crews, to golf course managers, to homeowners.  Combine ongoing rain with great conditions for turf growth and the result is either some wet mower operators or some tall grass.

Mowing when the surface is dry is ideal from a cutting quality standpoint, as well as lessening concerns like the spread of fungal diseases. Mowing when the turf surface and the soil are wet has several drawbacks. Mulching and discharge features on mowers usually do not work as effectively, and clippings often clump unattractively. The negative effects of less-than-sharp blades or out-of-adjustment mowing decks are magnified. The potential for soil compaction and wear injury to the turf are increased, especially when turning equipment. The slick surface can result in slips and falls while walk-mowing, or even loss of control while riding, especially on slopes.

The message, therefore, is that mowing during wet conditions should be avoided whenever possible. Realistically, however, this is not always feasible. There are schedules to keep, deadlines to meet, and you can only let the grass grow out so far before you end up with bigger problems.

The best advice involves common sense. Take it slow, make sure your blades are sharp and that cutting height is properly adjusted. Overlap your passes a little more than usual to account for increased chance of skips and misses. Avoid turning equipment on the turf surface when at all possible. If clumps of clippings are unacceptable, we won't hold it against you if you bag a time or two, but those soggy clippings are much harder to handle. Wear sturdy footwear with good traction while walk-mowing. Exercise extreme caution or avoid mowing significant slopes when wet, especially with riding equipment. If you opt to wait out the wet weather and the height of the turf becomes excessive, bring it down gradually over a few mowing events rather than all at one time.

Report by Jason Lanier, Extension Educator, UMass Extension Agriculture and Landscape Program

Garden Retailers

Botrytis on Plants in Retail Areas

Cloudy, rainy weather, cool nights and retail yards full of hanging basket and other herbaceous plants provide an ideal environment for Botrytis. Botrytis blight has been seen just about everywhere and has been especially severe on the more tender and or plant tissues plants (Diascia, Nemesia, Geraniums, New Guinea impatiens, centers of combination planters, Calibrochoa, Basil). In outdoor perennial yards susceptible plants include lilies and peonies. Botrytis symptoms may include leaf spots, flower blights, bud rots, stem cankers, and stem and crown rots and can be mistaken for other causes.

Generally, Botrytis spore germination and infection depends on a film of moisture for 8-12 hours, relative humidity of 93% or higher and temperatures of 55-65º F. After infection plant tissue colonization occurs at temperatures up to 70º F

To manage Botrytis, keep plants in retail areas clean. Remove dead and injured plants and spent flowers a couple times a day even during the busy season. Clean plants by shaking hanging baskets over a trash barrel to dislodge spent flowers and keep the trash barrel covered with a lid. Encourage employees to carry pruning shears and wear work aprons with large pockets where they can keep dead flowers and debris from plants in the sales area until they can find a waste can. Botrytis and high ethylene concentrations from decaying plant tissue cause premature loss of foliage and flowers.

During cloudy weather, water sparingly, running plants on the dry side. Spot water areas as needed to prevent over-watering. Avoid watering late in the day or when water will sit on leaf surfaces for long periods of time. Water by lowering the breaker down near the soil surface of the pot and move from pot to pot, watering each plant individually (rather than to hold the wand high overhead like a shower). This allows the waterer to control the amount of water that goes into each pot by holding the breaker at each pot for a consistent 1-2-3 count (depending on the size of the pot). This minimizes the amount of foliage that gets wet and water and fertilizer is directly delivered into the pot efficiently.

Reported by Tina Smith, UMass Extension Floriculture Specialist

Additional Resources

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For a complete listing of upcoming events, see our Upcoming Educational Events page.

For commercial growers of greenhouse crops and flowers - Check out the New England Greenhouse Update website

For professional turf managers - Check out Turf Management Updates

For home gardeners and garden retailers - Check out home lawn and garden resources. UMass Extension also has a Twitter feed that provides timely, daily gardening tips, sunrise and sunset times to home gardeners, see https://twitter.com/UMassGardenClip

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