Landscape Message: May 8, 2015

May 8, 2015
Issue: 
8

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 15. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.

Scouting Information by Region

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: This reporting period started off on the grey and chilly side, with temperatures in the low 50s F and with a brisk breeze off the water most days. While it was warmer off-Cape, our temperatures have remained cooler. Temperatures began to improve by 5/4 and have remained mild since then. There has been no rainfall this past week, which, when combined with the below average rainfall for April, has left our sandy soils rather dry. With no foreseeable steady rain over the next few days, gardens are drying out and could benefit from irrigation. Early tulips are beginning to bloom. Daffodils are in full bloom. Pulmonaria and Creeping phlox are beginning to bloom in the perennial border.  Pests/Problems: Winter moth caterpillars continue to hatch and will soon be in the free feeding stage as tree foliage begins to expand. Small webs of eastern tent caterpillar can be seen in branch crotches of wild black cherry. Monitor crabapple for this pest and remove while the webs are small. Monitor mugo pines for hatching European sawfly caterpillars. Ant nests can be observed in thin turf in sunny, dry areas.  Dandelions are in bloom, along with garlic mustard, bittercress, and shepherd’s purse. Crabgrass is germinating.  Remember to do thorough tick checks after working outdoors. Be sure to use a repellant.

Southeast Region (Hanson)

General Conditions:  The weather warmed up into the 70s this past week with 80 degrees happening on Monday. Hanson received trace (0.03 inches) amounts of rain. Soils are dry and spring flowers are wilting. Without moisture and/or cooler temperatures, spring flowering plants may quickly go by. Plant development is still behind this season, but catching up fast.  Cornus florida (flowering dogwood) bracts are expanding and starting to show color. Cercis canadensis buds are swelling but have not yet opened. Magnolia ‘Elizabeth’, Magnolia x soulangeana (Saucer Magnolia), Magnolia stellata (Star magnolia), Magnolia kobus var. loebneri ‘Leonard Messel (Magnolia 'Leonard Messel'), Prunus sp. (cherries), Pyrus calleryana (Callery pear), Sassafras albidum, Chaenomeles speciosa (Common Floweringquince), Azalea ‘April Snow’, Azalea ‘April Love’, ‘PJM’ rhododendron, Spiraea prunifolia (Bridalwreath Spirea), Spiraea thunbergii ‘Ogon’, Lonicera fragrantissima (Winter honeysuckle), Rhododendron mucronulatum, Forsythia, Pieris floribunda, Pieris ‘Brouwer’s Beauty’, heaths, heathers, Stylophorum diphyllum (Wood Poppy), Glaucidium palmatum, Dicentra spectabilis (Bleeding Heart), Epimedium sp., Muscari botryoides (Grape Hyacinth), Phlox subulata, Arisaema dracontium, Saruma henryi, Lamium sp., Trillium sp., Pulmonaria sp., Uvularia grandiflora, Anemone sp., Primula sp., Omphalodes verna, Corydalis solida, Corydalis scouleri, Sanguinaria canadensis (Bloodroot), Brunnera macrophylla, Dicentra cucullaria (Dutchman’s Breeches), Pachysandra terminalis, Helleborus foetidus, Helleborus x hybridus, (Lenten Rose), daffodils, Tulips, Hepatica, Ranunculus ficaria and Vinca minor are in full bloom. It is a fabulous year for flowering cherries! Magnolia ‘Wada’s Memory’, Corylopsis spicata, Corylopsis pauciflora, Abeliophyllum distichum, Norway maple, Lindera benzoin (Common Spicebush), Cornus officinalis and Cornus mas have ended or are ending bloom.  Pests/Problems: Winter moth caterpillars are in very late first instar and some are in second instar. They are small, about half the length of an eyelash, and pale green. They will quickly grow and will feed usually until the end of May. Damage is not very noticeable now but will become more so as they become larger and continue to feed. Caterpillars were found in the expanding tips and/or free feeding on the foliage of the following plants: Oaks, Maples (Norway, sugar, red Japanese); European and American beech; birch, apple and crabapple. They were also found in the developing flower buds of blueberry and apple. Continue to monitor plants susceptible to winter moth caterpillar feeding and manage early to contain damage. Snowball aphid stem mothers were found in the distorted foliage of mayflower viburnums. These aphids will produce many more aphids. Bright red lily-leaf beetles are feeding, mating and laying eggs on true lilies. Manage early to avoid damage. Continue to monitor for European pine sawfly on Mugo and other pines. Eastern tent caterpillars, ants, mosquitoes, deer ticks, dog ticks, hover flies (beneficial), honeybees, wasps, carpenter bees, bumblebees, and solitary bees are active. Violets, chickweed, and bittercress are in bloom. Bittercress is also setting seed. What a banner year for dandelions and violets! Deer, squirrels and rabbits continue to be problematic. Hosta has emerged and is a “deer favorite food”. Squirrels are once again eating Rhododendron buds, before they open. Hummingbirds are back, along with Baltimore Orioles!

North Shore Region (Beverly)

General Conditions: This reporting period was dry with no precipitation. Most days were sunny with clear skies and temperatures rising up to the high 70s. It felt like summer on sunny days. Although the conditions were dry, plants are not showing moisture stress yet. Lawns are are greening up and gardeners and landscapers were busy doing spring clean up. Many plant species continue to be in full bloom and others are beginning to bloom. Woody plants in full bloom include: Giraldi forsythia (Forsythia giraldiana), Tremonia border forsythia (Forsythia x intermedia 'Tremonia'), Higan Cherry (Prunus subhirtella) Merrill magnolia (Magnolia x loebneri 'Merrill'), Magnolia cylindrica, Winter hazel (Corylopsis winterthur), Norway maple (Acer platanoides), Pieris (Pieris japonica), Korean rhododendron (Rhododendron mucronulatum). Woody plants beginning to flower include: Shadbush (Amelanchier canadensis) and early Azaleas (Rhododendron sp.). Herbaceous plants in bloom include: Trout lilies (Erythronium americanum), Daffodils (Narcissus spp.), Bloodroot (Sanguianaria canadensis), Puschkinia (Puschkinia libanotica), Pachysandra (Pachysandra terminalis), Vinca vine (Vinca minor), Bishop’s heart (Epimedium grandiflorum), Forget-me-not (Myosotis palustris) and Japanese wood poppy (Glaucidium palmatum). Herbaceous plants in bloom include: Tulips (Tulipa spp.) and Bleeding hearts (Lamprocapnos spectabilis).  Pests/Pests: Spring weeds such as Dandelions (Taraxacum officinale) and Henbit (Lamium amplexicaule) are in bloom. Ticks were very active because of warmer temperatures. Make sure to check for ticks after working outdoors and use tick repellents before going outdoors. Winter moth eggs have all hatched. You can apply a registered insecticide spray before the young larvae start to cause a lot of damage.

East Region (Boston)

General Conditions: Summer arrived on May 4th, basically skipping spring. We reached a high of 85º F on the 4th and 79º F on the 5th. We gained 54.5 Growing Degree Days over the past seven days, more than doubling our total accumulation for the year for a total of 105 GGD’s. Turf is green and growing. Many plants are flowering and adding color to the landscape. The earliest flowering magnolias have succumbed to the heat while many others are coming into full bloom. Several hybrid magnolias (M. ‘Elizabeth’ and M. ‘Galaxy’) are in peak bloom. Many flowering Prunus sp. (almond, apricot, cherry, peach and plum) are in full bloom. Early Azaleas (Rhododendron sp.), crabapples (Malus sp.) and spiraeas (Spiraea sp.) are flowering. Maples (Acer sp.), elms (Ulmus sp.) and oaks (Quercus sp.), are flowering and distributing pollen. The low-growing Mahonia aquifolium (Oregon grapeholly) is adding colorful yellow to the understory. The rare pink flowered Staphylea holocarpa ‘Rosea’ (bladdernut) is in full bloom. Pests/Problems: Despite the late spring snow melt – soils have quickly dried out. We received 0.02” of precipitation over the past seven days. Recent transplants require supplemental watering. Typical weeds are running rampant throughout the landscape. Garlic mustard (Alliaria petiolata) is flowering. Japanese knotweed (Fallopia japonica) has emerged and is 4-6” tall in some areas. Dandelions (Taraxacum officinale) are blooming in unmanaged turf areas. The larch casebearer (Coleophtera laricella) is active in the larval stage. Winter moth caterpillars remain relatively small but are actively feeding as susceptible hosts experience bud expansion. On May 5th the Arboretum was the grateful recipient of the release of 2000 Cyzenis albicans (fly) from the labs of Joe Elkinton, Professor of Environmental Conservation at UMass, Amherst . Research has shown that this tachinid parasitoid can control winter moth populations in 3-4 years if the flies successfully colonize the area.

Metro West (Acton)

General Conditions: Spring is exploding with the recent spell of summer like temperatures. Lawns continue to green up and the mowing crews are out in force. The total rainfall recorded for the month of April was 2.26", significantly shy of the monthly average of 4.16". That trend continues into this first reporting period for May with 0.01” of rain recorded for the week. Woody plants seen in bloom this past week are Amelanchier spp. (Shadbush, Serviceberry), Cercis canadensis (Redbud), Chaenomeles speciosa (Common Flowering Quince), Forsythia spp. (Forsythia), Fothergilla gardenii (Dwarf Fothergilla), F. major (Large Fothergilla), Magnolia x loebneri 'Merrill', M. x soulangeana (Saucer Magnolia), M. stellata (Star Magnolia), M. 'Butterflies' (Magnolia Butterflies), M. 'Yellow Lantern (Yellow Lantern Magnolia), Lindera benzoin (Common Spicebush), Pieris japonica (Japanese Pieris), Prunus spp. (Cherry), Pyrus spp. (Pear), Rhododendron mucronulatum (Korean Rhododendron), R. 'P. J. M.', Spiraea thunbergii (Thunberg Spirea), Vaccinium angustifolium (Lowbush Blueberry), V. corymbosum (Highbush Blueberry), 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: Anemone nemorosa (Wood Anemone), Asarum europaeum (European Ginger), Aurinia saxatilis (Basket of Gold), Caltha palustris (Marsh Marigold), Chionodoxa luciliae (Glory of the Snow), Claytonia virginica (Virginia Spring Beauty), Crocus spp. (Crocus), Dicentra canadensis (Squirrel Corn), D. cucullaria (Dutchman's Breeches), 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), Helleborous x hybridus (Christmas Rose), Hyacinthus spp. (Hyacinth), Mertensia virginica (Virginia Bluebells), Muscari sp. (Grape Hyacinth), Myosotis sylvatica (Forget-me-not), Narcissus spp. (Daffodil), Omphalodes verna (Blue-eyed Mary), Pachysandra procumbens (Allegheny Spurge), P. terminalis (Japanese Pachysandra), Phlox subulata (Moss Phlox), Primula spp. (Primrose), Pulmonaria longifolia (Lungwort), Puschkinia libanotica (Striped Squill), Sanguinaria canadensis (Bloodroot), S. canadensis 'Multiplex' (Double Bloodroot), Scilla siberica (Siberian Squill), Shortia uniflora (Nippon Bells), Stylophorum diphyllum (Wood Poppy), Tiarella cordifolia (Foam Flower), Trillium erectum (Red Flowering Trillium), T. grandiflorum (WhiteFlowering Trillium), Tulipa spp. (Tulip), Uvularia sessilifolia (Bellflower), Vinca minor (Periwinkle), Viola spp. (Violet) and Waldsteinia ternata (Barren Strawberry).  Pests/Problems: Snowball Aphid is evident on Viburnums, Imported Willow Leaf Beetle on Willows and caterpillars, albeit quite hard to detect are actively feeding on the foliage of Malus (Crabapple). Weeds seen in bloom include: Glechoma hederacea (Ground Ivy), Lamium purpureum (Purple Dead Nettle) and Taraxacum officinale (Dandelion). Weeds emerging but not in bloom include: Alliaria petiolata (Garlic Mustard), Arctium minus (Lesser Burdock), Impatiens capensis (Touch-me-not) and Polygonum cuspidatum (Japanese Knotweed). Ticks are active so continue to monitor yourself and others for these parasites. Wear light color clothes to make the job easier on you.

Central Region (Boylston)

General Conditions: Warmer days and evenings have prevailed since last week bringing many more plants into bloom and advancing the GDD. Conditions are quite dry and turf and gardens will need irrigation soon. Fire hazard is still high. Among the plants blooming this week are: Magnolia ‘Elizabeth’, Magnolia ‘Coral Dawn’, M. x soulangeana, Magnolia x loebneri ‘Merrill’, Shadbush (Amelanchier sp.), Cherries (P. subhirtella, P. ‘Okame’, P. sargentii); Andromeda (Pieris floribunda and P. ‘Brouwer’s Beauty), Ash (Fraxinus sp.); Elm (Ulmus americana), Narcissus, Tulips, European and Canadian Ginger (Asarum europaeum, A. canadensis), Purple Trillium (Trillium erectum), Trout Liliy (Erythronium dens-canis), Merry Bells (Uvularia grandiflora); Forsythia x intermedia, Bleeding Heart (Lamprocapnos spectabilis), Daphne cneorum, Winterhazel (Corylopsis pauciflora), Mayflower (Epigea repens), Bluets, early Violets, Virginia Bluebells (Mertensia virginica), hybrid Lenten Rose (Helleborus x hybridus), Lungwort (Pulmonaria sp.), Periwinkle (Vinca minor), and early Primrose (Primula denticulata).  Pests/Problems: The first bright red Lily Leaf Beetles were seen on Monday. Eastern tent caterpillars have hatched and are on the move creating small webs in the crotches of branches. . Black Flies have emerged, caterpillars. Dandelion and Gill-over-the-Ground (Glechoma hederacea) are now blooming.

Pioneer Valley Region (Amherst)

General Conditions: Conditions have warmed up dramatically over this past reporting period in the Pioneer Valley, accelerating spring development. Numerous landscape and forest trees and shrubs are now leafing out. Between 5/1 and 5/4 high temperatures shot from the low 60s to upper 80s. Gusty winds accompanied the warm weather, with a maximum gust of 39 mph on 5/3 at Barnes Airport in Westfield. Night-time temperatures are still cool, hovering between the upper 30s and mid-40s on most days. There was no measurable precipitation across the valley during this past reporting period. The warm temperatures, gusty winds and lack of rainfall over the past two weeks have created dry soils in the upper horizons. The water table is still relatively high here in the valley, so established trees and shrubs should have plentiful soil moisture as they begin or continue flushing new growth. But, recently planted trees, especially those with shallow root systems (e.g. birch, hemlock and true fir) should receive supplemental water if we don’t receive at least 0.5” of rain over the next week. The most current U.S. Drought Monitor report for the Commonwealth shows that over 70% of the state is in the “abnormally dry” condition, including the entire Pioneer Valley (http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?MA). The long-term forecast calls for continued highs in the mid- to upper-80s with no considerable rainfall aside from scattered thunderstorms on 5/12. Despite their highly conspicuous nature, these fast-moving thunderstorms typically do not provide soaking rainfall.  Pests/Problems: The sunny and dry weather, coupled with breezy conditions have suppressed most fungal pathogens from initiating new infections. Many opportunistic foliar and shoot blight pathogens are ready and waiting for rainfall so they can begin producing and disseminating spores. Fire blight predictions coming out of the UMass Cold Spring Orchard are not promising. A combination of forecasted rain showers and the beginning of the bloom period for apple and crabapples means there is a very high risk for disease development. 2014 was a big year for this bacterial pathogen (Erwinia amylovora) and considerable inoculum is present on the landscape to initiate new infections. Blue spruce buds are swelling but there’s no sign of new growth just yet. Newly developing needles should be treated with an appropriate fungicide if needle cast from Rhizosphaera is a concern. Cultural control alone is not sufficient for trees growing in screens or low light settings with established infections. Japanese knotweed has started flushing new growth. This terribly invasive plant, especially abundant along streams and rivers in the valley, doesn’t flower until very late in the growing season. Boxwood leafminer larvae are maturing. The swollen and distorted leaves often develop circular lesions that can be readily found during scouting. Prune out and destroy these infested plant parts before the larvae mature and leave the plant.

Berkshire Region (Great Barrington)

General Conditions: What a difference one week can make. In the last report it was mentioned that a light snow had covered the ground in many parts of Berkshire County (on April 23) and temperatures continued to be well below normal. In the past week, temperatures have soared to levels well above normal with several days of 80+ degrees F. As a result, a semi-barren landscape has rapidly transitioned into one of many bright colors and of shades of green. Previously, the unseasonably cool temperatures had delayed or extended the bloom of many early flowering plants. With the sudden “heat” wave, many other plants which normally supersede the early bloomers have come into flower producing a combination not often seen at this time of year. It makes for an amazing array of flowers. The main concern at this time is the lack of rainfall. Through May 5, precipitation is 3.3 inches below normal. Only a trace of rain has fallen over the past 13 days. Soil moisture levels are low in most areas. This has slowed growth of grass a little and has left some lawns looking patchy with brown spots. The brown areas could also be an indicator of grub infestation. To check, lift or roll back sections of sod where brown grass meets green grass and look for the grubs. Speaking of lawns, there is a tendency to cut fast growing lawns low in spring. This is a mistake. Mowing height should be at a minimum of three inches. This high mowing height promotes a deeper root system – especially important during this dry weather – and shades out annual weeds.  Pests/Problems: Blacklegged ticks, spruce spider mites, and carpenter bees remain active, with population levels of the ticks being very high. Some boxwood leaf miners are still in the larval stage but many have gone into the pupal stage. Emergence of adult flies should occur at the time Weigela comes into bloom. Eastern tent caterpillars (ETC) have made an appearance and tent formation is visible. The larvae are about ¼ inch in length. Black cherry, apple, and crabapple are the common hosts for ETC. If clipping out the tents, this is best done in the evening when the larvae are in the tent. The warm weather has expanded the amount of noticeable browning of foliage on winter injured evergreens, rhododendrons and hollies in particular.

Environmental Data

The following growing-degree-day (GDD) and precipitation data was collected for an approximately one week period, April 30 through May 6. Soil temperature and phenological indicators were observed on or about May 6. Total accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments for the 2015 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
(1-Week Gain)

GDD
(Total 2015 Accumulation)

Soil Temp
(°F at 4" depth)

Precipitation
(1-Week Gain in inches)

Cape Cod

26

72

58

0.00

Southeast

35

73

69

0.03

North Shore

33

79

55

0.00

East

54.5

105

61

0.02

Metro West

52.5

72

60

0.01

Central

49

95

52

0.00

Pioneer Valley

76

126

59

0.00

Berkshires

57

83

58

0.00

AVERAGE

48

88

59

0.01

n/a = information not available

Phenology

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

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT NAME (Botanic/ Common) CAPE S.E. N.S. EAST METRO W. CENT. P.V. BERK.
Cornus florida (Flowering Dogwood) begin begin * begin * * * *
Rhododendron spp. (Early Azaleas) begin begin begin begin * * begin *
Malus spp. (Crabapple) * * begin begin begin * begin/full *
Cercis canadensis (Redbud) * * full begin begin * begin/full begin
Pyrus calleryana (Callery Pear) begin full full full begin/ full full full *
Amelanchier spp. (Shadbush, Serviceberry) begin begin begin begin/ full full full begin/full full
Chaenomeles speciosa (Common Floweringquince) begin full begin/ full begin full * begin/full begin
Rhododendron 'P. J. M.' full full full full full full full begin/full
Prunus serrulata (Japanese Flowering Cherry) full full full full full full full full
Magnolia x soulangeana (Saucer Magnolia) full full full full/ end full full full/end full
Forsythia x intermedia (Border Forsythia) full full full full/ end full full full/end full
Rhododendron mucronulatum (Korean Rhododendron) full full/end full end full/ end full full/end full
Magnolia stellata (Star Magnolia) full full/end full/end end full/ end full end full
Pieris japonica (Japanese Pieris) full full/end full full full/ end full/end full full
* = no activity to report/information not available
  • 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 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 woody ornamental diseases of interest seen in the UMass Extension Plant Diagnostic Laboratory:

Diplodia shoot blight and Lophodermium needle cast of eastern white pine (Pinus strobus). Young trees, approximately 10-years-old, growing in a forest understory. Symptoms included cankering and wilting of young shoots. Diplodia can be regularly found on eastern white pine but it rarely causes serious damage. Light stress due to suppression in the understory likely facilitated disease development.

Infestations by the minute cypress scale (Carulaspis minima) and spruce spider mite (Oligonychus ununguis) on arborvitae (Thuja). Six-year-old shrub present at the site for nearly as long. The spider mite infestation was severe and many needles displayed the typical flecking damage before becoming brown. The minute cypress scale, despite its name, is clearly visible with the naked eye. This pest does not appear to be particularly abundant in Massachusetts.

Transplant shock, winter injury, black vine weevil (Otiorhynchus sulcatus) infestation and stem cankering caused by Phomopsis on rhododendron. Several shrubs with ages varying from 5- to 15-years-old. Some of the shrubs were planted in fall 2014 and this spring, many leaves were brown and prematurely shed. Circular feeding wounds on the leaf margins were visible along with dark-colored, blighted shoot tips. Black vine weevil larvae feed on roots and when populations are high they can cause significant damage.

Diplodia shoot and needle blight, pine needle scale (Chionaspis pinifoliae) infestation and Dothistroma needle cast on Scots pine (Pinus sylvestris). Large stand of plantation trees, approximately 50-years-old. Over time, many trees have suffered serious crown dieback starting in the lower crown and progressing upward. Roughly 10% of the trees have died. Height growth repression is a likely predisposing stress.

Boxwood leafminer (Monarthropalpus flavus), boxwood spider mite (Eurytetranychus buxi), Volutella leaf and stem blight and Macrophoma leaf spot on boxwood (Buxus sempervirens). Multiple shrubs of various ages and differing locations. Boxwood harbors several destructive insect pests and fungal pathogens. Many of the pathogens gain entry and are spread through the aggressive annual pruning desired by most boxwood owners. Winter injury is also apparent on many of the submitted samples. The invasive boxwood blight pathogen has yet to be observed in the lab this year.

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.

Weeds

Treat garlic mustard (Alliaria petiolata) now.  Applications at this time of year will control second year plants before they go to seed as well as first year seedlings.  Look for seedlings at this time, as these seedlings will be next years flowering plants.

Landscape mulch should be the first defense against weeds in landscape beds.  Mulching can be done now at the beginning of the season before summer annual weeds germinate.  Freshly mulched landscape beds will not require a preemergence herbicide application because the fresh mulch should supply adequate weed control in the short term.  Preemergence herbicide application should be considered now on mulched areas that have not been freshly mulched or a bit later in the season.  Preemergence herbicides should be applied on top of landscape mulches not underneath them.  Compost is not recommended as a mulching material.

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

When scouting for weed in the landscape, observe areas underneath and around bird feeders.  Some of the most interesting weeds that are sent to me come from these areas.  Many of these plants are from other regions of the country and therefore have the potential to be aggressive and pernicious.

Treat winter annual and perennial weeds in ornamental beds with glyphosate and glufosinate.  These applications are easier if done now before woody ornamentals leaf-out.  The new growth of herbaceous perennial ornamentals can be very susceptible to spray drift, so exercise extreme caution.  Non-chemical products containing clove oil, citric acid, acetic acid or orange extract can be used on small winter annuals but not on large winter annuals or perennials.  Remember these organic/non-chemical products do not translocate and will not control established perennial weeds but will control young winter annual weeds.  Many winter annuals are just beginning to flower and have not set seed and should be controlled now.

Common landscape winter annual weeds being observed now are:

Japanese knotweed, Polygonum cuspidatum, has begun to emerge from rhizomes.  Do not attempt to control this weed at this time as herbicide applications are not effective.  Repeat cutting or mowing can be used as a non-chemical strategy and if that is the control strategy selected then cutting and mowing should begin now.  Repeat cutting or mowing should be done as regrowth reaches 4 to 6 inches.

Report by Randall Prostak, Weed Specialist, UMass Extension Agriculture & Landscape Program, Amherst.

Management Practices

Spring has arrived, but many reminders of the rough winter are still in the landscape. As new growth emerges it is a good time to assess the extent of winter damage and to start cleaning up damaged plants. The strategy for cleaning up winter damage will differ depending on the extent of damage and type of plant. Some deciduous plants, such as Hydrangea macrophylla are showing much dieback, with leaves only present on lower branches that were insulated by snow. Dead branches should be pruned out to encourage new growth. Some plants may grow from the base this year as upper parts not covered by snow have been damaged.

Many broadleaf and needled evergreens are showing burned tips, desiccation of leaves, and salt damage. Depending on the extent of the damage new growth my “push” old growth off as it expands. For minimally damaged plants you can also use your hands to brush off damaged leaves. For more extensive damage, where dieback also extends to stems, pruning back to below the damaged parts will be necessary. It is a good plan to wait to prune until new growth has begun to best assess what parts of the plant are healthy.

Also check plants for rodent damage. Damaged plants will need time to heal wounds, but check for complete girdling (removal of a circle of bark around the plant). If girdling has occurred the plant will likely die. It is best to check for damage now. Sometimes winter damage and rodent damage can be overlooked in the spring, but impact plant health later in the season after winter damage has been forgotten. It is best to wait and check if stems are completely dead before pruning as new growth can be delayed as the plant recovers. As the year moves on it will be important to make sure that damaged plants avoid becoming further stressed. Mulching and watering will be especially important in helping these plants recover.

Hydrangea macrophylla are showing much dieback, with leaves only present on lower branches that were insulated by snow    Many needled evergreens are showing winter damage   Many needled evergreens are showing winter damage

Report by Mandy Bayer, Extension Assistant Professor of Sustainable Landscape Hortulculture, Stockbridge School of Agriculture, UMass Amherst.

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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