Landscape Message: April 15, 2016

April 15, 2016
Issue: 
4

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 April 22. 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 7 through April 13. Soil temperatures and phenological indicators were observed on or about April 13. 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

5

53

55

46

1.65

3:00 PM 4/13

Southeast

7

54

55

48

1.45

3:15 PM 4/13

North Shore

0

48

43

41

0.97

10:00 AM 4/13

East

1

58

53

50

1.60

3:30 PM 4/13

Metro West

3

38.5

41

39

1.31

5:45 AM 4/13

Central

4

58

39

39

1.56

8:15 AM 4/13

Pioneer Valley

0

41

44

42

1.23

11:30 AM 4/13

Berkshires

0

37

43

42

1.33

9:30 AM 4/13

AVERAGE

3

48

47

43

1.39

-

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.
Rhododendron 'P. J. M.' * Begin   * * * Begin *
Prunus serrulata (Japanese Flowering Cherry) Begin Full Full * Begin * * *
Forsythia x intermedia (Border Forsythia) Begin Full Full Full/End Begin Begin Full/End Full
Rhododendron mucronulatum (Korean Rhododendron) Begin/Full End * * * * * *
Magnolia stellata (Star Magnolia) Full Full Full * Full/ End Begin Full/End *
Pieris japonica (Japanese Pieris) Full Full Full Full Full * Full Full
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: This reporting period has had temperatures quite below average for this time of year. Early morning lows ranged from 18° F on the morning of 4/6, 22° F on 4/9, and 24° F on 4/10. In between we had temperatures up into the low 50s with rain and winds in the 60mph range on 4/7. Temperatures have moderated somewhat by the beginning of this week, although winds off the water have kept the Cape cooler than inland areas. Plant development has progressed at a slower pace than earlier in spring. Lawns have greened up and the mowing season is getting underway, along with spring clean-ups. Daffodils, Glory of the Snow (Chionodoxa), Grape muscari (Muscari spp.), and Lungwort (Pulmonaria cultivars) are providing color in the landscape. Forsythia is beginning to bloom, although there was some flower bud injury as a result of the below freezing temperatures. ‘Leonard Messel’ magnolia is beginning to bloom and it experienced less damage than Star magnolia as its buds were still closed when temperatures dropped. Peepers are singing in the wetlands!

Pests/Problems: Several plants are showing injury as a result of below freezing temperatures. Star magnolia (Magnolia stellata) was just beginning to bloom when it occurred and any flowers that had opened appeared water soaked and then turned brown. Buds that were partially opened had the outer petals damaged while the inner portions of the flower survived. The result is a very spotty bloom at this time. Corylopsis paucifolia (Buttercup winterhazel) also lost those flowers that were open during the freeze. Subsequent buds have flowered with no evidence of damage. Corylopsis spicata (Spike winterhazel) was not in bloom at the time of the freeze but lost all of its flower buds, which turned completely brown. Foliage of crabapple shows scorched edges.

Larry Dapsis, entomologist with the Cape Cod Extension, has observed the hatch of winter moths in Barnstable. We are at the very beginning of the hatch period. Fruits such as blueberry and apples should have an application of spinosad to protect the fruit buds. Eastern tent caterpillar is active. Small nests can be seen on wild black cherry. White pine weevil will become active when temperatures reach 60° F, which is forecast for next week. Cut worms are active in turf. Monitor Hemlocks for the Hemlock adelgid. The first orange, gelatinous gall of cedar-apple rust was observed following a period of rain. Dandelions and bittercress are blooming.

Southeast Region (Hanson)

General Conditions: April began with a cold spell, but warmer weather has finally come in and plant and insect development are progressing. Hanson received 1.45 inches of rain this past week, and soils are moist. Damage from the previous cold freezing weather continues to show up, as plant development continues. In Hanson, flower buds of ‘PJM’ rhododendrons blasted as have the buds of Stachyurus praecox, Corylopsis spicata and many cultivars of Hydrangea macrophylla. Tips of some Japanese maple buds were killed by the cold, as were the developing shoots of Arisaema ringens. Many plants, Magnolia stellata (Star magnolia) and Magnolia ‘Wada’s Memory’, M. x loebneri 'Leonard Messel', Forsythia, Chaenomeles speciosa (Common Floweringquince) and Lonicera fragrantissima (Winter honeysuckle),damaged by the early April freeze, have rebounded and are displaying flowers, maybe not as full as in previous years, but it is something. Some Star magnolias that were in full bloom were hit the hardest, but Star magnolias which had buds yet to open are producing flowers. As mentioned last week, many Forsythia buds were killed in February by the freezing weather. Overall, right now, the spring landscape is not as colorful as it usually is. The following plants are in full bloom: Cercidiphyllum japonicum (Katsuratree), Pieris japonica (Japanese Pieris), Pieris ‘Brouwer’s Beauty’, Pieris floribunda, Lindera benzoin, early heaths and heathers, Salix sp. (pussy willow), red maples, Pachysandra terminalis, Vinca minor, Petasites japonicus, Sanguinaria canadensis (Blood root), Corydalis solida, Dicentra cucullaria (Dutchman’s breeches), Trillium, Helleborus niger, H. foetidus, H. x hybridus (formerly orientalis), Ranunculus ficaria, Anemone blanda, Primrose, early daffodils, early tulips, Hyacinths, Crocus, Scilla siberica and Chionodoxa luciliae. Pulmonaria sp., Violets, Lamium, and Brunnera macrophylla have started bloom. Daphne mezereum (February Daphne) Cornus mas (Corneliancherry Dogwood) and Cornus officinalis are ending bloom. Lawns are green and mowing has begun.

Pests/Problems: With the warmer weather, winter moth caterpillar eggs resumed hatching. As of April 13, approximately 50% of the eggs had hatched on the tree we are monitoring in Hanson, and numerous tiny, 1st instar caterpillars were observed on the tree trunk. 1st instar caterpillars were also found in the expanding buds of: apple, blueberry, European beech, Norway maple and Japanese maple. Please see UMass Entomologist, Tawny Simisky’s report in the Insect Section below, especially if you have clients who are growing blueberries or apples. The cold weather may have killed some of the early hatched winter moth caterpillars, but probably not enough to make a difference. Dr. Elkinton’s lab will provide more information on this as the season progresses. Continue to monitor developing buds for winter moth caterpillars on susceptible plants (oak, birch, maple, blueberry, apple, crabapple, etc) with a history of winter moth damage and manage early to minimize damage. Also continue to monitor hemlocks for the white cottony egg masses of Hemlock Wooly Adelgid (HWA). As mentioned previously, there was high mortality of HWA this past winter, but this is an insect that rebounds, so continued monitoring is necessary. Begin monitoring for red Lily Leaf Beetle which should be making an appearance soon, if not already. Lilies are up and on warm days; look for the bright red beetles. Monitor for eastern tent caterpillar on crabapple, wild cherry, apple, plum, cherry, etc. Deer ticks remain active. Continue to conduct deer tick checks frequently and consider using a repellent. Solitary, honey and bumble bees are active. Overwintering insects like ladybugs and western conifer seedbugs are making appearances indoors, all trying to get outdoors. A brown marmorated stink bug was found indoors in an office in Raynham. This is a newly arrived pest and one that also seeks to overwinter indoors. For more information, go to: https://ag.umass.edu/fact-sheets/brown-marmorated-stink-bug

Wild turkeys have started to roam the landscapes. Rabbits are active and browsing plants like: lilies, hosta, tulips, Epimedium, etc. Dandelions and chickweed have started to bloom, and bittercress continues to bloom and set seed. Spring cleanups continue and hopefully, hazard tree assessment and removal will continue. Now might be a good time to prune and renovate any bud-killed spring flowering plants like Hydrangea macrophylla, Corylopsis, 'PJM' Rhododendron, etc. Usually we recommend waiting until immediately after bloom to prune or renovate spring-flowering trees and shrubs, but if the flower buds were killed by cold, why wait?

North Shore Region (Beverly)

General Conditions: It seems like we are starting to settle into seasonal spring weather after sub-zero temperatures on 4/4, 4/5 and 4/6 last week. Since then the temperatures have stabilized with highs in the low 50s and high 40s. Minimum temperatures have been above freezing on most days. The weather forecast for the next few days calls for mostly sunny days and temperatures in the upper 50s. This will help accelerate plant growth and flowering for some trees and shrubs. Rain showers in the last few days have helped to keep the soil moist. The freezing temperatures last week caused some damage to some plants. The new growth on most of the bleeding hearts (Lamprocapnos spectabilis) was scorched by the freezing temperatures. The flower stalks of the daffodils that had started to bloom before the freezing temperatures are all bending down. The flower petals of some of the magnolia trees that were in full bloom have been browned and scorched by the freezing temperatures. Woody plants seen in bloom include: Leonard Messel Magnolia (Magnolia x loebneri), Merrill Magnolia (Magnolia x Loebneri ‘Merrill’), Sargent Cherry (Prunus sargenti), Star magnolia (Magnolia stellata), Beatrix Farrand forsythia (Forsythia ‘Beatrix Farrand’) and Border forsythia (Forsythia suspensa var. sieboldii). Non woody plants seen in bloom include: Vinca vine (Vinca minor), Daffodil (Narcissus spp.) and Hellebores (Helleborus orientalis).

Pests/Problems: Ticks resumed activity resumed when temperatures started to rise again above freezing. Protect yourself when working outdoors. Hemlock woolly adelgid was observed in Danvers. Fig buttercup (Ranunculus ficaria) is blooming on lawns not covered by snow at Long Hill.

East Region (Boston)

General Conditions: Unseasonably cool temperatures have continued and we gained only 1.0 GDD since last week, bringing us to 58.0 on the year. The most recent growing degree day was recorded on April 11th as we reached a high of 60° F and a low of 42° F. High temperatures averaged 52.9° F (ranging from 42.9° F to 60.2° F) and low temperatures averaged 33.5° F (ranging from 18.5° F to 42.2° F). Due to an arctic system, the morning of April 6th saw temperatures drop to 18.5° F, temperatures not seen since February 19th. April 8th was an eventful day in terms of weather, conditions alternating between sunny and cloudy with hail falling twice that day. We have been receiving intermittent precipitation totaling 1.6 inches over the past seven days keeping most soils moist and workable. Despite these cooler fluctuating temperatures, plants are slowly leafing out. The predominant color in the landscape is provided by early flowering Prunus [P. alleghaniensis (Allegheny plum), P. apetala (clove cherry), P. cyclamina (cyclamen cherry), and P. sargentii (Sargent's cherry)] as Forsythia sp. (forsythia) and early Magnolia sp. (magnolia) were severely damaged by the cold temperatures, destroying most blooms for this year. Plants currently in bloom: Amelanchier arborea (common serviceberry), Mahonia aquifolium (Oregon grapeholly), Spiraea prunifolia (bridalwreath spirea), and Xanthorhiza simplicissima (yellowroot).

Pests/Problems: The cold snap in early April has left many early flowering magnolias with unsightly brown petals. Lesser celandine (Ficaria verna) has recovered well following cold temperatures and is profusely flowering throughout the landscape, especially in more moist locations. The majority of winter moth eggs have hatched and have been found feeding within the buds of a wide range of species. Hemlock woolly adelgid crawlers are active.

Metro West (Acton)

General Conditions: With the recent rain, soils are moist and are suitable for planting but be sure to protect the roots from the wind and you may want to consider staking trees if the root system is not supportive or if it is a conifer. I drove by a new planting the other day. It was a screen of mixed conifers and most of the trees had a good lean to them. The wind was responsible and it has been relentless. Gusts up to 38 mph were recorded on the 11th. I’ve seen whole trees wind thrown with root plates included. Much is in bloom for this time of the year, including the following woody plants: Erica sp. (Heath), Forsythia spp. (Forsythia), Lindera obtusiloba (Japanese Spicebush), Pieris japonica (Japanese Pieris) and Rhododendron mucronulatum (Korean Rhododendron). Contributing even more color and interest to the landscape are some flowering herbaceous plants and spring ephemerals including: Caltha palustris (Marsh Marigold), Chionodoxa luciliae (Glory of the Snow), Crocus spp. (Crocus), Helleborus niger (Christmas Rose), Hyacinthus spp. (Hyacinth), Mertensia virginica (Virginia Bluebells), Muscari sp. (Grape Hyacinth), Narcissus spp. (Daffodil), Pachysandra procumbens (Allegheny Spurge), Petasites japonicus (Japanese Butterbur), Primula spp. (Primrose), Pulmonaria longifolia (Lungwort), P. rubra (Salmon colored Lungwort), Puschkinia libanotica (Striped Squill), Sanguinaria canadensis (Bloodroot), Scilla siberica (Siberian Squill), Symplocarpus foetidus (Skunk Cabbage), Trillium erectum (Red Flowering Trillium), Tulipa spp. (Tulip), Vinca minor (Periwinkle) and Viola spp. (Violet).

Pests/Problems: A cold temperature of 12° was recorded on the 6th and between the cold and the heavy wet snow, flowers, foliage and buds have been injured. Some daffodil flowers that typically stand upright, now have broken stems and are lying broken on the ground. Magnolia and azalea flowers that were just emerging have browned and withered, and some foliage on early emerging trees and perennials have also suffered from some cold injury. Draba verna (Spring Whitlow Grass) and Lamium purpureum (Purple Deadnettle), Stellaria media (Common Chickweed), all winter annual weeds, as well as Taraxacum officinale (Dandelion) were observed in bloom. Ticks are active.

Central Region (Boylston)

General Conditions: Cooler, more seasonable conditions prevailed over the reporting period with daytime temperatures generally in the 40s to 50s, and night time temperatures ranging between the upper 20s to low 40s. Soils are extremely wet and care should be taken to avoid vehicle and heavy foot traffic which will cause further compaction. Damage from the cold night-time temperatures of the previous week are evident in the foliage of Daylilies (Hemerocallis cvs), Apple and Crabapple (Malus), Abelia mosanensis, White Forsythia (Abeliophyllum distichum), Daffodils (Narcissus cvs), Willows (Salix sp.), a bit on Seven Son Flower (Heptacodium miconioides) and Flowering Quince (Chaenomeles cvs). The flower buds of Winter Hazel (Corylopsis spicata), Forsythia (Forsythia x intermedia), Fragrant Honeysuckle (Lonicera x purpusii), Magnolia x loebneri. Some of the Narcissus stems broke under the snow, others are bent but not returning to an upright position, still other buds seem to have been damaged by the cold. In bloom in the landscape are Fumewort (Corydalis solida), Bloodroot (Sanguinaria canadensis), Hellebores (Helleborus x hybridus, H. foetidus), Lonicera x purpusii, Siberian Squill (Scilla siberica), Glory of the Snow (Chionodoxa forbesii), Iberis ‘Little Gem’, Erica cvs, Daffodils (Narcissus cvs.), Puschkinia libanotica, Crocus tommasinianus, Mountain Andromeda (Pieris floribunda), Brouwer’s Beauty Andromeda (P. ‘Brouwer’s Beauty), and Moss Phlox (Phlox subulata) is beginning to bloom.

Pests/Problems: Other than ticks and excessively wet soil no major problems have cropped up in the landscape this past week.

Pioneer Valley Region (Amherst)

General Conditions: It appears we have finally settled into a pattern of seasonal spring weather in the valley. After the arctic air mass blasted the region with abnormally cold weather between 4/4 and 4/6, conditions slowly stabilized with highs in the upper 50s, steady winds and occasional rain showers that, in total, accumulated to over an inch throughout the valley. The long-term forecast calls for full sun, high temperatures in the 60s and 70s and lows above freezing. This will accelerate plant growth and many trees and shrubs should be flushing by our next reporting period. Soils remain moist due to the regular rainfall but soil temperatures continue to stagnate in the lower to mid-40s throughout the region. Optimal soil temperature for root growth varies widely by plant and age. Fine root development for trees and shrubs is very seasonal, much like aboveground parts: a flush of fine roots are produced in the spring and there can be significant mortality in the fall. From this perspective, early planting could benefit the root system by providing more time for fine roots to become established and avoid injury upon planting. A study from southern Michigan showed that 25% of annual fine root development for sugar maple took place before mid-May. Young trees and shrubs allocate a significant percentage of their resources to construction of coarse and fine roots, whereas older, established trees and shrubs must maintain existing roots and budget for the annual turnover of large masses of short-lived feeder roots. As soil temperatures increase, so does root respiration, which can amplify drought stress during extended dry periods. Planting beds with adjacent stone, asphalt or concrete can experience very high soil temperatures during the growing season due to conductive heating. It is essential to provide supplemental water to recently transplanted trees and shrubs in these settings during mid-summer dry periods to avoid drought-induced root mortality. Conversely, as soil temperature increases so does nutrient availability to the roots. Therefore, warm soils can be beneficial for roots as long as moisture is high enough to avoid drought stress.

Pests/Problems: Crabapples suffered the worst from the abnormally low temperatures on 4/5 and 4/6. Numerous landscape and nursery trees have burned leaf margins. This necrotic tissue will be colonized by an array of weak and more aggressive pathogens (e.g. the anthracnose pathogen Colletotrichum). Star and saucer magnolias were also badly damaged although some closed buds did survive and have since opened. Scout for white pine weevil damage on eastern white pine and Norway spruce. Young trees in full sun are most susceptible to infestation. Adult weevils that overwintered in organic debris at the base of the tree will feed on the main leader, close the terminal buds. Look for evidence of feeding, resin flow and wilting of the terminal. Prune these infested parts out. The soilborne pathogen Armillaria will be producing new rhizomorphs for the season over the coming weeks. Remove or grind stumps (and remove debris) if Armillaria is present at the site and replanting will take place in the immediate vicinity.

Berkshire Region (Great Barrington)

General Conditions: This past week was one of arrested development. Colder than normal temperatures on all but one day (4/7) slowed or halted plant development; not much has changed since the last report, other than cold-induced damage to plants. A couple of days of rain reduced the total rainfall deficit for the year to a little over one inch. Soil moisture levels are moderate to high, but that could change as sunny, breezy and much warmer temperatures are predicted for the week ahead. Though flower buds on many early blooming trees and shrubs were killed by the record low temperatures of last week, mid-season narcissus are in bloom as are Scilla, Anemone blanda, and Pulmonaria. With woody landscapes still dominantly gray, one green plant stands out, and that is garlic mustard (Alliaria petiolata). Plants seen now are in the second year of their biennial life cycle and will bloom in a few weeks. Since they are so visible, this is a good time to administer control measures to eradicate this invasive species, each plant of which is capable of producing thousands of seeds. Another invasive species - now in bloom - is the lesser celandine (Ficaria verna). A spring ephemeral, lesser celandine has heart-shaped leaves and attractive yellow flowers. It grows as a dense carpet in shaded areas and easily displaces other plants in that habitat.

Pests/Problems: Eriophyid mites are now active on hemlocks, though the numbers on the plants which were inspected are few, and control (horticultural oil) may not be warranted. Deer ticks remain active. Though some hardy cultivars of Forsythia are in full bloom, no evidence of hatching of Eastern tent caterpillar could be found. Most of the problems observed this week relate to the record low temperatures of last week. Leaf tip burn could be seen on most woody plants, e.g. deciduous azaleas, lilacs, and viburnums, which were beginning to leaf out when the abrupt cold occurred. Crabapples seemed to be hardest hit, and entire leaf bundles are now completely brown and drooping. Emerging blossoms on Magnolia stellata are a total loss. Removal of the closed flower buds on a Magnolia soulangiana in the Stockbridge area revealed that the flowers were dead. Though the blossoms of many early blooming narcissus were short-lived due to the beating they took from the snow and bitter cold of last week, later blooming cultivars are doing well. Some of the foliage of the affected narcissus was also damaged by cold temperatures. Inspection of daffodil leaves found that some were softened or water-soaked, indicating disruption of cell integrity. This week, those damaged leaves have turned brown. The effects of recent frigid temperatures are becoming more and more apparent.

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:

Transplant shock and Cytospora canker on white fir (Abies concolor). Three trees, seven-years-old, planted 18 months ago at a residential site. Last summer symptoms of establishment stress appeared and included: yellowing needles, premature needle shedding and branch dieback. One tree is now dead. Trees were planted in full sun and provided with supplemental irrigation. Cytospora, like many cankering fungi, is highly opportunistic and can spread readily through weakened tree canopies.

Severe juniper scale (Carulaspis juniperi) infestation of Hinoki falsecypress (Chamaecyparis obtusa). Tree is 25-years-old and has been present at the site for 10 years. In late winter, the south-facing side of the tree became brown and desiccated, resembling winter injury. This armored scale is not considered a serious pest of landscape trees and shrubs but when populations are high, as they were here, significant needle dieback can develop.

Needle blight caused by Phyllosticta and Pestalotiopsis and stem cankering caused by Botryosphaeria on Japanese falsecypress (Chamaecyparis pisifera ‘Plumosa’). Tree was between 40 and 50-years-old and began showing symptoms of decline during the summer of 2015. Specifically, foliage began to die in sections in the lower canopy, spreading upward. In autumn of 2015 the dieback worsened and the tree died. Other factors are likely involved, but the combination of Phyllosticta and Pestalotiopsis can cause significant needle loss on Thuja and Chamaecyparis.

Armored scale (Lepidosaphes sp.) infestation on umbrella pine (Sciadopytis verticillata). Tree is approximately 20-years-old and has been present at the site for roughly 15 years. Needles began browning in 2015 with some developing a “banding” pattern characterized by necrotic blotches interspersed along the green needles. This armored scale is similar to the oystershell scale (L. ulmi) but was morphologically distinct and may represent the umbrella pine scale (L. sciadopitysi). The white-colored scales were clustered at the base of the needles, partially obscured by the remnants of the sheath.

Caption: Blue spruce (Picea pungens) suffering from needle cast caused by Rhizosphaera (top) and Stigmina (below). Rhizosphaera produces spore masses on symptomatic needles that appear purple to brown. Stigmina, meanwhile, produces fruiting bodies on green needles which have hair-like appendages that can be seen in the highlighted box (lower left). These two infected needles were directly next to each other on the shoot, illustrating the ability of Rhizosphaera and Stigmina to co-occur.

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: (Continued monitoring) As mentioned in last week’s Landscape Message, the eggs of Operophtera brumata have been observed turning blue and hatching in eastern Massachusetts. Dr. Elkinton and his lab report that some of the caterpillars that hatched early this year that made their way into buds are looking healthy and protected from the cold. Some of those early-hatched, protected caterpillars in Hanson, MA are reaching the 2nd instar. Those that were hatched but not within the bud during that time may not have survived as well. The Elkinton lab will have more information regarding early season mortality of winter moth due to previously cold temperatures in the coming weeks, so continue to look to the Landscape Message for further information. Dr. Elkinton and his lab also report that 40-50% of the winter moth eggs are currently on their hosts and may hatch by the end of this week, particularly with the warmer temperatures forecast for the weekend in the 60’s. They are currently finding winter moth caterpillars in buds in West Bridgewater. For most areas, winter moth egg hatch may be completed by the end of this week/beginning of next. For the North Shore and Cape areas, hatch may continue beyond this for an additional week-10 days. Larry Dapsis of Cape Cod Cooperative Extension reports that winter moth caterpillars are now very active in Barnstable, MA and are being found in blueberry buds. The Elkinton Lab reports that some areas of the Cape may be behind in hatch but will be catching up in the next week. Reports from Deborah Swanson in Hanson, MA indicate that 1st instar caterpillars are found in blueberry, apple, red maple, and Norway maple at this time. In blueberry, if buds are still tight or just beginning to open, an application of spinosad would be appropriate at this time to manage this second wave of hatching eggs and new caterpillars (that is, if you are not also dealing with spotted wing drosophila, in which case you may need to reserve your spinosad applications for that insect). If plants are already flowering, do not spray. In apple, the same treatment would be appropriate if plants are still in the green tip stage or as buds open and separate. For green industry professionals looking to manage winter moth in the landscape this season, monitor for caterpillars on bud scales or wait until leaves have opened to treat with insecticides. This will not prevent the early feeding done by the smallest caterpillars in the buds, but will allow for better coverage of the leaf surface so caterpillars do not need to damage more leaf surface before ingesting the pesticide. Apples, crabapples, and other flowering plants should not be sprayed with these products while in bloom to avoid unintended impacts to pollinators.

  • Balsam Twig Aphid: Mindarus abietinus is active between 30-120 GDD’s, base 50° F. 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.

  • Cooley Spruce Gall Adelgid: Adelges cooleyi is active between 20-91 GDD’s, base 50° F. 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. Control overwintering nymphs prior to gall formation on spruce. Oil applications on Douglas fir should be made before bud break to avoid phytotoxicity. Do not plant spruce and Douglas fir close together.

  • Eastern Tent Caterpillar: (Continued monitoring) Eastern tent caterpillar larvae will have begun to hatch in areas accumulating between 50+ GDD’s, base 50° F at this time. Prune and remove any remaining egg masses that have not hatched yet and monitor host plants for any small webs found in the crotches of branches over young larvae and remove. There is still plenty of time to remove Forest Tent Caterpillar egg masses before we reach 192 GDD, base 50° F, when hatch will occur. Continue to monitor for Gypsy Moth egg hatch as we reach 90 GDD’s.

  • 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. Now that temperatures are on the rise again, and when they remain above freezing for 24-48 hours, horticultural oils may be used to manage hemlock eriophyid mite if they are found when inspecting the needle surfaces.

  • Lily Leaf Beetle: Lilioceris lilii will begin to feed on its hosts as soon as they emerge from the ground. With these warming temperatures, monitor for the presence of this insect. Management can be achieved by hand-picking and removing adults and larvae. Some chemical management options are available for this insect, but if caught early mechanical management may be effective. See the Insect section of last week’s Landscape Message for more information.

  • Viburnum Leaf Beetle: Pyrrhalta virburni, now is the time to inspect susceptible plants (viburnum) for over-wintering eggs on stems toward branch tips. Removal and destruction of infested stems, if small in number, can be effective. If management this way is not possible, larvae may be treated with a product containing spinosad once they appear soon after bud break.

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: Pieris japonica

Pieris japonica is a broadleaf evergreen that grows 8-12’ tall and 6-8’ wide. It is an ericaceous plant, preferring a well-drained soil rich in organic matter in full sun to part shade. One of its best ornamental features is the 3-6” long pendulous panicles of white urn shaped flowers in April that are attractive for 2-3 weeks. Flower buds set for the next year in late summer, so pruning should be done after flowering. New growth is bronze turning dark green. Cultivars offer a variety of sizes and ornamental features. ‘Mountain Fire’ has bright red new foliage. ‘Cavatine’ is a compact version growing 2-3’ tall and wide. ‘Valley Valentine’ has deep pink flower buds and pink flowers. Dieback from Phytophthora and leaf spots can be problems. Lace bug can be prevalent causing yellowing of foliage. Pieris japonica is an early season pollinator plant very popular with bees.

Pieris japonica      Pieris japonica

Additional Resources

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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