Landscape Message: August 26, 2016

August 26, 2016
Issue: 
19

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Massachusetts Green Industry professionals in the management of our collective landscape. Detailed reports from scouts and Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. The following issue has been updated to provide timely management information and the latest regional news and environmental data.

The Landscape Message will be updated bi-weekly July through September. The next message will be available on September 9. 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 two week period, August 11 through August 24. Soil temperatures and phenological indicators were observed on or about August 24. 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
(2-Week Gain)

Time/Date of Readings

2-Week Gain

2016 Total

Sun

Shade

Cape Cod

359

2059

78

69

0.33

3:45 PM 8/24

Southeast

339

1,964

81

68

0.70

4:35 PM 8/24

North Shore

n/a

n/a

n/a

n/a

n/a

n/a

East

389

2286.5

72

66

1.43

8:30 AM 8/24

Metro West

339.5

2100

81

69

3.19

4:45 AM 8/24

Central

329

2149

74

69

2.58

4:44 PM 8/24

Pioneer Valley

348

2208

72

66

0.68

12:30 PM 8/24

Berkshires

304

1887

71

67

1.42

11:30 AM 8/23

AVERAGE

90

2093

76

68

1.48

-

n/a = information not available

Drought Conditions Update: 100% of Massachusetts is currently under drought status, of that 91% of the Commonwealth is classified as at least 'Moderate Drought', 72% is classified as 'Severe Drought', and nearly 17% is classified as 'Extreme Drought' (a large portion of Middlesex County and nearly all of Essex County).  For more information see http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?MA

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.
Styphnolobium japonicum, formerly Sophora japonica, (Japanese Pagodatree) * * * * * * * *
Polygonum cuspidatum (Japanese Knotweed) Full Full * * Full Full Full Begin
Clethra alnifolia (Summersweet Clethra) Full End * End End End End Full/End
* = no activity to report/information not available

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The drought conditions continue on the Cape as well as in the rest of the state. The weather has been wonderful if you are visiting or on vacation but is very stressful for many landscape plants. Lawns are brown and crispy and plants are flagging. ‘Goldsturm’ Black-eye Susan (Rudbeckia fulgida var. sullivantii ‘Goldsturm’) and Garden phlox (Phlox paniculata cultivars) are blooming in the perennial border while Vitex (Vitex agnus-castus) is blooming in the shrub border, along with the few Crepe myrtle that survived the winter.

Pests/Problems: Drought conditions continue to be the most critical issue in the landscape. The rain gauge in Marstons Mills only recorded 0.33” over the past two weeks. On 8/12, 0.12” was recorded, with another 0.04” falling on 8/14. The next precipitation event didn’t occur until 8/22, when 0.17” was recorded. Even with supplemental irrigation, plants are showing signs of stress. Many maples in non-irrigated locations are showing brown foliage. Daylilies and hosta, among the most drought tolerant perennials, are looking quite stressed, in some cases lying flat on the ground. Rhododendron leaves are curled up. Lawns are totally dormant unless under regular irrigation. Marginal browning of foliage is common on many trees and shrubs. Hardest impacted are those oaks that were defoliated by winter moth and gypsy moth. If there is any upside to the drought, it is that researchers are saying that it has also impacted deer ticks, possibly lowering their populations.

Japanese beetle populations have disappeared, as have Oriental beetles. Asiatic garden beetles are still active. Spider mites are active. Wasp populations are high.

Southeast Region (Hanson)

General Conditions: And the heat goes on; with many areas in MA being designated “Extreme Drought”. Hanson received only 0.70 inches of rain over the last two weeks, not nearly enough to make a dramatic difference. Soils remain extremely dry. Albizia julibrissin, Rose-of-Sharon, Campsis radicans, Hydrangea paniculata, Hydrangea quercifolia, Butterflybush, Veronicastrum virginicum, Hosta plantaginea and other late blooming Hosta, roses, Rudbeckia ‘Herbstonne', Rudbeckia subtomentosa ‘Henry Eilers’, Rudbeckia triloba, Rudbeckia fulgida ‘Goldsturm,’ Persicaria amplexicaulis, Liatris sp., Campanula sp.,Joe-pye-weed, Echinacea purpurea and hybrids, Corydalis lutea, Ligularia sp., Heliopsis ‘Summer Sun’, Helianthus 'Lemon Queen', perennial hibiscus like Hibiscus 'Summer Storm’, and Hibiscus ‘Old Yella’, Lobelia syphilitica, Lobelia cardinalis, Lobelia hybrids, Coreopsis ‘Harvest Moon’, Perovskia sp., and Phlox paniculata are in full bloom. Platycodon, Echinops ritro, Clerodendron trichotomum, Monarda didyma, and Lysimachia clethroides are ending bloom. Ornamental grasses are beginning to bloom. As long as they receive water, annuals and tropical plants, like banana, Canna, Cuphea, coleus, sweet potato vine, geranium, Lantana, and Salvia continue to add color and texture to the landscape.

Pests/Problems: There is not much going on insect-wise in the landscape. The biggest challenge continues to be the lack of significant rainfall and warm temperatures. Plants in non-irrigated landscapes continue to show decline due to drought stress: leaf drop; premature fall color; wilting; brown leaf margins; etc. Many non-irrigated lawns appear brown; however, be sure and monitor those lawns for chinch bug and sod webworm activity. Damage by these insects can be very similar to symptoms displayed by drought stress.

Continue to monitor for Asian Longhorned Beetle (ALB); dogwood sawfly larvae; viburnum leaf beetle; redheaded pine sawfly larvae; introduced pine sawfly larvae; hibiscus sawfly larvae.

The following insects remain active: Andromeda, rhododendron and azalea lacebugs; spider mites, boxelder beetles, stinkbugs, leafhoppers, ticks, biting flies and sunflower moth caterpillars. Japanese and Oriental beetles are about done if not done already. I saw one Japanese beetle last week. Asiatic garden beetles remain active. It is a good year for butterflies, especially swallowtails and fritillaries. I’ve even seen a few monarch butterflies this year. Beneficial insects like ladybugs, hoverflies and ambush bugs remain active.

With all this dry weather, along with slugs and snails, mosquito populations appear to be reduced; however, continue to take precautions and use a repellent, like DEET, when working outdoors. Wasps are very active so continue to be on the look-out for ground nesting wasps and the grey-paper-like nests of the bald-faced hornet which are easily hidden, hanging within the branches of trees and shrubs.

Not much seems to be going on in the plant disease department. Tar spot is showing up on Norway maple and powdery mildew is showing up slightly on garden phlox, Helianthus, Lonicera, Monarda and dogwood, but not as significantly, as in past years.

Unfortunately, weeds like crabgrass, spotted spurge, purslane, and clearweed are doing very well and thriving, and ragweed has started to bloom.

Now is a good time, before fall and winter storms come in, to remind clients who need tree work done to make an appointment with a Mass. Certified Arborist. It is also a good time to make plans to renovate or put in a lawn.

Deer, chipmunks, starlings, squirrels and rabbits continue to be a landscape nuisance.

North Shore Region (Beverly)

No report available this week.

East Region (Boston)

General Conditions: Conditions remain dry. We did receive one significant rain event on August 21st delivering 0.75” of much needed moisture to the grounds. Three other minor rain events occurred for a total of 1.43” over the past two weeks. Herbaceous perennials continue to add color to the landscape. Various hybrid roses continue to bloom. Species roses are forming a variety of colorful sizes and shapes of hips. Clerodendrum trichotimum (glory bower) continues to flower.

Pests/Problems: The landscape is visibly suffering from drought stress. Early leaf drop is apparent throughout the collections. Early fall color is occurring on many maples. Lace bug continues to multiple and feed on any available plant. (Non–specific hosts.) Unwanted vegetation continues to flourish under these conditions. Supplemental irrigation is required.

Metro West (Acton)

General Conditions: The average rainfall for the month of August is 3.72" and with thanks to the 3.19” of the rain recorded during this past two-week recording period, the total for this month is at 3.42”. Unfortunately, much of the rain received came fast and hard and also brought with it a tornado that touched down in Concord early Tuesday morning causing much tree damage and many power outages. This summer’s lack of rain and hotter temperatures has taken much of the sting out of our flowering plants. Woody plants seen in bloom this week are Albizia julibrissin (Silk Tree), Buddleia spp. (Butterfly Bush), Hibiscus syriacus (Rose-of-Sharon), Hydrangea paniculata and its many cultivars including 'Tardiva', and Syringa reticulata (Japanese Lilac). A woody vine seen in bloom is Campsis radicans (Trumpet vine). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Boltonia asteroides (Bolton’s Aster), Cassia marilandica (Wild Senna), Cichorium intybus (Chicory), Daucus carota (Queen Anne's Lace), Echinacea purpurea (Coneflower), Eupatorium purpureum (Joe Pye Weed), Patrinia gibbosa (Patrinia), Perovskia atriplicifolia (Russian Sage), Phlox carolina (Carolina Phlox), C. paniculata (Phlox)and its many cultivars, Rudbeckia fulgida 'Goldsturm' (Black-Eyed Susan), and Solidago spp.(Goldenrod).

Pests/Problems: Despite the heavy rain that fell these past two-weeks, extreme drought conditions have been declared for this area and for most of the central and northeastern regions in the State by the National Drought Mitigation Center. Signs of plant stress are apparent in the landscape including premature leaf drop, early fall color and wilting. Powdery mildew is evident on Monarda (Bee Balm), Phlox and Syringa (Lilac). Emergence season is upon us for the Asian Longhorned beetle so continue to check your trees for oviposition sites, frass, exit holes and the beetle. Most importantly, begin to scout for the Asian Longhorned beetle! Monitor the 12 host genera: Acer (Maple), Betula (Birch), Ulmus (Elm), Salix (Willow), Aesculus (Horsechestnut), Fraxinus (Ash), Platanus (Plane Tree), Populus (Poplar), Sorbus (Mountain Ash), Albizia (Mimosa), Cercidiphyllum (Katsura) and Keolreuteria (Golden Raintree) for this invasive pest.

Central Region (Boylston)

General Conditions: We are grateful to have received 2.58” of rain in the past two weeks, though two of the rain events came hard and fast, with much of the rain running off quickly. Still, turf has greened up again and many of the plants look relieved. We are still considerably under average for rainfall, and irrigating will likely resume this week, where permissible, in areas where the rainfall failed to penetrate the soil. In bloom in the gardens and landscape now are Anemonopsis macrophylla, Anemone tomentosa ‘Robustissima’, Angelica gigas, Hydrangea paniculata cultivars, Hibiscus moscheutos, Perovskia atriplicifiolia, Rudbeckia 'Goldsturm', R. subtomentosa 'Henry Eilers', R. laciniata 'Herbstsonne', Hibiscus syriacus, Veronicastrum virginicum, Phlox paniculata 'Bright Eyes', Eupatoruim 'Gateway', and many annuals and tender perennials.

Pests/Problems: Blister beetle remains active on Anemone tomentosa ‘Robustissima’ and A. ‘Pamina’… we are seeing cross-hatched cabbage worm on kale, and Fall Webworm is appearing along roadside edges.

Pioneer Valley Region (Amherst)

General Conditions: This reporting period has seen starkly contrasting environmental conditions. Within a single week the Pioneer Valley has experienced a record high temperature of 89° F on Saturday, August 20, followed by several cool nights, including a record low temperature of 46° F on Tuesday, August 23. The landscapes are still struggling under moderate to severe drought conditions with very little rainfall during this reporting period. The cooling night temperatures have also been paired with increased humidity these past few days, which may be favorable for fungal pathogen infection over the coming weeks.

Pests/Problems: Turfgrasses, annuals, perennials, and woody plants are continuing to show the extended effects of heat and drought stress. Foliar blights and anthracnose diseases have taken their toll on many woody landscape plants, and several shade trees are also displaying characteristic leaf scorch and dieback as a result of the prolonged abiotic stress conditions. Several annual and perennial plantings have become inundated with Cercospora leaf spot. Powdery mildews are beginning to appear on horse chestnut and dogwoods, as well as some herbaceous plant material. Arborvitae plantings around the UMass campus are looking particularly beaten back, and the Japanese Pagodatrees have apparently failed to flower this year. Ericaceous landscape plants have also suffered significant losses, likely due to winter-damage. We have seen several instances of stem-cankering fungal pathogen damage over the past few weeks, as well as foliar injury due to beetle and spider mite infestations.

Berkshire Region (Great Barrington)

General Conditions: It’s at this time of year when senescence becomes apparent as many ornamental plants are showing signs of decline. Most have reached full maturity and many are looking worn and tattered. This is a sign that some cleanup is in order, not only to improve the look of gardens and landscapes but also to remove diseased and pest infested plant materials. Nevertheless, there are still a number of late season bloomers lighting up gardens. Hydrangea paniculata, Rose-of-Sharon, asters, Rudbeckia, Echinacea, Eupatorium, Anemone tomentosa, and various daisy species are in bloom. Though total precipitation for the year is well below normal, recent rains have left soils moist, for the moment. Leaf drop on Amelanchier, birches, and many other tree species due to pests, foliar disease, and weather factors is a common sight as is premature fall coloring on stressed woody plants. Add Sophora japonica to the list of trees which failed to flower this year, most likely due to the extreme cold of Valentine’s Day weekend in February.

Pests/Problems: The spore forming structures, called aecia, of cedar-apple rust on apple and crabapple are more fully mature and are releasing spores which now infect the alternate host, Juniperus species. Downy mildew has appeared on basil plants but the strain infecting impatiens has not been observed this year. Spruce spider mite and two-spotted spider mite have been active as are Asiatic garden beetle, oak lace bug adults and nymphs, magnolia scale crawlers, aphids, leaf hoppers, and a myriad of nuisance pests including mosquitoes, wasps, hornets, ticks, and ants. Extensive browsing by deer has been occurring, especially on tender herbaceous plants such as hosta. The populations of voles, chipmunks, and rabbits have been very high this year resulting in considerable damage to plants in landscapes and vegetable gardens.

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:

Black spot, caused by Stegophora ulmea, on Japanese zelkova (Zelkova serrata). Tree has been present at the site for two years and is approximately 6” in diameter. In July of this year, leaves began browning and prematurely shedding throughout the canopy. The tree resides in full sun and receives lawn watering. While black spot is most common elm, this anthracnose pathogen can also attack species of Zelkova. Lawn watering often wets portions of the canopy, creating ideal conditions for pathogen development. Overall, black spot of elm has been uncommon this season due to the drought.

Decline of shamrock holly (Ilex glabra ‘Shamrock’) caused by the anthracnose pathogen Colletotrichum. Nursery-grown plant is two-years-old and irrigated with overhead sprinklers. Destructive analysis of the roots revealed the plant was potted too deep and many adventitious roots had developed. While none of these had developed into girdling roots, the root mass was highly circled and tangled. Most of the foliage was blighted and shed and the majority of canopy stems were blighted. Overhead watering readily disperses fungal spores to nearby, healthy plant parts.

Lower canopy dieback on Leyland cypress (✕Cupressocyparis leylandii) caused by Diplodia cupressi. Trees are approximately 15- to 20-years-old and have been present at the site for 10-15 years. Planted as a hedge in compacted, gravelly soils. Drip irrigation is provided and trees are pruned to maintain a 20’ tall screen. This year, lower canopy needle browning was observed and submitted canopy branches were cankered by D. cupressi. This pathogen has been only recently detected on Leyland cypress and appears most prominent on trees suffering from stress.

Dogwood anthracnose, caused by Discula destructiva, on kousa dogwood (Cornus kousa). Tree has been present in the currently location for only two years and over the past month, marginal leaf browning has developed. Drip irrigation is provided and the tree is growing in a full sun setting. Kousa dogwood is highly resistant to dogwood anthracnose but can be infected, especially when trees are stressed. A marginal foliar blight is the most common symptoms and stem cankering would be rare, but possible, on this host.

Decline and dieback of English yew (Taxus baccata) due to overwatering. Tree is over 30-years-old and has been present at the site for nearly as long. Planted in a retaining wall with others shrubs and ivy. The plant has been watered daily and the soils were very saturated. Submitted roots were decayed and dead but no pathogens were detected. The upper canopy is very thin and many needles have been prematurely shed. Yews are extremely drought resistant and require little, if any, supplemental irrigation once they become firmly established at a site.

Eastern filbert blight, caused by Anisogramma anomala, on contorted filbert (also known as Harry Lauder’s walking stick; Corylus avellana ‘Contorta’). Tree is nearly 20-years-old and has been present at the site for many years. In July of this year, browning leaves and stem dieback was observed. Eastern filbert blight is a serious disease for many species of Corylus, leading to death if not treated. On cankered stems and branches, distinctive black pads of fungal tissue (stromata) can easily be observed. On the submitted sample, the pads were extruding a pink-colored mass of spores.

Dutch elm disease, caused by Ophiostoma novo-ulmi, on American elm (Ulmus americana). Tree is approximately 80-years-old and is regularly treated to prevent DED. In June, branch tips began to flag and die. The drought has exacerbated this disease on numerous elms this season. Site is on a well-drained slope with dry soils prone to drought.

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:

  • Asian Longhorned Beetle, Anoplophora glabripennis, ALB adults continue to be active in Massachusetts in August. In fact, the US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) has called August Tree Check Month, as it is a prime time to find ALB adult beetles and report any insects or signs of infestation. They are asking the public to take 10 minutes and inspect their trees, particularly maple. Look for the insect itself (a shiny black bodied beetle with white spots and long antennae with black and white bands) or signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches.

    They ask the public to take the following steps:
     
    • Make note of what you found; take a photo when possible (of suspicious damage, the beetle, etc.)
    • Capture the suspicious insect when possible; place it in a container and freeze it
    • Report your findings

      The regulated area for Asian longhorned beetle is 110 miles2 encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn. If you believe you have captured an Asian longhorned beetle or have seen damage caused by this insect, such as exit holes, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938. To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: http://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report.
       
  • Emerald Ash Borer (EAB): Agrilus planipennis readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus). Adults are finishing their activity, depending on local temperatures, by the end of this month. For a map of the known locations of emerald ash borer in the state, as well as further information about this insect, please visit: https://ag.umass.edu/fact-sheets/emerald-ash-borer.
  • Andromeda Lacebug: Stephanitis takeyairemains active on Japanese Andromeda and will continue into September. Inspect plants known to have S. takeyai in the past (or exhibiting yellow stippling on the upper leaf surface) and inspect undersides of leaves for this season’s lacebugs. Before populations become too large, treat with a summer rate horticultural oil spray as needed. Be sure to target the undersides of the foliage in order to get proper coverage of the insects.
  • Azalea Lacebug: Stephanitis pyrioidesis active on evergreen azaleas. This insect may be more damaging on plants located in warm, sunny locations. Like andromeda lacebug, this insect will remain active into the fall. Plants in hot, dry, sunny sites may be severely impacted at this time. Horticultural oil sprays targeting the undersides of the foliage can be very effective for this pest.
  • Fall Home-Invading Insects: Various insects, such as ladybugs, boxelder bugs, seedbugs, and stink bugs will begin to seek overwintering shelters in warm places, such as homes, throughout the next couple of months. While such invaders do not cause any measurable structural damage, they can become a nuisance especially when they are present in large numbers. While the invasion has not yet begun, if you are not willing to share your home with such insects, now should be the time to repair torn window screens, repair gaps around windows and doors, and sure up any other gaps through which they might enter the home.
  • Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock and is in its summer dormant period which will last until approximately mid-October. Dormant nymphs can be treated throughout the summer with a horticultural oil spray at the summer rate, however be careful to follow all label instructions to avoid injury to the plant. Avoid using oils when temperatures are close to or above 90°F and when humidity is high.
  • Redheaded Pine Sawfly: remains active at this time. This caterpillar-like insect is yellow with rows of black spots and a rust-colored head capsule. Clusters of these hymenopterans can be seen feeding on pines and will continue into the autumn months. Inspect needle tips for clusters of larvae. Prune out or destroy with a gloved hand in the case of small infested areas. Spinosad is effective against these larvae, whether younger or older.
  • Spruce Spider Mite: Oligonychus ununguis, a cool season mite, has resumed its activity following a break during the hottest days of summer. This particular pest may be active throughout October. Inspect for new yellow stippling on spruce, fir, and hemlock. Population size can be monitored by shaking branches over white pieces of paper and then inspecting with a hand lens. If you are seeing more than 10 mites per tap, treat with a horticultural oil at the summer rate if necessary. All management should strive to preserve predatory mites, as they are the most effective managers of these pests.
  • Viburnum Leaf Beetle: Adults have been actively feeding and will continue into September. Adult beetles may be targeted with a pyrethroid; however, adult beetles are generally more difficult to manage than the larval stages. Planting species of viburnum that are most resistant to the viburnum leaf beetle can help manage this pest. Resistant varieties include V. bodnantense (dawn viburnum), V. carlesii (Koreanspice viburnum), V. davidii (David viburnum), V. sieboldii (Siebold viburnum), and others. Highly susceptible species of viburnum frequently attacked by this beetle can include V. dentatum (arrowwood viburnums), V. opulus (European cranberrybush viburnum), and V. rafinesquianum (Rafinesque viburnum).

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 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. 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 UMass 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: Hydrangea paniculata ’Limelight’

Hydrangea paniculata ‘Limelight’ is a medium growing cultivar of H. paniculata growing 6-8’ tall and wide. Limelight hydrangea blooms July to September with the creamy white flowers turning to a light green-lime color as they mature and aging to a rose pink. The cone shaped panicles can be up to 8”, with flowers tending to be smaller when there are numerous blooms on the shrub (thinning can help to create larger flowers). Large blooms can weigh branches down. Flowers are on the current year’s growth so pruning can be done in late winter to early spring. Leaves are dark green, ovate, and serrated. Plants are best in full sun to part shade and are tolerant of urban conditions. Plants are attractive both as specimens and as a hedge or in mixed shrub borders. Hydrangea paniculata ‘Limelight’ has no serious insect or disease problems.

Hydrangea paniculata ’Limelight’     Hydrangea paniculata ’Limelight’     Hydrangea paniculata ’Limelight’

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

Landscape Turf

Helping Turf Recover from Summer Stress - Drought and Heat

There is no secret that this summer has been hot and exceptionally dry here in New England. The U.S. Drought Monitor (http://droughtmonitor.unl.edu/) shows Massachusetts to be seriously affected. Ten of the state’s 13 counties are experiencing a ‘Severe’ or ‘Extreme’ level of drought that extends northeast through southern New Hampshire and up into southern Maine.

The stress of drought coupled with repeated periods of high heat and windy conditions has left many lawns, parks and sports fields in trouble. Many unirrigated sites have been dormant for several weeks. The longer the drought dormancy, the higher the heat, and the more the turf is used (walked on, played on, etc), the more likely that the turf is suffering and will need specialized care in order to recover. In some locations recent rains have provided a modicum of relief while lower temperatures, particularly at night, have returned to levels conducive to rooting and turfgrass growth.

While many lawns will survive and the grasses will regrow, some hard hit areas are exhibiting thinned, damaged turf that is easily invaded by weeds and pests. Steps taken now and over the next few weeks will help turf to recover well, go into the winter in good shape, and be ready for whatever challenges that next year’s growing season may bring. Recovery strategies should be focused on protecting the turf from further damage, encouraging rooting and taking steps to ensure a dense canopy of desirable grasses. A deeply rooted, dense turf is the first line of defense against pests and stress.

First, take stock of the situation: What is the condition of the turf?

Is the grass is still dormant (brown or straw colored with no green growth)? Then protect it from further damage. Strictly limit foot and vehicle traffic, or risk damaging the turfgrass crowns from which new growth will arise. Do not mow unless turf growth warrants it. Do not fertilize dormant turf. Instead, wait until the weather cools and moisture returns, when signs of regrowth – new green sprouts - begin to appear before considering a fertilizer application.

Has the grass begun to show any signs of recovery… new green shoots coming from the crown at the base of the plant? Great!

Has the turf been kept out of dormancy through regular irrigation? Adjust the irrigation schedule so as not to overwater, especially as temperatures moderate and the sun’s intensity decreases through the earth’s natural rhythm. Overwatering will actually make turf less tolerant to drought, and can decrease rooting while increasing the potential for disease, as well as wasting a precious natural resource.  For a current list of Massachusetts communities with water restrictions, see http://www.mass.gov/eea/agencies/massdep/water/watersheds/municipal-water-use-restrictions.html

If the soil has not been tested in the last few years, this is a good time to do so. For directions on how to take a sample and submit it, visit the UMass Soil and Plant Nutrient Testing Lab at UMass Amherst: http://soiltest.umass.edu/. Results will indicate if liming is needed, and specify if additional nutrients are needed. Providing for adequate soil nutrition is a foundation stone in growing a healthy turf.

Insect pests

Pests can take advantage of the weakened condition of stressed turfgrasses, and the damage of some insects, particularly chinch bugs, can mimic drought symptoms. Scout for insect infestation and plan to manage damaging populations if needed.

Adults of turfgrass damaging white grubs will be more likely to lay their eggs and continue their life cycles on schedule in turf that has not experienced moisture stress. Eggs have already begun hatching and first instar grubs are busy feeding in some irrigated lawns. Adult beetle egg-laying may be delayed on non-irrigated sites that have been heavily stressed or that have gone into dormancy. See Dr. Pat Vittum's recent Management Update for considerations for managing insect pests given the current drought situation.

Weeds

Many weeds will out-compete stressed turfgrasses. Determine if unacceptable weed infestation has occurred, and plan to manage the situation. Crabgrass in particular will move into summer stressed turf and thrive under hot and dry conditions. If crabgrass is present and going to seed then you can be assured that there will be an infestation next season in the absence of corrective action.

If the weedy grasses are flowering and seeding, then bag the clippings when mowing and dispose of them properly. Use a pre-emergence herbicide next spring.

Crabgrass will begin to lose vigor as temperatures cool, and will die out after a frost or two. However, if the lawn has deteriorated to the point at which a renovation should be done before waiting for frost, then use of a post-emergence herbicide that will not interfere with subsequent seeding may be a part of a pre-plant weed control strategy.

Mowing

Once growth has resumed, mow at highest height of cut appropriate for the situation and mow frequently enough to maintain that height. Mowing actively growing grasses frequently at the proper height of cut will encourage shoot and canopy density. Again, bag and remove clippings if crabgrass or other weeds are going to seed. Otherwise, drop the clippings as long as they do not clump.

Fertilization

Avoid fertilizing turf that is dormant. The plants do not have the ability to take up the materials and respond until growth resumes. Moisture is the key to pulling turfgrasses out of dormancy, and fertilizer will not be effective until new growth starts. Once that happens, proper fertility provided during the late summer – early fall period is critical to both the short-term and the long-term vigor of the turf and its ability to withstand pests and stress.

Fertilization of stressed turf should focus on encouraging root growth balanced with increasing shoot density. The particulars of a fertilization plan will depend on several factors including turfgrasses present, management level, turf use, and site factors, such as shade, that may impact growth. Opt for fertilizer materials with the highest percent of slow release nitrogen for the particular turf whenever possible. See Table 7 in UMass Extension’s Best Management Practices for Soil & Nutrient Management in Turf Systems for suggestions about fertilizing during this late summer – early fall period.

Plan to overseed thin or damaged areas.

Late summer-early fall is the best time of year to make improvements. Temperatures cool and moisture is usually more available, typically for several weeks, providing the conditions in which our cool season grasses thrive.

Thinned turf and bare spots invite weeds, and the loss of cushioning from turf cover can lead to compacted soil. It is important to get desirable turfgrasses growing before weeds can move in and compaction can occur.

‘Establishment, Renovation and Repair’, section 5 in UMass Extension’s Best Management Practices for Lawn and Landscape Turf, contains guidelines for improving turf from simple spot repairs to major renovations.

Use drought tolerant cultivars of grass species appropriate for the site and use. Adjust pH if needed and follow soil test recommendations for phosphorus and potassium fertilization prior to seeding.  For more information on selecting drought tolerant turfgrasses check out the Turfgrass Water Conservation Alliance at http://www.tgwca.org/ and the National Turfgrass Evaluation Program at http://www.ntep.org.

If the physical condition of the soil is poor, then core aerate in conjunction with seeding and apply an organic topdressing such as a finished compost.

Alternatively, use a slice seeder to overseed the area.

Watering is critical when new grass is being started. If water use for irrigation is restricted, wait until mid-September to overseed to take advantage of potential precipitation increases heading into the fall. While there is no guarantee that precipitation will increase (recall that in 2015 we experienced an extended period without significant or widespread rainfall in late summer through early fall), seeding a little later provides a better chance of favorable conditions.

If you have no water available at all for making repairs, mulch seeded areas to conserve any naturally occurring moisture. Another option is to try a dormant seeding very late in the fall, after there is no chance of germination happening this year, and in hope of new growth taking hold very early next spring as the turf emerges from winter.

Evaluating the condition of the turf now and taking steps to aid in turf recovery will ensure that the lawn or park or playing field recovers and thrives, both keys to creating a drought and pest tolerant turf.

Report by Mary Owen, Turf Specialist and Program Coordinator, UMass Extension Turf Program

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.

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