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 bi-weekly July through September. The next message will be available on August 8. 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: The dog days of summer have certainly made their appearance for this reporting period. Daytime temperatures have held in the upper 70s to mid 80s F with fairly high dew points, making for muggy conditions. Thankfully, the Cape usually has a good sea breeze which keeps the air moving and makes the heat and humidity more comfortable. Most rain storms again passed west of the canal but the Cape did receive 1.75" on 7/16 and another ½" on the 20th. Hydrangeas on the north side near the Bay are blooming and look little damaged from the winter while those in the mid-Cape and away from the water are green and leafy with few blossoms. Daylilies, annual Black-Eyed Susan, and Coneflowers are blooming in the perennial border. Pests/Problems: Annual cicadas are buzzing in the trees. Soils are still on the dry side but the Cape has received a bit more regular rainfall. Still, pay attention to newly planted material with limited root systems and be sure to keep them hydrated. Adult viburnum leaf beetles are actively feeding on V. dentatum, V. trilobum, and V. plicatum tomentosum. Japanese beetles, Oriental beetles, and Asiatic garden beetles are all active. Second generation Pieris lacebugs are active. Daylily thrips are active. Mites have been observed on Baptisia. Small looper caterpillars are feeding on the petals of Rudbeckia. Various leafhoppers are active on a number of perennials. Mosquitoes are still biting. Powdery mildew is quite visible on susceptible phlox and bee balm. A leaf spot has been observed on River Birch. Rust is active on hollyhock. For clients with vegetable gardens, second generation Colorado potato beetles are active, along with Squash vine borer and Squash bugs. On tomatoes, Early blight and Septoria leaf spot are active.
Southeast Region (Hanson)
General Conditions: This has been a warm summer and the hot, humid weather has continued for the past two weeks. Hanson was fortunate to receive 3.20 inches of rain over the past two weeks. Other areas of the county received more and some areas, less. Continue to remind clients to water newly planted trees and shrubs and drought-stressed plants, during this hot, dry weather. Oxydendron arboreum (Sourwood Tree), Albizia julibrissin, Aesculus parviflora (bottlebrush buckeye), Campsis radicans, Indigofera kirilowii, Indigofera amblyantha, Hydrangea macrophylla, Hydrangea quercifolia (Oakleaf Hydrangea), Hydrangea arborescens (Smooth Hydrangea), Hydrangea paniculata 'Praecox' and other early cultivars, Clematis, roses, Rose-of-Sharon, Rubus odoratus, Echinacea sp., Acanthus spinosus, Acanthus mollis, Platycodon sp., Arisaema fargesia, Liatris spicata, Lysimachia clethroides, Actea (formerly Cimicifuga) racemosa, Perovskia atriplicifolia, daylilies, Hosta, Corydalis lutea, Phlox paniculata (Garden Phlox), Shasta daisy, Nepeta sp., Heliopsis 'Summer Sun', Helianthus sp., Monarda didyma (Beebalm), Silphium sp., Spigelia marilandica, Lavender, Rudbeckia sp., Oriental lilies, Coreopsis verticillata, Astrantia major and Campanula sp. are in full bloom. Echinops ritro (Globe Thistle) and Sedum sp. are beginning bloom. The colorful fruit of crabapples are starting to add color to the summer landscape. The warm weather has been great for flowering annuals and unfortunately, also for weeds. Pests/Problems: Oak sawfly was reported skeletonizing oak foliage. Spider mites continue to be a major pest on Phlox paniculata. Japanese, Oriental and Asiatic garden beetles continue to be active. Biting flies (deer flies, horseflies, and the very large, black horseflies, etc) are active. These biting flies are attracted to moving objects. Earwigs, aphids, ticks, lily leaf beetles, slugs, snails, stinkbugs, four-lined plant bug, lacebugs, leafhoppers, wasps, hornets, carpenter bees, ticks, and mosquitoes are all active. Eastern equine encephalitis (EEE) was found in a mosquito test pool in Bridgewater, MA. Continue to take precautions against mosquitoes and ticks and use a repellent, like, DEET when working outdoors. Giant tar spot is beginning to show up on Norway maples. Various other leafspots and anthracnose are also being reported on various susceptible plants. Blackspot is very evident on susceptible roses. The fruit on Oriental bittersweet and Euonymus alatus is getting bigger. Remove plants and/or prune back to remove fruit. Reports continue to come in of deer continuing to browse plants, especially hosta.
North Shore Region (Beverly)
No report available this week.
East Region (Boston)
General Conditions: We gained 317 GDDs over the last two weeks bringing us to 1380.5 GDDs on the year. High temperatures ranged between 73° F and 89° F (averaging 81° F); low temperatures ranged from 58° F to 72° F (averaging 64° F). This year continues to be significantly cooler; at this point last year, we had experienced 15 days of temperatures in 90's compared to only 3 days this year. We received adequate rainfall over the last couple of weeks, accumulating 1.76 inches; all of it falling over a four day period with the majority arriving over two days of soaking rain on the 14th and 16th of July. Plants in bloom include: Clerodendrum trichotomum (Harlequin glorybower), Euonymus carnosus (fleshy-flowered spindletree), Eutrochium sp. (Joe-Pye weed), Helianthus tuberosum (Jerusalem artichoke), Hibiscus moscheutos (rose mallow), the unusual Poliothyrsis sinensis (Chinese pearl tree), Rhododendron prunifolium (plumleaf azalea), and Silphium perfoliatum (cup plant). Pests/Problems: Black swallowwort (Cynanchum nigrum) seed pods continue to develop and mature. Enchanter's nightshade (Circaea lutetiana) seeds are mature and can be found attached to one's clothing or pets. Weeds in flower include: Chicory (Cichorium intybus), Hairy galinsoga (Galinsoga ciliata), Pineapple weed (Matricaria matricarioides), Prostrate Spurge (Euphorbia maculata), Purple loosestrife (Lythrum salicaria), Slender rush (Juncus tenuis), Tumble pigweed (Amaranthus albus), Wild carrot (Daucus carota) and Yellow nutsedge (Cyperus esculentus). Male cicada killers have emerged and although seem aggressive at this time, are buzzing around defending their territory and investigating all visitors in the area.
Metro West (Acton)
General Conditions: The Acton area gained 322 GDD during this two week recording period and received 1.80" of rain. The average rainfall for the month of July is 4.07" and so far for this month I have recorded 4.17" of rain. Woody plants seen in bloom this week are Buddleia spp. (Butterfly Bush), Hibiscus syriacus (Rose-of-Sharon), Hydrangea arborescens (Smooth Hydrangea), H. quercifolia (Oakleaf Hydrangea), Oxydendron arboreum (Sourwood), Potentilla fruiticosa (Potentilla), Rosa 'Knockout' (The Knockout family of Roses), Rosa sp. (Rose) and Spirea japonica 'Alpina' (Daphne Spirea). Woody vines in bloom are: Campsis radicans (Trumpet vine) and Clematis spp. (Clematis). Contributing even more color and interest to the landscape are some flowering herbaceous plants including: Achillea millefolium (Yarrow), Actaea racemosa (Black Cohosh), Alcea rosea (Hollyhocks), Aruncus aethusifolius (Dwarf Goat's Beard), A. dioicus (Goat's Beard), Asclepias syriaca (Common Milkweed), A. tuberosa (Butterfly Weed), Astilbe spp. (False spirea), Cichorium intybus (Chicory), Coreopsis verticillata (Threadleaf Coreopsis), Daucus carota (Queen Anne's Lace), Echinacea purpurea (Coneflower), Filipendula sp. (Meadow Sweet), Hemerocallis 'Stella D'Oro' (Daylily), H. spp. (Daylily), Heuchera spp. (Coral Bells), Hosta spp. (Plantain Lily), Lavendula angustifolia (Lavender), Leucanthemum sp. (Shasta Daisy), Liatris spicata (Spike Gayfeather), Lilium spp. (Lily), Limonium latifolium (Sea Lavender), Lychnis coronaria (Rose Campion), Lysimachia cletheroides (Gooseneck Loosestrife),Monarda didyma (Bee-Balm), Oenothera macrocarpa (Ozark Sundrops), Perovskia atriplicifolia (Russian Sage), Platycodon grandiflorus (Balloon Flower), Rudbeckia fulgida 'Goldsturm' (Black-Eyed Susan), Tradescantia sp. (Spiderwort) and Veronicastrum virginicum (Culver's Root). Pests/Problems: Aphids have been sighted on Catalpa and Liriodendron (Tulip Poplar). 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. Monitor the 13 host genera: Acer (Maple), Betula (Birch), Ulmus (Elm), Salix (Willow), Aesculus (Horsechestnut), Fraxinus (Ash), Platanus (Plane Tree), Populus (Poplar), Celtis (Hackberry), Sorbus (Mountain Ash), Albizia (Mimosa), Cercidiphyllum (Katsura) and Keolreuteria (Golden Raintree) for this invasive pest. One of our most aggressive weeds, Cynachum nigrum (Black Swallowwort) is flowering and will be setting seed soon. Already setting seed and quite visible is Ailanthus altissima (Tree of Heaven). Look for it growing along roadsides and in medians.
Central Region (Boylston)
General Conditions: Hot & humid weather continues to push annuals and vegetables to fruition. Among the many things in bloom in the gardens are Daylilies (Hemerocallis); many colorful annuals, Deinanthe caerulea, Hardy Cranesbills (Geranium cvs.), Russian Sage (Perovskia atriplicifolia), Summer Phlox (P. paniculata), Glorybower (Clerodendron trichotomum), Bottlebrush Buckeye (Aesculus parviflora) and many others. Queen Anne's Lace (Daucus) and Purple Loosestrife (Lythrum salicaria) are in full swing. Pests/Problems: Cedar Apple rust and Fireblight are apparent on apples and crabapples. Fireblight is also showing up on other members of the Rose family including Spirea, Pears, Cherries and roses. Powdery mildew is beginning to show on Aesculus, Phlox and Peonies.
Pioneer Valley Region (Amherst)
General Conditions: Conditions over this past reporting period can be generally characterized by warm and muggy weather with numerous scattered thunderstorms. The mercury has been steadily in the 80s to near 90, but with the high humidity it has felt much hotter at times. A four-day stretch of measurable precipitation occurred from 7/13 through 7/16 in the valley, with about an inch of rain on the 16th alone. Overall, July has been a wet month, with an average of five inches of precipitation across Franklin, Hampshire and Hampden Counties. Yet, it's tough to complain about wet weather this time of the year, when temperatures soar and trees, shrubs, lawns and vegetables can become scorched and drought-stressed quickly on well-drained soils. In addition, drought-stress often amplifies disease and insect issues that can be contained by trees that have sufficient water. On average, August is one of the driest months of the year, so a good soaking prior to the final month of summer is a good thing. According to the Northeast Regional Climate Center, this summer (from 6/1 to 7/15) has been up to two degrees warmer than average for most of Massachusetts. Also, much of the Pioneer Valley has experienced higher than average precipitation, with the exception of eastern Hampshire and Hampden Counties. Parts of western Franklin and Hampshire Counties have experienced up to 150% of normal precipitation over this six week period, reflecting the heavy downpours from the scattered thunderstorms in late June and early July. Pests/Problems: Sooty mold fungi are very common on a number of different trees and shrubs right now (e.g. linden, tulip poplar, elm, and oak), indicating active aphid, leafhopper and scale populations on these plants. These fungi are saprophytic and cause no damage to plants. Powdery mildew fungi are also starting to appear, with the dry conditions over the past week. Most powdery mildew fungi are inhibited by free moisture on plant surfaces but require high humidity to develop. The most common host, lilac, remains free of the disease throughout most of the valley. Dry stretches in August are when large outbreaks can occur. It's been a good year for leaf gall mites, and while these pests often do very little damage to their associated host, they are highly conspicuous and cause alarm. The successive days of rain, and overall wet month of July we're experiencing, was conducive to the development of certain pathogens that will sporulate and spread throughout the growing season. Opportunistic shoot blight and anthracnose pathogens like Phomopsis, Volutella, Colletotrichum and others possess the ability to produce vast volumes of spores over a wide temperature range as long as conditions are wet. The four days of wet weather (7/13 through 7/16) almost certainly led to mass spore production and spread of these pathogens. Failure to prune and discard blighted shoots on easily accessible trees and shrubs can lead to increased disease development as the season progresses. Aspens, poplars and dogwoods developing numerous small, angular leaf spots may be infected by Septoria leaf spot, which tends to be a later season disease in our area. Infections are usually minor but in certain years can be more severe. Entomosporium leaf spot on hawthorn is developing but is not readily apparent just yet. By September, leaves can be completely consumed with dark leaf spots and blotches leading to leaf curl and early leaf drop. Right now, symptoms appears as pale green to yellow spots and blotches, mostly in the center of the leaf and are easily missed.
Berkshire Region (Great Barrington)
General Conditions: For much of the reporting period, soils were moist to muddy due to a pattern of frequent showers. Temperatures for the most part were near or just below normal though some very cool nights occurred following the passing of a cold front after a couple of thunderstorms. Given these conditions, lawns and landscapes remain lush. Hydrangeas are the dominant woody species in bloom in landscapes. Daylilies are at their peak. Humidity has started to build at the latter part of the period to levels more typical of summer. With few exceptions disease and pest pressures have not been bad. Pests/Problems: Japanese Beetles continue to be the dominant pest in gardens and landscapes. A number of adult forms of species of Cerambycidae (Long-Horned Beetles) have been found inside houses and on landscape plants. They attract attention due to their large size, long antennae, and color patterns. The color patterns of some species mimic wasps and bees. Many of the species are wood borers, but not all are considered damaging to valuable landscape trees or shrubs. Except for the most notorious Cerambycids, i.e. Asian Long-Horned Beetles, Emerald Ash Borer, identification can be difficult due to the very large number of species within the family. Another large insect attracting attention is the Cicada Killer Wasp which reaches a length of an inch or slightly more. These wasps were spotted emerging from underground burrows. Despite their size and appearance, the wasps are not considered harmful to humans. Other prominent insects observed this week include Asiatic Garden Beetle, aphids, and stink bugs (not the Brown Marmorated Stink Bug). Two-spotted Spider Mite is active but the most damaging pests of herbaceous plants are slugs and snails. Impatiens Downy Mildew was found at one site. Powdery mildew is present but not severe as yet.
Environmental Data
The following growing-degree-day (GDD) and precipitation data was collected for an approximately 2 week period, July 10 through July 23. Soil temperatures and phenological indicators were observed on or about July 23. Total accumulated GDDs represent the heating units above a 50° F baseline temperature collected via our instruments for the 2014 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 |
GDD |
Soil Temp |
Precipitation |
|
Cape Cod |
293 |
1338 |
78 |
2.25 |
|
Southeast (Wareham) |
n/a |
n/a |
n/a |
n/a |
|
Southeast (Hanson) |
280 |
1364 |
79 |
3.20 |
|
East |
317 |
1380.5 |
77 |
1.76 |
|
Metro West |
322 |
1239 |
80 |
1.80 |
|
Central (Boylston) |
306 |
1171 |
70 |
1.02 |
|
Pioneer Valley |
293 |
1406 |
79 |
2.27 |
|
Berkshires |
247 |
1082 |
74 |
1.94 |
|
AVERAGE |
143 |
1283 |
77 |
2.63 |
|
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. (Wareham) | S.E. (Hanson) | EAST | METRO W. | CENT. | P.V. | BERK. |
| Clethra alnifolia (Summersweet Clethra) | * | * | * | begin | begin | * | begin/full | * |
| Hibiscus syriacus (Rose-of-Sharon) | begin | * | begin/full | begin | full | begin | full | begin |
| Buddleia davidii (Butterfly Bush) | begin | * | full | begin/full | full | full | begin | * |
| Oxydendron arboreum (Sourwood) | begin | * | full | full/end | full | full | full/end | * |
| Campsis radicans (Trumpet Vine) | * | * | full | begin/full | full | * | full | full/end |
| Koelreuteria paniculata (Goldenrain Tree) | * | * | end | full | * | * | end | * |
| Hydrangea paniculata (Panicle Hydrangea) | begin | * | begin/full | end | full/end | begin/full | begin | 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 (Wareham) - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from Wareham.
- SOUTHEAST REGION (Hanson) - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, reporting from Hanson.
- 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 (Boylston)- 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 and insect pests of interest seen in the UMass Extension Plant Diagnostic Laboratory:
Privet thrips (Dendrothrips ornatus) on privet (Ligustrum sp.). Mature hedge, estimated to be over 50-years-old growing in full sun. Symptoms include "flecking" and yellowing of the foliage throughout the canopy. While the entire hedge is infested, one section that was temporarily transplanted to facilitate septic tank repairs five years ago is suffering more severe damage. Thrips are very small insects that feed on plant foliage and the privet thrips can be very destructive to California privet (L. ovalifolium) and regal privet (L. obtusifolium regelianum).
Shoot and needle blight caused by Sirococcus tsugae on eastern hemlock (Tsuga canadensis). Trees are approximately 30-years-old tree and are growing as a pruned hedgerow. Bare spots developed with premature needle shedding and shoot dieback. Tip blight of hemlock caused by S. tsugae is an emergent disease that is quite damaging in parts of northern New England. Blighted shoot tips curl unnaturally, and younger, shaded trees are more susceptible.
Shoot and needle blight caused by Diplodia pinea, needle cast caused by Lophodermium and Rhizosphaera and infestation by the pine needle scale (Chionapsis pinifoliae) on Mugo pine (Pinus mugo). For some samples, it's more appropriate to ask, "What disease or insect pest doesn't it have?" Needle yellowing/browning and premature shedding were observed. The Rhizosphaera infection was severe, based on the submitted sample, yet it was the Diplodia infection that did most of the damage.
Needle and shoot blight caused by Kabatina juniperi and Pestalotiopsis funerea on eastern redcedar (Juniperus virginiana). Trees at two separate properties with symptoms of tip blight scattered throughout the canopies. One tree is >40-years-old while the other is <10-years-old. Kabatina primarily infects one-year-old shoots while Pestalotiopsis is often found on current years and older shoots.
Spruce spider mite infestation (Oligonychus unuguis) infestation on Frasier fir (Abies fraseri). 12 trees, less than five-years-old, planted very close together and heavily pruned to create a privacy hedge. Last year, the trees began to yellow and prematurely shed interior needles. This year's needles were asymptomatic, but older needles were heavily infested with severe "flecking" damage caused by the spruce spider mite. Stress brought on by the improper use of this plant as a screening hedgerow likely facilitated infection.
Root and butt rot, caused by Armillaria, on sugar maple (Acer saccharum). Tree is roughly 75 to 100-years-old and is growing in a woodland garden. A previous sample of a nearby Hydrangea was also infected by Armillaria. Symptoms of infection included: thinning crown, undersized foliage, branch dieback, flaring on the lower trunk with sap flow and dead areas of bark. Rhizomorphs and mycelial fans were observed.
Brown needle spot, caused by Mycosphaerella dearnessii, on eastern white pine (Pinus strobus) and a hybrid cross between eastern and western white pine (P. monticola x strobus). White pine needle cast continues to be a problem throughout New England and New York and M. dearnessii is one of the primary pathogens responsible. Interior needle yellowing/browning and premature needle shedding throughout the canopies on both trees.
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: http://extension.umass.edu/landscape/diseaseguide
Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass, Amherst.
Weeds
Be sure to check out UMass Extension's Online Weed Herbarium!
Name that weed! (Click photo to enlarge, and click here for answer)
Landscape Turf
Management Practices
Fine-Tuning Summer Irrigation
The majority of the 'listening area' has received a healthy amount of rainfall as a result of periods of unsettled weather over the last few weeks. In the average year, however, the months of July and August are typically the driest among all the months of the growing season. Moisture shortages during this time, coupled with peak average temperatures, often mean that turfgrass systems lose water to evapotranspiration (ET) faster than it can be naturally replenished. In many years, if supplemental irrigation is not provided in summer then the turf may wilt, lose green color, and eventually enter drought dormancy.
Dormancy is a natural, adaptive response of turfgrasses to extremes of the growing environment. When circumstances permit and with the right approach, dormancy of well-established and otherwise healthy turf can lead to substantial savings of time, labor and management resources. Drought dormancy, however, is commonly not compatible with higher expectation levels in terms of appearance (higher-end lawns) and function (golf courses, premier athletic fields). This leaves the turf manager with two basic choices: to manage for dormancy or commit to supplemental irrigation.
The purpose of irrigation is to continually replenish water lost to ET, to help ensure that a soil moisture reservoir or 'pool' adequate for growth is readily available. There are a number of factors that influence the potential size of the soil moisture pool at any given point in time, the two primary contributors are as follows:
Soil characteristics – The inherent ability of the soil to retain plant-available moisture against gravitational drainage is largely dependent upon the size and number of soil pores. Soil pore space is influenced to a great degree by soil texture (soil particle size), and also by other factors such as organic matter content and cultivation practices. Coarse textured (sandier) soils will typically have lower moisture retention due to larger pore spaces through which water drains more readily, but from which it is easier for plants to draw water. Finer textured (more silt and clay) soils generally have better moisture retention from smaller pore spaces that hold water more effectively, but from which it is somewhat harder for plants to access the water.
Turfgrass species and varieties present – Turfgrass species and varieties vary, sometimes considerably, in their inherent consumptive water use rates. Furthermore, significant interaction frequently exists between species or varieties and specific aspects of the growing environment. Differences also exist among turfgrass species and varieties in terms of rooting potential; deeper rooted varieties have greater 'reach' to access water in the soil, thereby increasing the potential size of the plant-available moisture pool.
The size of the soil moisture pool, along with prevailing conditions, are the principal drivers of the necessary irrigation frequency. Longer intervals between irrigation events are desirable, because longer intervals help to reduce the total number of irrigation events over the course of the season and increase the chance of aid from natural rainfall. Summer stress factors, however, tend to shorten required irrigation intervals considerably. In general, higher temperatures increase the rate of biological processes within the turfgrass plant, leading to greater water use and demand. Sunny, dry and/or breezy conditions increase the 'pull' of the atmosphere on moisture in the soil, leading to higher ET rates and more rapid depletion of plant-available water.
How do I know when to water? Sophisticated equipment that tracks soil moisture or ET rates and enables accurate and efficient water replenishment is more readily available and easier to use than ever. In the absence of such tools, the fundamental guideline is to irrigate deeply and infrequently. A best practice for irrigation frequency is to follow a wilt-based irrigation strategy. Wilt-based irrigation involves withholding irrigation between events until the first onset of mild moisture stress, typically indicated by symptoms such as turf color change, leaf fold and roll, and footprinting.
What about how much? The goal is to effectively recharge the root zone, while minimizing loss to evaporation, runoff, and gravitational drainage. Again, in the absence of monitoring tools such as tensiometers or TDR probes, getting the hang of it often requires some trial and error. This means irrigating for a measured period of time and using a good old traditional soil probe to determine when the soil is wet to at least the depth of the primary root zone, perhaps 6-8" or more. All else equal, the same duration can be used as a guide for future irrigation events. Care should also be taken to avoid watering during the heat of the day to reduce direct evaporative loss, as well as watering at a rate appropriate for the slope and the infiltration capacity of the soil.
In the end, summer weather conditions are beyond the scope of our control. Nevertheless, opportunity exists to shape watering need and enable water conservation by managing expectations, maintaining good soil structure, and planting well-adapted, superior turfgrass cultivars with increased rooting capacity and lower consumptive water use rates.
Report by Jason Lanier, Extension Educator, UMass Extension Agriculture & Landscape Program
Insects
White Grubs
I saw European chafer adults flying in mid June, and have seen oriental beetles and a few Japanese beetles flying since early July. Sadly all these observations were in my own yard. The point is that the beetles are right "on schedule", which means many of the females are laying eggs now. That means that we are in a good period to apply a neonicotinoid to control the grubs that will soon be hatching from those eggs. Remember, however, that all the neonicotinoid labels specify that you should not apply the product on plants where bees are foraging. Since this seems to be a bumper year for clover in lawns, you need to be particularly careful and pay attention to details. (Studies conducted in Dr. Dan Potter's lab at the University of Kentucky indicate that the impact of neonicotinoids on honey bees and other pollinators can be greatly reduced in lawn settings by mowing just before the application - at a height that removes the clover blossoms.) However, scientists are still trying to determine the impact of the neonicotinoids on flowering trees and shrubs that might be located near the turf application. "Discretion is the better part of valor", so in my humble opinion, when in doubt, you probably should avoid or delay the application until the trees or shrubs are no longer flowering.
Chinchbugs and Billbugs
The regular rain pattern we have seen in much of New England so far this summer, and the cooler temperatures compared to last year, have enabled our cool-season grasses to grow better than they sometimes do during the hot months of July and August. But chinchbugs and billbugs may still be active in these grasses, especially the ryegrasses, fescues, and bluegrasses. So if you do see some areas that are browning out, take a look. Chinchbugs can be seen moving in the upper thatch, just by getting on your hands and knees and teasing the turf apart gently. Billbug larvae are likely to be feeding in or near the crowns of the plants at this point. (Larvae are pearly-white, and range from 1/16 to 1/4 inch long with a distinct brown head and no legs.)
Chinchbugs can be managed quite successfully with an application of a pyrethroid. Unfortunately it is very difficult to control billbugs once the larvae reach the medium or large stages.
Report by Dr. Pat Vittum, Professor & Extension Entomologist, UMass Stockbridge School of Agriculture and Interim Director, UMass Center for Agriculture Food and the Environment
Other Relevant News / Pest Alerts
Late blight has been confirmed this week on both potato and tomato in Franklin and Hampshire Co. MA, and is also present in eastern NY, Long Island, and southern ME. For a map of late blight reports and photos of symptoms, see http://usablight.org. The late blight we have found in MA is more virulent on potato than in the past several years, and is also very aggressive on tomato. Growers should scout both potato AND tomato for symptomatic water soaked lesions and begin protective or curative sprays with a late-blight specific fungicide immediately.
Basil downy mildew (Peronospora belbahrii) was confirmed last week in field-grown basil Middlesex Co. and the week before at a box store in Franklin Co., MA. Researchers at UMass have found Peronospora belbahrii in or on commercial seed. It is important to ask your seed supplier if the seed has been tested before planting or purchasing seed for next year.
