Defoliators:

Lepidoptera:

• Winter Moth is through feeding for the year.
  
• Forest Tent Caterpillar (FTC) is close to maturity in the caterpillar stage. Large caterpillars are now pupating. Look for light-colored silken cocoons that will appear on sides of buildings, especially in the joints where walls meet ceilings; this insect likes to pupate where two perpendicular surfaces come together. However, it does pupate in many different kinds of places.
  
• Gypsy Moth is not expected to be in large numbers across the state, but it is not uncommon for small, localized areas to experience gypsy moth in outbreak proportions. This caterpillar is now about halfway to its ultimate size in most of the state. No reports of large populations have yet been received. Monitor for their activity and treat if necessary. It is too late for Bacillus thuringiensis Kurstaki.
  
• Eastern Tent Caterpillar has pupated and is finished feeding for the year. Any caterpillars that remain on host plants or in the silken webs are most likely parasitized or diseased and are best left alone to help perpetuate these natural controls. Overall, numbers of this pest were much lower in the state than they have been for several years.
  
• Fall Cankerworm is now pupating. Pockets of FCW have been reported from Martha’s Vineyard, Plymouth County, and Shutesbury (north Quabbin area in western MA).

Hymenoptera:

• European pine sawfly has the potential to completely defoliate branches and entire plants. Monitor mugo pine, in particular, for clusters of this green caterpillar, which are almost the same color of the needles. Larvae are reaching full size; and if treatments are deemed necessary, a product that contains spinosad or one of the pyrethroids will work best at this stage.
  
• Azalea sawfly caterpillar is now approaching the end of its feeding cycle in much of the state. This pale green caterpillar is almost the exact color of the host plant foliage and often hugs the leaf margin while it feeds. Therefore, it is very cryptic and much damage can be created before it is noticed. Only deciduous varieties of azalea are attacked, especially the 'Exbury' and 'Mollis' varieties. This pest is capable of creating total defoliation of the host plant. Treat established populations with a product that contains spinosad or with one of the registered pyrethroid products that is labeled for this pest.
  
• Rose Slug Sawfly Caterpillar (aka Roseslug) - This pale green caterpillar feeds mostly on the upper leaf surface of rose foliage by skeletonizing and thus creating a “window-paning” effect. Large numbers of this pest usually result in unsightly injury that can affect most of the foliage. Inspect for the damage and the presence of the small caterpillars. Treat with an insecticidal soap spray or with a product that contains spinosad. This pest is nearing the end of its feeding.

Coleoptera:

• Lily leaf beetle has been mating and laying eggs for several weeks now. Larvae have been seen feeding in the warmer regions of the state (Amherst) for a couple of weeks now, and they are beginning to become more prevalent in other areas. Feeding injury, showing up as notches to leaf margins and holes in the foliage, are both quite obvious now. Larvae skeletonize the foliage and destroy it. Eggs, on the undersides of leaves, in the form of an irregular tan-colored line about one inch in length are becoming more prevalent. Treat the adults with a registered and labeled pyrethroid. Later on, treat the larvae with a product that contains spinosad. NEEM products do work to deter feeding activity of the larvae, but they need to be reapplied every 10-14 days for as long as the pest is active, which is much of the growing season. NEEM, therefore, is a good choice in smaller plantings of true lilies.
  
• Viburnum leaf beetle, although not yet commonly found in MA, is active in the larval stage. Inspect susceptible plants for dead twigs that have a “sandpaper” texture, which may indicate an egg-laying site. Also, inspect for the yellowish-colored larvae that are now chewing holes in the foliage. This is a very serious pest and needs to be treated when found. Spinosad products work very well against the larvae. Report any finds of this pest to Bob Childs at UMass Amherst (413-545-1053 or rchilds@psis.umass.edu). For more information about this pest and to view high-quality photographs, visit the following Cornell University web site at http://www.hort.cornell.edu/vlb
  
• European chafer adults should start to appear within the next few weeks, especially in the warmer regions. This large scarab often goes unnoticed due to its nocturnal habits, but it sometimes clusters by the hundreds or even thousands on individual plants for mating purposes. While there, they can often create plant injury in the form of large ragged notches on the leaf margins. Rhododendrons are common host plants along with many others. If suspected, inspect at night with a flashlight for their presence. Treat with a pyrethroid, if necessary.

Piercing-Sucking Pests:  

• Many spider mite species are now active. Inspect foliage with a hand lens for their presence; also, make note of the ratio of predatory mites to spider mites. Spider mites are often present on plant foliage, and predatory mites usually keep their numbers in check. Treatments for spider mites are usually only necessary if populations of them are high and when numbers of predators are low. One of the cool-season mites, spruce spider mite, is very active now. Monitor spruces and hemlock by shaking branches over a white sheet of paper and inspecting with a hand lens.
  
• Many aphid species are now very active. Certain early-season feeders, such as snowball aphid on many different species of viburnum, is now virtually finished for the year. However, those other species that are found on various species of maples (including Japanese maple), catalpa, linden and other deciduous hosts, are still quite active. Balsam twig aphid is nearing the end of its activity. Inspect for clusters of aphids, honeydew, sooty mold, and distorted foliage. Unlike most of the other piercing-sucking pests, aphid feeding usually does not result in yellow stippling injury. Treat large populations, if necessary, with a spray of insecticidal soap or with a systemic application of a product that contains imidacloprid.
  
• Honeylocust plantbug is well past the stage for causing any serious injury now that the foliage is fully expanded on the host plant.
  
• Boxwood psyllid has virtually finished its activity for the year.
  
• Hemlock Woolly Adelgid remains very active, and the white cottony masses are quite obvious right now. Once foliage has fully expanded, treat with a horticultural oil spray at the summer rate. Small populations can be treated with a systemic application of imidacloprid. This pest is actively feeding and has now produced the eggs for the second generation, which will be hatching soon.
  
• Most lacebug species are now beginning to appear in warmer regions. Such hosts as Japanese andromeda, azalea, rhododendron, cotoneaster, hawthorn, and others should be monitored for any lacebug injury that occurred last year. If damage is noticeable, then one should expect large numbers again this year. Those species that attack shrubs usually overwinter as eggs that are embedded in the undersides of the foliage or in the shoots.

• Elongate hemlock scale (aka Fiorinia Scale), is a tiny and elongate-shaped scale found attached to the undersides of hemlock needles. It is a very serious pest and should be treated when found. It can often be mixed in with hemlock woolly adelgid on the same plant. Horticultural oil sprays work well, especially during the crawler stage (late May into mid June) and when sprays are targeted to the needle undersides. Some of the newer neonicotinoid products, such as Safari ™ (Valent) are showing good results against armored (hard) scales and may work well for elongate hemlock scale. However, bear in mind that no published results have yet appeared for the efficacy of this product for this particular pest.

• Azalea bark scale is active. In particular, inspect the axils of branches and the main stem of the plant for small, white cottony masses. This pest also produces much honeydew, which generates much sooty mold. In this stage, it often resembles mealybugs. Treat with a horticultural oil spray at the summer rate or with one of the registered chemical insecticides.
  
• Pine needle scale crawlers may already have appeared in the warmer regions. Treat with a horticultural oil spray if populations are large. Mugo and scotch pines are common hosts.

• Galls, which are abnormal plant growths that have been stimulated by an outside organism (usually an insect or mite species), are generally just curiosities. They are commonly found on oaks (mostly cynipid wasp species) and on maples and cherries (eriophyid mite species). Overall, galls that occur on the foliage or flower parts are not considered to be problematic, even when they are very obvious. Either way, once the galls appear, there is nothing one can do to treat them. Galls that form on the woody portions of plants often kill the shoot, branch, or entire tree. Fortunately, these are not all that common.

Oddities:

• Periodical Cicada - Much national attention has been focused on the parts of the Midwest (e.g., Chicago area) where they are experiencing a peak year for the periodical cicada. This particular species emerges in the adult stage every 17 years and then disappears underground where it feeds on tree roots, as an immature, for the next 17 years. Witnessing an emergence of this species is an opportunity to experience one of the truly neat natural wonders of the insect world. Although appearing by the millions, they do not cause harm (although, sometimes, alarm). Periodical cicada has bright red eyes, and the males produce a ringing sound as their mating call. On warm and sunny days, the multitude of male cicadas ringing can reach decibel levels of close to 100. Since the media coverage has begun, Extension offices have received many calls asking if Massachusetts will have a peak year for this insect in 2007. The answer is no. We do have the remnants of a formerly large brood of periodical cicada on Cape Cod. The last peak year was in 1991, so the next peak year will not be until 2008 - one year from now. However, we do have other species of cicadas that will be appearing later in the summer in much smaller numbers, such as the Dog Day Cicada. These are physically larger and don’t have red eyes. The males of these also produce a high-pitched buzzing sound as opposed to the ringing of the periodical cicada. Due to heavy people-pressure on the landscape of Cape Cod, populations of periodical cicada were much lower in 1991 than 17 years previous to that. We are waiting for next year to, once again, evaluate the health of this species on Cape Cod, where the bulk of this particular periodical cicada brood still exists in the state.

DISEASES -

Botrytis blight is noticeable as a gray moldy blight of flowers, leaves and shoots in herbaceous perennial gardens, as well as on some young woody plants with dense foliage. Cool temperatures and shaded conditions enhance the damage by this fungus. To manage Botrytis blight, remove dead plant material that the fungus uses as a beachhead for the development of more inoculum. Irrigate before mid-afternoon so foliage dries before nightfall. Consider fungicide applications to protect succulent growth on high value plants from becoming infected. Repeat applications at labeled intervals until warm, drier weather prevails, and Botrytis blight is less able to infect plants.

Now is the time to scout rose, dogwood, sycamore, phlox, and horsechestnut, to name a few susceptible woody plants, for powdery mildew . The fungus is now visible as dusty, gray to white spots on foliage and green shoots. Once established on plants, powdery mildews grow superficially on both upper and lower leaf surfaces as well as green shoots and flower buds. They are obligate parasites and derive sustenance only from living host plants. They do this using minute, tube-like structures (haustoria) that penetrate the epidermal cells and draw out material they need to survive. Generally, the damage caused by powdery mildew is of minor consequence to healthy plants and does not warrant chemical control if unsightliness is not a critical concern. If considering chemical control there are a number of applied materials labeled to protect susceptible plants. They include summer horticultural oil, commercial baking soda preparations (sodium bicarbonate and potassium bicarbonate), anti-transpirants, as well as a number of conventional fungicides. Chemical spray programs are most effective when begun just as symptoms of powdery mildew begin to show. Once powdery mildew is extensive on the plant, there is little benefit from chemical control that season. Applications need to coat the surfaces of all susceptible plant parts to prevent infection. Spray on a regular schedule, and repeat more often during warm, humid weather.

Oak leaf blister is showing up on red, white, and pin oak leaves as faint, yellow-green, puckered spots. This is a not a serious fungal disease problem in our area. Yet, if a severe outbreak is occurring on high value trees, note that for future reference. Next spring, start chemical control activities just as buds open and repeat at labeled intervals if wet weather persists.

Sycamore , maple, oak, and ash anthracnose are evident now as dark-green to dark-brown curling leaves and shootson sycamore, maple, ash, linden, walnut, and oak. Anthracnose is widespread on early leaves and shoots this year due to the abundance of inoculum on overwintering twigs and fallen leaves, as well as the consistently wet weather. These diseases cause some premature leaf loss, but that is not going to seriously harm an otherwise healthy tree. In the fall, fine prune infected twigs, if practical, as well as collect and dispose of fallen leaves. Promote drying of foliage by pruning and spacing plants to increase the penetration of sunlight and air circulation in and around plants.

Flowering dogwoods susceptible to dogwood anthracnose are vulnerable to infection during wet seasons. Reapply fungicide to protect developing leaves on high value trees when the bracts fall and repeat it about four weeks later. If this is a persistent problem, consider planting one of the many resistant cultivars of flowering dogwood and kousa dogwood now available.

Reapply fungicides to protect emerging apple and crabapple leaves from apple scab now and continue this 1-2 additional times at 7-10 day intervals (assuming wet conditions linger). In addition, prune densely branched trees to increase air circulation and sunlight penetration that speeds drying of foliage. There are numerous resistant varieties of apple, crabapple, and mountainash to grow and simplify disease management.

Maximize the effectiveness of fungicide treatments in the management of black spot on rose by initiating them early and repeating the applications per label directions into the fall. Provide good air circulation and irrigate early in the day to minimize the period of plant wetness to further suppress the disease. If the problem persists, gradually replace susceptible varieties of roses with those resistant to black spot to reduce buildup of inoculum and the need for fungicide treatment.

Ramorum blight , also known as sudden oak death (SOD) and ramorum dieback. Since 1995, oaks and tanoaks have been dying in the coastal counties of California. Since then, surveys found other plants infected or associated with this disease caused by the water mold Phytophthora ramorum . Researchers in the U. S. first isolated the pathogen in Mill Valley ( Marin County) on tanoak, but since that time additional surveys confirmed the pathogen on various native hosts in fourteen coastal California counties and in Curry County, Oregon. Through ongoing surveys of nurseries, USDA-APHIS-PPQ continues to define the extent of the pathogen’s distribution in the U. S. and limit its artificial spread beyond infected areas through quarantine and a public education program.

Status of Phytophthora ramorum in 2007:

Forest Detection Survey - The USDA Forest Service (FS) Sudden Oak Death National Detection Survey reported water finds in Mississippi and Washington. The MS find was adjacent to a positive nursery, while the WA sites were downstream from current and previously positives nurseries. FS will be surveying watercourses in approximately half the states, targeting water downstream of nursery properties with some association with Phytophthora ramorum.

Federal Regulation, State Inspection, Nursery Survey, and Other Finds - The National Agricultural Pest Information System (NAPIS) currently reports that Virginia has surveyed in two counties, obtained 119 samples, with no positives. To date, Virginia is the only state that has reported survey results through the Cooperative Agricultural Pest Survey (CAPS) program.

Reported by Dan Gillman, Plant Pathologist, UMass Extension Plant Diagnostic Lab, Amherst

WEEDS -

Scout for annual weeds in ornamental beds. Treat these weeds before they get too large. Spot spraying with a non-selective herbicide is usually a better strategy than hand-weeding because it does not break the mulch barrier.

DISEASES -

Moderate temperatures and adequate rainfall during the first weeks of June have resulted in good conditions for turfgrass growth. Outside of several cases of pink snow mold from Northern New England, the most prevalent turfgrass disease arriving at the UMass Extension Plant Diagnostic Lab has been necrotic ring spot, which has been seen on golf courses (Poa annua), athletic fields (P. pratensis), and utility grass (Festuca rubra).

Necrotic ring spot is caused by Ophiosphaerella korrae, an ectotrophic root infecting fungus which causes a patch disease primarily on Poa species. The pathogen is active in the cool, wet weather of the spring and fall; symptom expression of wilt and straw colored patches may also occur in the summer stress period. Infection centers that develop in the fall may persist through winter and into early spring. Recovery is slow. Patches often have a frog-eye appearance.

Management of necrotic ring spot includes cultural measures such as the avoidance of drought stress by light, daily irrigation, and the use of slow release nitrogen fertilizers in the summer stress period. Avoid nutrient deficiencies and provide adequate and balanced fertility, particularly nitrogen, potassium, and phosphorous as determined by soil or foliar tissue tests. Overseeding infected turf with Lolium perenne, more resistant cultivars of Poa pratensis, or Agrostis species will limit symptom expression and disease severity.

Biological management options include LawnRestore™ or TurfRestore™ which contain both beneficial microorganisms and food to stimulate the natural microflora. Aerifying, improving drainage, and reducing compaction aid in disease control. Thiophanate methyl fungicides (Cleary’s 3336™, FungoFlo™) can be applied curatively in early to mid spring, being sure to thoroughly irrigate turf first as these fungicides only move upwards (acropetal penetrants). Propiconazole (Banner MAXX™), fenarimol (Rubigan™), and iprodione (Chipco 26019™) work best when applied preventively.

Reported by M. Bess Dicklow, Plant Pathologist, UMass Extension Plant Diagnostic Lab, Amherst.

Mushrooms in lawns often develop from thatch, buried logs, dead roots, stumps, or even construction debris. They have many different sizes, colors, shapes, and habits of growth and develop fruiting structures or mushrooms in lawns after prolonged wet weather. The fungi that produce these mushrooms are beneficial because they decompose organic matter in the soil, making nutrients available to other plants. These mushrooms usually are harmless to grasses, but some people consider them unsightly or want to get rid of them because young children play in the area. Neither spray applications nor drenches of fungicides are effective in controlling these mushrooms. Simple way to remove mushrooms is to mow the lawn while collecting the clippings or raking them up. Elimination of excess thatch and aerating the soil to improve water penetration also helps in some cases. In addition, the mushrooms left alone disappear when the weather becomes dry.

Reported by Dan Gillman, Plant Pathologist, UMass Extension Plant Diagnostic Lab, Amherst

WEEDS -

Germinating crabgrass is well underway especially in areas of thin turf. Begin actively monitoring for crabgrass and treat with a postemergence crabgrass herbicide.

Those sites that are on a split-application program should receive their second application. If you see a large number of crabgrass plants now, consider replacing your second preemergence split with a postemergence application.

Continue to apply broadleaf postemergence herbicide. Application to control white clover should be done after flowering, so wait a week or two if clover is present.

Postemergence herbicide combinations that contain triclopyr should be used for wild violets and ground ivy. Spring treatment will usually not provide complete control with one application. Retreat at first sign of regrowth or accept partial control for the time being and retreat in September.

Reported by Randall Prostak, Weed Specialist, UMass Extension Landscape, Nursery and Urban Forestry Program, Amherst.

IMPORTANT INFORMATIONAL RESOURCES

UMass Turf Research Field Day is Wednesday, June 20, 2007 at the Joseph Troll Turf Research Center in South Deerfield, MA. For complete information, visit http://www.umassturf.org/education/annual_events/field_day.html or e-mail fieldday@umassturf.org with questions.

The MNLA/MFGA Summer Meeting and Trade Show is Wednesday, July 18, 2007 at the Tower Hill Botanic Garden in Boylston, MA. Visit http://www.mnla.com for complete information.

For a complete listing of upcoming events, see our Conferences and Workshops page.

Don't forget to visit the UMass Extension Online Weed Herbarium!