Defoliators:

Lepidoptera:

• Winter Moth is through feeding for the year.
  
• Forest Tent Caterpillar (FTC) has reached 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. Any forest tent caterpillars that are seen now are most likely diseased (Entomophaga sp.) or are parasitized.
  
• 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 half way 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 far too late for Bacillus thuringiensis Kurstaki. Products that contain spinosad should still work well.
  
• Fall Cankerworm has pupated statewide. Pockets of FCW have been reported from Martha’s Vineyard, Plymouth County, Cape Cod, and Shutesbury (north Quabbin area in western MA). Although much damage is noticeable in these areas, feeding has ceased for this year.
  
• Euonymus caterpillar is now pupating. The adult moths will appear within 2-3 weeks, and these will produce another generation of caterpillars. Very little feeding occurs from the second generation and usually does not warrant control.

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 has finished feeding for this year.
  
• Rose Slug Sawfly Caterpillar (aka Roseslug) is near the end of its larval period and will soon disappear statewide for another year.
  
• Birch sawfly caterpillar is very active. Although it attacks many birch species, river birch can be a common host plant. There exists more than one species of what is commonly called birch sawfly. However, their feeding, damage, and controls are all very similar. Monitor birches for clusters of sawfly caterpillars hugging the margins of foliage. Typical to most sawfly caterpillars, they will curl their abdomens and writhe when disturbed. Treat the very young larvae with an insecticidal soap, spray the older larvae with a product that contains spinosad or with one of the registered pyrethroid insecticides that is labeled for this pest.

Coleoptera:

• Lily leaf beetle larvae are now quite commonly found statewide. These leaf beetle larvae cover their bodies with their own excrement giving them a rather repulsive appearance. In small plantings, larvae can be physically removed and destroyed. In larger plantings, 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 re-applied 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. Certain pyrethroid insecticides are also effective.
  
• Viburnum leaf beetle, larvae are now quite commonly found statewide. These leaf beetle larvae cover their bodies with their own excrement giving them a rather repulsive appearance. In small plantings, larvae can be physically removed and destroyed. In larger plantings, 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 re-applied 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. Certain pyrethroid insecticides are also effective. 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
  
• Willow leaf beetle remains active. As an adult, this pest is small, rounded and a shiny bluish-black color. There are multiple generations of this pest throughout the growing season. Adult beetles chew holes in the foliage while the larvae line up on the leaf surface and severely skeletonize the leaves. By August, on heavily infested trees, damaged foliage dies and turns brown and gives the tree the appearance of having been swept by fire. Larvae can be treated with a product that contains spinosad while adult beetles are better managed by a pyrethroid-type insecticide. There will be overlapping generations of larvae and adults all active at the same time throughout the season.
  
• 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.
  
• Asiatic garden beetle adults started becoming active a couple of weeks ago and are now commonly seen. Their feeding damage will begin to appear on a number of differing host plants as chewing injury. This pest has a very wide host plant range. It is a night feeder and hides during the day in soil and leaf litter. Occasionally, this pest is attracted to outdoor lighting. Inspect susceptible host plants at night with a flashlight. They commonly feed from the time it is completely dark (around 9 PM) until about midnight. Treat with a registered pyrethroid insecticide 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, are now mostly 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 has finished feeding for this year. 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.
  
• 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 have been hatching in the warmer regions of the state.
  
• Most species of lacebugs 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. Insecticidal soap sprays or horticultural oils at the summer rate can be effective when targeted to the undersides of the foliage. Systemic applications of imidacloprid can be very effective against these pests.

• 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 other 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.
  
• Taxus mealybug, which technically is not a scale but can appear scale-like, is active. Inspect the branches on the interior of the plant. Just inspecting the foliage will not reveal this pest. Occasionally, it appears in large numbers and can be responsible for much honeydew, sooty mold problems, stunted growth, and chlorosis of the host plant. Systemic application of imidacloprid can be helpful. Also, horticultural oil sprays at the summer rate that are targeted to the inner branches can also be effective in controlling this pest. Do not confuse it with cottony taxus scale (aka cottony camellia scale), which also occurs on the inner branches as well as on the foliage of taxus.
  
• Cottony taxus scale (aka cottony camellia scale) is very active right now on taxus, in particular. Inspect inner branches and the undersides of foliage for the white, cottony, oval egg masses. Some of these egg cases may still have the dead adult female body attached (eventually they fall off), thus giving one end a light brown color. Newly hatched nymphs will migrate to the leaf (needle) undersides and feed with their piercing-sucking mouthparts. This pest also produces honeydew, which leads to the unsightly buildup of sooty molds. Extensive feeding can stunt plant growth and contribute to chlorosis. Treat the same as mealybugs on taxus.
  
• White prunicola scale in Massachusetts is a pest mostly seen on Japanese cherries and sometimes on lilac. A very similar species (white peach scale) can also appear on lilac but is not all that common in MA. In the field, however, both species are nearly identical. Crawlers of white prunicola scale will be active soon, and this provides the best opportunity to manage this difficult and serious pest. Heavily infested branches will appear heavily encrusted with bright white scales (males). If left untreated, this pest is quite capable of killing branches, shoots and entire plants. Treat with a horticultural oil spray before the crawlers wax over. Another generation of crawlers will appear in early August.

• 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.

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 -

No report this week.

DISEASES -

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 -

No report this week.

IMPORTANT INFORMATIONAL RESOURCES

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!