Defoliators:

Lepidoptera:

• Winter Moth is through feeding for the year.
  
• Forest Tent Caterpillar (FTC) has pupated, and its silken cocoons are quite commonly found on buildings. The adult moths will be active soon and will mostly go unnoticed except when attracted to outdoor lighting at night. Adults do not feed.
  
• Gypsy Moth has begun pupation and is virtually finished feeding for the year. No heavy pockets of defoliation were reported this year in the state.
  
• 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 has pupated. The adult moths will appear within 2-3 weeks, and these will produce another generation of caterpillars. However, very little feeding occurs from the second generation and usually does not warrant control.

Hymenoptera:

• European pine sawfly is finished feeding for the year in much of the state. There will not be another generation this year.
  
• Introduced pine sawfly will appear within the next couple of weeks. It is not as common in the state as is European pine sawfly and the redheaded pine sawfly, but it has the potential to be every bit as destructive. It tends to be more prevalent in the eastern portion of the state than in central or western MA. Treat the very young larvae with an insecticidal soap spray and larvae of all ages with a product that contains spinosad or with one of the registered pyrethroid insecticides. Redheaded pine sawfly will appear in late July or early August and can be active well into September or later if temperatures remain mild.
  
• Azalea sawfly caterpillar has finished feeding for this year.
  
• Rose Slug Sawfly Caterpillar (aka Roseslug) has ceased its feeding activity.
  
• 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, which gives 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, 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. Winter moth caterpillars do feed on viburnum and can cause injury that is very similar; inspect carefully. If the culprit is viburnum leaf beetle, it will be present and actively feeding now; winter moth is done for this year. Viburnum leaf beetle will begin pupation within the next week or two, and then the adults will appear around mid July. 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
  
• Imported 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, damaged foliage dies and turns brown, on heavily infested trees, 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.
  
• Japanese beetle adults will begin to appear any time now. This pest has a two month staggered emergence, which begins about now, peaks in early July, and then tapers off into September. At first we will only see a few adult beetles, but the number of new beetles emerging from the soil every day will continue to increase into August. This pest has a huge host plant range and can be extremely destructive. Monitor for its activity and treat when necessary. Pyrethroid knockdown sprays seem to work well against the adults. More than one application may be necessary over a two-month period in order to protect individual plants.

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 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. The nymphs will settle on the twigs to feed but will go dormant around mid July. Applications of horticultural oil at the summer rate will still be effective even when they are dormant. However, be cautious of applying oils on hot and humid days, which increases the risk of phytotoxicity. Pyrethroids are effective as well. Soil or trunk injections of imidacloprid may be more effective if applied in mid August rather than now in this hot and dry weather.
  
• All species of lacebugs are active. Such hosts as Japanese andromeda, azalea, rhododendron, cotoneaster, hawthorn, and others should be monitored for any lacebug injury. 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. Pyrethroids are effective as well.

• Elongate hemlock scale (aka fiorinia scale) - This tiny and elongate-shaped scale is 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 ä (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 have been active. 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 thus giving one end a light brown color; these, however, eventually fall off. 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.
  
• In Massachusetts, we mostly see white prunicola scale 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.

DISEASES -

Cedar-apple rust infections are visible as orange-yellow spots on susceptible hawthorn, apple, and crab apple leaves. By mid summer tiny yellow-white tube-like fruiting structures will extend from the underside of infected leaves. From mid summer to autumn, spores are wind-carried from the apple leaves and, when conditions are wet, they infect green shoots and needles of junipers. Pea-sized to two inches diameter round, brown galls develop on susceptible juniper needles and twigs between 12 and 20 months after infection. The best long-term approach to manage this disease is to grow cedar-apple rust resistant apple and juniper varieties. Also, prune dormant galls on juniper during the summer, fall, winter, and in early spring before jelly-like horns form. Avoid growing susceptible junipers close to apples. The time to apply fungicides to protect high value apples from cedar-apple rust has passed for this spring. If desired, apply fungicide to protect eastern red cedar and rocky mountain junipers from early July through early September.

Hawthorn (Entomosporium) leaf spot is visible as red-purple spots of on green to yellowed leaves on susceptible hawthorn. Now that the fungus is established, it regularly produces spores; and with recurring wet periods, the disease spreads via these secondary infection cycles. There is little benefit from chemical controls of this disease when begun this late in the season. A long-term management strategy to consider is replacement of susceptible hawthorns with resistant trees. Otherwise, apply preventative fungicides as buds open or when the first rains begin after the leaves start to develop in the spring; repeat these at labeled intervals several times until early summer.

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 on 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.

Sycamore , maple, oak, and ash anthracnose are evident now as dark-brown curling leaves and shootson sycamore, maple, ash, linden, walnut, and oak. Anthracnose was 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. The time for fungicide protection of the foliage has past for this season. 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 were vulnerable to infection during the spring, and gray-brown blotches as well as blighted shoot tips are visible on infected trees. The time for fungicide protection of the foliage is over for this spring. If this is a persistent problem, consider planting one of the many resistant cultivars of flowering dogwood and kousa dogwood now available.

The critical time for fungicide protection of emerging crabapple leaves from apple scab has likely passed for this season. It is still helpful to 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 - There was no report this week.

Federal Regulation, State Inspection, Nursery Survey, and Other Finds - There was no report this week.

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

WEEDS -

Annual weeds have made a major push in the last one to two weeks. Continue to scout. 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. Contact/burndown non-selective herbicides will require large spray volume to obtain good coverage if weeds are large.

Pelargonic acid, Scythe™, can be used to remove tree suckers.

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

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 -

Crabgrass has increased in size in the last few days of heat. Begin actively monitoring for crabgrass and treat with a postemergence crabgrass herbicide.

Continue to apply broadleaf postemergence herbicide only if turf and weeds are not showing signs of drought or heat stress. Sites without irrigation might be too stressed for broadleaf applications. Attempt to finish broadleaf application by the first few days of July. Application to control white clover can begin now.

Postemergence herbicide combinations that contain triclopyr should be use for wild violets and ground ivy. Spring treatment will usually not provide complete control with one application. Re-treat 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

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!