Sample Issue From 1999 Volume 6 No. 10 September 3, 1999 Dawn Dailey O'Brien and George W. Hudler, editors Contents... Scouting Report—Conifers: European Pine Sawfly, Spruce Spider Mite Broad-leaved Trees and Shrubs: Armillaria Root Rot, Birch Sawfly, Black Stem Borer, Curled Rose Sawfly, Hickory Tussock Moth, Locust Borer, Oak Gall Wasp, Oak Apple Gall, Poplar and Willow Borer, Feature Article—Menacing Mulch Regional Reports Things to Look For—Fletcher Scale, Honeylocust Spider Mite, Magnolia Scale Miscellany—Amanita muscaria, Asian Long-Horned Beetle, Two New State Records for Pine Shoot Beetle, Thank You Growing Degree Days Please Note: Where a specific product is listed after a recommended pesticide, only that product is labeled for that use. Not all products listed are labeled for all uses, so be certain you are getting the right formulation (with the use(s) you want), before you purchase the pesticide. Note:This information is valid for New York. It may or may not apply in your area. The Scouting Reports list chemicals registered for control of specific pests. Our recommendations are taken from the 1999 Pest Management Recommendations  for Ornamental Trees and Shrubs. These recommendations apply to New York State. The recommendations given in Branching Out  are not a substitute for pesticide labeling. Read and follow the label before applying any pesticide! Scouting Report Conifers European Pine Sawfly (2)—Although we have yet to observe a second generation of European pine sawfly this year, with the very warm and dry summer that we have had, we might still see another generation. Keep watch for this pest. Although injury caused by the first generation may have successfully covered up much of the early feeding damage, a second generation would feed upon the current year's needles as well, possibly leaving large spots devoid of foliage. Squash colonies where found unless large numbers of colonies are present. Then, a spray directed at the colonies should provide good control. Several non-restricted products are registered for use against this pest including carbaryl, chlorpyrifos, cyfluthrin, imidacloprid and spinosad. At this late time, a good strong blast of water will also probably disperse the larvae enough to reduce their potential for visible damage.Link to an INFORMATIVE WEBSITE regarding European Pine Sawfly -placed on the web by Ohio State University Extension. Link to a good photo of European Pine Sawfly placed on the web by Keystone Tree Experts. Spruce Spider Mite (52)—Spruce spider mite populations may increase rapidly during cool weather. In early September we often see an explosion of this pest on conifers such as balsam and Fraser fir and blue spruce. The adults are about 1/64 inch long, have four pairs of legs, and vary in color from dark green to dark brown. The immatures are smaller and lighter in color. The eggs are reddish brown and oval to round in shape. Damage caused by this pest in the spring should now be visible. The feeding of the mites results in flecking, stippling, or bleaching of foliage. Don't be fooled. Although you may see many mites at this time, their feeding damage now will not cause such visible symptoms as was caused during the spring feeding when the needles were tender. However, the mites are still drawing vital nutrients and fluids from the trees and controlling them now will help to prevent stress on the tree(s) as well as to decrease the population and the number of eggs that overwinter. There are many chemical options for management including relative benign materials such as insecticidal soap, horticultural oil or abamectin as well as conventional insecticides like bifentrhin, chlorpyrifos, dicofol, fluvalinate, oxythioquinox, hexythiazox, dimethoate (arborvitae, juniper, cedar) or pyridaben. Treat in late August through mid-September (2375-2806 GDD50).Link to an INFORMATIVE WEBSITE regarding Spruce Spider Mite found on the web at the Christmas Tree IPM Pest web page sponsored by the Department of Plant Pathology at Cornell University.There are several good photos on this site. -----> Go to top of the page Broad-leaved Trees and Shrubs Armillaria Root Rot (148)—The mushrooms (fruiting bodies) of Armillaria species would normally be expected soon. However, they do not always appear during a dry season like this. The mushrooms are honey-colored, 4 to 6 inches tall, produced in clumps of 10 to 50 or more at the bases of infected trees. Other signs to look for are sheets of fan-like mycelium under the bark and black "shoestrings" on infected roots. Armillaria species are notorious opportunists and aggressively colonize stressed trees. Severe drought stress predisposes trees to attack by Armillaria. Restore vigor of the trees by watering and managing other pests to minimize stresses they may impose. .Link to an INFORMATIVE WEBSITE regarding Armillaria Root Rot- Placed on the Web by the U.S. Department of Agriculture Forest Service. There are MANY good photos on this site. Birch Sawfly—Two weeks ago we saw birch sawfly (Arge pectoralis) larvae devouring leaves of birch in central New York. A report also came in from an arborist in Monroe County of these sawflies defoliating a birch. All birch species, and occasionally alder and willow, are susceptible. The larvae have pale yellowish green bodies with rows of black spots and dull orange heads. They're likely to be active until mid-September. Management is not required. If the insects become a cause for concern, squash them. The birch sawfly can be differentiated from the dusky birch sawfly (Croesus latitarsus) by comparing head color of mature larvae. The dusky birch sawfly has a shiny black head and yellowish green body. Black Stem Borer (Xylosandrus germanus)—Dan Gilrien from Cornell Cooperative Extension of Suffolk County reports to us that they just had a case of black stem borer (Xylosandrus germanus, a scolytid bark beetle) in Stewartia in a landscape. It had caused dieback from the infested point upward on several branches (most starting around 3/4 - 1/2 inch diameter upward). X. germanus attacks healthy as well as weakened trees. This tree was on a well-managed area, not particularly stressed (except maybe everything is stressed this year). These beetles are also referred to as ambrosia beetles. Adults are 1/8 inch long and resemble bark beetles in size and appearance but differ greatly in habits. The beetles bore directly through the bark and into the sapwood and often the heartwood rather than in and under the bark. It is reported on beech, birch, holly, honeylocust, elm, linden, maple, oak, planetree, sweetgum, tuliptree, and willow. Dan has seen it kill Japanese holly in a landscape when the crown or larger basal portions were attacked. The female beetle may introduce Fusarium into the tree as she excavates her tunnel into wood. The females bore in 2-3 mm before excavating brood chambers. They carry in fungal spores in mycangia (spore pockets) on the abdomen. This fungus causes a cankered area in the wood, usually causing top dieback and resprouting from the base of the tree. Cankering, however, is not always apparent. The fungus stains the surrounding wood, creating black holes or localized stains in the wood. Fusarium fungus was found associated with this sample. The adult is the damaging stage with these beetles, as the larva does no tunneling. External entrance holes are about 1/32 inch in diameter, and are sometimes referred to as pinholes. No chemical controls are known to be effective or practical. Fortunately infestations tend to be sporadic. Suggested control is to prune and destroy trimmings which contain the beetles (and their various stages). Note that X. crassiusculus, a different species, is causing great concern in areas to the south and we are hoping it will not move into this area. X. crassiusculus is reddish brown and up to 3 mm long females are 2.1 to 2.9 mm long. Its common name is granulate ambrosia beetle. X. germanus is dark brown to black and females are 2.2 mm to 2.4 mm long. Curled Rose Sawfly (58)—Our scouts are continuing to see curled rose sawflies, Allantus cinctus, devouring rose leaves in central New York. These sawflies eat leaves from the margins to the veins, leaving just veins in their wake. They also bore into new shoots and the pith of pruned canes. This can open the plant up to secondary fungal infections. Larvae are easily recognized by their yellowish-green color with white dots on the thorax and abdomen and 1/2 inch long tapered bodies. The head is yellowish with black eye spots. They appear suddenly and do their damage quickly. Keep in mind that a few larvae can seriously damage a rose plant. If control measures are warranted spray with acephate (TT&O), carbaryl, cyfluthrin, imidacloprid or spinosad. Alternatively, wash larvae from plants with a strong jet of water.Link to an INFORMATIVE WEBSITE regarding Curled Rose Sawfly-Placed on the Web by the University of Minnesotta Extension Service. There are some good photos on this site. -----> Go to top of the page Hickory Tussock Moth (72)—We have been seeing many hickory tussock moth larvae in several different locations, including a site filled with black locusts and another of mixed hardwoods. These larvae are hairy white caterpillars with several tufts of black hairs prominently protruding out near the head and rear. Host trees include hickory, walnut, butternut, linden, apple, basswood, birch, elm, black locust, and aspen. Although we are seeing larger numbers than usual, populations aren't high enough to require treatment..Link to an INFORMATIVE WEBSITE regarding Hickory Tussock Moth - Placed on the Web by the Maryland Department of Agriculture. There is a good photo on this site. Locust Borer (129)—We have recently seen these brightly colored adult beetles feeding on pollen of goldenrod blossoms. The adults are 3/4 inch long, cylindrical, long horned beetles and have yellow markings similar to that of a wasp. The W-shaped yellow mark on the wing covers are characteristic of this borer. Black locust is the only host tree. Nevertheless, there are cultivars of black locust that are resistant to the locust borer. Egg laying occurs from late August through early October. Females lay eggs in crevices of the bark and around wounds. The eggs hatch in about a week and the small, white larvae bore into the inner bark of the trunk and branches where they spend the winter. Drought weakened trees are especially susceptible to borer attack. As with many borers, vigorous trees are less susceptible to this pest. Treatments can be applied in late summer to protect the trees from newly hatched larvae attempting to penetrate the bark. If treatment is warranted use carbaryl, chlorpyrifos, lindane (note not all uses of lindane are registered in NY state), permethrin or bifenthrin (Talstar L&T Flowable) in late August through mid-September (2271-2805 GDD50). Removing goldenrod from around specimen trees may help also as the adult feeds on the golden rod pollen.Link to an INFORMATIVE WEBSITE regarding Locust Borer- Placed on the Web by the U.S. Department of Agriculture Forest Service. There are some good photos on this site. Oak Gall Wasp (213)—Tom Kowalsick from Suffolk County CCE reports that they have recently seen symptoms of oak gall wasp damage on black oak, similar to that caused by Bassettia ceropteroides about 10 years ago. So far the symptoms have not been widespread and severe, but considering the damage done from the last infestation on Long Island it is worth watching closely. This tiny gall-making wasp causes damage to black, red and scarlet oaks. The twigs from the current season are slightly enlarged. Twigs and entire branches may be killed. With repeated infestation, a tree may die. Prune infested wood. Minimize stress on the tree where possible. Oak Apple Gall (215)—Walking around campus we have seen what seems to be an unusually large number of oak apple galls. Each gall is a round, 1-2 inch diameter growth with a thin, spongy, almost hollow, inside. These galls are seen on the leaves of scarlet, red, and black oaks. In general, galls on oak are caused by powerful growth-regulating chemicals produced by the insect - a tiny wasp in this case. These chemicals accelerate the normal rate of cellular plant growth. The oak apple gall does not affect the health or the appearance of the tree and therefore doesn't warrant control. Link to a good photograph of Oak Apple Gall placed on the web by Michigan State University Extension. Poplar and Willow Borer (126)—This borer may attack all willows and most poplars, except trembling aspen. The adults of this species are weevils, and are most abundant in August. The adult is 8-10 mm long with the posterior part of the wing covers and abdomen covered by pale yellow scales. The adult weevil, itself, causes only minor damage. It is the larvae that feed on the inner bark, boring inward and upward, that cause the real injury. If populations are high, treat with lindane in late August through mid-September (2271-2806 GDD50). (Note: not all uses of lindane are registered in NYS).Link to an INFORMATIVE WEBSITE regarding the Poplar and Willow Borer - Placed on the Web by Canadian Forest Service.There are some photos on this site. -----> Go to top of the page This publication contains pesticide recommendations. Changes in pesticide regulations or human errors are still possible. Some materials may no longer be available, and some may no longer be legal. These recommendations are provided only as a guide. All pesticides distributed, sold, or applied in New York State must be registered with the Department of Environmental Conservation (DEC). Questions concerning the legality and/or pesticide use in New York State should be directed to the appropriate Cornell Cooperative Extension office or regional DEC office.  Read the label before applying any pesticide. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by Cornell Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. -----> Go to top of the page Return to Branching Out  Home Page