Forest Pests: Insects, Diseases & Other Damage Agents

Ash Pests: A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury

Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 45 p.

This booklet will help nurserymen, resource managers, pest control personnel, and homeowner to prevent, identify, and control ash pests.

Keywords: Biology, borers, control, defoliators, Fraxinus, Fungi, identification.

Introduction

The ashes (Fraxinus spp.) are one of our more valuable hardwood resources- some 275 million board feet of ash lumber are sawn annually in the United States. White ash (F. americana L.) and green ash (F. pennsylvanica Marsh.), widely distributed throughout the Eastern United States and southern Canada, are the two most important species. Black ash (F. nigra Marsh.) is an important timber species in the Northeastern United States and southeastern Canada. Ash wood- tough, strong, and resistant to shock- is used for handles, oars, baseball bats, and furniture. Green, white, and black ashes grow best on fertile, moist, well-drained soils. But green ash, the most adaptable of the ashes, grows naturally on a wide range of sites from clay soils flooded up to 40 percent of the time to sandy, dry, harsh sites. Because of its hardiness, adaptability, and drought tolerance, green ash is used widely as an ornamental, in shelterbelts of the Great Plains, and for revegetation of strip-mining spoil banks. Green and white ashes are among only a few hardwood species being used to establish commercial timber plantations.

Insects, diseases, and pollutants are continuing problems for the ashes, but few actually threaten their widespread use. Disease, simply stated, is a condition of abnormal growth resulting from infection by a biotic agent (fungus, bacterium, or virus), or induced by an abiotic stress such as drought or air pollution. Fungi are the most common causes of diseases of trees. Diminished growth and vigor, brought on by one or more biotic or abiotic factors, are perhaps the most serious problems of white ash. Wood boring insects, the most damaging pests of green ash, have damaged shelterbelt plantings in the Great Plains and caused considerable degrade losses in logs and lumber in the South. An estimated one-third of the ash trees larger than pole size contain some heart-rot. Seed insects sometimes destroy up to 90 percent of the seed crop. Insects and diseases that destroy foliage can be disfiguring and cause growth loss, but seldom cause widespread damage. Because the gypsy moth, Lymantria dispar (L.), rarely feeds on ashes, ash species are often favored for planting in both forest and urban settings in the Northeastern States.

Cultural practices that maintain and promote tree health are encouraged to minimize losses. Control measures are not always feasible or needed for some ash pests covered in this guide, especially when light infestations or infections occur. The best procedure in these cases is to prevent problems by promoting and maintaining healthy trees. To this end, some recommendations are provided in the back of this guide in a section called "Maintaining Tree Health." However, chemical controls may become necessary as a last resort when all else fails.

This booklet will help nursery workers, resource managers, pest control personnel, and homeowners to prevent, identify, and control ash pests. The major insect and disease pests of ashes in the Eastern United States are emphasized. Descriptions and illustrations of the pests and their damage are provided to aid in identification. Brief notes are given on their biology and control to aid in assessing damage and making control decisions. Lists of chemical controls are provided, but recommendations are subject to change as certain compounds are discontinued and new materials approved. The chemical control section (tear sheet) in this booklet can be removed and discarded when outdated as indicated by registered uses on pesticide labels. For further information on pesticides or additional assistance with ash pests, contact your State forester, county extension agent, or the nearest office of the USDA Forest Service, State and Private Forestry, Forest Pest Management.

About the Authors

J.D. Solomon is supervisory research entomologist and project leader, T.D. Leininger and A.D. Wilson are research plant pathologists, and F.I. McCracken was principal research plant pathologist (retired) at Southern Hardwood Laboratory, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, Stoneville, MS 38776. In cooperation with: Mississippi Agricultural and Forestry Experiment Station and the Southern Hardwood Forest Research Group. R.L. Anderson is field office representative, Southeast Area, U.S. Department of Agriculture, Forest Service, State and Private Forestry, Asheville, NC 28802; L.C. Thompson is professor of forest protection, University of Arkansas, Monticello, AR 71655.