New Exotic Pest Identified in Michigan’s Ash Trees; State Issues Quarantine to Control, Prevent Its Spread

Editors note: Missourians should be on the lookout for this pest as well

Michigan and federal officials announced the discovery and identification of a new exotic pest from Asia - Agrilus planipennis or the Emerald Ash Borer - in five Southeast Michigan counties that affects ash trees. In response, state agriculture officials have issued a quarantine on all ash trees and timber products in the affected counties to help prevent and control the spread of this pest. Under this quarantine, ash trees, branches, logs, and firewood may not be moved outside the affected area unless certified for movement by the Michigan Department of Agriculture (MDA).

The Emerald Ash Borer, a pest belonging to a group of insects known as metallic wood-boring beetles, is not native to Michigan or anywhere in the United States. It was officially identified in July, 2002 by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) with assistance from Asian entomologists.

According to Ken Rauscher, director of MDA’s Pesticide and Plant Pest Management Division, the state has initiated its Invasive Species Emergency Response Plan, which included the creation of an Emerald Ash Borer Task Force. The Task Force has conducted detection surveys over the past two weeks to determine the borer’s range and extent of damage. To date, it has been identified in Livingston, Macomb, Oakland, Washtenaw, and Wayne counties, and infestations have been limited to species of ash trees-either white, green or black ash.

Homeowners and landscapers in southeast Michigan have been plagued by the loss of ash trees for the past couple of years. Specialists initially determined much of the problem was due to a combination of disease, drought, and poor soils. This new insect is likely another reason for the ash trees’ decline.

Emerald Ash Borer adults are dark metallic green in color, 1/2 inch in length and 1/16 inch wide. Larvae are creamy white in color and are found under the bark. Their appearance typically goes undetected until the trees show symptoms of being infested-usually the upper third of a tree will thin and then die back. This is usually followed by a large number of shoots or branches arising below the dead portions of the trunk.

For more information on the emerald ash borer, see http://www.na.fs.fed.us/spfo/eab/

From a July 16, 2002, news release by Sara Linsmeier-Wurfel, Michigan Department of Agriculture

Chris Starbuck, Woody Ornamental Horticulture, UMC (573) 882-9630