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Emerald Ash Borer – Threatening Michigan’s Ash Trees
By Robin Millsap, Information Officer & Communications Specialist, ANR Education & Communications Systems, Michigan Agricultural Experiment Station, Michigan State University
 The summer of 2002 proved to be a pivotal one for Michigan’s ash tree population. In June of that year, the small, metallic green beetle found infesting ash trees in six counties in southeastern Michigan was finally identified as the emerald ash borer (Agrilus planipennis Fairmaire), an Asian beetle never before seen in North America.
Since that time, Michigan State University researchers, MSU Extension specialists, local, state and federal officials, and the landscape and nursery industry have been locked in a race against the spread of this very destructive pest. In the six counties of Macomb, Washtenaw, Oakland, Wayne, Livingston and Monroe, five million ash trees are either dead or dying. It is estimated there are 700 million ash trees in Michigan. The pest is not picky—it will attack healthy ash trees as well as those stressed or diseased. All ash trees in the North America are at risk if this pest is not controlled. At this point EAB attacks only ash trees. Mountain ash is not a true ash, so it is unaffected by the pest.
It is presumed the emerald ash borer (EAB) came over in wooden packing material on ships from China. Since so little is known about EAB, MSU scientists have been working hard to understand the biology of the pest and find the best methods to control it. The Michigan Department of Agriculture (MDA) has put a quarantine on a number of counties, including Genesee, Ingham, Jackson, Lapeer, Lenawee, Livingston, Macomb, Monroe, Oakland, Saint Clair, Shiawassee, Washtenaw and Wayne. Under the quarantine, it is illegal to move ash trees, branches, lumber, firewood and other materials unless chipped to one inch in diameter.
 Ash trees infested with EAB exhibit top-down dieback. One-third to one-half of the branches may die in one year. Affected trees may have vertical splits in the bark 2-4 inches long. Although difficult to see, the adult beetles make a “D”-shaped exit hole in the bark, roughly 1/16-inch in diameter. EAB are dark metallic green in color, ˝-inch in length and 1/16-inch wide.
For many years, ash trees have been used by homeowners and municipalities to replace the elm trees that were lost to Dutch elm disease. Ash was considered a hardy tree with few disease and pest problems—until now. Experts say that, if not controlled, the EAB infestation could wipe out ash trees in the same manner Dutch elm disease wiped out elm. This affects the aesthetic quality of neighborhoods, downtown areas, along thoroughfares, golf courses, shopping areas, forests and parks. The six southeastern Michigan counties that were first found to have the beetle will most probably lose all their ash trees.
 One of the most important aspects in controlling emerald ash borer is to keep it from accidentally being transported to other areas of the state, or out of the state. Ash firewood is of particular concern. Presently campers, hunters, recreational vehicle and cabin owners are being told not to transport firewood, and if they do bring firewood to their property, they must burn it immediately.
MSU is also taking a look at alternative tree species to replace the dead and dying ash trees in southeastern Michigan. It is now realized that it is better to plant a variety of tree species rather than one species in municipalities and shopping areas.
Methods to control EAB are being tested by MSU researchers. Good results have been seen with an injectable product containing bidrin, and researchers hope to have more conclusive proof of its effectiveness when efficacy trials are conducted in September.
Educating and informing the public about EAB has been a collaborative effort by MSU, MDA, the Michigan Department of Natural Resources, USDA-APHIS and USDA Forest Service. MSU Extension offices in the counties affected by EAB and the EAB quarantine have information and resources to help landowners, governmental officials and tree and landscape nurseries handle the infestation. Information can be found on the Web site: http://emeraldashborer.info. MDA also has an EAB Hot Line at 888-325-0023 for anyone suspecting they may have an ash tree infested with EAB.
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