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Hot on 19 July 2002
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Emerald Ash Borer Beetle Killing Trees in Michigan

Indiana DNR asks homeowners to look for D-shaped bores

An exotic beetle, the emerald ash borer, has been eating and killing ash trees in Michigan, creating need for quarantines on tree stock shipments and creating worried homeowners, shadelovers, arborists and nursery dealers.

Indiana state entomologist Dr. Bob Waltz wants to make sure the pest hasn't already shown up in northern Hoosier counties. He's asking people with ash trees to investigate ash tree problems and become educated on what the beetle looks like.

"In these tight budget times, the DNR and other inspectors can't afford to inspect every suspect ash tree, but people who see the problems can help us identify the true threats," said Waltz. You can e-mail him and phone the agency to give information about true threats.

This borer beetle likely came in bulk steel shipments from Russia, scientists report. Chipped ash is used to cushion loads of steel so they don't shift on ocean voyages, and the beetles hitched rides into North American ports.

Any number of things can cause an ash tree's decline, some weather-relatedólike hard spring frosts, said Waltz. "But the emerald ash borer beetle (Agrilus planipennis) is a native of China, Korea and Japan and had not been seen previously in North America.

"This beetle is a threat because our native ash trees have no defenses against this pest, and few natural enemies. Northern Indiana counties are most likely to see the beetle because of their proximity to the known outbreak. However, the beetle could be introduced through Indiana ports and normal manufacturing trade pathways," said Waltz.

Signs to look for include metallic green beetles about 3/8- to 5/8-inches long. The beetles will actively fly and lay eggs on ash trees until autumn. Larval collections are found under bark and are S-shaped and wind back and forth. Larvae overwinter, pupate in spring and new adults can emerge next May.

The best sign for spotting a beetle infestation is a D-shaped exit hole on the bark of the trunk and large branches left dead by emerging adults. This new pest is known to affect only ash trees.

This new beetle is similar to native borers such as bronze birch borer and two-lined chestnut borer. But the new beetle is very aggressive and is killing reasonably healthy trees, as well as stressed ash trees.

"For several years, ash trees in and around Detroit, Michigan were reported as experiencing a disease known as 'ash yellows'. It turns out that many of the reports actually were caused by the beetle," said Waltz.

Ash trees are desirable for shade and have market value as timber. The presence of the beetle in Indiana would require shipment quarantines.

No known treatment is available for trees with infestations of this beetle, though scientists are working on a solution that will save trees.

People who find the beetle and have confirmed the identity should immediately call or e-mail Waltz. The e-mail address is depp@dnr.state.in.us; the telephone number is 317-232-4120.

You can go on-line at www.IN.gov/dnr/entomolo/pestinfo/ashborer.htm to see the beetle, or contact a professional arborist or your county extension agent.

"We don't want this problem to spread to our street trees, our backyards, our forests, our woodlots or our nurseries. Help from the public is going to be our first defense," Waltz said.

He recommends homeowners and landscapers diversify plantings by getting a good mix of native Indiana tree and shrub species that provide beauty, strength, cover and habitat, shade and economic value for yards, communities, cemeteries and commercial logging acreage.

"Diversity in nature is a good thing. Good tree management will include encouraging species diversity," said Waltz.

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Purdue University Cooperative Extension Service is implied. Any person using products listed assumes full responsibility for their use in accordance with current direction of the manufacturer. Purdue University is an equal opportunity/equal access institution.

Information listed is valid only for the state of Indiana.

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The Plant & Pest Diagnostic Laboratory at Purdue University