August 15, 2003
Emerald ash borer found two miles from Indiana border
WEST LAFAYETTE, Ind. An aggressive beetle that destroys ash trees is creeping closer to Indiana, and two Purdue University experts say it may already be here, based on a recently confirmed sighting in Ohio.
Cliff Sadof, a Purdue Cooperative Extension Service entomologist, said the discovery of the emerald ash borer in northeastern Indiana is "imminent." The beetle was recently found in Defiance County, Ohio, just two miles from the Indiana border. It's also been found in several counties in Michigan and one additional county in Ohio.
"Although every effort has been made to contain the insect, it certainly appears to be on its way to Indiana," said Jodie Ellis, a Purdue Extension entomologist and invasive forest pest educator. "When you consider that we have 147 million ash trees in Indiana, this is bad news for Indiana homeowners as well as the recreational, timber, horticulture, and nursery and landscape industries in the state."
Fort Wayne, Ind., is located close to the recently confirmed Ohio site and entomologists are concerned about ash trees in the city.
"At this point 6 million trees have been killed in Detroit alone," Sadof said. "The bad news is that there's no magic bullet for these pests. There's no known easy cure. What homeowners can do is water their trees and keep an eye out for signs of this pest."
Sadof said trees need an inch of water per week to remain healthy. Robert Waltz, state entomologist with the Indiana Department of Natural Resources, suggested that homeowners in northeastern Indiana who don't water their trees or turf should consider doing so. "It's important to maintain tree vigor," he said.
Waltz also warned Hoosiers about transporting firewood.
"Be alert if you use firewood," he said. "Be cautious about picking up firewood from infested areas, particularly if the bark is still attached. Debark all firewood if you're traveling, and be sure to burn all the wood you brought with you."
To keep infected trees from getting into the firewood supply, and to curb the spread of the pest, Ellis said trees killed by the emerald ash borer should be removed and either burned or chipped into 1-inch pieces to destroy any larvae that may still be in the wood.
The adult emerald ash borer is slender and a bright, metallic, coppery-green color. It is about one-third of an inch long, making it difficult to spot in tree leaves. The larval, or immature, form of the pest destroys live ash trees by eating the vascular tissue that supplies nutrients to the tree, Ellis said. The tree starves to death within three years after the vascular tissue is destroyed, she said.
"Infestations may go unnoticed for the first year, but after that the top third of the tree will thin out. Tiny D-shaped holes may be visible on the tree's bark, and the bark may develop lengthwise cracks or fissures," she said.
Sadof said it's very difficult to diagnose emerald ash borer damage because of the prevalence of other ash-boring pests in Indiana. Ellis conducted a survey earlier this year in West Lafayette, Ind., that yielded at least five native species of borers. The emerald ash borer differs from the native species because of the characteristic D-shaped exit holes in the main trunk and the rate at which it kills trees.
"Researchers are looking into ways to control the emerald ash borer," Ellis said. "Some methods look promising, but many are still in the research stage."
She said an injectable soil insecticide, Imidicloprid, is showing the most promise in protecting trees from the beetles but fails to protect them against the more common native moth borers. A mid-summer trunk spray with a contact insecticide that is labeled for borers may offer some control against the beetle and moths.
Sadof said Imidicloprid will probably work, but it's cost prohibitive.
"It costs $20 to treat a 10-inch tree," he said. "It may not be feasible to pay that much to treat for this pest. Not when you're talking about the number of trees that will be affected."
Sadof said only homeowners who live within 10 miles of a confirmed site should even consider insecticides to protect their favorite trees.
"Although it is too late in the year to control the beetle with a trunk spray, you can buy the Imidicloprid needed for a soil treatment at any garden center," Sadof said. "It takes about a quart to treat a 10-inch tree. When applying any insecticide, it is important to follow the directions on the label. Doubling the dose because you are especially worried will do more harm than good."
Writer: Kay Hagen, (765) 494-6682, firstname.lastname@example.org
Sources: Cliff Sadof, (765) 494-5983, email@example.com
Jodie Ellis (765) 494-0822, firstname.lastname@example.org
Robert Waltz, (317) 232-4120, email@example.com
Ag Communications: (765) 494-2722; Beth Forbes, firstname.lastname@example.org; http://www.agriculture.purdue.edu/AgComm/public/agnews/
A publication-quality photograph is available at http://news.uns.purdue.edu/images/ashborer.adult.jpeg.
A publication-quality photograph is available at http://news.uns.purdue.edu/images/ashborer.damage.jpeg.