University of Wisconsin - Extension

Madison - No one has seen one of the jewel-like beetles yet in Wisconsin, but entomologists and horticulturists are preparing for an attack of the Emerald Ash Borer, an exotic insect imported by accident from Asia, and which has killed some 5 million trees in Michigan. The beetle has spread from Detroit, where it probably landed, into Ohio. Some were recently spotted in Indiana.

"There's no evidence of it here (in Wisconsin) yet, but if it becomes established, the impact will be like what happened with Dutch Elm Disease," warns Phil Pellitteri, University of Wisconsin-Madison/Extension entomologist.

Ashes - black, white and yellow varieties - are common in Wisconsin. Because they are strong and hardy, cities plant them along streets, where they tolerate salt, minor car accidents, and other abuse better than many varieties of trees. Because they are pretty and well formed, ash trees are often used in home landscapes, parks and golf courses. They're also common in rural woodlots and forests.

In all, about 630 million ash trees grow in the state.

Pellitteri says an infestation of the Emerald Ash Borer could wipe them out, so the University, DNR and DATCP are collaborating in an attempt to hold the beetles at bay with early detection and sanitation. Researchers are working on chemical treatments that could protect specimen trees, and officials are looking at ways to keep infected nursery stock and wood out of the state. Pellitteri says it may be a tough fight.

"The frustration is that, with such a large area already hit (in Michigan), it's hard to believe sanitation will solve this," Pellitteri said. "It was going on for several years in Michigan before it was discovered."

Chris Williamson, a UW-Madison/Extension entomologist who specializes in insects that affect turf and ornamentals, said this borer is a very fast flier, a characteristic that could make it hard to stop.

Both Williamson and Pellitteri say several other diseases can cause ash trees to decline. Vericillium, a fungus, is the most common. But they say there are some different signs of infestation by the Emerald Ash Beetle. Here's what to look for if you have an ash tree that doesn't look well.

1. When the beetle emerges from the tree trunk it creates a D-shaped hole (the shape of its body) that is 2 to 3 mm in diameter.

2. If you peel back bark, look for wormy or serpentine tracks in the wood. That is the kind of track the Emerald Ash Beetle larva leaves behind.

3. An infested tree will die back gradually over three years. In the first year, the top third of the tree will yellow and drop leaves. In the second year, the second third will be affected. Finally in the third year, the bottom third will die. During the first year, if you see yellow in the top of the tree, check the base of the tree for suckers. This is a common defense against the ash borer, but rarely happens if the tree is affected by vercillium.

4. Look for the beetle itself. It is pretty -- a metallic green and is about 1/2 inch long and narrow.

For more information, you can go to a new website at http:///www.entomology.wisc.edu/emeraldashborer

Or you can call the Emerald Ash Borer hot line at 800-462-2803