PRINT ADS

The emerald ash borer, an invasive insect that has destroyed millions of ash trees in Michigan and other states in the Upper Midwest, has been discovered for the first time in Wisconsin.

Forest health officials investigating a citizen's report of dying ash trees in a private woodlot in Ozaukee County just north of Milwaukee, near the village of Newburg, discovered the insect. The discovery was announced at a news conference Monday held jointly by the state Department of Agriculture, Trade and Consumer Protection and the Department of Natural Resources.

Workers with both agencies have been conducting detailed searches for the insect for months.

"We expected to find the emerald ash borer in Wisconsin sooner or later, but this is still disappointing," said Agriculture Department Secretary Rod Nilsestuen.

Brian Kuhn, director of the plant industry bureau for the department, said even though officials were braced for it, the news was still unsettling because of the potential damage to the state's forests.

"It was a day we hoped would never come," Kuhn said.

The discovery of the beetle is likely to be of great concern to cities such as Madison, where about 30 percent of the city's 11,000 terrace and boulevard trees are ash.

"A lot is at stake in Wisconsin," said Darrell Zastrow, the director of the Office of Forest Science for the DNR. "There are an estimated 737 million ash trees in our forests and another 5 million in our communities. Impacts to the forest products industry, tourism and communities could be substantial."

The ash borer is a metallic green beetle about the size of a penny that came to this country from Asia by hitching rides in the wood of packing crates.

It's an example of one of the most threatening aspects of invasive species; it has no natural predators in this part of the world. The adults burrow into the bark of ash trees and lay eggs. The larvae from the eggs chew through the fluid-conducting vessels under the tree's bark, cutting off the nutrients that keep the tree alive.

Nilsestuen and other officials said the affected counties — Ozaukee and nearby Washington — will likely be quarantined to prevent movement of hardwood firewood, ash nursery stock, timber or any other article that could spread the ash borer. A survey of the area will be conducted to determine the size of the infestation and its possible source.

Kuhn said nursery owners and others affected by the potential die-off of ash trees have already started adjusting. Ash trees have been popular for homeowners and urban forestry programs because they grow fast and are hardy, but the threat of the ash borer has caused the popularity of the ash to rapidly decline.

"I've heard of nurseries plowing under entire fields of ash trees," said Kuhn.

Marla Eddy, Madison's city forester, said the potential destruction could be even worse than Dutch elm disease, which killed millions of the elms that arched across so many neighborhood streets. That disease took much longer to spread and kill trees, she said, because it spread through the roots. The emerald ash borer kills trees much faster, within a couple of years.

Madison has responded by no longer planting ash trees and increasing the diversity of the city's plantings, Eddy said.

Eddy holds out little hope that the spread of the ash borer can be halted. "I would like to be optimistic but there haven't been any surefire ways of stopping this insect," Eddy said.

Kuhn agreed. He said clearing out trees around the infected areas has not worked. Nor are there any effective pesticides. "We don't have the magic bullet at this time."

The only hope, Kuhn said, is that quarantines on moving firewood — the biggest culprit in spreading the insect — and other wood items may slow the spread enough to buy time for the discovery of an effective pesticide.

Such work is now going on at research universities, he said, including UW-Madison.

"Things have been moving along," Kuhn said. "And there are a number of areas where we may be on the cusp of a breakthrough. We just have to buy time until that research bears fruit."