FAIRFIELD — Robin Pruisner's prey isn't evident at a glance. It's a set of contradictions: big damage from a small bug that's flashy but hard to spot. But she knows it's there and wants to make sure it doesn't go any farther than it already has.
“The emerald ash borer is a metallic green wood-boring beetle. It's about half an inch long,” said Pruisner, the state entemologist. “Even though it's a showy beetle, it's small.”
The emerald ash borer has devastated ash trees since it was first identified near Detroit in 2002. Its discovery in Fairfield marks the third Iowa county in which it has been found. Allamakee County came first in 2010. It showed up in Des Moines County earlier this year.
The Iowa Department of Agriculture says the beetle, which is native to Asia, was found in a residential tree in Fairfield during a survey by a team trained to find the pest. Most infestations in the U.S. start with movement of firewood, nursery plants or sawmill logs, though the beetle is capable of flying short distances.
Tivon Feeley, a forest health specialist with the Iowa Department of Natural Resources, said the Fairfield infestation was found at the tail end of a forest health tour. The tour spotted a tree that showed symptoms of infestation, and a followup check confirmed it.
He suspects a couple of other trees in town also have the beetle already.
“I think it is likely there are at least other trees in Fairfield,” he said.
The discovery has implications for other counties in the area. The release from the state indicates a “multicounty quarantine” will be put into effect in southeast Iowa.
Pruisner is beginning the process of figuring out what form that quarantine will take. She's making calls and talking with people, trying to understand just how wood products move in southeast Iowa. The beetle wouldn't skip a county naturally, so its movement most likely came by hitching a ride from humans.
Iowa has an estimated 52 million rural ash trees. Another 3.1 million grow in urban settings. Emma Hanigan, the urban forest coordinator for the IDNR, said ash trees can make up as much as 15-20 percent of a community's tree population. That's a lot of cover at risk when the emerald ash borer moves into an area.
“If you lose 15 percent of your canopy, you're losing a lot of benefit to the community,” said Hanigan. She added that losses can be significant enough to impact property values.
Treatments can help protect ash trees, but there are catches. The trees need to be in good health, so a tree with advanced infestation probably isn't a good candidate. And they need to be small enough for the treatment to take hold; a huge ash tree probably can't be covered effectively.
Pruisner said treatment doesn't make much sense if you live more than 15 miles from where the emerald ash borer was discovered. Scam artists may take advantage of the announcement, so people need to be aware of who they're talking with.
“We may see a proliferation of companies that will knock on doors offering to treat ash trees. The reality is that the most effective treatment is in the spring,” Pruisner explained.
Since so much of the spread of the beetle appears linked to inadvertent transportation by humans, Hanigan said one of the best pieces of advice is simple. If you go camping, “buy and burn your firewood in that county.” On site is ideal. That's especially important as we move from summer into fall and more people will depend on fires to stay warm at campsites.
People can help by keeping a close eye on their trees. Feeley said woodpeckers are a good indicator that something is wrong. “Woodpecker flecking,” where woodpeckers remove bark from an area before digging into a tree, is easy to spot because it leaves a white patch behind. If branches with the flecking show signs of distress, especially toward the top of an ash tree, it's possible the tree is under attack from the beetle.
“If people think a private tree has the emerald ash borer, the best thing is to call the city,” Feeley said. “They will take the first look.”
Infestation is identified when the pest leaves a distinct pattern when its larvae bore into the wood. Once an inspector at the local level confirms it, that inspector will contact the state.
Additional announcements of infestations in Iowa in the coming months would not be a surprise. Traps set this year will be coming in soon for testing, and the Iowa DNR's evaluations will follow later this fall and early winter. The reality, all the experts say, is that humans play catch-up to the beetles.
“We rarely find an emerald ash borer infestation that's new,” Pruisner said. “It's already been there for a few years.”