The emerald ash borer, the killer of millions of ash trees in 18 states, is on the move in Iowa, the Iowa Department of Natural Resources reports.
The state agency on Tuesday said that larvae from the destructive borer have been found in two additional spots in Allamakee County in far northeast Iowa.
On May 14, 2010, state officials first identified the emerald ash borer in Allamakee County on an island in the Mississippi River.
Now, a statewide ash monitoring initiative has turned up the emerald ash borer in a tree at Pool Slough and a tree in the Black Hawk Point Wildlife Area south of New Albin.
Tivon Feeley, forest health program leader with the DNR, on Tuesday called the finding at Black Hawk Point particularly "significant," because the spot is the furthest to the west in Iowa that the borer infestation has been identified.
Feeley noted that the experience of states such as Michigan, Ohio and Indiana has shown that ash-killing insect establishes itself before it is discovered.
"They’re definitely on the move," he said on the ash borer in Iowa. " … And in the next three years, I think we’re going to see a big change for the state. I don’t think it’s just going to be a dot here and there in one or two counties. If we look at what happened in Indiana, they found just one or two in their northeast county in that first year, and just three years later, the entire state was lit up."
He noted that the emerald ash borer showed up south of St. Louis in Missouri, and now is across the state in Kansas City and has spread west into Kansas.
Feeley said budget constraints have prompted states to take a wait-and-see approach to the ash borer rather than, as in the past, spending large sums of public dollars to take down ash trees near where the bug has been spotted. It’s possible, he said, that some ash trees in a forest might have some tolerance to the bug. Some states, too, are exploring the use of a particular kind of wasp that is a natural parasite to the borer, he said.
In Cedar Rapids, city crews in recent years have been removing declining ash trees and replacing them with different species of trees, with the expectation that the ash borer will establish itself and start killing trees in the city.
"Although this is frustrating, this is not surprising," Daniel Gibbins, parks superintendent for the city of Cedar Rapids, said of Tuesday’s news of the ash borer movement in Iowa. "It is a reminder that early response by both landowners and cities to diversify plantings … is critical to reducing the impacts of such devastating pests."
Feeley and Gibbins both caution homeowners to consult with a qualified arborist if they choose to try to save a ash tree in the yard.
Feeley said an effective insecticide is available, though the chemical treatment is ongoing and an ongoing expense, he said. He said the treatment can cost about $12 per diameter inch of a tree and must be reapplied every three years. Often the insecticide can buy a homeowner some time to allow a new shade tree establish itself, he said.
Feeley said the DNR’s statewide borer monitoring program involves the examination of 416 ash trees across the state. In each instance, a portion of bark from the tree has been removed to attract any emerald ash borer into the tree.
Three of the insect’s white grub-like larvae were found in trunk of the tree at Black Hawk Point and two in a tree at Pool Slough in Allamakee County, he reported.Another 80 of the test or "sentinel" trees, most in southeast Iowa along the Mississippi River, have yet to be examined in the current review of the state’s 416 sentinel trees, Feeley said.