Tree-killing emerald ash borer found in 2 more Iowa counties

The tree-killing emerald ash borer has been confirmed in Dickinson and Humboldt counties for the first time, leaving only eight counties in Iowa where the pest has not been found since it was first detected in 2010 in the state.

Larvae were collected by Iowa Department of Agriculture and Land Stewardship staff just outside the eastern city limits of Arnolds Park in Dickinson County and in rural Dakota City in Humboldt County, the state announced last week. Federal identification confirmed the samples as positive for the borer.

It is the cumulative damage by larvae feeding on the inner bark that eventually kills ash trees, the state says. The feeding cuts off the tree’s ability to transport water and nutrients, typically killing a tree within two to four years.

Indicators of an infestation include canopy thinning, leafy sprouts shooting from the trunk or main branches, serpentine galleries under the bark, bark splitting and woodpecker damage.

“Because woodpecker damage can be a sign EAB has infested an ash tree, we receive a number of calls during the winter and early spring,” said a statement from Mike Kintner, Iowa Department of Agriculture’s emerald ash borer and spongy moth coordinator. “These latest new county detections were the result of green industry professionals alerting our department about the possibility of EAB infested trees based on the woodpecker damage they observed.”

While the borer can travel locally, long-distance spread of this insect is attributed to people moving infested material, including firewood.

The eight counties where the emerald ash borer has not been detected are Osceola, Emmet, Kossuth, Mitchell, Palo Alto, Plymouth, Woodbury and Monona, according to the state ag department.