Emerald Ash Borer located near Dakota City


The Emerald Ash Borer, an insect that causes significant damage and death to ash trees, has been identified near Dakota City, the Iowa Department of Agriculture and Land Stewardship reports. Photo courtesy of the USDA.

Emerald ash borer (EAB) has been found in Dickinson and Humboldt counties for the first time. The invasive, ash tree-killing insect from Asia has now been confirmed in all but eight of Iowa’s 99 counties since its original detection in 2010.
EAB larvae were collected by Iowa Department of Agriculture and Land Stewardship staff just outside the eastern city limits of Arnolds Park (Dickinson County) and rural Dakota City (Humboldt County). Federal identification confirmed the samples positive for EAB.
Indicators of an infestation may include canopy thinning, leafy sprouts shooting from the trunk or main branches, serpentine (“S”-shaped) galleries under the bark, bark splitting, woodpecker damage, and 1/8-inch D-shaped exit holes.
Now is the time to decide a course of action for ash trees at risk of EAB attack (within 15 miles of a known infestation). Landowners and managers can choose to wait and see what happens, remove declining ash trees and replace them with other species, or use preventive insecticide treatments to preserve and protect valuable and healthy ash trees. Spring, from mid-April to mid-May, is the best time to treat for EAB. Insecticides are most effective when the ash tree is actively growing, and uptake is at its peak. Tree service companies can apply insecticide trunk injections through the summer if soil moisture is available.
See Iowa State University Extension and Outreach publication ENT57, Emerald Ash Borer Management Options, for more details about EAB treatment.

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