Emerald ash borer (EAB) has been found in Calhoun, Winnebago and Worth counties for the first time. This invasive insect has now been found in 84 of Iowa’s 99 counties since its first detection in 2010.
Insect samples were collected from Forest City (Winnebago County) and Manly (Worth County). Officials with the U.S. Department of Agriculture (USDA) Animal and Plant Health and Inspection Service (APHIS) confirmed these samples were positive for EAB.
EAB threatens all ash species. The wood-boring insect feeds on the inner bark tissue, disrupting the transport of water and nutrients. The cumulative damage of EAB feeding eventually kills the tree. Infested trees usually die within two to four years.
Mike Kitner, Iowa Department of Agriculture and Land Services EAB Coordinator says there are indicators of an infestation.
Homeowners should look for these signs that something may be wrong with their ash trees.
Anyone concerned about the possibility of an Emerald Ash Borer infesting their ash trees should first determine that the tree is indeed an ash tree.
While the adult beetle can fly short distances, people have contributed to the spread of this pest by moving infested material, including firewood. People are reminded to use locally-sourced firewood where it will be burned to help limit the spread of EAB and other invasive pests.
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.