The Iowa Department of Agriculture has confirmed the presence of Emerald ash borer in Monona, Osceola, and Woodbury Counties for the first time. The invasive, tree-killing insect was first detected in 2010. Now, just three of Iowa’s 99 counties are free of the pest.
What is Emerald ash borer?
Emerald ash borer is a significant threat to native ash tree species, typically killing a tree within two to four years of becoming infested. The cumulative damage from the larvae feeding on the inner bark eventually kills ash trees as it cuts off the tree’s ability to transport water and nutrients.
What can farmers and other land owners do about Emerald ash borer?
The first step is identification. 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 ⅛-inch D-shaped exit holes.
If you have ash trees within 15 miles of a known infestation, now is the time to decide a course of action. Landowners and managers can wait and see what happens, remove declining ash trees and replace them with other species, or use preventative insecticide treatments to preserve and protect valuable and healthy ash trees.
The best time to treat for Emerald ash borer is in the spring, from mid-April to mid-May, says the Iowa Department of Agriculture. 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.
Anyone who suspects an infested ash tree in a county not currently known to be confirmed with Emerald ash borer is encouraged to contact one of the following:
- Iowa Department of Agriculture and Land Stewardship, State Entomologist Office, 515-725-1470
- Iowa State University Extension and Outreach, Entomology, 515-294-1101
- Iowa Department of Natural Resources, 515-725-8200
Photo credit: USDA
How does Emerald ash borer spread?
While adult beetles can disperse locally by flying, the long-distance spread of this insect is attributed to people moving infested material, including firewood. People are encouraged to use locally-sourced firewood where it will be burned to help limit the spread.
Learn more about Emerald ash borer
Iowa State University Extension and Outreach has produced a publication about EAB treatments.
Additional information on Emerald ash borer can be found at iowatreepests.com.
