The emerald ash borer, a destructive and invasive insect of ash trees, has been confirmed in 28 of Iowa's counties. The latest confirmation was for Dubuque IA. An additional infestation was confirmed north of the Oskaloosa city limits, expanding the known range in a previously confirmed county.
Read more about this most recent discovery and confirmations of infestation in the Iowa State University Extension and Outreach Yard & Garden news release from September 1, 2015.
The map below shows the current confirmed reports of EAB in Iowa. The circles around each confirmed infestation indicate a 15-mile radius, an area where ash trees are at risk of attack and it is suggested that homeowners decide which management option they will use to deal with the threat of EAB on their ash tree(s).
It is too late this year to make effective insecticide preventive treatments (soil injection, soil drench or granular application basal trunk sprays or trunk injection). For more on control options see ISU Extension & Outreach pamphlet PM 2084, Emerald Ash Borer Management Options.