Officials with the Iowa DNR say the emerald ash borer (EAB) can now be linked to 45 counties in Iowa, as Fayette and Madison counties are the most recent to be added to that growing list. EAB is a destructive wood-boring beetle that attacks and kills all ash tree species. The exotic pest was first discovered in Iowa in 2010.

In Fayette County, the insect was discovered in a city-owned ash tree in Oelwein. For Madison County, the finding took place in a rural area south of Winterset. Insect specimens taken from these sites were confirmed as EAB by a federal identifier.

The adult beetle is metallic green in color and measures approximately one-half inch long and can be noticed during the summer months. The larvae burrow through the inner layer of bark, eating away at the vascular tissue, which supplies nutrients to the tree. Starved trees usually die within two to four years.

A federal quarantine, enforced by the U.S. Department of Agriculture, remains in effect and restricts the movement of all hardwood firewood and ash articles out of Iowa into non-quarantined areas of other states. To help reduce the potential for people to unknowingly transport EAB and other destructive tree-killing pests, Iowans are strongly encouraged to use locally sourced firewood.

If a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation, the treatment window for protecting an ash tree begins very soon. Soil treatments should be made from mid-April to mid-May. Basal trunk sprays should be applied mid-May to mid-June. Trunk injections begin once the tree has a full canopy. Full details are available in Iowa State University Extension and Outreach publication PM2084: https://store.extension.iastate.edu/product/13114