Emerald Ash Borer Confirmed in Clarke County

New detection of invasive pest discovered in Osceola

November 28, 2016, 10:17 am | Dustin Vande Hoef, Julie Sparks, Laura Sternweis

Emerald Ash BorerDES MOINES, Iowa – Emerald ash borer, an invasive beetle that attacks and kills all ash species, has been positively identified in the city of Osceola in Clarke County. Since the first Iowa detection in 2010, EAB has now been confirmed in 39 counties. A native to Asia, EAB is considered to be one of the most destructive tree pests ever seen in North America.

The Osceola discovery came after an Iowa EAB Team member observed symptoms of an EAB infestation in a city-owned tree. Further examination of the tree by peeling bark led to the collection of a larva that was confirmed positive by national identifiers.

EAB-infested ash trees display canopy dieback beginning at the top of the tree and progressing downwards, S-shaped feeding galleries under dead or splitting bark, D-shaped exit holes, water sprouts (along the trunk and main branches) and increased bark damage by woodpeckers.

The Iowa EAB Team provides EAB diagnostic assistance to landowners and includes officials from Iowa Department of Agriculture and Land Stewardship, Iowa State University Extension and Outreach, the Iowa Department of Natural Resources, USDA Animal and Plant Health Inspection Service and the USDA Forest Service.

The adult emerald ash borer is a metallic green beetle measuring approximately one-half inch long. It is the larval stage of this insect feeding underneath the bark that disrupts the flow of nutrients, eventually killing the tree.

On their own, EAB can fly short distances, but can unknowingly spread further distances in firewood. The Iowa EAB Team strongly urges Iowans to use locally sourced firewood, burning it in the same county where it was purchased.

At this calendar date, the window for all preventive treatments has closed. If a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation, he or she should have landscape and tree service companies bid on work, review the bids this fall/winter and treat beginning spring 2017 (early April to mid-May).

Please contact Iowa EAB Team members to have suspicious-looking trees checked in counties not currently known to be infested. The State of Iowa will continue to track the movement of EAB on a county-by-county basis. Before a county can be officially recognized as infested, EAB must be collected by a member of the Iowa EAB Team and verified by USDA entomologists.

To learn more about EAB and other pests that are threatening Iowa’s tree population, please visit www.IowaTreePests.com. Please contact any of the following members of the Iowa EAB Team for further information:

About the Authors: 

Julie Sparks

Iowa Department of Natural Resources