Emerald Ash Borer Discovered in Mills and Shelby Counties

October 26, 2020, 9:42 am | Keely Coppess, Julie Tack, Laura Sternweis

emerald ash borer confirmed in Mills and Shelby counties Iowa.DES MOINES, Iowa ā€“ Emerald ash borer has been detected in Mills and Shelby counties for the first time. The invasive, tree-killing pest was collected from trees in Glenwood (Mills County) and Shelby (Shelby County).

EAB is a significant threat to all species of ash trees, infesting and killing both stressed and healthy trees. The destructive wood-boring pest tunnels just beneath the bark in the vascular tissue, interfering with the transport of water and nutrients. Infested trees generally die within two to four years.

Ash trees with low population densities of EAB have little or no external indicators. Infested trees may exhibit canopy thinning, woodpecker damage, leafy sprouts shooting from the trunk or main branches, serpentine (ā€œSā€-shaped) galleries under the bark, bark splitting and 1/8 inch D-shaped exit holes.

Native to Asia, EAB was first discovered in Michigan in 2002 and is now found in 35 states. The exotic pest has been detected in 76 Iowa counties since 2010. Before a county can be confirmed, a life stage of the insect must be verified.

EAB spreads short distances naturally, but large jumps in distribution are made possible by human-assisted movement. The larval stage of the insect can unknowingly be transported in wood products such as firewood. Leaving firewood at home and using locally-sourced firewood where it will be burned can help limit the spread of EAB.
At this calendar date, the window for all preventive treatments is 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 winter, and treat beginning spring 2021 (early April to mid-May).

More details pertaining to treatment are available in Iowa State University Extension and Outreach publication PM2084, Emerald Ash Borer Management Options. To find a certified applicator in your area, download PM3074, Finding a Certified Pesticide Applicator for Emerald Ash Borer Treatment, and follow the steps.

The State of Iowa monitors the spread of EAB on a county by county basis. Anyone who suspects an infested ash tree in a new location 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, 515-725-8453.

Additional information on EAB, including known locations in Iowa, can be found at http://www.iowatreepests.com.

For more information contact any of the following members of the Iowa EAB Team:

About the Authors: 

Julie Tack

Iowa Department of Natural Resources