Emerald ash borer now infests 80 Iowa counties

Invasive pest confirmed in Fremont, Lyon and Wright counties

Eighty Iowa counties have confirmed infestations of the emerald ash borer. Source: Iowa Department of Agriculture and Land Stewardship Entomology and Plant Science Bureau

DES MOINES, Iowa — The emerald ash borer has been confirmed in Fremont, Lyon and Wright counties, bringing to 80 the number of Iowa counties occupied by the invasive insect, according to the Iowa Department of Agriculture and Land Stewardship Entomology and Plant Science Bureau. Iowa has 99 counties.

Insect samples were collected from ash trees in rural Farragut (Fremont County), rural Inwood (Lyon County) and rural Dows (Wright County). Officials with the U.S. Department of Agriculture Animal and Plant Health and Inspection Service confirmed these samples as positive for EAB.

EAB is a significant threat to all species of ash trees. The wood-boring pest tunnels just beneath the bark in the vascular tissue, disrupting the transport of water and nutrients. Infested trees usually die within two to four years.

Indicators of an infestation may include canopy thinning, leafy sprouts shooting from the trunk or main branches, serpentine (ā€œSā€-shaped) galleries under the bark, bark splitting, woodpecker damage and 1/8 inch D-shaped exit holes.

Now is the time to decide on a course of action for ash trees at risk of EAB attack (within 15 miles of a known infestation). Landowners and managers can choose to wait and see what happens, remove declining ash trees and replace them with other species, or use preventive insecticide treatments to preserve and protect valuable and healthy ash trees.

Spring, from mid-April to mid-May, is the best time to treat for EAB. 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.

See Iowa State University Extension and Outreach publication PM2084, Emerald Ash Borer Management Options, for more details about EAB treatment.

The state of Iowa monitors the spread of EAB on a county-by-county basis. Before a county can be declared positive, a life stage of the insect must be collected and confirmed. 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.

The beetle flies short distances on its own, but people have contributed to the spread of the pest by moving infested material, including firewood. EAB can unknowingly be transported beneath the bark of firewood. Use locally sourced firewood where it will be burned in order to help limit the spread of EAB.

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

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

  • Mike Kintner, IDALS EAB coordinator, 515-745-2877, Mike.Kintner@IowaAgriculture.gov.
  • Robin Pruisner, IDALS state entomologist, 515-725-1470,
  • Robin.Pruisner@IowaAgriculture.gov.
  • Jeff Goerndt, DNR state forester, 515-725-8452, Jeff.Goerndt@dnr.iowa.gov.
  • Donald Lewis, ISU Extension and Outreach entomologist, 515-294-1101, drlewis@iastate.edu.
  • Emma Hanigan, DNR urban forestry coordinator, 515-249-1732, Emma.Hanigan@dnr.iowa.gov.
  • Tivon Feeley, DNR forest health program leader, 515-725-8453, Tivon.feeley@dnr.iowa.gov.
  • Billy Beck, ISU Extension and Outreach forestry specialist, 515-294-8837, wjbeck@iastate.edu.
  • Jeff Iles, ISU Extension and Outreach horticulturist, 515-294-3718, iles@iastate.edu.
  • Laura Iles, ISU Extension and Outreach entomologist, ISU Plant and Insect Diagnostic Clinic, 515-294-0581, ljesse@iastate.edu.


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