Farm Progress

Ash borer in more than half of Iowa’s counties

Tree-killing insect recently confirmed in five additional counties in Iowa.

June 27, 2017

3 Min Read
BAD BUG: The emerald ash borer has now been found in 50 of Iowa’s 99 counties. The invasive pest was most recently confirmed in Benton, Buena Vista, Floyd, Howard and Warren counties.

Iowa ag officials say an insect that has killed millions of ash trees has been found in five more counties in the state as of mid-June, bringing the total infested counties to 50. Since the first Iowa detection in 2010, emerald ash borer continues to expand its range across the Iowa landscape. With confirmed detections now in 50 counties, EAB has reached more than half of Iowa’s 99 counties.

EAB is an exotic pest that attacks and kills ash trees. The recent finds involve ash trees in Belle Plaine (Benton County), Alta (Buena Vista County), Charles City (Floyd County), Cresco (Howard County), and a rural area southwest of Milo (Warren County). Insect samples were submitted from these sites and positively identified by USDA.

“This is traditionally the time of year we experience an increase in calls from Iowans suspecting EAB-infested trees,” says Mike Kintner, the Iowa Department of Agriculture’s EAB and gypsy moth coordinator. “Now that trees have been given the opportunity to fully leaf out for the season, symptoms of an ash tree under attack by EAB are more noticeable.”

Infested trees usually lose top leaves first
EAB-infested ash trees display canopy dieback beginning at the top of the tree and progressing downward. Look for S-shaped feeding galleries under dead or splitting bark, D-shaped exit holes, water sprouts along the trunk and main branches, and bark that is stripped off as a result of woodpeckers hunting for EAB larvae.

The adult beetle is metallic green in color and measures approximately a half-inch long and can be observed during the summer. The damage is done by larvae burrowing through the inner layer of bark, feeding on the vascular tissue that moves life-sustaining water and nutrients throughout the tree. Starved trees usually die within two to four years.

The Iowa EAB Team provides diagnostic assistance to landowners and includes officials from Iowa Department of Ag and Land Stewardship, Iowa State University Extension, Iowa Department of Natural Resources, USDA Animal and Plant Health Inspection Service and USDA Forest Service. Anyone who suspects an infested ash tree in a county not known to have EAB is urged to contact the Iowa EAB Team. 

Follow guidelines for insecticide treatment
By mid-June, the window for soil-applied preventive treatments (soil injection, soil drench or granular application) has ended.

Basal trunk sprays for trees 23 inches in diameter (measured 4.5 feet above the ground) can be made until mid-June. Trunk injections can be done now through the end of August if a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation. Good ground moisture is essential for systemic insecticide movement in a tree. Full details are available in ISU Extension publication PM2084.

Quarantine restricts moving firewood
A federal quarantine, enforced by USDA, remains in effect and prohibits movement of all hardwood firewood and ash articles out of Iowa into non-quarantined areas of other states without a valid compliance agreement or permit. To help reduce the spread of EAB and other destructive tree-killing pests, Iowans are strongly encouraged to use locally sourced firewood. The transport of unknowingly infested firewood is the quickest way to spread EAB to new areas. This insect has killed tens of thousands of ash trees and has been confirmed in 30 states.

Additional EAB information and maps are available at For more information contact any of the members of the Iowa EAB Team:

• Mike Kintner, IDALS EAB coordinator, 515-745-2877, [email protected]

• Robin Pruisner, IDALS state entomologist, 515-725-1470, [email protected]

• Paul Tauke, DNR state forester, 515-725-8450, [email protected]

• Tivon Feeley, DNR forest health coordinator, 515-725-8453, [email protected]

• Emma Hanigan, DNR urban forestry coordinator, 515-249-1732, [email protected]

• Jesse Randall, ISU Extension and outreach forester, 515-294-1168, [email protected]

• Mark Shour, ISU Extension and outreach entomologist, 515-294-5963, [email protected]

• Laura Iles, ISU Extension and outreach entomologist, ISU Plant and Insect Diagnostic Clinic, 515-294-0581, [email protected]

• Donald Lewis, ISU Extension and outreach entomologist, 515-294-1101, [email protected]

• Jeff Iles, ISU Extension and outreach horticulturist, 515-294-3718, [email protected]

Source: Iowa Department of Agriculture


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