Emerald ash borer strikes another Iowa county

Emerald ash borer has been detected in Ringgold County, putting the total number of impacted Iowa counties at 52, state officials announced Thursday.

Ash borer was discovered by a tree service that reported suspect ash trees to the Iowa Department of Agriculture and Land Stewardship. Insect larvae were collected from a rural site west of Tingley and positively identified, according to a news release from the state agriculture department.

Emerald ash borer-infested trees can include branch dieback in the upper crown, water sprouts along the trunk and main branches, vertical bark splits, D-shaped emergence holes, S-shaped tunneling under loose bark, as well as woodpecker damage.

All ash tree species are susceptible to attack by in invasive bug. The larval stage of this insect kills ash trees by tunneling under the bark and feeding on the part of the tree that moves water and nutrients throughout the tree.

'We are already up to 13 new counties confirmed with EAB this year,” said Mike Kintner, Iowa Department of Agriculture and Land Stewardship emerald ash borer and gypsy moth coordinator. 'As we continue to track EAB's spread across the state, people are encouraged to report suspect trees in counties that have not yet been declared positive.”

In June, officials said the invasive species had spread to more than half of Iowa counties with discoveries in Benton, Buena Vista, Floyd, Howard and Warren counties. Later in the month, emerald ash borer also was discovered in Butler County.

The beetle is most frequently spread by the transport of infested firewood. Officials recommend residents buy local firewood and avoid moving it outside the area to prevent transportation of the destructive pest.

Emerald ash borer is native to Asia and was introduced to the United States in 2002. It was first discovered in Iowa in 2010 in Allamakee County.

It spread to Linn County in 2015 and Johnson County in 2016. Last week, officials in Cedar Rapids reported a new case of emerald ash borer and the first discovery in the city's core area.

According to the news release, the treatment window for soil-applied preventive treatment measures and bark sprays has ended. 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 from Iowa State University Extension and Outreach at store.extension.iastate.edu/product/13114.

To learn more about emerald ash borer, go to IowaTreePests.com.