DES MOINES, Iowa – With the discovery last week of a residential tree in rural southeast Dallas County, the presence of emerald ash borer (EAB) has been confirmed in more than one of every five Iowa counties.
According to the Iowa Department of Agriculture and Land Stewardship, the current EAB infestation was found as a result of an arborist contacting state officials about a suspect ash tree. Subsequent investigation revealed characteristic galleries chewed below the bark by larvae, recent woodpecker activity, and live larvae that were positively identified by federal identifiers.
“This finding is the closest to Polk County and Iowa’s capital city to date” said Iowa Department of Agriculture & Land Stewardships EAB and Gypsy Moth Coordinator Mike Kintner in a statement. “With this discovery, Iowa has declared three positive counties in 2015 where this ash-killing pest has been found.”
Since first being accidentally transported to the United States inside infested cargo from Asia in 2002, EAB has spread to 25 states. It’s been found in 21 Iowa counties, and without natural predators, EAB is expected to continue spreading across the state. However, it’s not a sure bet that EAB will infest every ash tree in Iowa.
“I do believe that we’re going to see ash that have some tolerance out there,” Iowa DNR Forest Health Coordinator Tivon Feely told reporters Thursday. “We’ve seen that with elm, with dutch elm disease and it’s taken many years for us to breed that resistance but you can go buy true American elm today that is tolerant to the disease. I think we’ll see the same thing with ash, where we can breed resistance in there and we’ll have ash available on the market. It won’t happen over night and it will take a long time.”
The city of Des Moines is currently working through an eleven-year, $10-million-dollar program to remove about 7,000 ash trees and treat another 6,000 ash trees. A remaining 34,000 trees are in woodland areas, and will be left to fall on their own.
In total the loss of ash trees and their benefits, and the cost to replace them, is expected to cost Iowans $2.5 billion.
The price tag is $27 million for Iowa’s wood products industry, which is largely centered in northeastern Clayton County. While EAB has not been found there, Clayton County is adjacent to Allamakee County in Iowa and Grant County, Wisconsin, both of which have confirmed emerald ash borer infestations.
For landowners who wish to protect their ash trees, the window for preventive treatment measures (trunk injection, soil injection, soil drench or basal trunk sprays) is mid-April to mid-May, according to IDALS. 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 and treat during the recommended treatment time.
To hear more about the threat of emerald ash borer in Iowa, click the audio player above this story.