Iowa State University Extension officials are advising Iowans to avoid treating their ash trees for emerald ash borer until the destructive bugs are found nearby. Last week, larvae of the Asian beetle were found in a tree in far eastern Iowa’s Clayton County, but no other infestations have been uncovered in Iowa.
Mark Shour, an I.S.U. Extension program specialist, says it’s premature for most Iowans to apply the insecticide used to kill emerald ash borers. "Based upon research that’s (been) done at Michigan and Ohio and Indiana, they found that it’s really not in the best interest of people to do preventative treatment unless the confirmed infestation for emerald ash borer is 15 to 20 miles away," he says.
According to Shour, the only place in Iowa where the insecticide may be beneficial is in Allamakee County which is right across the Mississippi River from Victory, Wisconsin where an emerald ash borer infestation was found in April.
"Even when it is found in the state — let’s say it’s found in northeast Iowa first, then southeastern Iowa and the rest of the state — central and western Iowa — really shouldn’t be worried about doing any treatments until that insect is closer to home, so to speak," Shour says.
But Shour says even in Allamakee County, residents must weigh the cost of repeat applications before hiring a certified arborist to start treating an ash tree. "All treatments are not guaranteed. They’re not going to be possibly…100 percent effective. The second thing is it can be expensive because it’s done every year, for the life of the tree," Shour says.
"And thirdly, when they consider the person that they’re working with, they need to make sure this person is accredited with the Iowa Arborist Association and possibly even the International Society of Arboriculture for treatment of that tree malady." .