Emerald Ash Borer Control Recommendations

From Phil Nixon, University of Illinois Entomologist, published in the University of Illinois Home, Yard, and Garden newsletter

A new publication has been produced on control recommendations for emerald ash borer (EAB). This is co-authored by entomologists from Ohio State University, Michigan State University, Purdue University, University of Wisconsin, and University of Illinois. Dr. Dan Herms, Ohio State University, and Dr. Deb McCullough, Michigan State University, are responsible for most of the content, but all five universities added to and endorse the publication.

The significant change in these control recommendations is the use of emamectin benzoate (Tree-Age) as the insecticide of choice injected into the tree every two years. Recent research, primarily conducted by Michigan State University and Ohio State University, shows that a high level of control is achieved for at least two years with each application of emamectin benzoate. This level of control is high enough to save trees even with very high pest pressure.

Other methods of control, including imidacloprid (Merit, Imicide, Xytect) soil and trunk injection and soil drench, and dinotefuran (Safari) trunk spray, provide a level of control adequate for lower pest pressure. These insecticides are more useful as a preventative before EAB becomes numerous in an area or after heavy infestations have ended and most untreated trees have died. In both of these situations, there are fewer beetles present to attack the trees, allowing less effective insecticidal control to be adequate. A basis for this recommendation is that many of the trees annually treated with insecticides other than emamectin benzoate in high EAB pressure areas of Michigan and Ohio have died.

We are still not recommending control in an area until EAB has been found within 15 miles. Recent research continues to indicate that most trees with up to 40% dieback from EAB will survive if treated with emamectin benzoate.