The emerald ash borer (EAB) is a small insect that is causing some big problems. Accidentally introduced into the U.S., this Asian native is thought to have arrived in wooden packing materials brought in by ship or air. Since its discovery in southern Michigan in 2002, it has cut a swath of destruction as it has steadily expanded its range. So far this damaging pest has killed tens of millions of ash trees in twenty-one states and two Canadian provinces. Many more trees are at risk if this invader is not contained.
What can you do to protect your ash trees if you live in an area that's been invaded? There are some insecticidal treatments that can be done on healthy ash trees in street and home landscape settings that can help protect them from infestation. To help homeowners and municipalities decide on the best preventative treatment options, Iowa State Extension has put together a newly revised, free, downloadable publication detailing current emerald ash borer management options. While written for Iowa homeowners and tree care professionals, this publication has information that tree owners in other states where the borer is active will find helpful. Consult with your local Extension Service for more advice specific to your state.
Iowa Extension's recommendation is to treat trees only if they are within 15 miles of a known EAB infestation. If you are outside this risk zone, continue to monitor the location of confirmed outbreaks in your state. If you live within a risk zone and decide to treat your tree, they recommend using trunk injection or soil injection or drench done by a commercial pesticide applicator, or a soil drench or granules applied by a homeowner according to label instructions. They do not recommend canopy sprays because these are less effective and more likely to harm non-target organisms.
Also available to help you decide if symptoms on your ash tree are due to EAB or some other problem is another downloadable publication on the common problems of ash trees. Amply illustrated with many clear photos, this will help you figure out if your tree is an ash, and shows you symptoms of EAB infestation, as well as those of problems that can be confused with EAB.
To download both these helpful publications, go to Iowa State University Extension.