Q. It has been awhile since I heard anything about the ash trees. Is it still not OK to plant them?
A. I still would not plant any ash trees, but maybe in the future things will change.
Emerald ash borer was introduced to North America during 2002 in an ash wood packing crate sent to Detroit – probably from China. As of January, emerald ash borer infestations were known to be present in 35 states as well as five Canadian provinces.
Emerald ash borer was discovered in Indiana in 2004 near Fremont by Tom Eichholtz, the then-agriculture extension educator in Steuben County. City forester Bill Dietrich and I met with Purdue Extension specialist Cliff Sadof a few years later in Fort Wayne to show Sadof the extensive damage in Allen County. We were the first to notice the severe woodpecker damage caused in ash trees infested with the emerald ash borer.
There are three major emerald ash borer control efforts that show great promise for the future. Beneficial wasps that exclusively attack and kill emerald ash borer continue to be released and increase in numbers in the wild. Eventually these insects may be able to lower the number of emerald ash borers and reduce the number of ash trees they are able to kill.
Researchers continue to discover and breed trees that are potentially resistant to emerald ash borers.
Pesticide control options are generally cheaper and provide longer-lasting management options.
Three species of small, stingless wasps are being used to control the emerald ash borer throughout Indiana and the U.S. These wasps kill large percentages of the beetles in their native range in Asia. All wasps have been tested to ensure that they will not attack native insects. Recent research in Michigan has shown increased survival of ash seedlings in native forests. Wasps are given only to professionals for release to ensure that they have the best chance for success. Wasps have been released in our area by Sadof almost from the time of the first infestation of ash borer in Fort Wayne.
Research has shown that native blue ash and Manchurian ash may be resistant to emerald ash borer.
It is now known that insecticides can extend the life of healthy ash trees during an emerald ash borer infestation indefinitely. Homeowners who protect large trees from the beetle will usually spend less money and have more shade than those who chose to remove them.
Treatment of ash trees is best done by professionals because improperly applied pesticides used for emerald ash borer control can be very toxic to bees.
Pesticides containing emamectin benzoate (Triage) have consistently provided highly effective emerald ash borer control for two and even three years by a professional with a single application.
The Plant Medic, written by Ricky Kemery, appears every other Saturday. Kemery retired as the extension educator for horticulture at the Allen County branch of the Purdue Extension Service.