UK Researchers Search for Ash Borer-Resistant Trees

Before the emerald ash borer arrived, ash trees made up about 4% of the trees across Kentucky. World famous Louisville Slugger baseball bats were traditionally made from white ash.

Ash trees infested by the emerald ash borer can take up to several years to die after first being attacked. Yet, relatively healthy ash trees have been  discovered amid stands of dead and dying trees. These survivors are known as “lingering ash.” They are untreated trees that are still healthy in areas where more than 95% of the other ash trees have been killed by the emerald ash borer. 

Researchers at the University of Kentucky (UK) hope to use the seed and genetic material from these lingering ash trees for breeding programs and research purposes to develop ash trees that confer some resistance to the emerald ash borer.

“The idea is those trees that have some natural genetic resistance to the emerald ash borer are going to be the future of ash,” said Ellen Crocker, UK assistant professor of forest health extension in the College of Agriculture, Food and Environment. “We’ve been trying to find some of these trees for several years now, and when we do, we get their seeds, so the Kentucky Division of Forestry can propagate them at their nursery and hopefully, get them back into the natural landscape.”

Identifying lingering ash trees may present a way forward for ash in North America, using seed and genetic material from these trees for breeding programs and research purposes, with the hope of developing ash trees that confer some resistance to EAB.

UK researchers are seeking the public’s help to find lingering ash trees. They said they can most likely be found in a stand where 95% or more of the trees have been dead for two or more years. The best lingering ash candidates would be greater than 10 inches in diameter.

In a similar vein, several years ago, the U.S. Forest Service and Ohio State University embarked on a collaborative effort to preserve and study the lingering ash through grafting, which allows both preservation and replication to study resistance to EAB.