Beware of falling ash trees

Dead ash trees fell near a trail at the Glen Helen Nature Preserve in Yellow Springs, Oh. (Photo: CFAES)

COLUMBUS, Ohio—Ash trees, some dead for years, are increasingly falling in Ohio, spurred by fungi feeding off of what the emerald ash borer has left behind.

First seen in Ohio in 2003, the emerald ash borer, an invasive beetle originally from Asia, has since killed off swaths of trees across the state and much of eastern North America, but some of those trees have remained standing for years.

Enter phase two of the problem. Various fungi, including one called turkey tail, have been slowly consuming what’s left of the dead trees, in some cases destabilizing the trees. Add some wind, and the dead trees come down.

“We expected this to happen,” said Joe Boggs, an entomologist with Ohio State University Extension, the outreach arm of The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES). “Now you have standing trees that are starting to break apart.”

Before the emerald ash borer arrived, Ohio was home to nearly 4 billion ash trees. About one in every 10 trees in Ohio was an ash.

The ash borer beetle lays its eggs on an ash tree, and when the eggs hatch, the larvae tunnel inward to feed on a ring of the tree, just beneath the bark. As the larvae grow, they etch deeper into the tree, destroying a part of the tree used to transport water and nutrients, eventually killing the tree.

When a tree becomes infested with the emerald ash borer, it can become weak and brittle, said Amy Stone, an OSU Extension educator in Lucas County, where the emerald ash borer was first seen in Ohio.

Once dead, ash trees can rot quickly because they have little resistance to decay. Almost as soon as an ash tree dies, turkey tail and other fungi begin feeding, but the decay is a slow process, which is why many long-dead ash trees have only recently begun falling.

People with ash trees on their property should have an arborist inspect the trees to ensure none of them pose any risk of falling, Stone said. If there is a risk, people should have the trees taken down, she said.

“The longer the tree stands dead, the increased chance of it falling. It needs to be on everyone’s radar,” Stone said.

And though some might fancy getting lost in thought on a hiking trail, it might be wise to stay aware of any standing dead ash trees.

“They can snap at any time without warning,” Boggs said. “There’s really nothing holding them up.”

For tips on choosing an arborist to inspect or remove an ash or another type of tree, visit


CFAES News Team
For more information, contact: 

Joe Boggs

Amy Stone