In the Garden: Ash borer: What is the threat?

On a recent fall drive, we spotted purple triangular boxes hanging from trees. I later learned that Ohio has joined 46 other states in using these purple traps to survey for the emerald ash borer (EAB) beetle, the news-making Asian import that has killed millions of ash trees in Michigan and has now infested trees in some 40 Ohio counties. 

Our county extension agent, Eric Imerman, says no infestations have been reported in Madison County, but the bordering counties of Union and Franklin have had reports. He says one in five to six trees in the county is an ash. Because of their prevalence, he is encouraging county residents to identify ash trees on their property, monitor their health and consider a plan for treating or removing the ash trees.

The larvae of these menacing beetles eat the live tissue beneath ash trees’ bark and kill their hosts within three to five years of infestation. Because the larvae overwinter beneath the bark, they can be inadvertently transported via firewood, logs or nursery stock—the sources of most of Ohio’s infestations, according to state statistics.

Identifying Ash Trees
Confused with boxelder and walnut trees, ash trees are distinguished by: 1) their branching pattern—branches arranged directly across from one another; and 2) their compound leaves with five to nine feather-like leaflets.

Watching for Beetles
While an infested ash tree’s decline is gradual, early symptoms include dead branches near the tree’s top or wild leafy shots growing out from its lower trunk. D-shaped exit holes and bark splits exposing S-shaped tunnels are more significant signs. Any suspected infestations should be reported to the state’s EAB hotline at 1-888-OHIO-EAB.

Prevention or Removal
Residents are now facing a dilemma to treat their ash trees with a costly preventative pesticide or remove the trees and replace them with other varieties. Research and experience have shown that insecticides can protect the trees, but success is not assured.  For more information on these pesticide options, visit or To save money in the long run, many are opting to remove the trees before they become larger and more costly to cut down, then replacing them with other varieties.

Teresa Woodard is a volunteer with the Madison County Master Gardeners. Questions and gardening news items are welcomed at 740-852-0809 or by e-mail at

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