How to help ash trees

Q. Several of my ash trees have lost substantial amounts of bark. The bark is smooth on the back, so I don’t think it is borers. What’s going on?

Dan from Canfield

A. The damage on black ash trees is from the non-native, invasive species emerald ash borer or EAB. The reason the bark is still smooth is because the woodpeckers have not gotten all the way through the bark layer.

Upon further investigation with a hatchet, you will eventually get down to the functional xylem (where water is transported in the tree) and see galleries where EAB has scarred this area.

The tearing of the bark by the woodpeckers is called “flecking.” This is becoming common here in the Mahoning Valley as woodpeckers feast on EAB.

This tree is obviously infested with EAB when we see this flecking. Other signs of EAB may be a thinning canopy (top of the tree), or in extreme cases lots of new sprouts on the tree on the bottom 6 or so feet of the main trunk. Ohio State University Extension has a website — http://go.osu.edu/ashborer — dedicated to helping homeowners and others learn about and deal with this invasive pest.

There are also treatment options on this website. The specific bulletin is titled, “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer.”

Some homeowners want to preserve high-value trees, whether it is a rare ash tree or a rather large tree right near the house. Treatments must be followed precisely, however.

Our experts state, “Multiyear studies have shown that if more than 50 percent of the canopy has been killed by EAB or if the canopy appears to be thin and carrying less than half as much foliage as it should, it is probably too late to save the tree.”

Homeowners, therefore, should be sure to read all the details in the above-mentioned bulletin before deciding if and when to treat an ash tree.

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hot line at 330-533-5538 from 9 a.m. to noon Mondays and Thursdays to submit your questions.