ActivePaper Archive Insect harmful to ash trees spotted in region - Johnson City Press, 10/9/2016

Insect harmful to ash trees spotted in region


Contributed/Chase Geibner

Damage to an ash tree behind its bark


The size of an emerald ash borer in relation to a penny

Even though its size is parallel to a cooked grain of rice, a small green beetle has decimated hundreds of millions of ash trees all over the United States.

And now the emerald ash borer, which originated in Asia, has been confirmed in Washington County.

“We had a client that called us out to look at an ash tree last fall and it was in western Washington County. So we took a sample and sent it to our diagnostic lab in Charlotte, N.C., and they confirmed it was an emerald ash bore,” said Chase Giebner, arborist representative for Bartlett Tree Experts.

While the adults nibble on ash leaves, its larvae create the real issue for ash trees. The larvae feed on inner bark, which disrupts water and nutrient flow throughout the tree. According to the Tennessee Department of Agriculture website, the larvae can kill an ash tree within three years of initial infestation.

In July 2010, the beetle was first sighted in Tennessee at an Interstate 40 truck stop in western Knox County. In subsequent years, the ash borer began spreading to more counties in the middle and eastern part of Tennessee.

While Dr. Karl Joplin, a local professor in biological sciences, said he hasn’t heard of any reported sightings in Johnson City, he has followed the insect’s spread across the state.

“They’re probably just following the distribution of the ash tree and being brought in on firewood, which is probably the best way they spread,” Joplin said.

According to a detection map on a website dedicated to the insect, the emerald ash borer was first confirmed in Washington County on July 29, 2014.

Officials believe the bugs are likely present in Unicoi and Carter counties based on its proximity to counties where sightings have been confirmed.

“So it’s actually been in Tennessee for a while, about six years now, but it took a while to get to Washington County. It’s kind of unique — if you travel I-81 from Greeneville to Knoxville, you can see hundreds of dead ash trees on the side of the road,” Giebner said.

“It’s not necessarily spreading on its own. It’s spreading by humans as well. People go camping on the weekends and take firewood with them and they don’t know they could be moving this pest from place to place easily.”

Giebner said the ash borer can only fly about half a mile on its own.

“So it would be a really slow spread if it was just nature doing its thing, but humans are moving it by firewood and shipping containers,” he said.

Experts believe the insect hitched a ride on wood packing material to make its debut in the United States in 2002.

The USDA Forest Service and Tennessee Division of Forestry estimates the state’s 271 million ash trees, with a value of $11 billion, could potentially become infested due to this small bug.

But it’s not too late to begin taking preventative measures.

“We’re at this point now where our area isn’t overrun and its like the perfect time to make people aware of it and learn how to identify it.” Giebner said.

While early detection can be difficult, the adult beetles do leave a “D” shaped hole in the bark when it emerges. Woodpeckers also eat the emerald ash borer larvae, so signs of heavy woodpecker damage could signify an infestation.

“(We judge it) on a tree-bytree basis. It depends on how far gone the tree is. Typically, we do it by percentage, so if there is 30 percent dieback in the canopy, the tree could possibly be saved. If it’s 20 percent, it certainly could be saved. If it’s more than 30 percent, it’s almost too late,” Giebner said.

A chemical treatment called emamectin benzoate is currently the most effective way to treat the infestation, Giebner said.

“Unfortunately, there are no current organic treatments that will work against (emerald ash borers). The good thing about the treatment is that the material is injected directly into the tree so there is no chance of damage to any off-target insects or environments and (it) provides up to two years of protection.”

Adult emerald ash borers are dark green and one-half inch in length and an eighth of an inch wide. The bugs fly during May and June, and its larvae spend the rest of the year beneath the bark of ash trees.

The Department of Agriculture urges residents to not transport wood within Tennessee, move firewood from outside the state and stay aware for signs of infestation.

To contact Bartlett Tree Experts, call 423-928-8754 or email

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