Ash borer found in Shelby

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By Walt Reichert

It is usually a good thing when Shelby County finishes first in the state. Not this time.


The emerald ash borer, a foreign-born insect that is decimating ash trees in the Midwest, was found near Cedarmore in Shelby County last week. That is the first confirmed sighting of the pest in Kentucky. A few days later, the borer was also found in Jessamine County, according to a press release from University of Kentucky entomologists.

UK Senior Nursery Inspector Joe Collins said entomologists are trying to determine the extent of the infestation in Shelby County, and he predicted “it will spread.”

Shelby County Cooperative Extension Agent for Horticulture Brett Reese and horticulture technician Corinne Kephart inspected the borer damage in Cedarmore on Tuesday and found extensive damage.

Reese estimated the borer has killed 90 percent of the ash trees in the area. That means the borer has been in the county for at least three years, he said, even though monitoring efforts have not led to a borer discovery until this year.

“Some reports say trees will die within one to three years after an infestation, and some say three to five years,” Reese said. “So saying it's been here for at least three years is a good guess.”

Collins said the borer likely arrived in Shelby County hitchhiking on firewood someone probably brought to the camp from a state that was infested with the insect.

Reese and Kephart also inspected ash trees on the grounds of the Shelbyville Country Club Tuesday that “looked sickly,” but they could find no evidence of emerald ash borer damage.

The ash borer, a native of Asia, has decimated millions of ash trees in the upper Midwest since it likely was introduced in wooden pallets from China in the Detroit area in 2002. The borer has spread south and east from there and is now in all states surrounding Kentucky except Tennessee.

The borer is approximately one-half inch in length and emerald green in color. But it is the larvae, not the adult, that damages the tree. The larvae create tunnels under the bark that cut off water and nutrients from the tree. Damage hits the tree from the top to the bottom, Reese said.

“By the time most people see damage, it's probably already too late to save the tree,” he said.

Reese said the ash trees that line the streets in downtown Shelbyville are very vulnerable to attack by the borer.

“The borers hit trees that are under stress first,” he said. “The trees there are already under stress because of the environment.”


The ash is a popular shade tree, grown for its rounded shape and purple or orange fall color and relatively fast growth. It also is valued as a provider of firewood and the wood for baseball bats. Green and white ashes are most common, but the species also comes in black and purple.

The borer has killed tens of millions of ash trees in the forests of the upper Midwest, and the damage likely will be as considerable here, Collins said. He said the ash accounts for approximately 8-10 percent of the trees in Kentucky's forests.

With the discovery of the borer here, the Animal Plant Health Inspection Service (APHIS) may impose a quarantine on ash trees and ash tree products.

Shelby County Judge Executive Rob Rothenburger said he is still waiting to hear whether any quarantine will affect just Shelby County, several counties or the whole state.

If and when a quarantine is announced, Rothenburger plans one or two public information hearings that will include Extension and the state Division of Forestry to let homeowners know what can come in and out of the county and what they can do to help stem the spread of the borer.

Anticipating a quarantine, Snow Hill Nursery owner Melvin Moffett said his workers have started grubbing up the ash trees in their fields.

“We didn't have that many left because they haven't been selling,” Moffett said. “We knew it [the borer] was coming.”


How to fight it

Because it is native to Asia, the ash borer has few natural enemies. Entomologists in the Detroit area are releasing some insects known to prey on the borer. Woodpeckers and parasitic wasps eliminate some of the borers in the wild.

Homeowners who have a favorite ash tree can take action to stop the borer with chemical controls, Reese said. He recommends Bayer Advanced Tree and Shrub insect control, a systemic insecticide that can be applied to the roots of the tree once or twice a year. But he said the treatment is not cheap, and homeowners can't skip a year.

“You can replace the tree for what it will cost to control the insect,” Reese said.

If ash trees succumb to the borer, Moffett recommends homeowners try oaks, maples, sweet gum, black gum, hornbeams, zelkova or the new American elms that are resistant to Dutch elm disease as replacements.

Meanwhile Collins said the public could help stem the spread of the borer to other states by not taking firewood into campgrounds in states where the borer has not yet spread.

For a map of states already infested and more information on the borer, visit www.emeraldashborerinfo.com.