U.Va. Takes Steps to Block Infestation of Ash Borer

July 5, 2011 — The emerald ash borer is a bright green menace.

The beetle is blamed for the deaths of tens of millions of ash trees in Michigan alone. While the adult beetles eat ash foliage, they cause little damage; the greater danger to the tree comes from the larvae, which feed on the inner bark and disrupt the tree's ability to transport water and nutrients.

The closest it has come – so far – is Fauquier County in Northern Virginia. But the University of Virginia isn't taking any chances. Although only about 10 percent of U.Va.'s hardwood trees are ash, they are in very visible locations.

"The Lawn is about 80 percent ash and McCormick Road along the West Range is 100 percent ash," landscape superintendent Richard Hopkins said.

President Teresa A. Sullivan saw the effects of the beetle when she was provost and executive vice president for academic affairs at the University of Michigan.

"The destruction done in the Lower Peninsula of Michigan was heart-breaking," she said, "and the state officials there are trying to stop the spread of the insect to the Upper Peninsula."

Discovered in southeastern Michigan in the summer of 2002, the borer may have arrived in the United States on wood packing material carried in cargo ships or airplanes originating in its native Asia. In addition to Michigan, its spread is blamed for killing tens of millions of trees in Illinois, Indiana, Kentucky, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and Wisconsin, as well as in Quebec and Ontario, Canada.

The ash borer has not yet been found in Albemarle County, said Chris Asaro, a forest health specialist and entomologist with the Virginia Department of Forestry. Quarantines have been set up in Northern Virginia to prevent the movement of contaminated ash wood. But, he said, the spread of the borer is inevitable.

"We are trying to slow the spread, but there is not any way we can stop it," Asaro said. "We are way past the point where eradication is feasible."

U.Va. landscapers are using emamectin benzoate, a pesticide registered under the name Tree-age (think "triage"), on the University's ash trees to prevent an infestation of the borer.

"We've hired an arborist to make chemical injections into the tree trunks," Hopkins said. "The injections are supposed to be good for two years and then they have to be repeated."

Last year, arborists treated ash trees on the Lawn, in the pavilion gardens and along Rugby Road, and this year Hopkins said ash trees on Carr's Hill and incidental trees are being treated.

The University has already lost tree species. "Hospital Drive had a lot of elms and we've lost them all," Hopkins said.

Asaro said that elm trees and the American chestnut have been nearly wiped out by a blight, which devastated its arboreal victims much faster than the emerald ash borer. Each borer causes a little damage, but the tree succumbs when it is overwhelmed by large numbers of the insect. And the borer is not easy to detect, since the larvae feed underneath the bark.

"By the time a tree shows symptoms, there will be hundreds of beetles feeding off the tree," Asaro said.

Ash trees are about 1.7 percent by volume of the state's hardwoods, but Asaro said there are concentrations of historic ash trees around the state, such as at Mount Vernon, George Washington's Fairfax County estate.

"The ash trees are scattered in the woods, so the borer will spread slowly," Asaro said. "If we don't protect the trees with chemicals, the only other way is to use bio-controls, insects that feed on the ash borer."

Besides Fauquier, the borer has been found in Arlington, Clarke, Fairfax, Frederick, Loudoun and Prince William counties and the cities of Alexandria, Fairfax, Falls Church, Manassas, Manassas Park and Winchester. Permits are required to move untreated ash wood products, such as logs, lumber and firewood.

"People such as loggers and firewood dealers need to have compliance agreements with the state Department of Agriculture, which enforces the quarantine," Asaro said.

Hopkins is concerned that firewood is one of the areas where the University may be vulnerable. Lawn residents have been discouraged from bringing firewood from other parts of the state, he said.

"We want to make them aware of the situation," Hopkins said. "We have recommended people who sell local firewood."

Said Sullivan, "We need the cooperation of the U.Va. community in the fight against the borers." 

— by Matt Kelly