BLACKSBURG — Michael Webb said he kept an alien invader in a plastic bag while he took his urban management and forestry final exam in May.
Webb had found a tiny green beetle on the bark of an ash tree near Norris Hall on the Virginia Tech campus and he thought it would be best to show it to his professor Eric Wiseman.
Webb finished his exam before several of his classmates and he said he sat outside the room until the last student was done. He then showed the bug to Wiseman. The pair agreed it was likely the emerald ash borer, an invasive insect that’s killed millions of ash trees across the country.
The Virginia Cooperative Extension’s Insect Identification Lab at Virginia Tech has since confirmed that it’s the first case of the insect’s presence in the New River Valley.
“It’s absolutely bad to have them here,” Wiseman said.
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The bugs will kill ash trees within two to five years without treatment and because native ash trees have no resistance and there are no natural predators, ash borers will likely kill every ash tree in the vicinity of where they’re first found within that five-year timeframe, Wiseman said.
Emerald ash borers lay their eggs in the spring. Their larvae then feed on tree’s cambium layer, the layer immediately under the bark that contains the most nutrients, until they become adults the following spring. They’ll then bore out of tree, leaving behind small holes. The activity is fatal for trees because of the heavy damage.
The confirmed presence of the ash borer was troubling for James Bock, a plant health care specialist with Tech’s building maintenance and grounds unit. Within an hour of being contacted by Wiseman, Bock said he was out taking preventative measures to protect some of the campus’ more than 100 ash trees.
Bock used chemical soil drench around many of the trees. Thirty-five trees have been cut down on Tech property. In the spring, Bock and other facilities workers will begin the process of trying to save about 30 of the remaining trees.
The trees will be injected with the pesticide emamectin benzoate. Facilities workers will make places for plugs on the trees and then inject the chemical into the tree’s central system. When it begins budding and transporting nutrients underneath its bark, the chemical will be dispersed throughout where it will kill the larvae of the ash borers.
The treatment is very expensive, Bock said. It costs $495 for a bottle that will usually only treat two or three adult ash trees for two years. There are less expensive options that are less effective, that Bock will try on other trees.
Facilities workers will try to save trees that aren’t displaying much damage and also will work on keeping a diverse population of ash species on campus.
If an ash tree’s canopy is more than 25 percent destroyed, it can’t be saved, said Webb, the former Tech student who graduated in May and is now a plant health care specialist for Bartlett Tree Experts in Roanoke. He has also found evidence of the bug in Roanoke and Salem.
Removing the trees will soon become a concern for other local governments as dead ash trees will be a public safety hazard.
Wiseman said others already aware of the beetle’s presence in other parts of the New River Valley have begun to cut down trees. He estimated about 7 percent of trees in Virginia are ash trees, meaning the losses won’t be as severe overall as the loss of the American Chestnut in the early 1900s, but will still be problematic.
Webb and Wiseman both suggested that property owners who have ash trees in their yards begin a management plan.
“Be proactive,” Webb said. “If you’re a person who is wondering about the health of your tree, you need to have it looked at.”