Continuous pesticide treatment is the only surefire method of protecting ash trees, which make up anywhere from 3 percent to 20 percent of trees in towns throughout Connecticut, from the invasive emerald ash borer, said Katherine Dugas, a research assistant at the CT Agricultural Experiment Station.
“The concern with ash trees is that when they die, it’s not like an oak tree that can stay standing,” Dugas said. “If you have an ash tree near roads, near power lines, that tree can quickly become hazardous.”
The emerald ash borer, a small green beetle from East Asia that’s larvae burrow beneath the bark of ash trees to feed, has been disrupting ecosystems in North America since it first appeared in port cities like Detroit in 2002. Claire Rutledge, an assistant agricultural scientist at AES, is part of the lab that first detected the beetles in Prospect, Connecticut in 2012, from which point they made their way into Tolland County earlier this year.
“It’s pretty safe to assume that it’s all over Connecticut,” Rutledge said. “We have actual beetles in hand for 70 towns.”
Rutledge said it has been estimated that the town of Bethany, located 10 minutes from where the beetles were first discovered in Connecticut, would need to set aside $1 million to take down the 950 infected ash trees endangering power lines in their area – and that preemptive pesticide treatment would carry a similar price tag.
“It turns out in most cases that taking down the trees and treating the trees cumulatively costs about the same, but you can space out and plan the treating of trees,” Rutledge said. “Instead of having to spend a million dollars in two years, you spread it out over 20 years.”
Plans such as this one, however, only take into account ash trees in residential areas said Gail Reynolds, Master Gardener Coordinator for Middlesex County.
“If they receive the pesticide treatment, there’s a good chance that they will survive, but the pesticide treatment isn’t practical in the forest,” Reynolds said.
This may send the ash tree the same way as the American chestnut tree went more than a century ago when a fungal blight swept through the eastern U.S., Reynolds said.
“With the chestnut, they’ll grow to a certain point and the fungus will get them and they’ll die,” she said. “It could be the same thing with the ash. They could sprout and get to a certain point and be infected with the emerald ash borer.”
Reynolds said that although there are many native wood-boring insects, most their predators are too selective to eat the emerald ash borer.
“They didn’t evolve together, it’s something new and it’s just not on any predators radar screen,” Reynolds said.
The U.S. Department of Agriculture’s solution to picky predators, Rutledge said, has been to introduce parasitoid wasps, one of the emerald ash borer’s natural predators in Asia, to limit the beetle’s population in American forests.
“Part of the theory is that the reason it’s invasive is because it left its parasites and predators and diseases at home when it came here,” she said. “The idea is to go back to the country of origin of your invasive pest and find yourself a control agent.”
The wasp is not considered a threat as an invasive pest itself because it is only evolved to lays eggs inside certain species.
“Most species of wasps are extremely host specific because of the strategy that is required to live inside the body of the host; you have to deal with the immune system,” Rutledge said.
Dugas, part of the AES’ outreach program, said residents with ash trees on or near their property should contact the station with photos of emerald ash borer damage to help track the species.
“If we detect it early, that’s going to help everybody out in the long run,” Dugas said.
In order to avoid transporting the beetle to other areas, Reynolds said residents who want to cut down their ash trees before they become a hazard should use the wood locally.
“It does fly, it spreads on its own, but moving it in firewood definitely makes the spread much faster,” Reynolds said.
Kimberly Armstrong is a staff writer for The Daily Campus. She can be reached via email at firstname.lastname@example.org.