By Josh Brown, The Tennessean
A conservation group and state officials are launching a tree-pest awareness campaign in a bid to head off a coming swarm that threatens to destroy wide swaths of Tennessee's forests in the years ahead.
The campaign is focusing on six invasive pests, some from as far away as Europe or Asia, that have already caused damage to Tennessee trees and others that are slowly making their way from neighboring states.
"Our trees have no resistance to these pests," said Katherine Medlock, the East Tennessee program director for The Nature Conservancy, which is sponsoring the campaign. "The threat is much greater that we may actually lose large tracts of forested land or lose entire species from the state."
The campaign is designed to educate homeowners, businesses and the public how to identify the symptoms of an infestation.
"These pests, if you find them early ... then your job becomes much easier," Medlock said. "You can actually prevent the wholesale infestation of forests across the state."
In 2010, a green beetle native to Asia called the emerald ash borer was found infesting trees around Knoxville. Typically once the beetles, and specifically their larvae, attack a tree, it takes only a few years to kill a tree. Three years later, the pest was detected in 21 counties across the state.
Evidence of the pest can be spotted in ash trees by looking for D-shaped holes in the bark. The beetle causes the bark to eventually crack and break away while large patches of the tree thin and wilt.
"If we look at our northern neighbors where it's been established, we can expect to see a large part of our ash population to be eliminated," said Tim Phelps, a spokesman for the Tennessee Division of Forestry.
Cities in Tennessee are particularly at risk for an infestation, given how popular the ash is with landscaping, Phelps said.
That's why teaching the public how to identify the pests is important not only for rural areas but also in cities and suburbs, he said.
"There's plenty of cities to look at where whether they're spending hundreds of thousands of dollars to remove and replace those trees," Phelps said. "It's a huge cost for cities to control that."
Forest managers have been dealing for years with another bug on the list -- the gypsy moth. The species has been in the United States for more than a century, and infestations have been eradicated in Tennessee before, said Heather Slayton, a forest health specialist at the division.
The insect threatens a range of trees from oak to alder, as the moth's caterpillar feeds on the leaves.
A newer threat is the hemlock woolly adelgid, which attacks Eastern and Carolina hemlock trees and feeds on their twigs.
The list also includes a tree-boring long-horned beetle from Asia that's not yet been found in Tennessee, a bark beetle that infests walnut trees with a fungus that causes it to break out in numerous cankers, and a fungus-like organism that can attack oak trees.
For all of the pests, the earlier they're identified, the less costly they are deal with, he said.
"There's only so many people who work for the state," Phelps said. "Really, our first line of defense is the homeowners, the landowners of Tennessee, to recognize something wrong with their trees and to report it to us."