A bug threatens millions of hemlock trees in KY, Appalachia. Can it be stopped?
Bundled against the low-30s cold, Melanie Denny and Teresa Bombard measured the diameter of an eastern hemlock tree towering more than 100 feet above the hillside overlooking a waterfall in the Daniel Boone National Forest.
That measure told Jake Royse, a forester with the U.S. Forest Service, how many ounces of milky-white chemical to pour into the soil around the base of the tree to kill an invasive bug sucking the life from the evergreen.
Denny and Bombard pushed fallen leaves over the wet soil to cover the insecticide, then the team moved on to treat other hemlocks in the cliff-lined valley below Vanhook Falls in Laurel County.
They were trying to beat back the hemlock woolly adelgid, a non-native pest that sucks sap from the twigs of hemlocks, hurting growth and killing the trees within a few years without treatment.
The bug has decimated hemlocks in some areas, including the Shenandoah National Park in Virginia.
Carried by the wind or by birds and animals, it was first found in southeastern Kentucky in 2006 and has since spread to 30 Appalachian counties in the eastern end of the state, according to the Kentucky Division of Forestry.
Hemlocks throughout the region have begun to decline and some have died, particularly in the southern end of the national forest and in the adjacent Big South Fork National River and Recreation Area, said Jim Scheff, director of Kentucky Heartwood.
“We’re at the point now if people aren’t working to treat trees, they’re gonna be gone,” said Scheff, whose organization works to protect and restore the state’s forests. “It’s absolutely critical that we save what we can save now.”
A 2017 Forest Service document said the adelgid could kill almost all the hemlocks in the Daniel Boone National Forest in 10 to 15 years without treatment.
That would be a grave loss; the hemlock plays a crucial role in the ecosystem, controlling stream temperatures to benefit some species; preventing erosion; and providing habitat, according to state and federal officials.
Losing hemlocks has “drastic effects” on some ecological processes, according to a University of Kentucky College of Agriculture publication.
“Extensive hemlock mortality leads to a loss of hemlock-dependent wildlife. Song birds are especially at risk,” the publication said.
The death of hemlocks would also degrade the scenery and create dangers to hikers and campers from falling limbs, the Forest Service said.
The Kentucky Division of Forestry and the Forest Service have been using a chemical insecticide called imidacloprid to treat hemlocks on state and federal land for several years.
Kentucky Heartwood has helped with the effort, identifying stands of trees to treat and coordinating volunteers to help with applying the chemical.
Denny, Bombard and a dozen other people, many from the Sheltowee Trace Association, volunteered on Wednesday for a day of treating hemlocks in Laurel County.
Bombard, a retired nurse, said she wanted to help preserve as much of the beauty and ecological integrity of the forest as possible.
Bombard has taken several of her six grandchildren hiking on the 333-mile Sheltowee Trace National Recreation Trail, which runs through the federal forest from Rowan County to the Big South Fork river and recreation area in Scott County, Tennessee.
“I think it’s pretty profound when a 5-year-old comes out of a forest and says, ‘That makes my heart feel better,’ “ Bombard said. “We’ve gotta save that, or at least do our best to try to save it.”
Jared Calvert, a forest silviculturist with the Forest Service, said volunteers help cover more ground in the effort to treat hemlocks.
Volunteers don’t touch the chemical, leaving that to state and federal employees certified to mix and apply the insecticide, but help with chores such as carrying water to use in mixing the chemical and measuring trees to determine how much to apply.
“It speeds up the process,” Calvert said. “Saving the hemlocks is definitely one of our top priorities and we appreciate all of our collaborators.”
The Forest Service has designated 92 hemlock conservation areas in the Daniel Boone covering 2,228 acres.
The agency also is identifying up to 3,000 more acres to treat.
Calvert said it appears the forest has already lost quite a few trees, but the forecast on saving others “is not completely bleak.”
There is some controversy associated with the chemical used in the treatment. It can hurt aquatic species and is in a class blamed for damage to bees that are critical for plant pollination.
But the teams using it to save hemlocks are careful to apply it in ways that are safe for stream life and pollinators, Calvert said.
Scheff said the chemical is the best tool available now, and using it represents far less of a potential problem than letting the adelgid wipe out hemlocks.
The hope is to use the chemical to preserve enough hemlocks to ensure the survival of the species until there is a better long-term approach.
“If we let the trees all die now, we’re not going to have anything to work with in the future,” Scheff said.
Researchers are working on other tools, including breeding beetles that eat the adelgid.
There have been several releases of the beetle in the Daniel Boone National Forest, Calvert said.
Kentucky Heartwood has been working to try to get private landowners to treat hemlocks.
Most of the forested land in the state is privately owned, so if the owners don’t get involved in trying to save hemlocks, millions will die even with the efforts on public land.
One way landowners can identify whether their trees are infested is by looking at the base of the needles. The hemlock woolly adelgid forms white, cottony-looking sacs at the base of the needles.
Cold weather can kill or slow down the bug. The relatively warm weather this winter has done little to stem the spread.
“It’s accelerating really fast,” Scheff said.
Kentucky Heartwood has set up a web page called hopeforhemlocksky.org that has information landowners can use to treat their trees.
It’s not an expensive job, costing as little as 8 cents for a small tree and a little over $2 each for large trees, and the application can last four years or more.
Many of the state’s hemlocks will never be treated and will die, but more could be preserved with work by private landowners and public agencies, Scheff said.
“We can save a lot of hemlocks,” Scheff said.
