Kentucky forestry officials urge private landowners to join fight to save hemlock trees

bestep@herald-leader.comApril 27, 2014 

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    Landowners who want information about the hemlock woolly adelgid or help treating trees may call Alice Mandt or Jody Thompson at (502) 564-4496, or email alice.mandt@ky.gov.

The trail by the Cumberland River wanders through deep green and cool shade at the base of a rock cliff, with eastern hemlock trees towering above and rhododendron on either side. A creek splashes over a rocky ledge and riffles past moss-covered banks on the way to the river.

Hard to believe there's a killer along the trail in McCreary County.

It's called the hemlock woolly adelgid, a tiny invasive insect that sucks nutrients out of hemlock trees.

Its move into Kentucky was discovered in Bell County in 2006; since then it has spread to nearly 30 counties, according to the Kentucky Division of Forestry.

State and federal agencies have been fighting the insect with a chemical treatment for several years, but it has continued to spread, killing thousands of trees.

Now, the Division of Forestry is making a push to raise private landowners' awareness of the threat and to try to get more of them to treat their trees.

The reason is that most of the state's forested land is in private hands.

That means even if agencies treated all the hemlocks on public land, there could be staggering losses of the stately evergreens.

"If private landowners don't step up, there's gonna be a massive loss of hemlock in Kentucky," said Alice Mandt, coordinator of the hemlock woolly adelgid program for the state Division of Forestry. "If you don't treat them, they're going to die. There's no getting around it."

The good news is that there is a simple method to treat the trees: soaking the ground at the base with a chemical called imidacloprid.

It's relatively inexpensive — about $10 a tree for a 10-inch tree every three or four years, said Rusty Rhea, an entomologist with the U.S. Forest Service who coordinates the agency's efforts against the insect across the Southeast.

"It's a lot cheaper than cutting a tree down" after it has died, Rhea said.

Mandt said the state Division of Forestry can't pay for the chemical drench for private landowners or apply it on their land, but its employees can show them how to apply the treatment and provide equipment.

"We'd like to be overwhelmed with private landowner calls" seeking help, Mandt said.

Now is a good time to look for the insects, which attach to the needles on the undersides of branches. The females cover their eggs with a sticky white substance; an infestation looks like tiny clumps of cotton.

The insect is carried from an infested area by birds, the wind and even on people's clothes.

The adelgid multiplies quickly and can kill a hemlock within two or three years once the tree is fully infested.

The danger in losing hemlocks, which can grow to more than 100 feet tall, is that the tree is a keystone species, playing a crucial role in the ecosystem where it grows.

Hemlocks grow in damp coves and along streams, keeping water and soil temperatures lower, which is important for a number of species, including trout. Hemlock branches provide year-round cover and nesting areas for birds.

There is evidence that in the Smoky Mountains, for instance, 95 percent of the nests belonging to the wood thrush are in hemlock trees, which have been devastated by the adelgid, Rhea said.

Losing the trees would alter fundamentally the ecology of some of the most biologically diverse places in Kentucky.

"The hemlock trees create this entire ecosystem that's under there," Mandt said.

She said state and federal agencies have treated more than 150,000 hemlocks in Kentucky, concentrating on priority areas such as high-quality waterways; spots with threatened and endangered species; and popular trails, so hikers don't get hurt by falling trees or limbs.

But there are more than 70 million hemlock trees in the state, which shows how extensive the damage could be.

Rhea said the hemlock woolly adelgid came into the United States on nursery stock from the Far East during the early 1950s. It has since spread to more than 15 states, according to information from the U.S. Forest Service.

The losses have been catastrophic in some places. The bug has killed more than 95 percent of the hemlocks in Shenandoah National Forest in Virginia, for instance, Rhea said.

The adelgid is among dozens of nonnative, invasive species causing problems in Kentucky.

In Lake Barkley and Kentucky Lake, for instance, the Asian carp has multiplied quickly, taking food away from native fish, said Ryan Oster, fisheries program coordinator for the state Department of Fish and Wildlife Resources.

The department sponsored a contest last year in which commercial fishers hauled in 42 tons of Asian carp in two days, but it made only a dent in the problem, Oster said.

"They have the potential to do the most damage to us," Oster said, although the state faces other threats in waterways, such as the zebra mussel that clogs water intakes.

And in Daniel Boone National Forest, Japanese knotweed has exploded, and nonnatives called garlic mustard and Chinese silver grass actually change the soil chemistry where they invade, said David Taylor, the forest botanist.

"They crowd out native species," he said.

The Forest Service is going through the process of seeking permission to use herbicides more widely in the Daniel Boone to get rid of invasive plants, Taylor said.

There also are other worries throughout the Southeast, but the hemlock woolly adelgid is one of the biggest threats, Rhea said.

Researchers are looking for answers to combat the various threats. A predator beetle that has been tested in Kentucky and other states could be the ultimate answer to fighting the adelgid.

It could take years, however, to produce enough of the beetles to get the upper hand on the adelgid.

The chemical treatment available now is a stopgap measure to save as many important stands of hemlock as possible until the beetle solution is more widely available.

"My job is to buy time," Mandt said.

Bill Estep: (606) 678-4655. Twitter: @billestep1.

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