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Chemicals, cold help battle pests in hemlocks

Class to help residents stave off invasive parasite

POSTED: January 26, 2014 12:01 a.m.
For The Times/

A hemlock woolly adelgid is seen on a hemlock tree branch. The invasive bug originally from Asia is less than 1/16 inch in size but has threatened hemlock trees since it began spreading south in Georgia in 2003.

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Hemlock trees are tall green trees, like Christmas trees.

You can look at hemlocks, with their branches full and see they are lush with color. But are they healthy? Or is something the naked eye can’t see causing a problem?

Some hemlocks could be under attack from a small but deadly killer, the hemlock woolly adelgid bug.

The adelgid is less than 1/16-inch in size, but thrives on hemlock trees, where it spends its whole life span of a few months, according to Donna Shearer of the Save Georgia’s Hemlocks organization.

On Feb. 8, Shearer will lead a two-part class program, the Hemlock Help Clinic, at the Hall County Board of Education building at 711 Green St. It begins at 9 a.m.

The bugs are beginning to show up in Hall County, putting some residents’ hemlock trees at risk. They were first recorded in Hall County in 2010, she said.

"So far, we haven’t lost trees that were treated in timely manner," Shearer said. "Many of the untreated hemlocks in North Georgia have already died."

She said that in North Carolina and Tennessee, "whole mountainsides" of hemlocks died because they weren’t treated in time.

According to Jim Wentworth, wildlife biologist for the U.S. Forest Service, the bugs came to Georgia in 2003, stationing themselves in the Rabun County area and moving further south every year.

The adelgids are originally from Asia, mainly China and Japan, and were brought to the U.S. on an ornamental plant by accident, Wentworth explained.

“The bugs themselves don’t fly but they are hitchhikers,” Shearer said. “They ride the wind, animals and people to wherever they end up.”

Once the bugs get to a hemlock tree, Shearer said they lay eggs. The babies, known as crawlers, hatch out of the eggs and use their mouth, or stylet, to sink onto the tree.

Wentworth said if you have hemlock trees, the egg sacs would be on the underside of branches.

“If people see egg sacs, then they need to do something as far as treatment,” he said. “Fortunately, it takes several years for the tree to be affected.”

Wentworth explained the bug has no natural predator in the Eastern U.S. But some colleges, including University of North Georgia-Dahlonega Campus, University of Georgia and Young Harris College, are raising predator beetles that are the main threat to adelgid bugs in Asia.

“We’re releasing the (predator) beetles with the hope that they can help control the adelgid population,” Wentworth said.

The weather can also help or hurt the population, as well.

“Climate is also very conducive for the adelgid to spread, as well,” he said. “The recent cold spell could help us. It may have well knocked back the adelgid population to help give us (some) relief.”

Wentworth said the population of the bugs in the northeastern U.S. decreased “considerably” due to their cold weather over the last decade.

Besides using predator beetles and hoping cold weather gives the bugs a fight, Shearer said you can go the chemical-control route, using Imidaclopride to kill them off.

To use this method, put the chemical in the soil at the base of the hemlock. The tree absorbs the chemical through its roots.

“Here’s some really good news: The chemical products aren’t expensive. They’re not dangerous as long as you follow the directions, like with anything,” Shearer said. “And once treated, it is good for five to six years.”

The first part of the Hemlock Help Clinic is an overview of the threat, how to recognize it and options for saving trees.

The second part, known as the facilitator workshop, will provide in-depth information about the trees, the bugs, assessing infestations, cultural controls, chemical treatments, biological controls, cost and safety, assisting property owners, working on public lands and more.

“I want people to take away that there’s a serious problem that’s time-sensitive and critical to the environment and economic health of the area,” Shearer said.

“Save Georgia’s Hemlocks is working hard to equip people to take action.”

Registration and clinic attendance are required for the facilitator workshop.


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