Spotting the hemlock woolly adelgid (ME)

Seacoast Online
May 10, 2007
By Amy Phalon

The hemlock, a slow-growing, shade tolerant coniferous tree commonly found throughout Maine, is under attack by a tiny, invasive insect.

As part of an effort to stem the spread of that pest, the hemlock woolly adelgid, the Maine Forest Service held a workshop called "Take a Stand for Hemlocks" on Saturday at the York Public Library.

Volunteers from York and surrounding communities gathered to learn how to identify hemlock woolly adelgid infestations in order to help the Forest Service gather information about the insect's spread. The workshop was conducted by Allison Kanoti of the Maine Forest service, with help from Wayne Searles of the Forest Service and Kyle Lombard of the New Hampshire Division of Forests and Lands.

"Our objective is to have people adopt a stand of hemlocks and survey it annually," said Kanoti. She acknowledged that since the hemlock woolly adelgid has arrived in Maine, it will be difficult if not impossible to eradicate the pest. The Forest Service's goal is to contain and manage the spread, she said.

During the presentation, Kanoti showed slides of hemlocks that had been severely infested with the insects. "Adelgids feed on the plant juices or carbohydrates in the tree," she explained. After prolonged infestation, the tree is weakened and "turns ghostly," she said.

The loss of hemlock trees would be devastating to Maine forests.

"We can not over-estimate the value of hemlock," Kyle Lombard said. Hemlock, is an important component of the ecosystem providing food, cover and maintaining soil and microclimate conditions for native species.

According to a publication, "Pest Alert: Hemlock Woolly Adelgid," released by the Forest Service, the insect can be controlled with "cultural, regulatory, chemical and biological" efforts. Kanoti explained that both Maine and New Hampshire have stopped the importation of nursery-grown hemlock from states known to be infested with the pest.

"Biological control appears to be the best tool for managing (hemlock woolly adelgid) in the forest," Kanoti said. Biological controls that have been employed in the York area include the recent release of 3,000 predatory ladybird beetles (Sasajiscymnus tsugae) at a hemlock stand on property managed by the York Water District.

Volunteers were able to see the predatory lady beetles at work when they headed out to the field to practice the surveying techniques. Unfortunately, according to forester Wayne Searles, there are no biological hemlock woolly adelgid predators native to Maine and the ladybird beetles must be introduced.

Kanoti said chemical insecticides are "appropriate" for control of hemlock woolly adelgid in landscape situations, but, "are not feasible in forest situations." Volunteers can use what they learned at the workshop to help the Forest Service in its efforts to monitor and control the spread of HWA and to manage hemlocks on their own property.

Volunteer George Sweet from Sanford learned a lot a the workshop. "Hemlocks are my favorite tree," he said. "I have over 100 hemlocks in my yard."

Other volunteers plan to help survey hemlock stands at Mt. Agamenticus and on public lands throughout York County.

NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is distributed without profit to those who have expressed a prior interest in receiving this information for research and educational purposes.

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