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DEC to manage second hemlock woolly adelgid outbreak in Adirondacks

Hemlock woolly adelgid (Photo provided — New York State Department of Environmental Conservation)

The state Department of Environmental Conservation announced it and several environmental partners are developing a treatment plan to control and prevent the spread of hemlock woolly adelgid (HWA) invasive insect on Adirondack Forest Preserve lands in the towns of Dresden and Fort Ann in Washington County.

DEC confirmed the HWA infestation in August, locating affected hemlock trees in the Glen Island Campground on the shore of Lake George. This is the second known infestation of HWA in the Adirondacks.

Partners include Cornell University’s NYS Hemlock Initiative, the Adirondack Park Invasive Plant Program and the Lake George Land Conservancy. Treatments will start this fall before HWA has the opportunity to spread next spring. In addition, DEC and Cornell are evaluating the use of biological controls to supplement these treatments.

According to the DEC, the most effective treatment for HWA control is the use of insecticides, spraying them at the base of the tree. The DEC said it will use dinotefuran, a fast-acting insecticide, to knock back HWA populations, and imidacloprid to provide long-lasting protection to hemlock trees and prevent spread to un-infested trees.

After the initial finding of HWA, DEC, Cornell, APIPP and LGLC staff conducted more than 500 hours of surveys at neighboring campsites on nearby islands and along 16.3 miles of shoreline to determine the extent of the infestation.

The partners identified an HWA infestation on nearly 250 acres along 1.5 miles of shoreline on the eastern shore of Lake George.

Most infested trees have a low density of HWA, with the densest HWA infestations located along the shoreline. This initial data suggests the infestation started along the shoreline — perhaps by migrating birds — and expanded from there.

Signs of HWA on hemlock trees include white woolly masses (ovisacs) about one-quarter the size of a cotton swab on the underside of branches at the base of needles, gray-tinted foliage and needle loss. DEC is asking the public to report signs of HWA by taking pictures of the infestation, with objects like coins for scale; taking note of the location and contacting DEC or the local Partnership for Regional Invasive Species Management by visiting www.dec.ny.gov/animals/47433.html.

The public are also asked to report the infestation to iMapInvasives at www.nyimapinvasives.org.

Gear used near an infestation should be cleaned afterward.

HWA, which comes from East Asia, was first discovered in New York in 1985. It attacks forest and ornamental hemlock trees by feeding on young twigs, causing needles to dry out and drop prematurely and causing branch dieback.

Hemlock decline and mortality typically occur within four to 10 years of infestation in the insect’s northern range. Damage from the insect has led to widespread hemlock mortality throughout the Appalachian Mountains and the southern Catskill Mountains with considerable ecological damage, as well as economic and aesthetic losses.

Eastern hemlock trees comprise approximately 10% of the Adirondack forest and are among the oldest trees in New York, with some reaching ages of more than 700 years.

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