The New York State Department of Environmental Conservation (DEC), which confirmed an invasive Hemlock Woolly Adelgid (HWA) infestation at Lake George in August, says that the infestation affects nearly 250 acres and 1.5 miles of shoreline on Forest Preserve lands in the towns of Dresden and Fort Ann, Washington County.
The affected hemlocks are located along in the busy Glen Island Campground area of the Narrows, including Glen Island and camping areas on the eastern shoreline. This is the second known infestation of HWA in the Adirondacks; an earlier infestation is believed to have been brought under control at the summit of Prospect Mountain, reached by the Prospect Mountain Veteran Memorial Highway, just outside Lake George Village.
After this second finding of HWA, DEC, Cornell’s NYS Hemlock Initiative, the Adirondack Park Invasive Plant Program, and Lake George Land Conservancy staff conducted surveys at neighboring campsites on nearby islands and along 16.3 miles of shoreline to determine the extent of the infestation. Surveyors have spent more than 500 hours surveying to date.
Surveys are expected to continue at priority locations to determine the extent of the infestation and find any additional infestations.
Those organizations are developing a treatment plan to control and prevent the spread of the pest, which can devastate hemlock forests like those in the Adirondacks. Eastern hemlock trees, which comprise approximately 10 percent of the Adirondack forest, are among the oldest trees in New York with some reaching ages of more than 700 years. These trees typically occupy steep, shaded, north-facing slopes and stream banks where few other trees are successful. The trees help maintain erosion control and water quality, and the hemlock’s shade cool waters providing critical habitat for many of New York’s freshwater fish, including native brook trout.
HWA, a tiny insect from East Asia first discovered in New York in 1985, attacks forest and ornamental hemlock trees. It feeds on young twigs, causing needles to dry out and drop prematurely and cause 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. HWA infestations can be most noticeably detected by the small, white, woolly masses produced by the insects that are attached to the underside of the twig, near the base of the needles.
Most of the 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.
According to an announcement sent to the press by DEC, The most effective treatment for HWA control is the use of insecticides. The treatment includes a basal bark application of the pesticides, involving spraying the pesticides at the base of the tree. The DEC announcement said they will use best management practices for applications of the neonicotinoid dinotefuran, a quicker-acting insecticide that is expected to quickly knock back HWA populations, and the systemic insecticide imidacloprid, which is expected to provide longer-lasting protection to hemlock trees in the area and prevent the spread of HWA to un-infested trees.
DEC and partners are planning treatments to start this fall before HWA has the opportunity to spread next spring. In addition, DEC and Cornell are also evaluating the use of biological controls to supplement these treatments.
Early detection and rapid response to invasive pests is considered critical by invasive species managers.
Signs of HWA on hemlock trees includes 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:
Take pictures of the infestation signs as described above (include something for scale such as a coin);
Note the location (intersecting roads, landmarks, or GPS coordinates);
Contact DEC or the local Partnership for Regional Invasive Species Management (PRISM);
Report the infestation to iMapInvasives; and
Slow the spread of HWA by cleaning equipment or gear after it has been near an infestation and by leaving infested material where it was found.
More information on HWA, including identification, control techniques, and reporting possible infestations can be found at Cornell’s New York State Hemlock Initiative or call DEC’s toll-free Forest Pest Information Line at 1-866-640-0652 to report possible infestations.
Photo of Hemlock Woolly Adelgid provided by DEC.