DRESDEN — A month after the second known infestation of the invasive hemlock woolly adelgid was reported in the Adirondacks, the state Department of Environmental Conservation and its partners have developed a treatment plan, set to be implemented this fall.
The DEC dispatched a forest health specialist in early August to survey trees on state forest preserve lands in Washington County, after a camper at a Glen Island area campsite reported a tree through the iMapInvasives mobile app. The specialist located “one heavily infested and two lightly infested” Eastern hemlock trees near the campsite along the northeastern portion of Lake George, some 30 miles away from the closest known HWA presence in southern Saratoga County.
With DEC personnel, staff from Cornell University’s NYS Hemlock Initiative, the Adirondack Invasive Plant Program and the Lake George Land Conservancy conducted follow-up surveys along 16.3 miles of Lake George shoreline and at nearby camp sites. Surveyors determined the HWA infestation extends across nearly 250 acres and along 1.5 miles on the eastern shore of the lake.
HWA was previously recorded in 2017 at Prospect Mountain, at the southern end of Lake George in Warren County, and has since been eradicated there.
The DEC reports the most effective widespread treatment for HWA control is the use of insecticides, and spray applications of the short-acting dinotefuran, a common insect pest control chemical, and imidacloprid, a type of neurotoxin for long-term protection, will begin in the coming weeks. The insecticides will be applied to the base bark of infected trees.
HWA, a sesame-seed-sized insect native to East Asia, damages hemlocks by feeding on tree tissue and nutrients through a thin, tubed mouthpiece. The wounds inflicted by the mouthpiece lead the tree to heal over the twigs, causing the twig tissue to become clogged from the healing attempt. The clogs then prevent effective water and nutrient flow to the ends of the twigs, and new growth — through new needle growth — cannot continue, and the tree eventually starves.
First recorded in New York in the 1980s, scientists believe HWA likely arrived in the state on nursery stock trees sold near New York City. By 2008, HWA had been discovered in the Finger Lakes region, as well as metropolitan areas, including Syracuse, Rochester and Buffalo.
The DEC reports HWA has been detected in 47 counties, mostly in the lower Hudson Valley and the Finger Lakes regions, with 17 other states from Maine to Georgia along the Appalachian Mountains having confirmed infestations.
Eastern hemlocks and Carolina hemlocks are most susceptible to widespread damage from HWA, and the two North American species are the only known hemlock species in the world to be “at risk for fatal HWA infestations,” the state Hemlock Initiative reports.
The Adirondack forest is comprised of about 10% Eastern hemlock trees, according to the DEC, with some individuals hundreds of years old and providers of crucial shade and erosion control along stream banks.
The DEC, Hemlock Initiative and a statewide network of hemlock and invasive species groups encourages reporting of suspected HWA sightings through iMapInvasives, a free mobile app for photographing and reporting invasive species locations. Suspected sightings can also be reported directly to one of the state’s eight DEC Partnerships for Regional Invasive Species Management, or PRISMs.