An infestation of invasive Hemlock Woolly Adelgid (Adelges tsugae) has been confirmed on Lake George in the town of Dresden, Washington County.
The affected hemlock trees were located near a campsite within Glen Island Campground on the shore of Lake George. This is the second known infestation of Hemlock Woolly Adelgid (HWA) in the Adirondacks. The first was located at Prospect mountain near Lake George three years ago.
After receiving a report from a camper at Glen Island Campground through iMap Invasives about a suspicious tree near a campsite, The New York State Department of Environmental Conservation (DEC) dispatched a forest health specialist to survey the area. This initial survey found one heavily infested and two lightly infested eastern hemlocks close to the campsite. Additional follow-up surveys are expected to be conducted to better determine the size and spread of this infestation.
This is the second recorded infestation of this invasive, exotic pest in the Adirondacks. Previously, it had been detected at Prospect Mountain in 2017, which was subsequently eradicated. Additionally, HWA has been detected in 46 other counties in New York, primarily in the lower Hudson Valley and the Finger Lakes region. Seventeen other states along the Appalachian Mountain range from Maine to Georgia also have HWA infestations.
As climate change contributes to more mild winters, experts anticipate more rapid movement and increasing HWA populations. Last winter in New York was extremely mild and there is a boom in HWA populations statewide as the existing population continues to expand.
DEC is evaluating means to eradicate this infestation and prevent it from spreading. This will not include cutting down trees, which is not as effective a means for controlling HWA as it is with other invasive forest pests.
DEC believes the most effective treatment method for control of HWA is the use of insecticides. The insecticide is applied to the bark near the base of the hemlock tree and is absorbed and spread through the tissue of the tree. When HWA attaches itself to the tree to feed, it receives a dose of the pesticide and is killed.
In the past three years DEC has treated infested hemlock trees with insecticides at a few select locations where the control is likely to slow the spread of HWA, or where the hemlocks provide a significant public value. New York State Office of Parks, Recreation, and Historic Preservation has treated many hemlocks trees at a number of State Parks.
Dispersal and movement of HWA occur primarily during the first life stage (“crawler”) as a result of wind and animals that come in contact with the sticky egg sacks and crawlers. Isolated infestations and long-distance movement of HWA most often occur as the result of people transporting infested nursery stock.
DEC monitors the distribution and spread of HWA by annual aerial and ground surveys as well as reports from partners and the general public. As shown by this detection, public reports are an importantn tool used in early detection of HWA. DEC and the New York State Hemlock Initiative have been involved in biological control efforts against HWA, and have released several approved natural enemies of HWA at locations in the Finger Lakes and Catskills regions.
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.
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. They 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.
Survey efforts by DEC and Cornell’s New York State Hemlock Initiative are expected to continue to determine the extent of this infestation and if other infestations are present in the surrounding area. As the closest known ongoing infestation of HWA is 30 miles away in southern Saratoga County, DEC is asking hikers, campers, boaters, sportsmen, and others recreating on or along forestlands in northern Saratoga, Warren, and Washington counties to check Eastern Hemlock trees and report any HWA infestations.
More information on HWA, including identification, control techniques, and reporting possible infestations can be found at Cornell’s New York State Hemlock Initiative. You can also call DEC’s toll-free Forest Pest Information Line at 1-866-640-0652 to ask questions and report possible infestations.
Photo of Hemlock Woolly Adelgid provided by DEC.