DEC develops treatment plan against woolly adelgid

The hemlock woolly adelgid exhibits white woolly masses from mid-fall through spring, pictured here. In the summer, HWA will appear as black sesame seeds with a thin ring of white around them. New York State Hemlock Initiative

DRESDEN — The state Department of Environmental Conservation on Tuesday confirmed a second known infestation of the invasive hemlock woolly adelgid in the Adirondacks.

The DEC dispatched a forest health specialist this month 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.

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. Follow-up surveys are set to be conducted at the Glen Island area in the coming weeks to better determine the extent of the infestation, which is some 30 miles away from the closest known HWA presence, in southern Saratoga County.

“This latest detection of Hemlock Woolly Adelgid is an important reminder for all New Yorkers to report and remain on the lookout for invasive species in communities around the state,” DEC Commissioner Basil Seggos said in a statement Tuesday. “Early detection remains a key tool in monitoring and addressing invasive species of all kinds, so continue to stay vigilant and informed to help protect our natural resources and economy.”

Native to East Asia, HWA is only a minor pest to native Asian hemlocks, as natural predators have helped control the sesame-seed-sized insect.

But in North America, where HWA was first discovered in the 1920s in the western United States, and in the 1950s in the eastern states, the insect can have devastating effects on hemlock forests.

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,” Cornell University’s New York State Hemlock Initiative reports.

The Hemlock Initiative, with other conservation groups and the DEC, facilitates a statewide network of individuals and organizations tracking new infestations and implementing treatment and management strategies.

Individuals reporting suspected HWA sightings through iMapInvasives, a mobile app for photographing and reporting invasive species locations, is key to the network’s statewide detection efforts.

The free app uses a mobile device’s camera and GPS capabilities, so it can initially collect information on a sighting even without a cellular connection. The app requires users to set up an account and be used in a participating state, including New York, Pennsylvania, Maine, New Hampshire, Vermont, Virginia and West Virginia, as well as a few southern and western states.

To spot HWA, the Hemlock Initiative advises people to look at the base of hemlock needles, where the needles meet the twig. At the needle base, HWA will exhibit characteristic, white woolly masses from mid-fall through spring, and in summer, HWA will appear as black sesame seeds with a thin ring of white around them.

HWA damages hemlocks by feeding on the tree’s 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.

DEC estimates indicate Eastern hemlock trees comprise about 10 percent of the Adirondack forest and are among the oldest tree species in the state. Typically occupying “steep, shaded, north-facing slopes and stream banks where few other trees are successful,” hemlocks help control stream erosion, maintain water quality and provide shaded water habitats for freshwater fish.

Management efforts in the Glen Island area are not expected to involve cutting down trees, as a clearing method is not as effective for controlling HWA as it can be for other forest invasives. Typically, insecticides are applied to hemlock bark near the base of trees, absorbing into and spreading through the trees’ tissue. HWAs are then met with the insecticide when they attempt to feed on the tissue.

More information and HWA identification techniques are posted to the state Hemlock Initiative’s website. To report possible infestations, call the DEC forest pest information line at 1-866-640-0652, or download the iMapInvasives app.

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(1) comment


Bayer chemicals of Europe has a great powder for killing these things, mix it with water , hit the roots of the host plant and they die within days. I have used it, its good stuff.

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