The hemlock woolly adelgid is a small pest that feeds off the sap of a hemlock at the base of the needles and if left untreated, leads to the hemlock’s demise.
Eastern and Carolina hemlocks are important to the environment as they are often located near streams providing critical habitat for plants and animals in the area, said Highlands-Cashiers Land Trust (HCLT) Stewardship Coordinator Kyle Pursel.
From left are HCLT’s Kyle Pursel and Americorps Volunteer Grace McCants removing flowering plants from the base of a hemlock about be treated for woolly adelgid in order to protect insect pollinators, particularly bees.
In fact, for more than a decade, the demise of hemlocks lining streams and rivers in the area – most notably the Cullasaja – has been evident.
“The eastern hemlocks that grow along streams are very important because they provide shade to the streams,” said Pursel. “Shade keeps the stream cold, and a lot of things need the cold to survive, especially trout.”
Americorps Volunteer Grace McCants records GPS data and other assessments of a hemlock’s condition to determine if it needs to be treated for woolly adelgid.
HCLT protects over 3,000 acres of forests, wetlands and vistas, and for more than 10 years part of this conservation has included treating for hemlock woolly adelgid (HWA) throughout those protected properties.
Pursel and Americorps Volunteer Grace McCants geared up on Tuesday and headed out to Pinky Falls and a private easement off Flat Mountain Road to treat hemlocks showing signs of HWZ infestation.
The white spot on the top of the branch in the middle in woolly adelgid feeding off the hemlock at the base of the needles.
Hemlocks are treated with Imidacloprid, a chemical applied at the base of the tree. Imidacloprid is a neonicotinoid systemic insecticide and has been known to be harmful to bees. For that reason, before a hemlock can be treated, Pursel and McCants remove any pollinator plants in the immediate area eliminating the chance bees can be exposed to the treatment.
“We try and make sure to take every precaution so that doesn’t happen,” said McCants. “We’re trying to be helpful, not hurt anything. The benefits of treatment outweigh the risks and we do everything we can to minimize those risks.”
If infested hemlocks are left untreated, the woolly adelgid ends up killing the tree over a year or two.
HCLT targets properties with older hemlocks, hemlocks located near streams, and areas with dense concentrations to treat groups at a time. If the trees are not treated, HWA slowly sucks the life of the tree over time. Treatment to prevent this from happening is done on a rotation basis throughout HCLT’s properties every 5-7 years.
A predatory beetle (brown spot at the intersection of hemlock branches) that feeds on woolly adelgid and is used as a treatment technique to battle the infestation of hemlocks in WNC. This beetle was found on another HCLT protected property, Brushy Face Preserve. Photo courtesy of HCLT.
“Adelgids attack the base of the needle and put the tree in a drought stress, basically the tree thinks its undergoing constant drought,” said Pursel. “If this is sustained, it stops producing new growth and after a couple of years it dies.”
HWA is native to Japan and was brought over to the United States in the 1950s. It was first discovered in a garden in Richmond, VA. In its native habitat, HWA is not a threat because there are other predatory species that feed on HWA and control the population. HCLT has also released predatory beetles in the past that feed on HWA and help minimize the damage it can cause, but the fight continues.
A partially infested hemlock that can be saved with treatment for woolly adelgid.
Article and photos by Brian O’Shea
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