The canopy of a big shady tree is the perfect place to relax during the summer months, however the trees providing shade may be under attack by the Hemlock Woolly Adelgid (HWA).
HWA is an invasive species from Eastern Asia that feeds on the sap produced in hemlock trees. They reproduce by leaving their woolly, white egg sacs on the underside of hemlock tree branches.
“Hemlocks mitigate the temperatures of the streams in the park and so when you have species that live in the stream, fish and amphibians, living in cooler waters, they’re going to be impacted if we lose those trees. There’s just not another native evergreen that can take the place of what the hemlocks do,” said Cumberland Gap National Historical Park Chief of Resource Management Jenny Beeler.
Certain birds nest in the limbs of hemlock trees and fish rely on the cooler water temperatures which hemlock trees protect. If HWA is not treated, it could mean the end of trout fishing in Appalachia.
HWA has been devastating hemlock forests from Maine to Alabama for decades. Locally they were found in November 2006 and treatment began a year after.
Once a tree is infected, they will only live between three to five years if they are not treated. Treatment in CGNHP is taking place with a combination of chemicals and a biological control species.
A soil drench is poured at the base of the tree which eventually makes its way up through the roots and sap. HWA feeds on the sap and is eventually killed by the chemicals in its meal. The drench is used to retreat every five years in the park.
Two types of biological control beetles are also being distributed on trees in the park. These beetles feed on the HWA insects and therefore reducing their numbers and their impact on the trees.
“We’ll never be able to completely get rid of HWA, but the hope is that we can eventually get enough of these biological control species to keep HWA in-check enough that the trees can remain healthy. If we can get to that point, we should be fine,” said Beeler.
More than 8,000 trees have been treated in CGNHP since January and treatment is ongoing.
The woolly egg sacs on the underside of hemlock branches is a dead giveaway that a hemlock tree is infected. If you suspect in infestation, chemical drenches can be purchased at home improvement stores. Local tree services may also be able to treat hemlock trees on private land.
Reach Kelsey Gerhardt at 606-302-9093 or on Twitter @kgerhardtmbdn.