Hemlockfest

Spreading awareness with Carolina Hemlocks

April 18 marked the annual Hemlockfest in the Mountain Rest community in Oconee County.

Every year on the Saturday before Earth Day, the non-profit group called Carolina Hemlocks sponsors this event to raise money and awareness for the plight facing our native hemlocks.

This is a topic very near and dear to my heart, because before I started at the Forestry Commission, I led the hemlock project for the Tennessee Division of Forestry.

In South Carolina, we have both eastern (Tsuga canadensis) and Carolina (T. caroliniana) hemlocks; both of which are susceptible to the invasive hemlock woolly adelgid (a-dell-gid), also known as “HWA.”

The HWA on the east coast is native to Japan and was first introduced to Virginia in 1951. It was in SC by 2001.

Without intervention, all of our hemlocks will die. This is especially problematic, not just because hemlocks are beautiful, but also because they fill an ecosystem niche that no other native trees can fill. 

We have pine adelgid in SC that is native, but it isn’t a pest because we have a species of beetle (Laricobius rubidus) that feeds on the adelgid, and our native pines have some natural resistance.

In the United States, we do have native HWA on the west coast, but their hemlocks have resistance, and there is a Laricobius species native there, too, that feeds on HWA. Our native hemlocks do not have any resistance, and the L. rubidus beetle doesn’t feed on hemlock adelgid. 

Within the integrative pest management (IPM) framework, managers are using multiple control methods to fight this problem. Chemical controls are effective; that was all I would do from October to May in Tennessee. There have been successful introductions of biocontrol using two Laricobius species known to eat HWA.

There are also ongoing experiments about establishing populations of a fly species from the west coast. In addition, some groups are collecting seeds from and breeding individual trees that seem to have some natural resistance.