Hemlocks still at risk from woolly adelgid

Hemlocks still at risk from woolly adelgid

September 17th, 2011 in Life Entertainment

Q: Are our hemlocks still in danger from the blight of the hemlock woolly adelgid?

A: Hemlocks in this region are severely threatened by this blight. The hemlock woolly adelgid is a very serious pest that can kill full-grown hemlock trees in a few years. Our recent drought has added to the stress on our hemlocks, making the trees more vulnerable to insect attack.

The pest has been discovered in many parts of Tennessee and Georgia, and state Agricultural Extension Services recognize the danger from this pest.

How can you tell if your hemlock has the problem? Look for the white waxy coating of the eggs. It will cluster at the base of the needles. It resembles snow from a distance.

The larvae, or crawlers, settle on twigs in spring and feed over the summer months and come out of their dormant period in about October and begin feeding. They suck the sap out of the needles over the cool season and lay eggs, which are protected by that white waxy casing. In spring, the second generation starts to feed.

You can see the white waxy coating in fall and spring on your trees. These are the two times per year that the pest is visible, but the danger is that they are feeding and destroying the tree before and after you observe the white casings.

Their appearance and visibility depends on the weather and climate conditions, not calendar dates. Our extremely hot and dry summer may influence the arrival of the egg casings.

In the home landscape, the adelgid is controllable. There are chemicals that can kill the adelgid and save valuable landscape trees. Recent research recommends that a soil injection process is the most effective method to control the pest.

Some homeowners have also had success with a soil drench and spraying efforts. The soil injection process is systemic, meaning the tree absorbs it. It can be effective for up to three to four years.

Researchers are exploring the possibility of using other insects to control the pest on public land, such as the national forests where spraying would be impossible.

The Web page www.savegeorgiashemlocks.org has photographs, treatment recommendations and lots of good information on the pest. Hemlocks are a very important part of our ecosystem, and saving them may begin with informed local tree lovers.

Email Pat Lea at lea.pat@gmail.com.