Serving Boone, Blowing Rock, Banner Elk, and other towns of the North Carolina High Country
Founded 05-05-05

Hope for the Hemlocks: An Eight-Point Strategic Plan

Story by Sam Calhoun and
Dr. Richard McDonald

Dr. Richard McDonald’s Symbiont Biological Pest Management and the Blue Ridge Resource Conservation and Development Council (BRRC&D), in conjunction with Virginia Tech and U.S. Forest Service researchers, have been addressing the hemlock wooly adelgid (HWA) problem in the immediate seven-county region—Ashe, Avery, Alleghany, Mitchell, Yancy, Watauga and Wilkes—since 1999. The partners have created a regional biological control program for hemlocks, and the winter-active predatory Laricobius nigrinus beetle is either established or in various stages of recovery at five sites. At the oldest release site, McDonald is seeing predation rates of the HWA between 60 and 90 percent of all sampled egg sacks (ovisacs) in only three years.

“These are encouraging results and we would like to see these predatory beetles expand their range and impact against HWA in the High Country,” said McDonald. “We are seeing hemlock regrowth in the presence of predators, and are cautiously optimistic that these trees will continue to grow out of the damage HWA caused them. The next three to five years will be critical in determining this at our release sites.”

McDonald and his partners have developed an eight-point strategic plan to use the Laricobius nigrinus beetle and two other predatory beetles to bracket both life stages of the HWA and kill the invasive pest.

1. Use the Forestry Advisory Council. The U.S. Forest Service, Cooperative Extension, Blue Ridge Resource Conservation and Development, NCDA&CS, Blue Ridge Parkway, Appalachian Voices, Laurelmor, ASU and other interested public and private organizations need to meet to discuss a regional plan to deal with HWA in all areas of the High Country. By creating a coordinated effort and identifying resources, we can work strategically to address the HWA problem in our region. A Forestry Advisory Council already exists with the BRRC&D; we need to include other organizations to make this a regional process. The Forestry Advisory Council would help to make decisions regarding resource allocations and predatory beetle release priorities.

2. Get as many winter/summer predators as quickly as possible into every watershed and create local field insectaries to achieve bracketing of HWA. Get Laricobius nigrinus and the summer predators Sasajiscymnus tsugae and Scymnus sinuanodulus into every watershed as soon as possible. We know that releases numbering as few as 75 L. nigrinus beetles have established and are contributing to predation of HWA. By having both winter- and summer-active predators, bracketing is achieved and successful biocontrol of the HWA can occur. We are seeing predation rates between 60 and 90 percent three years after releases of beetles at Hemlock Hill. It is especially important to release beetles in a 10-mile radius around Grandfather Mountain to get predators into the headwaters of every river system in the High Country and to identify sites that could be good insectaries. A Laricobius nigrinus guide sheet describing the life history and requirements this beetle needs to be a successful control agent of HWA will be made available to all interested parties.

3. Identify stewards of the release sites. Every watershed should have a steward—a person or an organization—to ensure that the release sites are not disturbed by logging, road building, brush clearing or other activities. This person will also assist in data gathering.

4. Conduct educational and fundraising programs to report to the public on biocontrol progress on a regular basis, along with website information. Public managers, landowners and resource personnel are receiving conflicting reports on the status of hemlocks and the future of these trees. We can provide the public with good science showing predation rates of HWA and the progress we have made in controlling the HWA at these release sites. The Rock for the Hemlock concert, the Jars of Dark CD and other similar fundraising events will help to raise awareness and participation in this program. The website drmcbug.com has a section on HWA biocontrol that includes a PowerPoint presentation with the latest data and information for people in the High Country.

5. Take good scouting and monitoring data. By following guidelines created by the U.S. Forest Service and Virginia Tech sample data sheets, we can ensure that beetle recoveries, tree health data and predation rates can be compared to other release sites along the East Coast. Not all sites will need to be sampled intensively. However, the data we have taken from our release sites shows that Laricobius nigrinus is establishing and predation rates are rapidly increasing. We also have establishment of Sasajiscymnus tsugae at one site and recoveries from two other sites.

6. Combine chemical and biological controls for an integrated pest management plan to control HWA in the urban community/forest interface. Studies are underway at Virginia Tech and other regional universities to integrate chemical treatments such as Merit (Imadocloprid), insecticidal soap, horticultural oil and other treatments with biological controls. Because of the small number of predatory insects initially available, chemical treatments can buy time for the hemlocks until enough predators are available for release. For example, as Merit dissipates from the hemlock by the third or fourth year, predatory insects could be released on previously treated trees as more predators become available for redistribution.

7. Provide something for everyone who has hemlocks. No matter what stage of dieback your hemlocks are in, we can offer something to help. For people with dead and dying hemlocks, remember that hemlock seedlings start on the dead bodies of their brethren—these are called nurse trees. We can connect these people to hemlock seedlings and predatory beetles. In the presence of predators, these seedlings will grow into the next generation of big trees for the High Country. Because most of the High Country is considered generally infested, most people are dealing with trees that are in some stage of dieback or regrowth. We can get these people on a list to get predatory insects as soon as they become available.

8. Develop a Strategic Vision. By formulating a regional plan and involving as many groups and resources as possible, we may be able to make up in strategy what we have lost in time. It is certain that we are going to lose some hemlocks because of the nature of the problem and the delayed response. Good science takes time, and time is a premium here. The worst course of action with the HWA is to do nothing. The real question is how we care for the remaining hemlocks. They can repopulate the region and protect our quality of life. Too many organisms depend upon the hemlock, and no other tree can do what the hemlock does—keep streams cool for trout and other wildlife. If we lose the hemlocks through our own inaction, gone too will be the trout and other organisms that live in the cool environment created by hemlocks. Hemlocks are God’s greatest air conditioning unit for our mountains.

“Mountain people take care of their own. Let’s get to it. There is no time to lose,” said McDonald.

For more information, click to www.drmcbug.com.