Part 2: A First Look at Treatmant Options
Story by Sam Calhoun
Last week, High Country News readers got a crash course in the Hemlock Wooly Adelgid (HWA)—a tiny insect that is killing trees thousands of times its size all over the East Coast. According to forestry professionals, the HWA is potentially more devastating than the chestnut blight because when the chestnut trees died, oak trees partially filled the void they left. No species will be able to fill the void left by the hemlocks, and an ecosystem will be lost along with the trees.
Over the past several years, the HWA has swept like a giant wave from the northeast down south, and the High Country sits at the crest of that wave.
There’s no inventory of the number of hemlocks in our area, but experts guess that we have millions of them. They dominate our forests, build our houses and are ornamental features in many landscapes. But the High Country isn’t the only region that has hemlocks, so why are we seeing such devastating effects?
The Beetle Solution
The answer is balance. Hemlock populations in the American Northwest have survived the HWA infestation because predatory beetles, in numbers equal to the quickly reproducing HWA, live there and feed solely on the insect. The High Country has no such beetles, at least not naturally.
“Right now, the HWA have all the numbers,” said Stewart Skeate, coordinator of the Wildlife Biological Program at Lees-McRae College.
Yet, biological control methods—both natural (beetles) and chemical—are available for help in this fight, even though at first glance it seems to be a losing battle.
According to Grandfather Mountain naturalist Jesse Pope, beetles have been released in the biopreserve and achieved some small results. This same practice has occurred on Hemlock Hill on the Lees-McRae College campus for the past three years.
In 2003, Virginia Tech, Blue Ridge Resource Conservation and Development Council and Lees-McRae released 300 Laricobius beetles at a test site in Banner Elk. The Laricobius beetle is a species native to the Pacific Northwest and is considered a specialist on the HWA because it feeds on both the adult and larvae.
The release was small, admitted Skeate, but the groups involved in the experiment point out that the beetles have reared three generations since their initial release in 2003. They are now considered the “F3 Generation” and are feeding on the HWA, “but they probably haven’t even put a dent in it,” admitted Skeate.
“It’s kind of like having a forest fire and throwing a bucket of water on it,” added Skeate, who pointed out that 300 beetles don’t compare to the number of HWA on Hemlock Hill.
The experiment showed that the beetle can live and breed here,but Skeate admitted that it will take years for the balance of beetles to HWA to catch up.
“But we have to do something. You can’t just sit back and let the trees die,” he added. “It needs to be done even though the odds are stacked against us. Hopefully, at some point, we can find that balance and have control.”
As a continuation of their research, Skeate and his team have started a program with the National Forest Service to study the fighting power of a species of lady beetle that feeds on the HWA during the summer. Because the Laricobius beetle only feeds on the HWA in the late fall, winter and early spring, summer is a lull in the beetles’ feeding cycle. Skeate and his team are hoping to cover all four seasons by combining different beetles in the same environment.
“It’s another weapon in the arsenal, so to speak,” said Skeate.
At the moment, they’re putting the beetle through a controlled study. If it’s successful, they’ll begin the release on Hemlock Hill.
But then the money factor comes in. The species of lady beetle must be reared in a laboratory, and Skeate pointed out that they are expensive. The Laricobius beetle is harvested in the west and then brought to the region.
“We need to be releasing thousands and thousands, but there are financial limitations,” he added.
Before releasing the Laricobius beetles, Skeate and his team looked at chemical options but determined that chemical methods weren’t financially feasible. Beetles appeared to be the best viable long-term solution for tall hemlocks. Tall hemlocks, Skeate postulated, were especially vulnerable to the HWA due to their large biomass, so the beetle was chosen as the first line of attack. Because of their smaller biomass, small hemlocks have can handle stress better and are more easily saved.
Beetles vs. Chemicals
Lear Powell and Greg Cratch, independent arborists in the area, also recognize the importance of the beetles for a long-term solution, but are well versed in the chemical methods of fighting HWA as well.
On the beetle side of things, the two men work as field representatives for Conservation Concepts—a predatory beetle rearing facility owned by Dawn and Dell Ponder and located in Old Fort, NC. Conservation Concepts (www.conservationconcepts.org) is the only private insectory in North Carolina that sells beetles to the general public.
Powell recommends the use of beetles in certain situations, understanding that large landowners cannot use chemicals for all of their trees—it’s impractical and can be expensive.
“If you have a big forest, your only hope would be biological control,” said Powell.
In such cases, he recommends the Sasajiscymnus lady beetle from Japan, which is sold by Conservation Concepts, and he claims that the Sasajiscymnus beetle is the number one biological control for the HWA, “because it lends itself to mass rearing.”
Sasajiscymnus beetles cost $2.29 each and the recommended release is 1,000 beetles. The $2,290 investment may work for a landowner with over 10 acres.
For homeowners with less than 10 acres and maybe 4 to 12 trees infested with HWA, Powell recommends chemical treatment—what he calls Integrated Pest Management.
The choice between biological and chemical control is a case-by-case decision.
The Chemical Solution
Powell has soaps, oils and chemicals and recommends that homeowners use these methods in the fall when the HWA is most vulnerable. Ultra Fine, an oil product, and M-Pede and Safer, both soaps, are available at local hardware, agricultural supply and pesticide stores. But the most popular treatment is MERIT, also known and sold as Bayer Advanced Tree & Shrub. 
All of these treatments can be applied through soil injections, injections into the tree or high-powered spray—depending on the instructions on the label.
There are two types of soil injectors. The first is called a Kiortz. This injector can do its job without using pressurized water. It looks like an inverted pyramid and holds a concentrated mixture of MERIT and water that is injected 6 to 10 inches around the base of infested trees. The second type of injector looks like an L-shaped pole that fits on the end of an agricultural pressure washer. This injector, according to Powell, spreads the treatment out more, and is more effective. Rain and moisture carry the injector treatments up into the tree.
Intravenous treatment is another option. The Mauget is a circular antibiotic applicator with an extended nozzle that is pushed into a small hole drilled in the tree. The tool has been used for 30 years for other tree problems and has recently become the tool of choice for HWA intravenous treatments. It’s very important not to drill the holes too deep; otherwise you will inject the chemical into the heartwood of the tree where it won’t rise but will collect like water in a reservoir.
Using the Mauget Applicator
The number of Mauget applicators that should be used for a tree depends on the DBH, or the diameter of breast height. Calculate the DBH by measuring the tree’s diameter with a tape measure at your own breast height and divide that number by 2. The resulting number is how many applicators are needed.
For instance, if at breast height, a tree has a 14-inch diameter, then 7 applicators are needed at the base of the tree.
Another option is the tree IV, a treatment that is similar to a human IV, but has multiple injection ports as opposed to one. Its base is a pump with a reservoir that is filled with a chemical concentrate such as AborJet, a product available at home improvement stores. Plastic tubes come out of the reservoir and are connected to metal injection ports that are fed directly into the tree, four at a time. For smaller trees, four ports may be all you need, but larger trees require more ports for effectiveness. The ports help get the chemical to the canopy faster, compared to soil injections that rely on rain or moisture to carry the chemical up into the tree.
The tree IV method is very time consuming because of all the ports that need to be placed on the tree. But the tree IV method is safer than injecting the soil if an underground well is nearby and it’s considerably faster.
Also in Powell’s arsenal are high-powered spray guns. These guns, when attached to pressure washers, can shoot chemical concentrates high into hemlock branches and clean out divisions of the HWA. Spraying, though, is usually used along with other treatments, such as soil injections.
The Cost
Cost is determined on a tree-by-tree basis and differs from company to company. As an example, however, Powell charges $5 to $15 per DBH. Most of the trees he has been working on cost roughly $75 per treatment. However, the necessity of using a tree IV with 12 ports on a tree on the Blair Farm at the entrance to Blairmont resulted in a treatment cost of $550.
Powell isn’t looking for customers. In fact, he’s “covered up” at the moment with jobs, but he offers this advice.
“Homeowners can do [these treatments], but it’s not going to be as effective,” he said. “A lot of times it pays to hire a professional—especially over a couple of trees.”
Powell recommends that people interested in saving their hemlocks call Meghan Baker at the North Carolina Cooperative Extension at 828-264-3061.
“Anyone who reads this article and thinks that they don’t have the [HWA], they’re wrong,” added Powell.
Our report on the treatment options for the HWA will continue next week. If you have comments or experiences that you think will help with this community education project, send them via email to sam@highcountrynews.info.
TO PART 3
If you have comments or experiences that you think will help with this community education project, send them via email to sam@highcountrynews.info.
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