Wooly Buggers
Our next module is set at Carrick Creek in Table Rock State Park. Currently park staff and scientists are concerned about the threat of the hemlock wooly adelgid, an invasive species of insect that destroys native hemlock trees, a major part of the tree canopy that protects and sustains the Carrick Creek environment.USDA site:
http://www.na.fs.fed.us/fhp/hwa/
posted by Riverventure at 11:09 AM
3 Comments:
The adelgid are thought to have come from the Orient by way of Virginia, hitch-hiking on birds and hikers. Their egg cases look like cotton underneath the branches of the Hemlock trees. Around SC, they’re said to have been found on the Chatooga River, at Ceasar’s Head, and Table Rock. Other studies are being conducted in Pine stands about the Pine Beetles.
There are similar blights with other species of trees, for example, the Sugar Maple blight in Pennsylvania. From observation of other areas with this particular problem, it is likely that Red Maple will fill in the spaces where Hemlocks get wiped out.
There are two methods being used right now to fend off the adelgids. Scientists have found success in the introduction of predatory beetles to affected areas. Chemcals "injections" sprayed on trees have also been effective, but this method requires very thorough application, and so is not practical for entire stands of Hemlocks, only single trees.
There are several methods available for control of HWA. Each should be a tool in any respectable arborist's toolbox.
Bioligical controls are certainly the most desirable. However, in my opinion they are a strategic fix and may not be "quick" enough for the tactical problem of saving a particular tree or group of trees.
There are three chemical methods of control each of which have their pros and cons. Spraying with dormant oil, an insecticidal soap or mix which may include an insecticide. Soil or root application of Imadacloprid. Trunk injection of Imadacloprid.
All are effective if, and of course this is a big if, done correctly. Each has it's place in a coordinated treatment plan. Any arborist that does not consider all three is working with only a partial set of tools.
Finally, the last tool is the chainsaw.
I would be glad to discuss chemical applications with anyone interested in more details.
Here are links to a couple of fact sheets the about the wooly adelgid, published by a UMASS extension office:
http://www.umassgreeninfo.org/fact_sheets/piercing_sucking/hwa_faq.pdf
http://www.umassgreeninfo.org/fact_sheets/piercing_sucking/hemlock_woolly_adelgid.html
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