[Bristol-Birds] Steele Creek Park infested with Hemlock Woolly Adelgid
- From: "Wallace Coffey" <jwcoffey@xxxxxxxxxx>
- To: "Bristol-birds" <bristol-birds@xxxxxxxxxxxxx>
- Date: Sun, 3 Jul 2005 00:35:45 -0400
Recent survey finds Hemlock Woolly Adelgid
has infested Steele Creek Park hemlocks.
The devastating infestation of Hemlock Woolly Adelgid, which has been spreading
through the Southern Appalachian forest at alarming rates during the past
several years, was discovered early last week in many of the graceful and
beautiful Eastern Hemlocks at Bristol's Steele Creek Park.
Park naturalists Kevin Elam, Chris O'Bryan and volunteer Wallace Coffey found
the insect present in an estimated 20 percent of the trees they surveyed along
Steele Creek Lake on Monday, June 27. The trio decided to make the survey
following the Cherokee National Forest's May release of a project report for
environmental assessment and suppression of the insect in 10 counties of the
forest.
Along Steele Creek Lake shoreline alone, 11 of 51 inspected trees were
infested. The largest and most beautiful trees (one 25-inches in diameter)
were the most heavily impacted. This infestation will likely change the
character and beauty of Steele Creek Lake shoreline forever. More pockets of
park hemlock are probably infested. The City of Bristol Tennessee will be
addressing the problem in coming months.
The problem is widespread. The adelgid is expected to decimate the hemlock
population. "The mortality rate is 100 percent," says U.S. Forest Service
hemlock woolly adelgid expert Rusty Rhea. "If you want to see how devastating
it is, visit Shenandoah National Park. It's jaw dropping."
The insect is spreading through the region at 10 to 20 miles per year.
Adelgids are moved through areas by wind, birds, deer, squirrels and other
forest-dwelling animals. They also can be dispersed by logging, hikers and
campers. The majority of East Tennessee counties are infested, including
virtually all with National Forest.
Mild southern winters could provide greater opportunity for the adelgid to
wreak havoc in Tennessee. According to Dr. Ernest Bernard, professor in the UT
Department of Entomology and Plant Pathology, "The hemlock woolly adelgid is
moving into a climate more like its native habitat. It will thrive here."
In addition to the serious culture and asthetic impact, hemlocks are among the
truly irreplaceable parts of their ecosystem. They stabilize soil and also
provide dense shade that lowers water temperatures as much as 6-8 degrees and
serve as cover and forage for many species of birds and wildlife.
Several bird species populations in the region may face devastating effects.
Small mammals feed on hemlock seeds, and many species of birds - including some
increasingly rare neotropical migrants- use hemlocks for forage and cover.
There are several treatment types available for adelgid-infested trees. There
is a soap spray and systemic treatments (by soil drenching, soil injection, or
trunk injection). Each treatment option has benefits and drawbacks relating to
cost, effectiveness at killing the adelgids, and ecological effects. Chemical
treatment will probably be out of the question at Steele Creek because of
environmental problems with soil drenching or soil injection near the open
water or in the rocky soil that will drain quickly to the lake. Many aquatic
creatures could be killed by such chemicals.
One hopeful possibility is the release of a lady bug type bettle which eats the
adelgid. Funded in part with grants from the National Park Service, the USDA
and the Friends of the Smokies, the University of Tennessee Beneficial Insects
Lab is growing attack beetles and is one among five beetle-rearing facilities
in the nation. A photo of the beetle is included with this message.
The adelgid has infested the Great Smoky Mountains National Park and, in April
2004, the Park Service released 2,500 of the bettles in the park in a war to
save whatever numbers of hemlocks possible. The Cheorkee National Forest will
used bettles and chemical treatment soon.
The beetles are expected to combat the hemlock woolly adelgid, an invasive pest
that has decimated Northeastern populations of the majestic and ecologically
valuable tree. The insect first appeared in the Great Smoky Mountain National
Park in 2002.
The adelgids in all of their life-cycle stages (eggs, nymphs, and adults) are
near microscopic in size so it is difficult to spot them. Fortunately, the sacs
that protect the eggs are woolly and white, looking something like tiny cotton
balls attached to the base of the needles on the UNDERSIDE of the twig (as
shown in the photograph with this message). This "wool," most visible from late
fall to early summer, is a sure sign that the adelgids are present in hemlocks.
Once the infestation has affected the general health of the tree, trees produce
no new growth on certain limbs or throughout the tree. Limb die-back will then
begin to occur. The insect feeds at the base of the tree's needles, mass
attacking it, and sometimes causing death in as little as one year but often as
long as 10 years.
The Hemlock Woolly Adelgid (Adeleges tsugae) is native to Asia where it is not
a problem to native hemlocks. It was introduced to the United States in the
1920s to the Pacific Northwest, and in the early 1950s to the Washington DC and
Richmond, Virginia areas. It lacks natural enemies in North America, so it has
since spread throughout the eastern United States creating an extreme amount of
damage to natural stands of hemlock, specifically Eastern Hemlock (Tsuga
canadensis) and Carolina Hemlock (Tsuga caroliniana).
Wallace Coffey
Bristol, TN
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