FreeLists / bristol-birds / [Bristol-Birds] Steele Creek Park infested with Hemlock Woolly Adelgid

["Wallace Coffey" <jwcoffey@xxxxxxxxxx>]

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