Just as wanted on America’s invasive pest list is HWA’s evil stepsister, the balsam woolly adelgid (BWA).
It is presumed that BWA was accidentally introduced to the US on infested nursery stock from central Europe in the early 1900’s. This pesky relative causes significant damage to true fir forests in the eastern and pacific northwestern areas of the United States.
In the southeastern US, BWA specifically infest Fraser firs and in the past four decades, the adelgid has spread to every fir stand in the southern Appalachians.
Like hemlocks, Fraser firs have a certain mystical quality to them. A high elevation sub-alpine species poised in the mist, Fraser fir can live for 150 years and are not only important for their scenic beauty, but also for providing a home for special creatures like the flying squirrel and the spruce-fir moss spider.
Over the past 50 years, because of the effects of this insect and the effects of increasing air pollution, over 95% of mature Fraser fir trees have been killed, leaving behind even more tall “ghosts” on the highest mountain peaks of the Appalachians.
Fraser fir is among the most popular Christmas tree in North America, and the Christmas tree industry provides an important economic resource for mountain communities.
The North Carolina Christmas tree industry is the second largest in the country and in NC alone, there are 50 million Fraser fir trees growing on over 25,000 acres, providing annual cash receipts of well over $100 million for trees, wreaths, ropes, and greenery.
Virtually all Fraser fir Christmas trees require treatment for BWA one or more times during a five to ten year rotation and chemical insecticides are currently the only successful way for controlling the adelgid but it can be very costly and time consuming.
The Christmas tree industry spends $1.5 million annually on BWA and the use of these pesticides minimizes the effectiveness of Integrated Pest Management strategies.
A couple of PhD students in the forest entomology lab at NCSU are researching host resistance against the adelgids in hemlock and fir trees. Kelly Oten is researching ways hemlocks react to HWA with the hope of developing HWA-resistant