Left: The infested trunk of a Fraser fir (Image: USDA Forest Service - Region 8, Bugwood.org). Top right: An adelgid-killed natural Fraser fir stand (Image: R.L. Anderson, USFS, Bugwood.org). Bottom right: After a tree becomes infested, tissues swell, a symptom referred to as gouting (Image: USDA Forest Service - Region 8, Bugwood.org).
The N.C. Fraser fir is the most popular Christmas tree around. It has been dubbed the “Nation’s Best” by the National Christmas Tree Association and has been selected as the official White House Christmas tree more than any other tree. Each year, millions of homes become more festive with ornamented N.C. Fraser firs. North Carolina growers ship the tree to every state, the Caribbean Islands and countries throughout the world. As a $100 million industry, North Carolina ranks second in the nation for number of Christmas trees harvested. Fraser firs are preferred as Christmas trees because they are exceptionally aromatic, have unparalleled needle retention, strong yet flexible branches, and needles soft to the touch.
But we aren’t the only ones who love a good Fraser fir. The balsam woolly adelgid, an exotic aphid-like insect, also likes fir trees.
The balsam woolly adelgid, which is native to Europe, was first introduced to the Eastern U.S. in the early 1900s. By the 1950s, it reached the Southeast, and now all naturally occurring Fraser fir stands are believed to be infested. Parts of Western N.C. are still riddled with standing ghosts of fir trees killed by the adelgid.
The insects attach themselves to the main trunk or large branches of the tree and feed on the internal components of the tree. As a result, tissue near or on the tree’s buds, branch nodes and stunted shoots often swell, a symptom referred to as “gouting.” There is no danger to bringing an infested fir into your home (most trees are treated to prevent an infestation anyways), but a tree infested with the adelgid can be unsightly. Not only is this not attractive, but often the tops of the trees curl over, causing the tree to lose its apical dominance — the shoot at the very top of the tree that is often used to hold the star or angel atop an adorned tree. If left untreated, needles lose color, fall off, and the firs eventually die as a result of the infestation.
North Carolina has already lost most of its native Fraser fir trees, and Christmas tree growers must combat the pest regularly. Chemicals are successful and can be used to protect susceptible trees, but there is a desire for longer-lasting, sustainable management options. Currently, research into implementing biological control and developing an adelgid-resistant fir are under way.
So the balsam woolly adelgid may be a mean one, Mr. Grinch, but don’t let it deter you from decorating your house this holiday season. The chances of getting an infested tree are extremely low, and there is no harm even if it is infested (some may even think the woolly material the insects cover themselves with look like snow).
To find an N.C. Christmas tree this year or to learn more about them, visit the N.C. Christmas Tree Association or visit www.ncfarmfresh.com.