Friday, May 08, 2009
Nightmare on Elm Street
Plagues kill plants as well as animals. Among the Ten Common Trees in Susan Stokes' children's book of that name (New York: American Book Company, 1901) are two species of trees which are decidedly uncommon a century later, the American Chestnut (Castanea dentata) and the American Elm (Ulmus americana). I've been reading Nicholas P. Money, The Triumph of the Fungi: A Rotten History (New York: Oxford University Press, 2007) the first two chapters are about chestnut blight and Dutch elm disease.
Chestnut blight destroyed billions of trees in the United States in the early 20th century and inflicted considerable collateral damage as well. "The disappearance of nuts in the forests had a tremendous effect in wildlife. Chestnuts had offered a large crop every year that fattened wild turkeys, deer, squirrels, black bears, and other animals." (Money, p. 6.) Robert Frost, in a 1936 poem (Ten Mills, IV. Evil Tendencies Cancel), wrote:
Will the blight end the chestnut?Frost's farmers guessed incorrectly. Few chestnut trees survive today. Donald Culross Peattie, A Natural History of North American Trees (1950-1953, new ed. Boston: Houghton Mifflin Company, 2006), p. 194, wrote:
The farmers rather guess not.
It keeps smoldering at the roots
And sending up new roots
Till another parasite
Shall come to end the blight.
All words about the American Chestnut are now but an elegy for it. This once mighty tree, one of the grandest features of our sylva, has gone down like a slaughtered army before a foreign fungus disease, the chestnut blight. In the youth of a man not yet old, native Chestnut was still to be seen in glorious array, from the upper slopes of Mount Mitchell, the great forest below waving with creamy white Chestnut blossoms in the crowns of the ancient trees, so that it looked like a sea with white combers plowing across its surface. Gone forever is that day...I learned from Money's book (p. 18) that a 60-acre stand of 2,500 chestnut trees in West Salem, Wisconsin, escaped infection until 1987, and according to Elliot Minor, "Rare American Chestnut Trees Discovered" (Associated Press, May 19, 2006), a small stand of chestnut trees miraculously survived unnoticed on Pine Mountain near Warm Springs, Georgia. In 2005 a biologist working for the Georgia Department of Natural Resources discovered the grove while hiking in the area.
The damage to chestnut trees was done before I was born. Dutch elm disease struck the United States later, starting in the 1930's. I remember the tall elm tree in our front yard on Chamberlain Street in Brewer, Maine, when I was a boy. We had to cut it down when it became diseased.
David Quammen, in The Flight of the Iguana: A Sidelong View of Science and Nature (New York: Doubleday, 1989), has an interesting chapter on "Street Trees: The Hard, Noble Life of a Stranger in a Strange Land" (pp. 70-76). Many American streets received their names from the trees lining them, e.g. Chestnut Street and Elm Street. The real nightmare on Elm Street is that there are now fewer elms on Elm Street.
Thanks to Bill Adamsen for the following remarks:
I read your blogpost and wanted to inform you that the status of the American chestnut is not as bleak as you portray. Across the former range there are hundreds of thousands, if not billions of chestnut sprouts that send up a shoot from the terminal bud (a not unique chestnut adaptation) and sometimes live long enough to flower and if pollinated openly or by man's intervention, send their genes to the next generation. I have personally documented literally thousands of these trees here in Connecticut. I have at least ten on my small 1 acre of property.
While it is true that early hopes were misguided, and even early scientific efforts were poorly informed, the same is not so for today's research. There are several programs nationwide with significant results attempting and apparently close to solving this problem. They take different approaches but all are scientifically valid and have passed some form of peer review. The American Chestnut Foundation has followed the breeding protocol devised by University of Minnesota Researchers Dr. Charles Burnham and Dr. Lawrence Inman. A different spin, with the same general approach has been taken by groups such as the American Chestnut cooperators and CT Agricultural Experiment Station and others. Perhaps the most interesting is the true Genetic Engineering Approach (transgenics) taken by Syracuse University professors Dr. Chuck Maynard and Dr. William Powell.
All of these have had success and especially The American Chestnut Foundation which is working with the US Forest Service have shown early promise. The USFS has documented some of their cooperative efforts in a 2008 Compass Magazine Publication. They are field (forest) testing thousands of BC3F3 trees right now, and the amount available for test will be increasing exponentially over the next years. These trees are over 93% American, and have shown resistance to blight. New trees with new "sources of resistance" and genetics, and regional adaptability are being released every year.