I'm 60 feet above the ground in the receptacle of one of those bucket trucks the electric company uses to fix power lines. My companion in the bucket with me is Bob Summergill, president of the Pennsylvania Chapter of the American Chestnut Foundation. It is July 7. From this height we are pollinating the flowers of an American chestnut tree growing on a game lands in Somerset County. Two weeks ago, on June 23rd we were at this same tree cutting the pollen bearing flowers off and tying a wax paper bag over the female or pistillate flowers. We had bagged over a hundred flowers on this tree to prevent them from being self-pollinated. Today we were taking the bags off, placing pollen from a Chinese chestnut on the stigmas and re-bagging them. In September we will be back at this same tree removing the bags and harvesting the nuts, which, when planted, will produce a tree that is 50% American chestnut and 50% Chinese chestnut. Every one of those trees will be blight resistant to the disease that killed most of the American chestnuts in the first half of the 20th century. When these trees grow and flower they will be back-crossed to another American chestnut, which, when planted, will yield a tree that is 75% American chestnut and 25% Chinese chestnut. Each of those trees will be tested to see if they received the resistant gene to chestnut blight. The test is done by drilling a small hole in the trunk and inoculating the tree with the blight. The disease operates quickly on young trees and the results will be known in a week. The blight resistant trees will quickly heal the wound and the susceptible trees will be dead in another week. The blighted trees will be removed from the orchard and burned. The surviving resistant trees will be allowed to grow and flower and once again be back-crossed to an American chestnut. This procedure will continue through six generations giving us a tree that will have 98% of the characteristics of the American chestnut with the blight resistant factor of the Chinese chestnut.
How far along is the program? Bob already has produced 4th generation trees. The nuts of those trees were sent to the Penn State orchard where the back-crossing will continue. This program has been in progress for 15 years and Penn State will have 6th generation trees by 2012. About 1/64th of those trees will be pure for the resistance (carry the resistance gene on both pairs of chromosomes). The offspring of those trees will produce the first Pennsylvania chestnut forest that will be blight resistant. We are looking at the planting of such a forest about 20 years down the road. In order to get more trees ready for future plantings, trees are continuously being back-crossed in 44 different nurseries across the country.
Why are we trying to save the American chestnut? For those of you unfamiliar with the story, the demise of the American chestnut was the ecological disaster of the 20th century. This magnificent species, the third largest tree on the continent, surpassed only by the redwood and sequoia, was the prize of the eastern deciduous forest. This species was the near perfect tree. It had all the desirable qualities you could possibly want in one package. It was fast growing, hard, but workable for carpentry and furniture. It was rot resistant and used for railroad ties and barn building. It made excellent smokeless firewood. But most of all, it bore a huge crop of delicious nuts every year without fail because it bloomed in mid to late June, well after the last frost. The nuts were the mainstay of wild turkeys, squirrels, deer, bears, mice, wood rats and passenger pigeons. The tree was also abundant making up 25 to 50% of the trees in the forest wherever there was well drained soil. What other tree species has even half these desirable characteristics?
In 1904 a fungus was introduced into the United States from either China or Japan to which our native chestnut had no resistance. Trees died within weeks after being infected and the disease, carried by the wind, spread quickly throughout the chestnut's range. It arrived here in western Pennsylvania around the late 1920's. Very few trees survived the blight. By 1950 the entire population throughout the Appalachians was gone. Although the portion of the tree above ground completely dies, the roots stay alive and send up new shoots. Because of the fast growing character of the chestnut, these sprouts often could reach a trunk diameter of 12 inches before the blight hits them. The tree would then die and new shoots would spring up. This has been going on for the past 80+ years giving us a source of chestnuts for breeding programs, but the number of trees is gradually declining. Members of the Chestnut Society are constantly on the lookout for healthy sprouts. The minute the tree becomes infected with the blight, it starts flowering. In fact, flowers are usually a sign that the tree has the disease, a last ditch effort to reproduce before death. How the tree knows this I have no idea. The nuts produced from these dying trees became the tool with which to save it. When it was learned the Chinese chestnut was unaffected by the blight, some people began collecting the nuts hoping to breed a hybrid blight resistant tree. Early efforts failed, but success is now only two decades away.
The return of the American chestnut will be a boon to wildlife. My grandparents dated by gathering chestnuts in the fall in the late 1800's. My grandmother said the chestnuts were often four to six inches deep. Remember these were big trees and highly productive. People could gather enough nuts in a few hours to roast chestnuts all winter long. There were more than enough nuts left over for the animals. Squirrels were far more abundant than today - and so were the hawks and owls that fed on them. I have read pioneer accounts where a family would shoot 300 squirrels on a single weekend. Squirrel migrations was a common phenomenon. The mice and woodrats of the forest waxed rich on the nuts and, in turn, fed the weasels and bobcats. Bears put on weight for winter hibernation and deer sustained themselves on chestnut fruit through the rut. This all ended with the demise of the chestnut.
The return of the chestnut may come in the nick of time. Many of our other tree species are declining from introduced diseases. Beech, dogwood, butternut, and elm have all been stricken in the past century. Now we sit in fear that the disease that's killing California's oaks will escape to the rest of the country. Oaks filled in for the chestnut, but being wind pollinated they bloom before the leaves break out when it is still cold and take their chances on frost damage, which in some years has totally destroyed the crop. We need the American chestnut. Thanks to the efforts of a handful of dedicated people in the American Chestnut Foundation we will see the return of this marvelous tree.
You can help by becoming a member of the organization. If you have a computer, you can print out an application form from http://www.acf.org Otherwise send a check for $40 to The American Chestnut Foundation P.O. Box 4044, Bennington, Vt. 05201-4044.
