TECA Chestnut Feature_TECA_0114_ 12/31/13 3:43 PM Page 12 King of the Forest Chestnut trees face extinction unless measures are taken Story by Debra Gibson Isaacs Photographs by Robin Conover D r. Gregory Weaver is too young to remember the American chestnut when it was the kingpin of trees — the most common and important tree in the eastern United States, a forest giant, often growing up to 100 feet tall and 5 feet in diameter. But chestnut blight, technically Cryphonectria parasitica, was accidentally imported from Asia, and by the end of the 1930s, the Tennessee chestnut forests were largely destroyed. Today, though, Weaver is one of the people determined to breed a blight-resistant cultivar of the American chestnut and return the tree to its rightful place as “king of the forest.” The tree earned its exalted title because of its many attributes. “Chestnut trees grow all the way up to Canada,” Weaver says. “They are resistant to 30 degrees below zero and can tolerate 100-degree Dr. Greg Weaver stands next to a dead chestnut trunk in the Great Smoky Mounheat and go without rain. tains National Park. The tree probably died in the 1930s. Its large stump, measuring When harvested, chestnut 15.5 feet in circumference at chest height, is still standing because of the rot resistwood is rot-resistant, ance of chestnut. Photograph courtesy of Dr. Greg Weaver lighter than oak but strong for its weight. It has a good combination of lightness, strength and rot-resistance. 12 T h e Te n n e s s e e M a g a zi n e TECA Chestnut Feature_TECA_0114_ 12/31/13 3:44 PM Page 13 The chestnut also does not require the use of wood preservatives.” In addition, the trees support wildlife from black bears to turkeys, songbirds, squirrels and chipmunks. The loss of chestnuts, a tasty and nutritious food source, is largely responsible for the 20th century decline in the number of black bears. Scientists don’t even know the full impact of the loss of the chestnut tree — considered one of the worst ecological disasters of the century — because ecological science was too primitive in the 1920s and ’30s. But, as Weaver notes, “You can’t erase 25 percent of a forest and not have an impact.” Members of the Tennessee Chapter of the American Chestnut Foundation (TACF) present Dr. Gregory Weaver with the National American Chestnut Foundation Volunteer A lifelong quest Service Award for his efforts with the organization. From left are Clint Neel, Vicki Turner, Weaver’s journey to help Sean Fisher, Paula Phelps-Weaver, Dr. Weaver, Tennessee Chapter TACF President Joe restore the American chest- Schibig, Jack Torkelson and Tim Phelps. Below, orange blight fungus grows on a damnut actually began more than aged chesnut tree. Photograph courtesy of Dr. Greg Weaver five decades ago, although “Daddy knew a lot about trees,” Weaver recalls, “and he he didn’t know it then. At the time, Weaver was just relishwould tell us about them. There were a lot of big chestnut ing Sunday afternoon walks on the family farm with his stumps on the farm, and he would tell us stories about how dad, Arles, mother Joyce and brothers Anthony and Tom. important the chestnuts once were. “Daddy remembered eating the nuts and how one of the signs of toughness as a young man was to stomp open the chestnut burrs with your bare feet. He could do it. Dad remembered watching the trees die, the tops dying first until they were just chestnut ghosts. Chestnuts are rot-resistant, though, so the trunks and stumps stood many years.” Stumps were still scattered around the family farm when Greg left for college for a degree in forestry. He didn’t like the idea of cutting down trees, so that degree soon changed to premed followed by medical school and a specialty in radiology. Weaver never lost his love of forests and trees, though, most especially the chestnut. In 1995, Weaver — by then a respected radiologist with a farm of his own — found a brochure about The American Chestnut Foundation (TACF) and the organization’s special breeding process. He joined immediately and went to its fall meeting. “My knowledge of what was going on in regard to the chestnut was limited,” Weaver says. “I knew the history of the tree, but I didn’t know where the science was. I found out there were a wide assortment of people — scientists, Januar y 2014 13 TECA Chestnut Feature_TECA_0114_ 12/31/13 3:44 PM Page 14 academics, people like me, industrial foresters — who are serious about restoring the American chestnut. This wasn’t a theory. They were going to do this.” Weaver is a doer. His idea of leisure is to haul rocks and build stately stone fences at the entrance to his farm on Leipers Creek Road just outside of Nashville. The goal of developing a stronger, blight-resistant strain of the tree intrigued him, although he knew prior attempts to breed blight-resistant trees in the mid-1900s were unsuccessful. Weaver soon planted TACF-provided chestnut seeds on his farm. “These were pure American chestAbove, Dr. Hill Craddock and his University of Tennessee at Chattanooga crew nuts, so we knew they would get a grade blight resistance and assess physical characteristics of American chestblight infection and ultimately die,” nut trees in Greg Weaver’s Williamson County orchard. The trees had been inhe says, “but I needed to learn the proper technique of planting the trees oculated in June 2012 with two strains of chestnut blight. Photograph courtesy of Dr. Greg Weaver. Below, a tree injected with the blight is marked. and how to care for them. An intermediate step for my chestnut-growing grow the generations of trees proximal efforts was to plant hybrids — trees that are partially to the ultimate goal.” blight-resistant and used to successively concentrate blight A recent addition to Weaver’s orresistance in their offspring. A lot of my work has been to chard are chestnut saplings that have already been crossbred. The trees — F3B3 chestnuts as they are known among TACF members — are 15/16 American chestnut and 1/16 Chinese chestnut. “We want an American phenotype Dr. Weaver that is a forest canopy tree,” he says. “Before the blight, it was common for American chestnuts to be 120 feet tall when fully matured.” But breeding a tree isn’t like other endeavors where you put the right ingredients together and create the product you desire. The breeding program has to go through six generations to reach the 15/16 American gene fraction, with the 1/16 for Chinese origin blight-resistance. “Along the way you select American chestnut traits,” Weaver says. “Only about 8 percent are blight-resistant enough to propagate to the next generation. We’re still in testing. We will have to see how they grow.” A microcosm of a bigger movement Weaver can see some of that growth in his own chestnut orchard set high on a hill at his farm (chestnuts grow best on the top of hills). Each year, he has planted more trees. “It’s important to keep planting,” Weaver says. “Some, the deer get; some, drought gets. Small rodents are a big problem. Voles, for instance, eat the plant roots and essen- 14 T h e Te n n e s s e e M a g a zi n e TECA Chestnut Feature_TECA_0114_ 12/31/13 3:44 PM Page 15 tially amputate the trees. The aim is to increase the number over time.” In this regard, Weaver says he and his fellow association members are farmers. “We’re growing a crop for a charitable cause and for future use, but we’re still farmers. We are subject to all the same problems that farmers are subject to.” Drought is particularly rough on the trees, according to Weaver. He has designed a system to collect rainwater in huge barrels and then distribute it with hoses so the trees can be watered when there isn’t enough rain. The system can capture 13,000 gallons of rainwater and does not require electricity. It was a significant development beSeeds from American chestnut trees backcrossed with Chinese chestnuts cause otherwise Weaver had to haul water begin growing in tubes. As they grow into saplings, they will be injected in 5-gallon buckets a half a mile up the with two strains of chestnut blight fungus to test their resistance. Trees steep hill. with good resistance will be used in future crosses. Photograph courtesy After years of protecting the seedlings of Dr. Greg Weaver from deer and other animals, keeping the constructing an informational display about chestnuts that young trees watered and building fences and watering syshe made from recycled chestnut lumber. The display is tems, last summer members of the Tennessee chapter of currently on extended loan to the Science Department at The American Chestnut Association came to poison the Volunteer State Community College in Gallatin. very trees Weaver had worked so hard to grow. “This work is very important to me,” Weaver says, “but I They deliberately infected Weaver’s trees with two viruam a small part of the total puzzle. We need everyone to lent strains of Cryphonectria parasitica. Then the trees were graded according to how they responded to the infec- volunteer, to do something. You don’t have to have a farm to participate. It is a huge commitment, and it is gratifying tion. Weaver said most of his trees were killed. “I have a to see people across the spectrum pulling together.” few left,” he says, “and they will become parents for the Now assisted by memnext generation.” bers and volunteers such as This process is being from Weaver in 16 state chapduplicated across the naters, TACF is planting fter the chestnut blight killed entire forests of trees, the tion. One of the leaders narestoration chestnuts in setrunks still stood tall for decades. In 1936, some farmers tionwide is the Hill lect locations throughout in Indiana decided to turn the tragedy into triumph, acCraddock, a professor at the eastern United States. the University of Tennessee cording to a December 2013 article in Rural Electric maga“My father’s generation at Chattanooga and one of zine. The farmers used the trunks to build an electric saw chestnut trees in the the world’s pre-eminent distribution system. Tall, strong and rot-resistant, the trunks forest,” Weaver says. “My chestnut scientists. Some were perfect poles, and soon, aided by a $100,000 loan generation is doing the 300 people in Tennessee from the Rural Electrification Administration, an electric work to get them back, but and 6,000 nationwide are cooperative was born and people who never had electricwe won’t know if we were doing their part to help reity before could now flip a switch and light their homes. successful for 400 years. store the tree. The first pole was set on My hope is that my chilIn October, Weaver was Feb. 12, 1936. The last one was dren will see the chestnuts honored for his work with taken out of service in 1997. introduced back into the a Volunteer Service Award The American chestnut’s repuforest.” from TACF. The award tation for being strong and rotThe website for the recognized his service as resistant remained true even American Chestnut Foun(past) president of the after the trees’ deaths. dation is www.acf.org. You Tennessee chapter and his These tree trunks were used can contact the Tennessee volunteer work growing as poles throughout the counChapter of TACF via email an orchard, giving lectures try. The trees were bought and at [email protected]. and presentations and sold in Tennessee and became an integral part of electrifying the nation. Triumph Tragedy A Januar y 2014 15
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