Powell says it was like having to “build a boat before we went fishing. In the 1990s Charles Maynard and Bill Powell at the SUNY College of Environmental Science and Forestry in Syracuse, New York, began that quest, using what was then emerging technology. Genetic engineering offers a controversial shortcut to creating a truly American blight-resistant chestnut. The promise, and peril, of genetic engineering The real question is, What is the right combination of genes to produce blight resistance? Breeding also requires many new generations to make progress, and each generation takes years. Scientists now believe that as many as nine gene regions working together may be responsible for providing blight resistance, which makes breeding a challenge. “Fast-forward 30-plus years of breeding work, and what we see is, blight resistance is much more complicated than we really thought,” says Tom Saielli, a forest scientist for the foundation. The American Chestnut Foundation began formal work on the hybrid in the 1980s. Efforts to breed American chestnuts with Chinese counterparts to create a hybrid resistant to the blight began as early as the 1930s and in earnest in the 1950s. In their attempts to save the chestnuts, foresters have sprayed the trees with fungicides, infected them with fungus-killing viruses, and even burned infected trees to the ground. But it’s a Sisyphean task blight is inevitable with age, and a tree’s ability to clone itself is not infinite. But as tree bark ages, it cracks, letting microscopic fungal spores enter the trunk, where they release oxalic acid that kills tree tissue.Īs a species, American chestnuts have survived by shooting up clones from the roots of dead trees. The fungus, Cryphonectria parasitica, spares the young. These splotchy indentations, reminiscent of a bruise, can choke off the tree’s flow of water and nutrients. The chestnut blight is caused by an insidious fungus that leaves orange-tinted cankers on a tree’s trunk and limbs. “What I say is: We’ve been playing the devil for ages, so we need to start playing God, or we’re going to start losing a whole mess of stuff.” How the fungus kills “Some people say, ‘You’re playing God,’ ” says Allen Nichols, president of the New York chapter of the American Chestnut Foundation. If it works for the American chestnut, perhaps it can work for other similarly afflicted trees. By tweaking its DNA, scientists say, they’ve created a blight-resistant tree that’s ready for a second act. Even Joshua trees, icons of the southwestern desert, are finding that the world is too warm.Īll this has led some scientists to ask: Can we build better trees, ones that are more able to cope? And here again the American chestnut may soon set a precedent-this time on the path to resurrection. And now climate change, with its catastrophic droughts, floods, and heat waves, is making it especially difficult to fight off attackers. It’s considered one of the worst environmental disasters to strike North America-and also a preview.Įmerald ash borer, sudden oak death, Dutch elm disease, oak wilt disease, walnut canker, hemlock woolly adelgid-in a globalizing world, many trees are facing pandemics of their own. Over the course of the 20th century, an estimated four billion of them, one-fourth of the hardwood trees growing in Appalachia, were killed by an Asian fungus accidentally imported in the late 19th century. They were skeletal remains of majestic trees that once grew to be as much as 100 feet tall and 10 feet wide. “We called them gray ghosts,” the now 77-year-old retired forester says of the American chestnut tree scattered throughout his former North Carolina home and still towering over the forest floors. By the time Rex Mann was old enough to work in the forests of Appalachia, they were full of the dead.
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