The Tree That Built America

Before 1904, roughly one in every four trees in the eastern United States was an American chestnut — an estimated four billion trees stretching from Maine to Mississippi, some reaching 100 feet tall and 10 feet in diameter. The nuts fed deer, bears, turkeys, and people alike, and the rot-resistant timber built fences, barns, furniture, and telegraph poles across the country. Then a shipment of ornamental Asian chestnuts arrived at the Bronx Zoo in New York, carrying a stowaway fungus called Cryphonectria parasitica. The blight spread at roughly 50 miles a year and within 50 years had killed nearly every mature American chestnut on the continent — over three billion trees, one of the fastest and most complete ecological collapses in recorded history. The species is considered functionally extinct: old root systems still send up sprouts, but the blight kills them before they can grow tall enough to produce nuts. Scientists are now working to bring it back by deliberately infecting thousands of seedlings with the blight fungus and searching the survivors for natural resistance, while a separate program at SUNY College of Environmental Science and Forestry has developed a genetically modified variety called "Darling 54" that carries a blight-tolerating gene borrowed from wheat — and for the first time in over a century, some of those trees are bearing chestnuts.