Ian Stewart, Matt Bailey and Joe Sebastiani
Last week an accidental discovery brought the Delaware Nature Society a link with a past that few of us had known. Bret Lanan, a knowledgeable deer hunter exploring an obscure corner of our Coverdale Farm Preserve in Greenville alerted Dave Pro, the DNS Land Steward, to what he suspected was a mature American chestnut tree. Dave quickly arranged a visit by a group of DNS staff and affiliates plus Bill McAvoy, the state botanist, who confirmed that it was indeed a healthy American chestnut (Castanea dentata) estimated to be at least 50 years old. Bill excitedly declared it to be the biggest one he’d ever seen!
To understand why we were so thrilled by a single tree you have to travel back over a century. The American chestnut was once a very common tree throughout most of the northeastern United States and in some hardwood forests one in every four trees was a chestnut. Chestnuts were a key component of the forest ecosystem, partly because they were so common, but also because they were large (up to 100 foot tall), bulky trees that many birds and mammals probably nested or sheltered in. Furthermore, each fall they produced large quantities of sizeable nuts that provided food for all manner of animals including bears, squirrels and turkeys.
Tragically however, the fate of the American chestnut was sealed in the early 1900s when a nursery in New York unknowingly imported a batch of Japanese chestnuts infected with a fungus known as chestnut blight. Although the Japanese chestnuts had evolved a resistance to the fungus and were able to tolerate it the new invader proved devastating to the American chestnuts. The blight spread rapidly through spores carried by the wind and killed an estimated 4 billion trees in just 40 years. By the time of the Second World War the American chestnut had all but disappeared, save for a few isolated trees planted in other parts of the country.
Although virtually all of the chestnuts are long gone the blight remains a potent threat. New shoots are still produced by the stumps of old chestnuts yet these rarely live beyond a few years before succumbing to the fungus. Something about the Coverdale tree’s genetic make-up may have enabled it to fight off the disease. This survivability makes it and other mature specimens precious resources for conservation biologists who are trying to save the chestnut by identifying genes associated with disease resistance or back-crossing American chestnuts with resistant strains of other chestnuts. There is a long and challenging road ahead for scientists and conservation agencies but if we work together then one day this beautiful native tree may once again be a familiar part of Delaware’s landscape.
Due to the sensitive nature of the location the chestnut is not accessible to the public but we will be conducting programs which involve a walk to this rare tree. The Delaware Nature Society extends its gratitude to the families who generously donated the land on which this survivor tree stands.
Learn more about American chestnuts at https://www.acf.org/about-us/ and also through this excellent book https://www.ucpress.edu/book/9780520259942/american-chestnut.