On a recent visit to The Merritt Family Forest, you may have noticed small plastic tubes and wire cages surrounding seedlings that have been planted throughout the field margins. A closer look would reveal that many of the structures are protecting seedlings of the American chestnut tree. The American chestnut (Castanea dentata), once so widespread that it comprised one quarter of the trees in the forests of the eastern United States, is now confined to a few stands of trees scattered across the country. The chestnut seedlings planted here represent a collaboration between GOSA and local representatives of the American Chestnut Foundation. Members of this foundation, along with scientists from several academic institutions, are seeking to develop an American chestnut hybrid that can withstand the fungus that has felled so many of these majestic trees.
A little over 100 years ago, there were an estimated 4 billion chestnut trees growing in the eastern part of the United States. In 1904, the first sign of disease was recorded in New York City, and was traced back to imported Japanese and Chinese chestnut trees and lumber. The imported trees had, over time, been able to develop resistance to the pathogen that causes chestnut blight. The American trees however, had no ability to fight off the powerful fungus that arrived in full force on the imported trees. By the 1940s, with rare exception, most American chestnut trees had succumbed to the blight.
Although the virus has been almost 100% effective in killing mature American chestnut trees, the roots and root crowns of the American chestnut have developed some resistance to chestnut blight. The root crowns are often able to send up sucker growth which occasionally survives long enough to produce seeds. These seeds provide critical genetic material for plant scientists who are working to develop an American chestnut that will have strong immunity to the chestnut fungus.
One of the methods currently being used to develop disease resistant seedlings is to produce hybrids that are 50% American chestnut and 50% non-native resistant species. These hybrids are then back crossed with American chestnut seedlings, producing a hybrid that is 75% American chestnut. From these hybrids, stock will be selected that has genetic resistance to blight and has the typical American chestnut form, which is straight and tall, unlike the shorter, broader and more extensively branched Chinese and Japanese chestnut trees.
The chestnuts growing on the GOSA preserves are pure American chestnut seedlings that are expected to succumb to the chestnut blight after a few years of growth. The value of these seedlings is that in caring for them, we will develop the cultural skills necessary to eventually grow mature chestnut trees. We anticipate that in the future, we will be given some of the precious hybrid stock and will be able to successfully grow disease resistant trees on our properties. The blue tubes and cages, which are there to keep wildlife away from the young seedlings, represent a small but critical step forward in the effort to reintroduce the once mighty American chestnut to the eastern American landscape?