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Bringing the American chestnut back to Connecticut forests

The American chestnut once dominated portions of the eastern U.S. forests. Numbering nearly four billion, the tree was among the largest, tallest, and fastest growing in these forests. However, at the turn of the 20th century, all the American chestnuts succumbed to a lethal fungus infestation, known as the chestnut blight, and an estimated 4 billion trees were reduced from giants to trees that grows mostly as a shrub. The blight cannot kill the underground root system and stump sprouts will grow again until they inevitably succumb to the blight. This cycle of death and rebirth has kept the species alive, but it is considered functionally extinct.

The scientists at The American Chestnut Foundation (TACF) and the volunteers in its local chapters are leading an unprecedented mission to restore the American chestnut tree to its native range, including in Connecticut forests, by employing complementary methods of traditional breeding, biotechnology and biocontrol. The newest and most promising tool in our quest to bring back the American chestnut is Darling 58, a revolutionary transgenic American chestnut tree with enhanced blight tolerance thanks to the introduction of a gene from wheat called OxO. The gene codes for an enzyme, oxalate oxidase, that detoxifies the acid produced by the fungus and prevents lethal cankers on the tree, essentially allowing the tree to coexist with the blight pathogen. This enzyme has been carefully chosen because it is well understood, commonly found in nature as a defense against pathogens, and is not harmful to human or animal health, or the environment.

Our Connecticut chapter is supporting these efforts by searching and inventorying wild American chestnuts in Connecticut forests (join us for these fun hikes in the Summer), manually pollinating them (many wild trees lack a pollination partner to produce viable seeds—we help them a little!), harvesting and planting these nuts in Germplasm Conservation Orchards all over the state (you can lend us your land to host an orchard!) to preserve the genetic diversity of the American chestnut in Connecticut. These trees will be bred with Darling 58 to produce the closest form to wild American chestnuts with blight resistance and provide regional adaptation to our Connecticut forests.

We invite you to join us to support these restoration efforts as it will give us a road map to save other trees infected with fungi (i.e., Dutch elm disease, Butternut canker).