Scientists Work To Bring Back Once-Thriving American Chestnut Tree

The American chestnut tree used to make up a quarter of the forests in the eastern U.S., but disease decimated these trees in the last century. Now there's an effort to restore the American chestnut.

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American chestnut trees used to make up a quarter of hardwood forest in the eastern U.S. Their nuts kept wildlife thriving all winter and played a large part in the economy of places like Appalachia. Today, from Maine down to Georgia, the trees are all but gone. Robbie Harris of member station WVTF reports on a project aimed at resurrecting the American chestnut tree.

UNIDENTIFIED WOMAN: And this is a nice, big knot. This will be viable for sure.

ROBBIE HARRIS, BYLINE: About a dozen people sit around a long farm table in Virginia's Roanoke Valley. They're extracting chestnuts from their bristly, green cradles.

NED YOST: And then we go to a very advanced technology to test these nuts for their viability.

HARRIS: Ned Yost is hosting this gathering in his barn at McDonald's Mill.

YOST: We have a little bit of water. We drop the nuts in. The good chestnuts sink. And those that will not produce a tree next spring - they float.

HARRIS: Around the turn of the last century, American chestnut trees were attacked by a fungus that arrived on trees from China. The Chinese imports have immunity. But the blight didn't wipe out every last trace of the American variety, says Carl Absher of the Virginia Chapter of the American Chestnut Foundation.

CARL ABSHER: What we have here are nuts that came from some of those survivors that managed to live long enough and have flowers and produce nuts again. The thing is most of them die before they get to be knee high.

HARRIS: Every fall, he and others carefully cross-breed the native trees with their blight-resistant cousins. They plant some of them here in this test orchard at the Catawba Sustainability Center.

ABSHER: That's the purpose of this little orchard here - is to determine which ones are resistant.

HARRIS: Two-year-old hybrid saplings are now several feet high. Some have the shorter, wider characteristic of the Chinese variety. And others are taller and thinner like the American forests of old.

ABSHER: The hybrids that we're looking to produce - we want them to be indistinguishable from the American tree. We want their characteristics to be like an American chestnut. They're still going to be - a sixteenth of their genes are Chinese genes.

HARRIS: It's those Chinese genes that confer blight resistance on the hybrids growing here.

ABSHER: Out of all these 150, we maybe will get at most a half a dozen to go on to the next stage of the breeding.

HARRIS: Breeding trees this way takes dedication and patience, inoculating each one with a blight fungus to see if it's immune, then waiting years for each new generation to grow to see if they would be ideal for cross-breeding. Scientists at Virginia Tech recently began genetic sequencing of the hybrids. Jason Holliday teaches forest genetics and biotechnology.

JASON HOLLIDAY: So if we can develop a genomically - if that's a word - informed model that will tell us about blight resistance without having to actually grow the trees, that'll be very helpful and definitely more cost-effective.

HARRIS: Preliminary results suggest the model is holding up. And Holliday says it will soon be applied to test orchards up and down the East Coast. That pleases Jared Westbrook. He's the science director of the American Chestnut Foundation in North Carolina. And now he's contemplating something that for so long seemed so far off.

JARED WESTBROOK: Now what motivates me to work on the chestnut is it's symbolic. We can actually use breeding and biotechnology to take a tree that's functionally extinct and bring it back to life.

HARRIS: Westbrook says if this can be done with the American chestnut tree, it should be possible with other threatened species like the hemlock, the elm and the ash. For NPR News, I'm Robbie Harris in Blacksburg, Va.

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