Podcast

Restoring the American Chestnut Tree

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The American Chestnut tree still lurks in our landscape and the American Chestnut Foundation is working hard to restore it as king of our eastern forests.Super Sod Logo
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Thanks to Super Sod for making this episode possible.

SISCO

There’s actually probably 4 million chestnut trees still alive in the state of North Carolina in the mountains.

JENKINS

4 million trees is nothing compared to the billions of chestnut trees that once dominated our forests.  But still, I was surprised to discover a chestnut tree this summer in Blowing Rock. The story of the American chestnut tree and it’s fate is one of ignorance and now possibly, redemption.

I’m Lise Jenkins and this is the Triangle Gardener show. We’re your guide to enjoyable gardening in North Carolina. Thanks to Super Sod for making this story possible.

Super-Sod is one of the South’s largest producers of turfgrass sod and seed, including TifTuf Bermuda and Leisure Time and Zenith Zoysias. If your shade trees are making it difficult to grow grass, ask about their more shade tolerant sod varieties. Stop by either of their convenient Triangle locations – at the Raleigh Farmers Market, or at 1900 NC Highway 55 in Cary – and let the Super-Sod experts help your lawn and garden thrive.

JENKINS

The American chestnut tree, soaring over 100 feet tall, was the dominant tree of our eastern forests.  Then shortly after the Civil War a New York plantsman imported Asian chestnuts and began propagating and marketing them.  The Asian trees were smaller and for thirty years these trees were introduced into gardens, estates, and public settings along the east coast.

Problem was these Asian natives harbored a fungus which they had co-evolved with and developed a resistance to. But our American trees —they were vulnerable. A small fungus toppled the giants of the American forest. Millions of trees were clear cut in an effort to stop the lethal virus. It didn’t work and by the 1930s the American chestnut tree had receded from view. But there’s some people who are determined to change that and bring the American chestnut back to our landscape.

SISCO

My name is Paul Sisco, I’m a retired geneticist with the American Chestnut Foundation now living in Asheville, NC where our headquarters are.

JENKINS

Dr. Sisco gave me a little tutorial on the efforts to develop a blight-resistant chestnut tree that can be re-introduced to our forests. He explained how the process works.

SISCO

There’s several different strategies being used to restore the American chestnut tree which I think is great because one, or a combination of them, is very likely going to work. The first strategy is to breed in resistance from the Asian species. The Chinese and Japanese cross easily with the American chestnut tree to make a hybrid tree.  Starting base as early as the 1920s and 30s both amateurs and the US government did this systematically.

Then the second part of the program was to intercross those distant cousins that had moderate resistance to bring up the resistance to high resistance. Then the second part of the program was to intercross those distant cousins that had moderate resistance to bring up the resistance to high resistance.  So think of it as a two step program.  The first part of the step which was four generations to make it more and more American by crossing to American each time.  Each time selecting for that moderate resistance that you get in a hybrid and then the last generation you take two distantly related cousins that have been crossed through a different series of ACT and so they’re not closely related, but they each have moderate resistance.  And when you intercross something with moderate resistance to another with moderate resistance you hope to get then high resistance. I call it like crossing two pinks to get a red.

JENKINS

Dedicated breeders had been working to develop a tree which has the resistance of the Asian varieties but is 15/16ths American chestnut. Breeding trees takes time. But Dr. Sisco explained that it’s not quite the timeline I had imagined.

SISCO

With good care and fertilization chestnuts can bloom fairly early. Some of the Chinese varieties actually bloom their second year.  I had one American chestnut tree that I gathered front the mountains and planted at the NC State Mountain Research Station that actually bloomed the first year after I planted it. So they are somewhat precocious which means they bloom early in their life cycle. With good fertilization we can get most them blooming after four years. At that point we are also screening them for blight resistance. Again, the initial ones have moderate resistance then we make the crosses. So a generation takes about six years.

JENKINS

The American Chestnut Foundation has been collaborating with a network of scientists and breeders for over 30 years. They believe they will soon have a blight-resistant tree that can survive in the wild.  Working with Boy Scout, Master Gardeners, and other community groups American chestnut tree trials are being planted in locations throughout Appalachia. But our landscape is very different from what it was when the American chestnut dominated the forest. And I wondered how reintroducing it into the wild worked. Dr. Sisco explained.

SISCO

Of course this is a question you get all the time. “Okay you’ve got the perfect tree. How are you going to re-introduce it into the woods and get 4 billion trees back?” Which is what they were before the blight. The best strategies we have, in my opinion, is planting on reclaimed surface mine lands.  There’s large areas of Appalachia which are in the same region where Chestnuts were dominate, which have been made moon scapes by surface mining. Where coal has been stripped mined and then the land is left barren.  There’s money from the coal companies to reforest these strip-mined lands. So that provides money. There’s huge acreage which have nothing green whatsoever.  They are somewhat acid in soil and the chestnut is especially adapted to acid soil.  So this, to us, is an ideal place where we can reintroduce a lot of chestnut trees at one time.  Not only helping our program by reintroducing a tree, but also restoring an environmental disaster of these strip-mined areas.  To me, that’s a win-win situation. We have a fairly large program to do that.

JENKINS

The fungus which caused the chestnut blight is counteracted by organisms in the soil. So while the fungus girdles the tree killing it from that point up it doesn’t kill its roots. Where chestnut trees roots remain in the ground they continue to send up sprouts.  They live a few years and then the fungus attacks them and they die back only to return and try again.

SISCO

There’s actually probably 4 million chestnut trees still alive in the state of North Carolina in the mountains. But they’re all root systems, small spouts that come up, catch the disease, die back, sprout up, catch the disease, and this is a cycle that keeps going.

JENKINS

I was surprised to discover a small chestnut tree while I was in Blowing Rock this summer.  You can just barely see the outline of the base of what was once a huge tree and above ground are three slender trunks. This got me thinking about the American Chestnut Foundation’s replanting efforts.  They have begun to distribute seedlings. So I had to ask if I could plant a chestnut tree.

SISCO

If you have a large garden you can plant a chestnut tree.  It just depends on the size of your property.  If you can plant an oak tree you can probably plant a chestnut tree. They will spread out a bit when they are in the open sun but otherwise they’ll tend to go straight up.  So again, if you can plant an oak, which I did on my little third of an acre, you can plant a chestnut tree.

JENKINS

As I look across the horizon the tallest thing I see is a cell phone tower.  It’s dressed up to look like a pine tree so I try to imagine a chestnut tree in it’s place. While I might not live to see the American chestnut dominating our forests as it once did I do believe I will live to see it creep out from the shadows. Over 100 years ago our actions knocked this giant off it’s throne but through hard work and dedication we may find redemption yet.

I’m Lise Jenkins and this is the Triangle Gardener show. We’re your guide to enjoyable gardening in North Carolina.  You can find this and other episodes of our podcast on iTunes or our website TriangleGardener.com   Thanks for listening.