Rescuing the American Chestnut

MYRNA BROWN, HOST: Today is Thursday, November 3rd. Thank you for turning to WORLD Radio to help start your day. Good morning. I’m Myrna Brown.

MARY REICHARD, HOST: And I’m Mary Reichard. Coming next on The World and Everything in It: conservation. Myrna, what comes to your mind when I say the word: “extinction”?

BROWN: The Dodo Bird, dinosaurs, or the black rhinoceros...

REICHARD: Well, extinction faces more than just the animal kingdom. Entire plant species can die out as well. The American Chestnut was one of the most common hardwood trees in the eastern United States before the early 1900s. But a fungus choked out billions of them and killed those trees.

BROWN: But, all is not lost. Scientists are working to rescue the American Chestnut and hope to bring the tree back to Eastern forests. WORLD’s Paul Butler has our story.

AUDIO: [MEADOWVIEW SOUNDS]

PAUL BUTLER, REPORTER: Vasiliy Lakoba looks every bit the forester—a full beard, slight tan, and strong, rough hands. He wears a dark blue ball cap that matches his untucked checkered shirt. He’s clearly at home in the woods.

LAKOBA: This is what a clean, disease-free American chestnut stem, you know, the bark looks like. And then you look just further down below, just a tiny little bit, and this is a canker from the blight.

Lakoba is research director for the American Chestnut Foundation laboratory farm in Meadowview, Virginia. The canker Lakoba’s pointing at is a visible sore on the tree. The lacerated bark looks almost like the tree is slowly exploding from the inside.

LAKOBA: Essentially, the limb is dying. And if you look further up the limb, all those leaves are dead…This is a pretty advanced stage of the disease. The limb is girdled.

Girdled—meaning completely encircled. The blight is choking everything in the tree at that point. When the branch dies, the leaves die, and that branch won’t flower or bear chestnuts. Then death works its way down the branch and trunk.

The blight is caused by a pathogenic fungus: cryphonectria parasitica. Before 1904, it was unknown in the United States.

LAKOBA: At the very early part of the 20th century, it came in on other plants that are able to host that…fungus.

The trouble started when the New York Zoological Garden imported a chestnut species from Japan: the fungus a stowaway on the trees.

LAKOBA: And after its discovery, it spread throughout the eastern United States and the Southern part of Canada very, very quickly, and within just a matter of years the American chestnut was decimated on this continent.

The American chestnut was in many ways the tree that built Colonial America.

LAKOBA: For human populations, it was a major timber species that fueled the construction of many cities throughout North America and also used for other types of goods.

Its straight grain, rot resistance and light weight made it an ideal building material. It was everywhere…from fence posts and flooring, to caskets and even eventually telegraph poles. It also provided crucial foraging for wildlife, livestock, and people.

LAKOBA: And for the wildlife of our continent, it was an enormously important food source, both in terms of the seeds and the leaves for smaller biota.

But within about 50 years time, the fungus spread from New York—up and down the eastern coast—from Maine to the Mississippi. The blight killed an estimated 4 billion Chestnut trees. Many dead trunks still stand tall in these forests.

AUDIO: [SOUND OF LAKOBA ENTERING LAB]

LAKOBA: This is a culture of the fungus that causes the chestnut blight.

In the lab, Lakoba holds a petri dish of the fungus. He and his fellow conservators at The American Chestnut Foundation are part of a long-term project to develop a blight-resistant American chestnut tree.

LAKOBA: We use this to give the disease to the trees so that we can test whether they're blight resistant or not.

For more than 30 years the foundation and its partners have been using traditional plant breeding techniques used with food crops to introduce blight resistance to the species.

LAKOBA: So these are 50% Chinese chestnut, 50% American chestnut.

The Chinese chestnut is naturally resistant to blight. After three generations of cross breeding, the Virginia test farm features two seed orchards with promising results.

Besides the breeding program, there is another approach: genetic engineering.

LAKOBA: We are working with our collaborators at the State University of New York College of Environmental Science and Forestry, with the transgenic chestnut project that they have developed.

The most effective introduced gene so far actually comes from wheat. The enzyme breaks down oxalic acid—the primary weapon the blight fungus uses against the chestnut trees.

AUDIO: [SOUND OF LAB]

Technicians at the laboratory farm test the new tree variety’s resistance to the blight fungus using young trees and saplings.

LAKOBA: Rather than waiting many years to see how they respond to the disease, what we do is we cut off the tops of the plants and place the fungus that causes the disease right on top.

Lakoba stands in front of two different specimens in one of their greenhouses.

LAKOBA: This stem in your right has only a little bit of symptoms right at the tip here, and so that indicate to us that this stem a good deal more blight resistance and might have better prospects for chestnut restoration.

Researchers are currently involved in a government mandated longitudinal safety study—to make sure the hybrids and genetically modified trees don’t create ecological or health effects of their own.

In the meantime, the original American chestnut hasn’t completely died out. Blight can’t kill the underground root system. So stump sprouts can regrow under certain conditions. But the new sprouts have a limited life-span as they will inevitably give-in to the blight as well—meaning the tree species is considered functionally extinct.

If the government approves the new American Chestnut trees, there’s still a lot of work to do.

LAKOBA: The huge range that it used to occupy in eastern North America, spanning from Mississippi to Maine and Ontario, is not something that we're going to be able to replant just with our own manual efforts.

Vasiliy Lakoba hopes to someday see his work reintroduce this American giant into our nation’s forests.

LAKOBA: It's going to start with a growing number of reintroduction populations that we plant and manage and allow them to reach maturity and hopefully reproduce. Because after a while, it's going to be important that those restoration populations are self-sustaining.

For WORLD, I’m Paul Butler.

* audio interview courtesy of AFP Forum

MYRNA BROWN, HOST: Today is Thursday, November 3rd. Thank you for turning to WORLD Radio to help start your day. Good morning. I’m Myrna Brown.

MARY REICHARD, HOST: And I’m Mary Reichard. Coming next on The World and Everything in It: conservation. Myrna, what comes to your mind when I say the word: “extinction”?

BROWN: The Dodo Bird, dinosaurs, or the black rhinoceros...

REICHARD: Well, extinction faces more than just the animal kingdom. Entire plant species can die out as well. The American Chestnut was one of the most common hardwood trees in the eastern United States before the early 1900s. But a fungus choked out billions of them and killed those trees.

BROWN: But, all is not lost. Scientists are working to rescue the American Chestnut and hope to bring the tree back to Eastern forests. WORLD’s Paul Butler has our story.

AUDIO: [MEADOWVIEW SOUNDS]

PAUL BUTLER, REPORTER: Vasiliy Lakoba looks every bit the forester—a full beard, slight tan, and strong, rough hands. He wears a dark blue ball cap that matches his untucked checkered shirt. He’s clearly at home in the woods.

LAKOBA: This is what a clean, disease-free American chestnut stem, you know, the bark looks like. And then you look just further down below, just a tiny little bit, and this is a canker from the blight.

Lakoba is research director for the American Chestnut Foundation laboratory farm in Meadowview, Virginia. The canker Lakoba’s pointing at is a visible sore on the tree. The lacerated bark looks almost like the tree is slowly exploding from the inside.

LAKOBA: Essentially, the limb is dying. And if you look further up the limb, all those leaves are dead…This is a pretty advanced stage of the disease. The limb is girdled.

Girdled—meaning completely encircled. The blight is choking everything in the tree at that point. When the branch dies, the leaves die, and that branch won’t flower or bear chestnuts. Then death works its way down the branch and trunk.

The blight is caused by a pathogenic fungus: cryphonectria parasitica. Before 1904, it was unknown in the United States.

LAKOBA: At the very early part of the 20th century, it came in on other plants that are able to host that…fungus.

The trouble started when the New York Zoological Garden imported a chestnut species from Japan: the fungus a stowaway on the trees.

LAKOBA: And after its discovery, it spread throughout the eastern United States and the Southern part of Canada very, very quickly, and within just a matter of years the American chestnut was decimated on this continent.

The American chestnut was in many ways the tree that built Colonial America.

LAKOBA: For human populations, it was a major timber species that fueled the construction of many cities throughout North America and also used for other types of goods.

Its straight grain, rot resistance and light weight made it an ideal building material. It was everywhere…from fence posts and flooring, to caskets and even eventually telegraph poles. It also provided crucial foraging for wildlife, livestock, and people.

LAKOBA: And for the wildlife of our continent, it was an enormously important food source, both in terms of the seeds and the leaves for smaller biota.

But within about 50 years time, the fungus spread from New York—up and down the eastern coast—from Maine to the Mississippi. The blight killed an estimated 4 billion Chestnut trees. Many dead trunks still stand tall in these forests.

AUDIO: [SOUND OF LAKOBA ENTERING LAB]

LAKOBA: This is a culture of the fungus that causes the chestnut blight.

In the lab, Lakoba holds a petri dish of the fungus. He and his fellow conservators at The American Chestnut Foundation are part of a long-term project to develop a blight-resistant American chestnut tree.

LAKOBA: We use this to give the disease to the trees so that we can test whether they're blight resistant or not.

For more than 30 years the foundation and its partners have been using traditional plant breeding techniques used with food crops to introduce blight resistance to the species.

LAKOBA: So these are 50% Chinese chestnut, 50% American chestnut.

The Chinese chestnut is naturally resistant to blight. After three generations of cross breeding, the Virginia test farm features two seed orchards with promising results.

Besides the breeding program, there is another approach: genetic engineering.

LAKOBA: We are working with our collaborators at the State University of New York College of Environmental Science and Forestry, with the transgenic chestnut project that they have developed.

The most effective introduced gene so far actually comes from wheat. The enzyme breaks down oxalic acid—the primary weapon the blight fungus uses against the chestnut trees.

AUDIO: [SOUND OF LAB]

Technicians at the laboratory farm test the new tree variety’s resistance to the blight fungus using young trees and saplings.

LAKOBA: Rather than waiting many years to see how they respond to the disease, what we do is we cut off the tops of the plants and place the fungus that causes the disease right on top.

Lakoba stands in front of two different specimens in one of their greenhouses.

LAKOBA: This stem in your right has only a little bit of symptoms right at the tip here, and so that indicate to us that this stem a good deal more blight resistance and might have better prospects for chestnut restoration.

Researchers are currently involved in a government mandated longitudinal safety study—to make sure the hybrids and genetically modified trees don’t create ecological or health effects of their own.

In the meantime, the original American chestnut hasn’t completely died out. Blight can’t kill the underground root system. So stump sprouts can regrow under certain conditions. But the new sprouts have a limited life-span as they will inevitably give-in to the blight as well—meaning the tree species is considered functionally extinct.

If the government approves the new American Chestnut trees, there’s still a lot of work to do.

LAKOBA: The huge range that it used to occupy in eastern North America, spanning from Mississippi to Maine and Ontario, is not something that we're going to be able to replant just with our own manual efforts.

Vasiliy Lakoba hopes to someday see his work reintroduce this American giant into our nation’s forests.

LAKOBA: It's going to start with a growing number of reintroduction populations that we plant and manage and allow them to reach maturity and hopefully reproduce. Because after a while, it's going to be important that those restoration populations are self-sustaining.

For WORLD, I’m Paul Butler.

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