Chestnut tree poised for comeback
A hybrid, 25 years in the making, is designed to resist a devastating blight.
WRENTHAM, MASS. — Tromping through a Massachusetts state forest, Brad Smith spots an old stump with dead shoots and one lone, green sprout – a sad but not uncommon remnant of a once-proud species – the American chestnut tree.
Except for a few mature trees, the species has struggled for 50 years to survive. It does that in the same way: Stumps send up sprouts that are quickly attacked by the same invasive blight that wiped out about 3.5 billion chestnut trees between 1904 and 1950.
"What you're seeing is the former king of the forest reduced to surviving as a mere shrub," says Mr. Smith, president of the Massachusetts chapter of the American Chestnut Foundation (ACF).
Now, however, an American chestnut revival may be imminent. Scientists using traditional plant breeding techniques are on the verge of a breakthrough. In fact, Smith smiles and shares a little secret: the "holy grail" of American chestnut trees – a hybrid supertree fully resistant to the blight – is alive and growing down south.
Hidden on a country road that winds through rural Meadowview, Va., is a 93-acre plot of ground that holds the future of the American chestnut: about 120 hybrid saplings. The trees – going on two years old and four feet tall – are considered "fully blight resistant" and are thriving.
At this rate, by 2010 there should be enough "holy grail" nuts to begin planting in selected test sites in national forests. By 2015, production from such plots is expected to grow exponentially – yielding enough nuts to allow for full-blown replanting – if everything goes well.
Cross-breeding American chestnut trees is a challenge because they do not produce fruit until their sixth year. Researchers have spent 25 years breeding resistant Chinese varieties of chestnut with nonresistant American versions – then "back-crossing" or breeding resistant American chestnuts with one another. It's a difficult project that the US government attempted but dropped long ago.
Restoring the species to its former glory has been the life's work of Fred Hebard, whom some regard as the American chestnut tree's Johnny Appleseed. What he's growing on his research farm in Meadowview is a tree now 15/16ths American chestnut that will grow tall and true, with 1/16 Chinese chestnut resistance.
"We're starting to produce the critical generation of fully resistant chestnut, the one we intend to release into the woods," he says. "Within three to five years we hope to begin putting out large numbers of trees, maybe 10,000 of them."
Known as the "sequoia of the East," the American chestnut was once dominant in forests from Maine to Florida, a majestic giant that easily grew four feet across, 120 feet high and lived for centuries. Its nuts were an important source of food for animals and humans and its rot-resistant wood prized by timber and furniture companies.
It's taken Dr. Hebard 18 years of painstaking hybridization to get to this point of having several hundred fully blight-resistant trees. Before him, predecessor Charles Burnham began the work in 1983.
Earlier this year, about 2,000 partially blight-resistant American chestnuts were planted on reclaimed mine land. Those trees may not survive beyond about six or seven years because they are not blight resistant. Even so, the effort will enable researchers to better understand growing conditions on such land.
Trials of the fully resistant American chestnut are expected within three years, when the ACF and the US Forest Service expect to plant thousands of the best of the "holy grail" seeds in two forests – in Kentucky and West Virginia – the heart of the chestnut's domain. About that same time, members of the ACF will also begin receiving seeds for planting.
Indeed, 13 state ACF chapters, whose orchards maintain about 40,000 partially resistant chestnut trees, will play a vital role in the chestnut restoration. Smith's Massachusetts chapter, like the others, is growing small orchards of the trees, slowly doing their own hybridization programs. Pollen from the best trees will be sent from Virginia to ACF chapters to accelerate development of varieties well-suited to regional weather and soil.
One new problem the foundation is facing isn't blight, but keeping the seeds from being sold on eBay for fat profits.
"Everybody and his cousin wants these seeds, but we've got to be real careful about naming it and what we're going to claim about [the trees' capabilities]," says Paul Sisco, a co-architect of the recovery plan with Hebard. "We won't really know how good it's going to be until about five years from now."
In fact, a tree labeled "fully blight resistant" may still contract the blight, but it should be able to ward off the fungus altogether.
Other groups, such as the American Chestnut Cooperators Foundation, are taking different approaches to breeding. Some hold out hope for a direct genetic-engineering fix, although that task is daunting because the tree's genes have not been sequenced.
"We are planting the hope, and making a commitment, that this noble hardwood will be restored to the American landscape and its vital ecological role in our nation's forests," Dirk Kempthorne, US Secretary of the Interior, said on July 26.
Today when consumers buy chestnuts for "roasting by an open fire" during the holiday season, they come from the Asian chestnut and other varieties that resist blight. But now it looks as if the American version could return one day. "I'm looking forward to growing a really big one in my backyard," Smith says.