Creating a blight resistant strain is the goal of conservationists
By Rachael Scarborough King, Register Staff
March 24, 2008
GUILFORD — Walk around the forests and parks of Connecticut, and you won’t see many American chestnut trees stretching into the canopy.
One hundred years ago, blight killed as many as 4 billion of the trees, which were once common from New England to western Tennessee.
The blight, a fungus that was imported to the U.S. on Asian trees, all but wiped out the American chestnut in the early 20th century.
Now, Guilford’s Conservation Commission, along with the Connecticut Chapter of the American Chestnut Foundation, is working to establish a blight-resistant chestnut tree in a 1½-acre orchard in the town’s Nut Plains Park.
The commission is planning to spend two Saturdays in April building a fence to protect the trees from deer, and another Saturday in May planting the first 100 nuts. There is also a kickoff event March 29 at 10 a.m. at the Nathanael B. Greene Community Center to introduce the project to town residents.
Last year, volunteers planted about 20 trees as a test orchard, which proved successful. Eventually, they may sow 400 to 500 of the blight-resistant nuts in the area.
“There were billions of trees, billions of chestnut trees in the Eastern states in the 1800s,” said Jennifer Allcock, a member of the Conservation Commission and orchard manager for the tree project. “They were a primary source of food, both for animals and for people, and the chestnut wood is one of the hardest, most durable that was available.”
Since 1983, the American Chestnut Foundation has been working to establish a species of blight-resistant chestnuts by crossbreeding American trees with Chinese chestnuts, which are naturally resistant. The nuts that will be planted in Guilford are a result of that process, with about 94 percent American genes.
The goal is to produce trees that look like American chestnuts — tall and straight, with hard, lightweight wood — but “breed true” for blight resistance, meaning that future generations of chestnuts will also carry the resistant gene. Bill Adamsen, the president of the Chestnut Foundation’s Connecticut chapter, said that some American chestnuts can still be found in the Eastern United States, although most of them eventually develop blight.
Adamsen said the strong, rot-resistant chestnut wood was important for early colonists, who used it to build barns, houses and bridges.
“This is a tree that we allowed to be killed essentially by inadvertently importing a pathogen, and I think there’s a certain cultural and even a spiritual aspect about trying to restore something that we have damaged,” he said.
To create a blight-resistant American chestnut tree, scientists at the foundation’s research farms first cross-bred native trees with Chinese ones, creating a plant that had half of each tree’s genes. They then continued to breed the resulting trees with American chestnuts, arriving four generations later at a tree that is about one-sixteenth Chinese.
Volunteers in Guilford are planning to plant about 100 of those nuts in the orchard this spring. Leila Pinchot, New England regional science coordinator for the American Chestnut Foundation, said that not all of the fourth-generation trees will be resistant to the blight. The ones that are resistant will be allowed to cross-pollinate, and by the sixth generation most of the trees should be highly resistant.
After the trees have matured — which takes four to seven years — they will be exposed to the blight to test for resistance. Adamsen said the group expects that one out of every eight trees will be resistant to the blight.
The blight, which kills the trees’ tissues and blocks the flow of nutrients, does not kill the underlying roots, Pinchot said. That means that many tree stumps sprout new saplings, but they may not grow old enough to flower, which is necessary for the pollination process.
“There’s probably millions of chestnuts in Connecticut, but most of them are pretty scraggly,” said Pinchot, a Guilford native. “They’re pretty much all going to eventually succumb to the blight — it’s a matter of time.”
Nuts from one of the trees the American Chestnut Foundation used in the breeding process come from a hybrid that a Yale professor, Arthur Graves, established in Hamden in the 1930s, Pinchot said.
“Connecticut actually has a really long history with chestnut restoration,” she said. “It’s better to have Connecticut genes in our trees.”
Guilford’s will be the fifth American chestnut orchard in Connecticut. In Woodbridge, volunteers planted 168 nuts two years ago and more last year. Some of the trees there are now 4 feet tall.
Orchard officials in Woodbridge are planning another planting of 170 nuts this spring. Each round of planting uses nuts bred from a different “mother tree,” Pinchot said, so that this will be the third line of chestnuts in the Woodbridge orchard.
Allcock said the Guilford program is costing about $8,000, most of which will go toward paying for the 1,200-foot deer fence. The money comes from the American Chestnut Foundation, the town of Guilford, and the Guilford Foundation, which funds community programs.
The Conservation Commission is looking for volunteers to help put up the fence and sow the first chestnuts. They are planning to work on the fence on April 19 and 26, and plant on May 3.
“The deer fence … needs to be put up around the orchard before we start,” Allcock said. “That is expected to help us manage the orchard for the first two years — after that the trees know what to do.”
For more information on the project, visit the Web site of the American Chestnut Foundation’s Connecticut chapter at http://www.ctacf.org.