Georgia chestnuts will need more than blight resistance

hduncan@macon.comDecember 23, 2012 

One down, one to go.

The American Chestnut Foundation has worked for decades to develop a blight-resistant chestnut tree with American characteristics that could be planted in the wild. They believe they’ve now achieved that goal.

But although the blight wiped out most of the giant trees that once dominated Georgia’s forests, it was actually the second wave of the foreign attack.

In Georgia’s Piedmont region, with its warm weather and lower elevation, many chestnuts were killed off by root rot during the 1800s before the blight even arrived. And Clemson University researchers have found that the new hybrid chestnuts remain very susceptible to root rot.

So the American Chestnut Foundation is just beginning the process of selecting plants to breed for root rot resistance, with the intent of making chestnuts resistant to both of its most devastating threats, the foundation’s director of operations told a large group of Georgia foresters in Macon recently.

Jeff Donahue, who heads up the chestnut breeding program for the foundation in Virginia, updated Georgia Forestry Commission foresters about progress at restoring chestnuts to the Eastern forests.

Foresters asked many questions about root rot, and Donahue asked them to help identify surviving American chestnuts in the Georgia woods. These foresters, who provide guidance to private forest owners, would likely be on the front lines of spreading the species.

Scott Griffin, a commission staff forester in Gainesville, told foresters that the commission planted a test orchard of chestnuts near Dawsonville this year, finding the site suitable for a large planting of the new, blight-resistant hybrids in fall 2013.

“We’re excited about the possibility of getting some of those seedlings,” he said. “Hopefully, if it got to where (chestnuts) had blight and root rot resistance, we’d work with landowners and researchers on how to establish it in the wild.

“It can be difficult to establish a slower-growing tree in the forest, but what we learn at that orchard could be part of the answer.”

However, Donahue told foresters that although the “Restoration 1.0” chestnut has been bred for blight resistance, “a good amount of seed coming out of these orchards is still not resistant.”

This first generation released for wild planting probably has an intermediate resistance to blight, said Martin Cipollini in an earlier interview. Cipollini is a Berry College professor who coordinates the Georgia chestnut breeding program for the Georgia chapter of the American Chestnut Foundation.

He explained that scientists used parent trees with varying amounts of blight resistance -- not just the most resistant ones -- to try to broaden the gene pool and prevent the pitfalls of inbreeding.

“The hope is that they’ll breed with wild chestnuts and capture their genetic diversity,” he added.

Dozens of Georgia sites

Although the national foundation has been working on its “restoration chestnut” for decades, Georgia’s own foundation chapter is working on its own regional chestnut lines, too. It crosses the American Chestnut Foundation hybrid trees with surviving Georgia chestnut trees like the ones at Pine Mountain, Cipollini said.

The state program is 5 to 10 years away from having its own blight-resistant chestnut with genetic material from Georgia trees, he said.

“In Georgia we have 100 or more sites where we’ve planted chestnuts, including hybrids,” he said. Among them was a demonstration planting of South Carolina chestnuts last year on the Dry Branch farm owned by Rolling Stones keyboardist Chuck Leavell.

In addition, Georgia is already home to two large plantings of the foundation’s restoration chestnut trees, Cipollini said. The first, near Lake Allatoona, includes 500 trees. A second was planted near Blairsville in November. The North Georgia planting included about 700 trees, said Tom Saielli, Southern Regional Science Coordinator for the American Chestnut Foundation.

These plantings will be monitored to keep tabs on their success, but they’ll be allowed to survive or fail on their own, Donahue said.

Georgia scientists are helping preserve the hybrids so their genetic material remains available even if they do struggle initially in the wild. Scott Merkle at the University of Georgia said he has cloned some of the new restoration chestnut genetic material, and the cloned plants are growing in pots now.

Merkle’s lab became part of the Forest Health Initiative in 2009, which focuses on genetic work instead of breeding. The initiative has accelerated work on identifying blight-resistant genes and inserting them into American chestnuts.

The initiative is funded by Duke Energy, the U.S. Forest Service, and the U.S. Endowment for Forestry and Communities, which provided Merkle’s lab with $1 million over three years. Merkle said he is in the process of applying for renewed funding now.

Some of the trees with genes inserted for blight-resistance have been planted in a test orchard in Athens, he said, but trees with the most promising genes will probably move outside the greenhouse for the first time next year.

The initiative also seeks to understand whether people will accept these transgenic chestnuts and how the federal approval process for them would work. Eventually, cloning techniques could allow commercial timber companies to generate enough seeds to plant 1 billion trees a year, Merkle said.

“Restoration 1.0” is a big step forward, but success remains unclear.

“It’s not over,” Cipollini said. “The goal is to restore the American chestnut to its native range. … The goal is not, and never has been, to generate a perfect tree and everyone can plant it in their backyard.”

The bigger issue, he said, is whether restoration can truly be sustained.

“If this organization can pull this off, it could be a template for the recovery of other species” such as hemlocks, which are being wiped out by an Asian bug.

The Associated Press contributed to this report. To contact writer S. Heather Duncan, call 744-4225.

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