Resurrecting a tree species is not for the impatient.
It’s been more than two decades since I first encountered efforts in New Hampshire to bring back the American chestnut, a magnificent tree that filled Appalachian forests until a blight wiped it out in the early 20th century. It was an established concern back then and it still is today.
Since at least 1989, when a research farm was established in Virginia, people throughout the Eastern U.S. have carefully collected nuts and pollen from the few American chestnut trees that survive long enough to flower before succumbing to the fungus. These are used to build up orchards of trees – five orchards exist in New Hampshire and Vermont alone, including one that opened in Epping last year and one planted in Windsor, Vt., on June 11 – that are cross-bred with each other and with Chinese chestnut trees, which are naturally resistant to the blight.
The idea is to create a tree that looks and acts American – big, fast-growing, with rot-resistant wood and huge nut production – but has a Chinese immune system. Sounds good but, as I’ve noted before, this attempt to speed up evolution has been disappointing.
“Crosses with American chestnut to build American character back into the cross failed to preserve the full effect of Chinese resistance and the further it goes, it seems the less resistance the tree has,” said Evan Fox, the new president of the VT/NH Chapter of The American Chestnut Foundation, the organization shepin herding most efforts. “If we built back a fully American tree, we’d lose the resistance. We’d have a little here and there but it’s not going to protect the tree … to create a tree that could be used to repopulate the Appalachians.”
Enter the biotech option.
Researchers at State University of New York College of Environmental Science and Forestry in Syracuse have created an American chestnut carrying a new gene common in grasses that neutralizes the fungal toxin, rendering the blight harmless.
Called Darling-58, this strain is being raised while the U.S. Department of Agriculture determines whether it should be the first genetically-modified tree to be released into the wild. A ruling is expected by summer 2023.
A University of Maine researcher is pursuing a similar idea, importing a gene from wheat to create what he hopes will be a resistant American chestnut.
As you might expect, bringing genetic modification into the mix isn’t everybody’s cup of tea. The American Chestnut Foundation saw some high-profile resignations when it decided to support that line of research, and a group is trying to get USDA to block the release of any GMO tree, arguing that the possible danger is too great.
(For what it’s worth, I think we should risk it because of the growing list of dangers to our forests – you may have read my column recently about how biocontrol efforts won’t save our ash trees.)
Even if the USDA gives a thumbs-up, Darling-58 trees will have to be spread out to see how well they actually do when competing with other species in the woods.
“That gene requires some energy from the tree, that civil war that goes on inside the tree (neutralizing the toxin) does sap a little bit of energy from the tree,” said Fox. “The question is, how opportunistic will it be in the canopy?”
Maybe Darling-58 and other genetic variants will be so weakened by fending off the blight that they’ll never thrive in the wild, remaining little more than a curiosity on town greens. Or maybe they’ll take up where the American chestnut left off 120 years ago, muscling their way back into the woods. We won’t know until we try.
Then there will be discussion about how exactly to take advantage of the limited production of nuts and pollen. Scatter them widely? Focus on most likely environments first? (Although with climate change, who knows what an environment will be like when a tree reaches maturity.) Cross-breed exclusively with the least bad of pure American trees? Cross-breed with the more numerous but less desirable Chinese-American hybrids? Something else?
Expect that debate to fill the air among members of the local chapter of the Chestnut Foundation.
Speaking of which, the Vermont-New Hampshire chapter of the group is quite active, including handing out free American chestnuts that can be planted.
The trees will get the blight and die but might live long enough to produce some flowers, and then if a resistant version comes along you’ll have a backyard tree to cross it with! Check it out at acf.org/vt-nh.
In the meantime, I remember Ecclesiastes 9:11 – “The race is not to the swift – and take solace that even if I never see mature chestnuts my woodland rambles, there’s a chance that others will.”