The Great American Chestnut Revival: How science is bringing chestnuts back to American soil

Illustration by Joel Hedstrom

Anyone who has ever come across a raw, wild chestnut—burr intact—will likely remember the experience. My first encounter came while hiking the Camino de Santiago, an ancient pilgrimage route in northern Spain. I entered a stretch of the path where elder chestnut trees—some nearing a thousand years of age—act as anchors for the rigorous journey. I identified them by their spiky burr-wrapped nuts, which resemble fist-sized porcupines: adorable but painful. 

I had plenty of time to reflect on the journey: imagining the pilgrims of old who would have eagerly collected the bountiful nuts for boiling, roasting, and grinding into flour; nourishing the dedicated thru-hikers along the way. How was it that I had never seen raw chestnuts before? Aren’t we all supposed to be roasting them over open fires? 

In the United States these once-ubiquitous trees were considered the “Redwoods of the East,” regularly measuring 8–10 feet in diameter and reaching 100 feet into the sky with their strong and rot-resistant wood. Across Appalachia, the American chestnut was used for food, fuel, and the construction of everything from barns to caskets. 

Once a true staple of the Eastern forest, mighty American chestnuts are now few and far between, almost impossible to find in their pure form due to a fungal pathogen called Cryphonectria parasitica. It infects chestnuts and produces oxalic acid, which causes the tree cells to burst—oozing out nutrients for the fungus to consume. For the tree, this infection is devastating and absolute; in the first half of the 20th century, nearly 4 billion American chestnut trees succumbed to chestnut blight.

American Chestnut // Illustration via U.S. Department of Agriculture Pomological Watercolor Collection. Rare and Special Collections, National Agricultural Library, Beltsville, MD 20705

The fungus arrived on North American shores hidden away in nursery stock of chestnut trees imported from East Asia, then favored for garden cultivation due to their more shrubby growth habit. Asian chestnut species co-evolved with C. parasitica, so they carry a natural immunity to the fungal blight. The American chestnut, sadly, was extremely susceptible to the hungry fungus and as its spores traversed the eastern seaboard on wind and water, it wiped out nearly every mature chestnut in its path.

The fungal blight made its way to Europe too, but the majestic stalwarts on that continent have fared better than their North American counterparts. There, the oldest look tired but strong; though twisted and weathered, they persevere. In part, this is because of an early discovery of CHV-1 hypovirus, a beneficial virulent strain that reduces the toxicity of the fungal blight C. parasitica and seems to have moved into Eastern Europe with the blight early on. After its discovery, CHV-1 was rigorously studied and employed throughout Europe to protect chestnut trees from the full force of C. parasitica. 

American researchers also employed CHV-1, but without the Europeans’ success; the American chestnut ecosystem is still nearly extinct on the continent. The only reason the tree itself is not entirely extinct is that C. parasitica causes bark lesions, which kill the above-ground tree but allow the roots to persist. New shoots can still be found erupting from ancient chestnuts whose mass was removed decades ago; these chestnut ghosts have preserved the genetic material of the American species and are critical for modern restoration research. 

The American Chestnut Foundation, an environmental nonprofit headquartered in North Carolina and dedicated to reviving the departed American chestnut ecosystem, has been working to restore these monumental trees through multiple breeding programs. Their goal is to hybridize a mostly American chestnut, borrowing blight resistance from the Chinese species but otherwise maintaining the pure American chestnut’s genome through backcross breeding. 

An alternate realm of chestnut restoration research has come out of the State University of New York College of Environmental Science and Forestry, where several researchers have successfully genetically modified American chestnuts to host a gene from wheat that neutralizes the oxalic acid toxin. Trials have been promising—and controversial. Although this transgenic research has been done in collaboration with the American Chestnut Foundation, a couple of its members resigned in protest after it was revealed that the project had received support from global genetic giants Monsanto and ArborGen. 

A third path lies somewhere in between. Eschewing both the purist nostalgia and the gene-splicing labs, perennial food-focused farmers from Vermont to Oregon have found success with hybrid chestnuts containing DNA from the original American trees and the foreign resistant varieties. In Florida, Chestnut Hill Tree Farm, a major source of planting stock for the hybrid Dunstan chestnut, reports that Dunstans can produce 2,000–4,000 pounds of nuts per acre per year at maturity. Given that the U.S. imported 6.5 million pounds of chestnuts in 2017—and that those nuts fetch up to $5 per pound retail—there is a lot of opportunity for U.S. growers. Indeed, domestic production of chestnuts has slowly but steadily been rising, from 3,784 acres in 2012 to 4,228 in 2017, according to the USDA Census of Agriculture. 

Charlie NovoGradac and Debbie Milks are chestnut farmers near Lawrence, Kansas. When they purchased their farm 25 years ago, the soil was dead. “It looked like something between sand and sawdust with a grey-ish hue,” Milks recalls. “And this used to be the richest farmland because we’re in the Kansas River bottoms where farmers have intensively farmed for over 150 years.” Heavy tillage and annual monocultures have resulted in topsoil loss to the magnitude of 4 tons of soil per acre per year.

NovoGradac and Milks started planting chestnut trees in the lifeless land. “In the beginning, it was a serious struggle,” Milks explains. The depleted soil couldn’t support the woody growth of the hybrid Dunstan chestnuts they wanted to grow. They kept at it, though, and their trees kept working to pump carbon back into the carbon-less soil. Today, Chestnut Charlie’s is a green oasis in a sea of brown. The couple takes reservations for their “on-farm u-pick” because the demand is so high for their bountiful nuts, and the local mycological clubs come year after year to scope out the diverse mushrooms vigorously growing throughout their land—a testament to the restored soil. 

American Chestnut // Illustration via U.S. Department of Agriculture Pomological Watercolor Collection. Rare and Special Collections, National Agricultural Library, Beltsville, MD 20705

American Chestnut // Illustration via U.S. Department of Agriculture Pomological Watercolor Collection. Rare and Special Collections, National Agricultural Library, Beltsville, MD 20705

The USDA Census of Agriculture reports that the number of chestnut farms in the U.S. increased from 919 in 2012 to 1,587 in 2017. The Agricultural Marketing Resource Center correlates this rise in domestic production with the rapid expansion of the agritourism industry and the local food movement, both of which support on-farm u-picks and regional farmers markets. As a crop whose quality declines rapidly after harvest, chestnut production is especially sensitive to local food demand. 

Tom Wahl and Kathy Dice are pioneer chestnut farmers near Wapello, Iowa. In a predominantly corn and soy state, Red Fern Farm is unique and people are paying attention. Just like NovoGradac and Milks, Wahl and Dice have watched chestnuts restore the health of their land; Wahl believes they can also restore the livelihoods of family farmers. These low-input, high-production crops are better for the soil and the environment as a whole and can be grown with other perennial fruits and nuts to provide a high rate of return per acre, and perhaps even more calories and nutrients than annual crops like wheat and corn.

When asked if he thought chestnuts could solve some of the problems we’re facing in modern agriculture—topsoil loss, rural depopulation, soaring debt—Wahl couldn’t have been more sure in his response: “Yes. This has exceeded our wildest expectations by many orders of magnitude,” he says. He explains that mature chestnuts can bring in around $10,000 per acre, “and all you really have to do is mow.” Visitors are eager to save a couple of dollars per pound by picking their own nuts, which saves time and labor for farmers while still paying the bills. 

Red Fern Farm isn’t concerned with growing trees that contain purely American genetics. In fact, most of their trees are almost entirely Chinese. Instead, they value the nut for the hope it provides. They see chestnuts—combined with other perennial crops—as a major contender that will give conventional agribusiness a run for its money. Countless food traditions around the globe include chestnuts as a staple, why not ours? 

Over the past decade, Midwestern states like Iowa, Michigan, and Ohio have seen their chestnut acreage grow. What’s needed now, say NovoGradac and Milks, is more long-lasting institutional support for the advancement of perennial agriculture. Farmers need support while trees get established, and they know there is an eager market ready to adopt chestnut beer and chestnut flour in place of the standard wheat options. We may never see the “Redwood of the East” restored to its former glory, but the perennial revolution is happening across the Midwest and chestnuts are at the heart of it.