Blight-Tolerant Chestnuts From the Land of Seth Sprague ’75 Planted at the White House

Blight-Tolerant Chestnuts From the Land of Seth Sprague '75 Planted at the White House

Tom Klak, an environmental scientist at the University of New England, carried a shovel on the White House lawn on April 24, Arbor Day. With federal officials from the National Park Service, Environmental Protection Agency, and US Department of Agriculture, he was celebrating the planting of three five-year-old blight-tolerant American chestnut trees.

In a photo, Klak beams from behind a fifteen-foot, five-year-old tree. Not yet leafed out, the tree-youthful but strong-symbolizes a long-held dream: returning the American chestnut to the forests of the eastern United States.

The majestic American chestnut once flourished from Maine to Mississippi, and its nutritionally dense nuts sustained wildlife, rural communities, and regional economies. But the trees proved tragically vulnerable to an invasive blight and were all but wiped out by 1950.

The young chestnuts planted on the White House grounds were cultivated in a test orchard in Cape Elizabeth, on the family land of Seth Sprague '75. Sprague and his family manage their 2,200-acre Ram Island Farm as an ecological refuge. They have inherited a conservation ethic passed down by Seth's great-grandfather, Boston businessman Phineas Warren Sprague, Seth's grandfather, Phineas Shaw Sprague, and his father, Phineas Sprague '50 (also a founding member of Bowdoin's Outing Club).

Known within the family as PW, Phineas Warren Sprague began buying coastal farms in the early 1900s to create a family estate set within a protected natural landscape. "He had seen what was happening in Old Orchard Beach and Higgins Beach-all these tiny little houses crowded on top of the beach," Seth Sprague said. "Over here, it wasn't like that. There were beautiful undeveloped beaches and farmland. He was interested in keeping it that way."

In doing so, PW set in motion the circumstances that would eventually lead to chestnut trees from Maine becoming a symbol of environmental renewal in Washington, DC.

Wild Types

About sixteen years ago, Seth Sprague learned from another chestnut expert that twenty wild American chestnut trees were still alive on his Ram Island Farm. Though these wild holdouts will eventually succumb to disease, they embody valuable genetic information and will play a critical role in revitalizing the species. "I was just fascinated by that discovery," Sprague said.

While scattered chestnuts can still be found in eastern forests, Klak said the species is functionally extinct. Most die before reaching maturity, and the remaining population is too sparse and weakened to produce enough viable seeds to sustain itself.

To learn more about how he might contribute to restoration efforts, Sprague attended an American Chestnut Foundation conference in South Portland in 2017. There he met Klak, a professor at University of New England in Biddeford.

Before moving to Maine and launching his chestnut research program, Klak worked on native plant restoration in southwestern Ohio, focusing on wildflowers and grasses. But when he and his family relocated to Maine in 2011, he soon shifted his focus to one species, the American chestnut. "There is no native plant more important to the eastern US," he said.

Meeting Sprague at the conference proved pivotal. "That moment will always be etched into my brain," Klak said. "Seth was there to meet the chestnutters, and that's when our synergistic relationship began. I can't overstate the importance of that beginning, because so much of the progress-including the trees now on the White House grounds-would not have been possible without it."

Sprague offered a more succinct summary: "Tom had the knowledge and scientific experience, and we had the chestnut trees and the land."

After receiving approval from family members, Sprague offered a plot of land to Klak to grow and test chestnut trees. The site now contains 800 specimens-the result of years of work by Klak and UNE students to develop a chestnut capable of returning to the forest after a seventy-year absence.

Reversing the Tragedy

Ram Island Farm is a vast, sprawling land of fields and forests, dotted with a few houses and barns. Within the big estate, Klak led me directly to a solitary, blighted wild chestnut barely clinging to life at the edge of a small clearing.

The tree-which Klak and Sprague affectionately call the Log Landing Tree-has bark that is splitting apart, exposing vulnerable living layers. Its branches are bare. The tree resembles a burned husk.

The blight that is killing it arrived when Chinese and Japanese chestnuts were imported into the United States in the late 1800s for landscaping. "It was the love of the American chestnut that killed the American chestnut," Klak said. "People loved it so much, but it was very tall, with nuts high up in the canopy. The solution was to import the Japanese chestnut, which is shorter and easier to harvest."

But the Asian chestnut species had co-evolved with the fatal fungus Cryphonectria parasitica, developing strong blight tolerance. American chestnuts had none.

By 1950, roughly four billion American chestnuts-about 99 percent of the population-were dead. The loss has been described as one of the greatest ecological disasters in US history.

Their disappearance sent economic and environmental shock waves through forests and rural communities. Entire towns, particularly in Appalachia, lost a major source of income from gathering and selling chestnuts. The timber industry also suffered: American chestnut trees were prized for growing quickly to 100 feet or taller, their rot-resistant wood, and straight grain.

Populations of forest mammals, birds, and insects declined. Several species disappeared entirely, including six types of moths. "As a food source, the chestnut is unprecedented," Klak said.

The nuts, encased in spiny burs, provide a more consistent and abundant food supply than beeches and oaks. Old-timers recall chestnut burs lying a foot deep across forest floors. Farmers used to release pigs into forests to fatten up on chestnuts.

"The burs with the nuts in them would drop around October 1 in the Northeast," Klak said. "So you had this food supply going into winter. And the sheer quantity of chestnut mast is like nothing else. Studies have shown it far exceeded what today's replacement trees produce, particularly the various oak species that filled the gaps after chestnuts disappeared."

The chestnut, he said, "sustained wildlife populations at levels we can hardly imagine today."

After examining the dying tree, we visited a tiny wild chestnut sapling growing nearby. Though it appeared untouched by blight, its fate is sealed: eventually it, too, will become gnarled and disfigured.

We then drove down a narrow dirt road to the test orchard. The one-acre site, fenced to keep out deer, is in a secret spot, hidden behind a dense maritime forest. Eight hundred chestnut trees grow in neat rows, each tagged with its unique genetic identity. The orchard contains a mix of chestnut varieties for comparative study.

Sprague met Klak and me at the orchard to explain why he had converted a productive hay field into a chestnut research site. "When you think about the fact that there were once four billion of these trees, and now we have an idea about how to bring them back-who wouldn't want to be part of that?" he said.

The idea he referred to emerged from the State University of New York College of Environmental Science and Forestry (ESF), where researchers found that inserting a gene from wheat into the chestnut could produce a potentially blight-tolerant tree. The gene-found naturally in mosses, grasses, and many other plants-codes for oxalate oxidase, an enzyme that detoxifies the oxalic acid the fungus uses to kill chestnut tissue.

"They figured out what was killing the trees," Sprague said. "It was the oxalic acid. Then they figured out what would neutralize it-and it was all around them, in grass."

One of Klak's major contributions has been developing methods to accelerate chestnut growth in the lab so he can collect pollen and breed modified trees more quickly. Gesturing toward one flowering tree, Sprague said, "Normally it takes five to ten years for a tree to produce flowers. This one is just two years old."

Though rapid growth can stress trees, Klak said speed is necessary. "You can learn a lot by accelerating the growth," he said. "An American chestnut can live for 500 years, so it's not in a hurry. But we are."

The three chestnut trees planted in President's Park all contain the wheat gene. They belong to a lineage of transgenic chestnuts known as Darling 54. Each DC tree was crossbred with a different wild tree in Maine, New York, and Virginia, and the offspring were transplated on the Sprague land.

Klak has pollinated several of Sprague's wild trees using modified pollen, including the Log Landing Tree. To accomplish this, he rides a cherry picker forty feet in the air to apply pollen grains directly to flowers in the canopy. Months later, when the nuts are ripe, about half inherit the Darling 54 gene.

Klak's research suggests the Darling trees could user in an American chestnut rebirth. This May, he and coauthors published a paper in the journal New Forests with their findings: After two years of field tests, Darling 54 chestnuts in the experimental plot outperformed both their wild-type siblings and Chinese-American hybrids. (They test chestnuts by applying blight directly to tree branches.)

Still, the trees are young, so the trial remains early. Also, Klak and his University of Maine collaborator E. Han Tan have discovered that the inserted gene in the test chestnuts disrupts a native gene. "This is something we're studying," Klak said. "We're comparing wild-type trees with Darling 54 trees carrying one copy of the gene versus two copies."

So far, the genetic changes appear minimal. Research on other plant species also suggests the modification might even improve drought tolerance. "It's possible the gene disruption helps the tree, or it could be neutral, or problematic," he said. "It's certainly an open question."

Near the test orchard, Klak is also cultivating a separate orchard of entirely wild chestnuts, to ensure a supply of genetic diversity. Additional American chestnuts have been planted around the property to test which micro-environments they prefer. It turns out they grow best near white pines. "I think they love each other," Klak said. Then he added, "Chestnuts prefer more acidic soil," which pine needles help create. "And it's moister there."

Sprague said this habitat information will matter once reintroduction begins on a larger scale. "If you're going to repopulate forests, you need to know where to put them."

But that repopulation is still a way off. Because Klak's solution involves genetic engineering, regulatory hurdles remain with both the United States Department of Agriculture and Environmental Protection Agency.

And not everyone involved in chestnut restoration agrees that genetic engineering is the best path forward. Some researchers favor traditional crossbreeding between American chestnuts and the naturally blight-resistant Chinese varieties.

Sprague, however, argues that this approach produces something fundamentally different. "You end up with something that is neither fully Chinese nor fully American," he said. "To us, the answer is what Tom is working on-using genetic modification to add the wheat gene while keeping the American chestnut intact."

The American Chestnut Foundation is currently developing a hybrid tree that is roughly 70 percent American and up to 30 percent Chinese. "That would mean losing more than 10,000 native American chestnut genes," Klak said. "These are genes that evolved in situ, in American forests, where they did great for tens of millions of years until we came along."

He paused. "I want all 35,000 of those wild genes in there because they know what they're doing. Plus one," he said, referring the wheat gene.

Either way, the new chestnut won't be the same as the old chestnut-it can't be. Klak said he intentionally chose to publish the results of his field study in New Forests because "the idea behind 'new forests' is that we're never going back to the old forest. We've changed ecosystems too much. I use the word restoration all the time, but it's not really accurate. We won't restore forests to exactly what they were. But that doesn't mean we can't do good and improve forests."

Sprague said he is frequently asked whether the work being done with chestnuts could help other threatened tree species, such as ash trees endangered by the emerald ash borer and hemlocks threatened by the woolly adelgid. Southern chestnut populations also face another pathogen.

"Research is happening on all these imported pests and pathogens using lessons learned from chestnut science," Klak said. "The chestnut has become a model-not just scientifically, but also for navigating the regulatory process."

He looked out across the orchard. "I believe there's momentum now, especially with our chestnut trees going to DC," he said. "I've always dreamed that some of these trees could begin going out into the world to share their beauty and their ability to survive."