IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, we’ll talk about the surfing electrons that contribute to dramatic Northern Light displays. And a disaster scientist takes on the new movie Don’t Look Up.

But first, if you’ve ever hiked around the forests of the eastern US, you might have noticed all the oaks and the pines and the maples. But there’s a key player that’s missing, the American chestnut. The American chestnut towered over these canopies a little over a century ago.

One of these trees could grow over 100 feet tall and 12 feet wide. And there were lots of them. So many, people like to say, a squirrel could go from New England to Georgia leaping chestnut to chestnut without ever touching the ground.

But then an invasive fungus wiped them out. Billions of trees gone in the span of a single generation. Now, decades later, people are trying to bring them back using science to resurrect these old giants. But not everyone’s happy about it.

Here with the story are reporters Shahla Farzan and Science Diction’s Johanna Mayer. Full disclosure, Johanna’s partner’s aunt works for The American Chestnut Foundation. They come up later in this story. And with that, here is the tale of the vanishing chestnut trees.

SHAHLA FARZAN: Back when there were still American chestnuts, every year the trees produced baskets of rich, sweet nuts, each one encased in a spiny jacket. You could eat them right off the tree, or grind them up into flour, or even cook them into toasty little snacks. People just adore these trees.

SUSAN FREINKEL: I’ve heard people talk about it being the people’s tree, our tree.

SHAHLA FARZAN: Susan Freinkel is the author of American Chestnut– The Life, Death, and Rebirth of a Perfect Tree. She says for a lot of people, especially in Appalachia, this tree held a treasured place in their lives.

SUSAN FREINKEL: It really was like a member of the family. And when the trees started to disappear, people wept over them. People had pictures in the family scrapbooks of the trees that they would visit each fall to harvest nuts from.

JOHANNA MAYER: And from an industry perspective, the American chestnut was a dream too. The lumber was light, made it a lot cheaper to ship. And it was rot resistant thanks to the high tannin content. And by the late 1800s, Americans were making just about everything out of chestnut– railroad ties, telegraph poles, church pews, pianos.

SUSAN FREINKEL: It really furnished people’s lives cradle to grave. People made cradles out of it. They made coffins out of it.

SHAHLA FARZAN: But one summer day in 1904, a forester named Hermann Merkle was strolling the grounds at the Bronx Zoo when he noticed something strange. The leaves on one of the chestnut trees were wilted. And when he looked closer, he saw the branches were covered in tiny orange specks.

Merkle didn’t know it at the time, but those little dots were from a fungus native to East Asia. No one knows exactly when or how the fungus got to the US. But general consensus is that it hitched a ride with a different chestnut species from Japan.

JOHANNA MAYER: And once it landed, it spread, fast. In 1908, just four years after Herrmann first noticed those wilted trees, the New York Times ran an article announcing quote, “chestnut trees are doomed.” By 1912, all the chestnuts in New York City were dead. And over the next few years, the fungus spread to Pennsylvania, and North Carolina, and Georgia, and Tennessee. By the 1950s, the blight had effectively finished off all the American chestnuts.

SHAHLA FARZAN: The fungus spreads through tiny spores that enter the tree through a wound or a little crack in the bark. And then it basically strangles the tree, siphoning off water and nutrients until the tree is dead. Well, mostly dead, because this fungus doesn’t attack the roots. So chestnuts can keep on sending up shoots, which get to a certain size before eventually the fungus kills them again, and on, and on.

SARA FITZSIMMONS: You can still find thousands and thousands of these small sprouts in the understory, most of them blighted. And again, because there are these sprouts and they’re not producing chest– most of them are not producing chestnuts anymore, we call them functionally extinct.

SHAHLA FARZAN: Sara Fitzsimmons is the Director of Restoration with The American Chestnut Foundation, a nonprofit that’s been trying to bring this species back since the 1980s. But people have been trying to save the chestnut for much longer, really since the blight first landed.

JOHANNA MAYER: First, people tried walling off the fungus. New York and New Jersey’s chestnuts were clearly goners. And in Pennsylvania, the whole eastern part of the state, east of the Susquehanna River, was a lost cause. But west of the river was looking pretty good. So they came up with a plan to cut down vast swaths of trees, create a kind of firebreak, except by the time they finished game planning, the fungus had already jumped the river, strike one.

SHAHLA FARZAN: Another option, don’t stop the fungus, fix the tree. The American chestnut was basically helpless in the face of the blight. But the Chinese chestnut, it’s resistant. So what if you combined the two. It’s called backcrossing, creating a hybrid, then breeding that hybrid again and again with a target species.

The idea is to make a tree that’s just like an American chestnut but still has some Chinese chestnut genes that make it resistant to the blight. The problem with that plan, chestnut trees take years to reach maturity. And plant breeding is really slow when you’re working on that kind of timeline. It just wasn’t sustainable, strike two.

JOHANNA MAYER: Then there was the nuclear option.

SARA FITZSIMMONS: There was irradiation experiments. That was one of my favorite.

JOHANNA MAYER: It started in the ’50s, back when nuclear radiation was on everyone’s mind. The idea was that if you irradiated enough chestnut seeds, you’ll induce a bunch of mutations.

SARA FITZSIMMONS: Much like 1,000 monkeys and 1,000 typewriters, maybe we’ll get a mutation that causes resistant in American chestnuts.

JOHANNA MAYER: Alas, none of the monkeys hit the typewriters, strike three. Eventually, a team at the State University of New York landed on a new strategy, genetic engineering. It gave them a lot more control than traditional plant breeding. Instead of slowly working toward a lucky genetic combination, they could choose specific genes from other species and put them directly into the chestnut genome, creating a transgenic species.

And in time, the SUNY scientists found just the fungus-fighting gene they needed, in wheat. When they put that wheat gene in American chestnuts, the seedlings could ward off the fungus, as well as Chinese chestnuts. The team published that work almost a decade ago back in 2013 but now they’re facing a new kind of hurdle.

SARA FITZSIMMONS: The previous ones were primarily scientific, and the current one is more political and social that we’re now facing in getting these out into the forest.

JOHANNA MAYER: The first hurdle, bureaucracy. There are three different federal agencies involved in this process. The US Department of Agriculture is involved in approving genetically modified plants. The Environmental Protection Agency is studying the chestnuts’ possible environmental impact. And the Food and Drug Administration is in charge of reviewing the food safety of transgenic nuts. These agencies probably won’t release their decisions before 2023 at the earliest.

SHAHLA FARZAN: So more than a century after that strange orange fungus was spotted in the Bronx, the American chestnut might be coming back, except some people are wondering, is this even a good idea?

NEIL PATTERSON, JR.: It’s sort of like, what’s the rush? Why the push? Let’s make sure we’re acting in the trees’ best interest.

SHAHLA FARZAN: Neil Patterson, Jr. works at the Center for Native Peoples and the Environment at SUNY and is a member of the Tuscarora nation. The Tuscarora are part of a group of six nations known as the Haudenosaunee Confederacy. Neil says the American chestnut once played an important role in their lives.

The Haudenosaunee peoples extracted oil from the nuts or ground them up to make flour. The leaves were used for medicinal purposes. And the wood became the backbone of their long houses. One of the arguments for restoring the American chestnut has been this idea that Indigenous peoples could reintegrate it into their. Traditions.

But Neil says he’s morally opposed to planting transgenic chestnuts in the wild. He’s worried they could affect the forest ecosystem in unexpected ways. And what then?

NEIL PATTERSON, JR.: One of the concerns that I’m slowly trying to understand is the potential to recall this technology at some point in the future.

SHAHLA FARZAN: The people trying to restore the American chestnut say a lot of work is going into ensuring the trees are ready for release. There’s the long governmental review process and a lot of research to back it up. Researchers have studied how the transgenic trees would affect bees, the soil, even tadpoles and water. And they haven’t found any adverse effects.

But Neil says even beyond the specific environmental concerns is a deeper question– whether we should try to restore the chestnut tree just because we can. In other words, should we meddle with the Earth? The people who want to preserve the chestnut argue we should. People created this problem, people should fix it. But these kinds of fundamental philosophical questions are the hardest to answer.

[MUSIC PLAYING]

In October, Neil Patterson and about a dozen other Indigenous people went to pick chestnuts in a small town in upstate New York. The trees were planted about 20 years ago by volunteers from The American Chestnut Foundation. They’re not hybrids, not transgenic trees. They’re the original.

And even though they’re struggling with the blight, some trees were just big enough to actually produce nuts. For most of those on the outing that October day, it was their first time picking chestnuts, feeling the spiny burrs prick their fingers.

NEIL PATTERSON, JR.: And then it sort of hit me at some point to think about this as perhaps the last time Haudenosaunee people will gather what we can say for fairly certain are non-transgenic American chestnut.

SHAHLA FARZAN: Neil says, over the years, some of the history of this tree has been lost. The blight arrived at a time when Indigenous children were being sent to boarding schools, told not to speak their native languages. He says some nations don’t even have a word in their language for chestnut anymore. Others, like the Tuscarora, are rediscovering it.

NEIL PATTERSON, JR.: In my own language [TUSCARORA], [TUSCARORA] is how we say chestnut in Tuscarora. So I’ve been making it a habit to, when I see a chestnut, call it its real name, the name that it was meant to hear, [TUSCARORA].

SHAHLA FARZAN: Now, he says, they’re starting to think about what to call this new transgenic chestnut, trying to figure out where it fits in.

IRA FLATOW: That story was produced by Shahla Farzan and Johanna Mayer, along with Elah Feder.

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