🎓 On Chestnuts Roasting on an Open Fire

Blights are a big deal, particularly for organisms lacking genetic diversity. Is there a metaphor here?

The Christmas Song was written in the ‘40s, originally popularized by Nat King Cole. It’s been covered a ton of times, most memorably for my generation by Christina Aguilera. It made the chestnut iconic in America — but it’s always been an important food. Around the Mediterranean, the chestnut tree is called “the Bread Tree” — street vendors traditionally sell them roasted in winter, and the Romans made them one of my favorite examples of food as currency.

The one time I had a chestnut, I didn’t like it, but I’m curious if that was because of the packaging or the variety. Fresh, home-grown tomatoes taste way different from store-bought, and pre-packaged sun dried tomatoes bear little resemblance in flavor or texture to either. Apparently, the American chestnut is “smaller and sweeter” than other varieties. I’m from Maryland, and I can definitely taste the difference between a blue crab caught in the Chesapeake Bay the same day I eat it, and the ones imported from the Gulf or Asia. For that matter, the difference between the Gulf shrimp I got when I visited Louisiana a few years back and the shrimp I get from my local grocery store have some pretty stark taste and texture differences.

But if the sermon at church last weekend is anything to go by, not many people realize that the American chestnut is nearly extinct — or how big a deal that the chestnut blight was for Appalachia.

Blights are caused by fungi.

Types of fungi include mold, yeast, mushrooms, lichen and truffles. Fungi digest their food externally by releasing enzymes into their surroundings. Some fungi are useful.

Caterpillar fungus, the world's most valuable parasite, is harvested atop the Tibetan plateau and sells for up to $63,000/lb. Agarikon fungus—a tree-decaying species of mushroom that forms in thick mats—was used in the Americas by indigenous peoples to make pouches. The fungus has a leathery texture and is also useful for bandaging wounds, preventing diaper rash, and treating tuberculosis.

“Desert truffles” are tubers that are roughly 30% each of protein and carbohydrates, 13% fiber, 7% fat, and 5% ascorbic acid. They have all essential amino acids, in good quantities, and can be salted and dried for preservation. But because they were associated with nomadic raiders, the Sumerians hated them. Egyptian pharaohs, by contrast, considered them exclusive royal delicacies.

Chestnuts aren’t just a delicacy.

I first learned about the trials and tribulations of the American chestnut from Dr. Sara Taber, a crop scientist who tweets a lot of “did you know” stuff about American agriculture. She’s very skeptical of the pop culture narrative of the American farming and writes a lot of useful stuff about why the “ugly fruit” trend is ridiculous and why farming infrastructure matters.

One of her threads talked about (budgeting for) the American chestnut, which suffered a major blight about a hundred years ago. The American chestnut was not the only tree to suffer from this blight – other species like the European chestnut and the Chinese chestnut were also affected – but it was hit the hardest. The fungus, called Cryphonectria parasitica, attacks the tree through wounds in the bark, causing cankers to form. The cankers eventually girdle the tree, which is a technical term that basically means strangling it — severing the bark, cutting off its water and nutrient supply and killing it. It wiped almost all the American chestnuts out. Roughly 3.5 billion trees died, which isn’t just ‘a shame’ — it devastated the Appalachian culture & economy.

Evidently they’re a really great tree (and we know how I feel about including trees in fiction) that produce excellent timber for housing and furniture. Their wood was, like cedar, prized for its strength and rot-resistance. Plus, apparently one chestnut tree could produce over ten bushels of nuts during harvest season — a year’s supply for a family of four. They ripen around the winter holidays.

Chestnut forests are a great place to fatten up livestock like pigs and cattle, which by the way do just fine in forest environments. They’re also an important source of food for game animals like squirrels, turkey, and deer. Although deer are basically considered suburban rats where I live, they’re an important source of food in rural areas, and one deer can feed up to 200 people.

The thing I find most fascinating is the economic impact the chestnut blight had on Appalachian families. Since chestnut lumber is straight, easy to work and rot-resistant, it was used for everything from fence posts to building construction to instruments. Chestnuts themselves were an important cash crop, not just because of the holiday season, but also for feeding livestock. Aside from that, chestnut tannins were used for the tanning industry; the southern Appalachians produced half the U.S. supply.

The loss of the American chestnuts literally destroyed the self-sufficient Appalachian mountaineer way of life.

Yet, the loss of these trees never seems to get mentioned in political conversations about the economic problems facing the Appalachian region. I hear a lot about anger at environmentalists for wanting an end to coal-mining, and how vital coal-mining is to the identity of people in Appalachia. But if we’d managed to keep the invasive Cryphonectria parasitica fungus out of the continental US — would so much of the Appalachian economy have wound up dependent on coal? Or would it still be farm & timber country?

Chestnuts weren’t uniquely vulnerable.

The chestnut blight isn’t the only fungus that destroyed a major cash crop for a region. A blight is also what switched us over from "delicious sweet" bananas that allegedly tasted like banana-flavored Starburst, to the kind of banana we're eating now — the Cavendish. Although farmers and scientists thought that this variant is immune to Panama disease, turns out it is only immune to a particular variant of Panama disease.

Modern bananas, like seedless varieties of oranges, require human intervention to breed. This makes them even more susceptible to blights than potatoes are.

The new variant of Panama disease first started showing up in Malayasia; bananas are native to Southeast Asia, so it makes sense that diseases that can cause problems for them are more common in Southeast Asia. One of the advantages that invasive species have when they travel to an extremely different place than where they're native to is that the organisms native to their new home don't have defenses against them — and aren't prone to preying on them.

Something similar happened with the American Chestnut blight in the early 1900s. That blight inspired my flash fiction story Cat and Wolf, but it was essentially the opposite phenomenon: the imported trees weren't as susceptible to the Cryphonectria parasitica fungus, because they had been exposed to it already and built up an immunity.

In the case of the American chestnut, the blight was brought to its native range and acted as an invasive species. In the case of the banana, the invasive (but vulnerable) banana had no defenses against the native fungus. Historically, banana stands are pretty isolated, and the fungus wasn't able to spread much. Now, with our global supply chains and farmers who move from plantation to plantation with contaminated boots, the fungus spreads easily. It hasn't made it to the Western hemisphere yet, but experts think it's only a matter of time.

We might lose the Cavendish banana the same way we lost the Gros Michel variety... and the American chestnut. There are many countries and regions whose economies are extremely dependent on the banana. It's the world's largest fruit crop, and the bestselling fruit in America (even though apples actually grow here, and are sturdier!).

If the banana gets wiped out by a fungal blight, it’s likely to have devastating consequences for the economy in many tropical countries, and disrupt the dietary habits of a great many people — including me. My family eats 4-6 bananas a day alone.

After living through years of a respiratory virus pandemic, most of us are attuned to the idea that people raising the alarm about the possibility of a devastating epidemic weren't just being alarmist. History is full of devastating epidemics, like the Black Death. Epidemics have been a problem for urban civilizations since the dawn of urban civilizations; entire articles have been written about ancient epidemics in the cradle of civilization. I don't want to dwell on epidemics now, but I do want to point out that blights have been a problem for many cultures and civilizations throughout history. The ancient Israelites and Mesopotamians both had rituals for how to handle fungal infestations.

According to Alice Roberts in Tamed (great book — here’s my review) the ability for plants like bananas (and potatoes — which, when blighted, caused the famous Irish Potato Famine) to clone themselves functions as a backup method of dealing with environmental challenges.

The domestication process short-circuits some of the natural backups found in nature; less diversity makes it easier for humans to mass produce food, but it also makes for more fragile systems.

The American Chestnut can be saved.

The blight wiped out most of the American chestnut trees. A handful survived, mostly in isolated, rocky places where the fungus couldn’t get a foothold. There’s a 60-year-old tree in Delaware that’s about 65 feet high, though most of the remaining big ones are up in Maine. Even some of the remaining big trees are blighted and barely alive. The rest are tiny, less than an inch in diameter — they die and resprout in a repetitive cycle and never actually produce any nuts.

The American Chestnut Foundation seems to have successfully cross-bred the healthy trees to produce a fungus-resistant variety — but it’s surprisingly tricky work to properly plant them, because knowledge about how much maintenace they need, how long they take to grow, how long they produce nuts for… has all been pretty much lost. We’re going to have to get it back the long, hard way — and hopefully it’ll be worth it.

Christmas is, in many families, a time for traditions. Even cultures with only a passing familiarity with Christianity itself have acquired traditions surrounding it, like Jewish families ordering Chinese on Christmas, or Japanese people ordering Kentucky Fried Chicken. For me, it’s also a time to reflect on knowledge and skills that never quite got passed down to me for one reason or another…

…and how with enough dedication and effort, I can recover those traditional activities anyway.

Do you have a big or small ‘cultural’ tradition you care about that got lost for awhile and regained? I’d love to hear about it!

For myself, I’m very excited to have started baking semi ‘daily’ bread, and making homemade butter for it… it’s a lot easier than I expected!