An Update on America’s most treasured tree
How the American chestnut became critically endangered and why we should care
“The devastation of the American chestnut by the chestnut blight represents one of the greatest recorded changes in natural plant population caused by an introduced organism.” William MacDonald, former professor of plant pathology at WVU, 1978.
Little kid, big tree.
I was no more than 10 years old when first introduced to the plight of the most magnificently shaped tree I had ever seen.
A favorite uncle made our walk across the rolling farmland of southern Ohio to a single tree a somber and formal affair. It was as though we were visiting the grave of a dead loved one.
As we walked, Uncle Bud described his childhood memories of the American chestnut; it was pure nostalgia.
Many people in Uncle Bud’s youth had favorite chestnut trees that they claimed bore more or sweeter nuts. Some people even had photographs of an individual cherished tree. Losing them would have a massive impact on Appalachia.
Uncle Bud was a genuinely talented and funny comic; he kept all around him in stitches and could have been a standup comedian today. My uncle’s tone that late September day bespoke an emotion out of character with his usual sharp-witted personality.
As we came upon the lone tree Uncle Bud wished to show me, he placed an open hand reverently upon the massive trunk and held it there as he spoke. He told me that the range of the American chestnut tree extended from Alabama and Georgia in the deep south and as far north as Maine and the very southern margins of Ontario.
It was the dominant tree in its range throughout Appalachia. In some areas, the chestnut accounted for 30 percent of the total tree population; in others, it was as high as 50 percent.
Uncle Bud’s American chestnut tree was immense for those in southern Ohio, a good six feet in diameter, and its canopy spread out wide and symmetrical. In other parts of the tree’s range, the chestnut was over 100 feet in height and 13 feet in diameter.
There was not a square centimeter of sun-dappled ground under Uncle Bud’s tree. Even at noon, it offered unbroken shade. As a respite for the farmer, the cool shade made the chestnut a favorite place to indulge in a mid-day nap.
The lone chestnut tree stood like a sentry in the middle of a large hayfield. The ground underneath the canopy was covered with spiny burrs. Most of the burrs had split open, revealing three rich brown nuts encapsulated within the protective jacket.
Before Uncle Bud could stop me, I grabbed a prickly chestnut burr, letting go immediately. Chestnut gathering lesson number one was learned in a millisecond and remembered for a lifetime; the burrs were there to protect the nut and bore the armament to do so.
Unfortunately, the next chestnut I foraged would be from a Chinese chestnut. Our American variety was nowhere to be found.
My uncle told me something on the walk that was novel to me at the time. Yet I would hear it and its several geographic iterations, often in the years ahead, whenever the subject of the American chestnut came up.
He said, “These trees were so dense when I was a youngster that a squirrel could go from the Ohio River to Lake Erie without ever touching the ground.”
The American chestnut, like many native trees, had withstood many assaults through millennia. The root-rotting Ink Disease of the mid-1800s is an excellent example of the intermittent onslaughts suffered by the American chestnut and other tree species.
But it would be an invasive pathogenic fungus, Cryphonectria parasitica, native to South and East Asia, that would spell its near-total extinction.
The importance of the American chestnut to the economy and lifestyle of those living in Appalachia cannot be overstated.
A recent National Public Radio Science Friday episode describes the chestnut tree as an integral part of Appalachians’ lives from “cradle to grave.” Chestnut, after all, was the preferred wood for making cradles and coffins.
Chestnut wood was treasured for its light weight, beauty and resistance to rot. Many chestnut fence posts and rails are still around because of the tannin contained primarily in the bark, although it is also found in slightly lesser amounts in the nuts, leaves and interior wood.
(I am presently looking out my window at an old chestnut post listing precariously but still holding its own. No doubt it is chestnut and has supported the fence for many decades.)
The chestnut’s tannin content made the tree highly desirable to the growing tanning industry. At the industry’s peak of operation, there were 178 tanneries in West Virginia. Of course, after the blight had decimated the chestnut trees, hemlock became the tree of choice for tanning operations.
Chestnut trees also provided a staple food for Native Americans and white and black mountaineers. They gathered the sweet and healthful nuts for selling and trading right up until the blight. Native Americans were known to mix the chestnut meal with corn to make nutritious and filling bread.
Black bears were heavily dependent on the calories derived from eating chestnuts. The loss of this vital food source, deforestation, and the fur trade negatively affected black bear populations throughout much of Appalachia.
Appalachian life of many forms depended upon this single species of tree. So much so, that attempts to reintroduce a blight-resistant version of this valued tree began shortly after the blight was discovered and continues to this day.
The Chestnut blight and how we responded to it.
A forester named Hermann Merkel was walking through the Bronx Zoo one day in 1904. He noticed wilting leaves and tiny orange specks on the branches of several chestnut trees.
We will remember Mr. Merkel as the first person to discover the pathogenic fungus, Cryphonectria parasitica. The virulent and air- borne blight wasted no time spreading and stripped away the major tree of our beloved Appalachian mountains within a few short decades.
A 1908 article in the New York Times proclaimed the American chestnut tree “doomed.”* This was not “fake news” but an astute observation.
By 1912, just four years later, there wasn’t a live chestnut tree in New York City, whose streets and parks were previously and proudly lined with the American chestnut.
Like Sherman’s March to the Sea, the blight continued its rampage south. In its wake, over 3.5 billion dead American chestnut trees were left standing from New England to Georgia as nothing more than tall bare snags.
All this loss to our Appalachian heritage occurred in just three decades.
So, how did we counter the loss of our American chestnut trees?
In the years since the chestnut blight arrived in New York from Asia, several major attempts were made to restore this precious tree, beginning with a method used to control forest fires.
Firebreaks are areas cleared of trees and vegetation that effectively halt or control some types of forest fires.
These firebreaks, of course, did not work because of the method of fungal seed distribution, spores. Spores are light and quickly become airborne and then spread by prevailing north-to-south winds.
It was obvious that the blight, composed of trillions of airborne spores, could not be contained. So a new approach was called for – backcrossing.
Scientists, at a time when cross-breeding of species was well understood and practiced with many agricultural and ornamental cultivars, tried breeding American chestnut with one spec-ies known to be resistant to the blight, the Chinese chestnut.
It was a long shot, and after thousands of attempts to make the American chestnut as blight resistant as the Chinese variety, they came up empty-handed.
Fortunately, scientists would not be deterred; such was the love of the stately American chestnut.
By the 1950s, there was much concern about the effects of radiation due to the recent use of nuclear weaponry. We learned from unfortunate experiences and experimentation that radiation could cause genetic mutations.
Perhaps, scientists thought, they could irradiate the fruit of the American chestnut and get a mutation that resisted the blight. Unfortunately, this attempt also failed.
In 1973 scientists created a new bacterium by inserting the DNA from one bacteria into another. Voila, genetic engineering was born.
A few years later, attempts began to find a gene that would make the American chestnut resistant to blight. Scientists finally struck gold with a variety of wheat.
But, of course, there’s always the bureaucracy that one must overcome.
Before we can introduce this newly developed transgenic chestnut to our forests on a large scale, several regulatory hurdles lay before us. And we all know too well that government bureaucracy moves at the speed of a three-toed sloth.
This new variant of the American chestnut must get the green light from not one but three federal agencies.
First, the USDA (United States Department of Agriculture) has to approve any genetically modified plant.
Then, the EPA (Environmental Protection Agency) ensures that before we plant this new chestnut tree, we want to know how it will affect the environment.
(I could not find any studies about how the transgenic chestnut might affect the underground mycelial network. But I’ll keep looking.)
We’ve learned from past mistakes that it is all too easy to introduce a species that can wreak havoc on the already embattled forest.
Finally, the FDA (Food and Drug Administration) is there to make sure that the transgenic nuts do not pose a health problem to consumers.
So, from a practical standpoint, we are still a few years away from a massive campaign of replanting our Appalachian forests with a genetically tweaked version of the tree America loves to love.
Be patient, and someday our great-grandchildren will once again walk among the giants that we call the American chestnut.
Until next week,
* Science Friday, episode 12/24/2021 The Resurrection of the American Chestnut, and the American Chestnut Foundation. Additional citations available upon request.