by Eric Rutkow
“The Most Deadly Plant Parasite Known”
AMATURE AMERICAN CHESTNUT tree was a marvel of the forest, one that distinguished itself from other woody plants during all seasons. In the winter, when its branches were bare, it stood out on size alone, its columnar trunk soaring upward, its silhouette, often one hundred feet tall, shadowing nearly all other hardwoods. In the springtime appeared its distinctive leaves, long and canoe-shaped, punctuated with sharp points along the sides—botanists focused on this last feature when selecting a name for the species: Castanea dentata, the second part being derived from the Latin word for “tooth.” In the summer, usually in mid-July, long after most forest trees had flowered, the American chestnut finally set forth its blooms, a brilliant display that added a burst of color to the landscape—President Theodore Roosevelt, in his autobiography, fondly recalled that time each year “when the blossoming of the chestnut trees patche[d] the woodland with frothy greenish-yellow.” Of course, most Americans who thought about these trees thought about the fall months, when the species came into fruit. Each autumn, the branches grew heavy with an abundance of spiny green burrs, and inside of these, coddled in tan velvet, was one of the treasures of the forest, the American chestnut, whose sweetness and rich flavor were admired far and wide. Thoreau, in describing these nuts, once wrote, “They are plump and tender. I love to gather them, if only for the sense of the bountifulness of nature they give me.”
The American chestnut tree originally dominated much of the forestland in the eastern United States. Its natural range stretched north-south from central Maine to lower Alabama and east-west from the Atlantic seaboard to the far shore of the Mississippi River. Nearly everywhere within this massive territory, the tree appeared in substantial numbers—by some accounts it constituted 20 percent of all trees east of the Mississippi. Legend claimed that at one point a squirrel could bounce along the chestnut canopy from Georgia to New England without ever hitting the ground.
The finest region for chestnuts was the southern Appalachian Mountains, an area that included parts of North Carolina, Tennessee, Virginia, and West Virginia. There, individual specimens could reach prodigious sizes, sometimes 120 feet tall and 12 feet in diameter. And in certain parts of the Appalachians, chestnuts grew in almost pure stands for miles on end. The nut production of these regions was remarkable—the chestnut mast could be more than a foot deep by late fall. Frederick Law Olmsted, who traveled through the southern Appalachians in the years before his appointment as superintendent of Central Park, observed, “[T]he chestnut mast is remarkably fine. The swine at large in the mountains, look much better than I saw them anywhere else at the South. It is said that they will fatten on the mast alone.”
Early American colonists needed little time to recognize the importance of chestnut trees to daily life. The nuts, a favored food source for many Native American tribes, offered easy sustenance in a foreign environment. But settlers also found special value in the tree’s timber. Chestnut wood, though weaker and softer than oak, was nonetheless lightweight, rot resistant, plentiful, and easily split, qualities that made it ideal for many construction tasks. The wood’s most widespread use was for fencing, a ubiquitous feature across the colonial landscape, necessary both to denote property ownership and to keep animals out of the homestead and away from the crops. Most colonists favored the snake fence, in which logs were stacked several feet high in an interlocking zigzag pattern—the technique required minimal skill but demanded immense quantities of wood, most often chestnut.
The heavy demand for chestnut trees only increased the species’ predominance across the eastern forests. As soon as a mature tree was felled, new shoots sprang up from the stump and grew vigorously—other hardwoods possessed this sprouting ability but rarely on the same scale. Farmers exploited this quality, turning chestnut groves into woodlots that could be harvested periodically and repeatedly, a technique known as coppicing.
During the nineteenth century, the emerging technologies of the Industrial Revolution brought additional uses for the American chestnut. The fast-growing train network required millions of rail ties, and the chestnut’s abundance and durability made it one of the most popular sources across the East. In the 1840s, the introduction of the telegraph created a new demand for tall poles to support transmission wires. Chestnuts filled this role as well, especially east of the Mississippi River—the number of chestnuts used for poles only increased with the arrival of telephones, electricity, and streetcars, all of which used high-strung cables. But it was not just the structural value of chestnut timber that made it a darling of the new industries. Its wood, like the bark of the hemlock, contained high concentrations of tannin, an essential ingredient in producing leather (and also the chemical that made chestnut so rot resistant). Thus, in many parts of the East, laborers harvested chestnut for tannin as well. P. L. Buttrick, an early-twentieth-century forester and professor who wrote about the tree’s role in industry, concluded that it had “a greater variety of uses than almost any other American hardwood.”
But the impact of the chestnut on the nation’s industrial system formed only part of the story. The tree also proved indispensable to domestic life. Chestnut, in addition to being durable, looked attractive when given a natural finish and could hold paint well. Decorators preferred it for a host of features inside middle- and upper-class homes: trims, casings, panelings, ceilings, almost anything other than floors, as chestnut was too soft to withstand excessive wear. And few woods played as large a role in the manufacture of American furniture. This was especially true from the early nineteenth century onward, after the forests had been stripped of prized species like black walnut and white oak. Less-expensive furniture was often constructed wholly from chestnut, while more-costly pieces frequently used it as core stock, upon which was glued veneers from fancier woods like black walnut, black cherry, white oak, curly maple, burl elm, mahogany, and rosewood.
In southern Appalachia, chestnut trees took on yet one more responsibility. The heart of chestnut territory was one of the most economically underdeveloped parts of the East throughout the nineteenth century. Many inhabitants continued to live in log cabins—constructed of chestnuts—long after the rest of the nation transitioned to more modern and elaborate home designs. Though the region hosted a thriving lumber industry, practically none of the wealth reached the people who populated the mountains. Most were poor, isolated from the outside world, and remarkably dependent on their forest trees. The annual chestnut harvest provided not only a bountiful source of food for families and their animals, but also an income stream—each fall, Appalachian residents gathered up the inexhaustible supply of chestnuts and hauled them to the local general store, which paid a nominal fee and then sold them to traders. As one Appalachian phrased it, “[C]hestnuts were like the manna that God sent to feed the Israelites.”
The seemingly endless utility of the American chestnut made it perhaps the nation’s most important tree species by the beginning of the twentieth century. The lumber industry was cutting above half a billion feet of chestnut timber per year, the highest amount of any single hardwood species. Americans rode on chestnut-paneled trains running along chestnut rail ties to reach jobs behind chestnut desks to receive messages transmitted over chestnut utility poles. They dined on chestnut stuffing at chestnut tables while wearing leather clothes tanned with chestnut. In 1915, Buttrick noted: “At last when the tree can serve us no longer in any other way it forms the basic wood onto which oak and other woods are veneered to make our coffins.” From the cradle to the grave, then, the chestnut tree affected almost every phase of life. If something were to happen to this inimitable species, America would be forever altered.
IN THE SUMMER of 1904, Herman Merkel, chief forester of the New York Zoological Park (now known as the Bronx Zoo), was strolling along the grounds when he noticed something troubling. Some of the leaves on one of the park’s American chestnut trees had withered and turned brown. Merkel moved to inspect the tree an
d discovered that the infected branches displayed a ring of dry bark and were peppered with tiny orange dots. It looked like a fungus, but nothing he’d observed before. As Merkel continued walking through the park, he spotted other chestnuts with brown leaves as well. He decided to treat all the diseased trees with a fungicide, hoping that the problem would stop there. But by the following spring it was evident that this initial approach had failed completely. Nearly every chestnut tree in the park was now infected.
Merkel was desperate for a solution. The park, barely five years old, was drawing more than a million visitors annually and the chestnuts formed an integral part of its landscape. Their eradication would be a calamity. He determined to send samples of the diseased bark to the USDA with a plea for assistance. His urgent package landed in the hands of Flora Patterson, a government mycologist (who later served on the inspection team that rejected the 1910 delivery of sakuras from Tokyo). She suggested that it was a common fungus, Cytospora, and recommended that Merkel aggressively prune infected branches and spray the trees with “Bordeaux mixture,” a chemical cocktail originally developed to fight the grape blight that had terrorized much of Europe in the mid-nineteenth century. Merkel followed Patterson’s instructions, but, skeptical of her conclusions, contacted William Alphonso Murrill, the recently appointed mycologist at the nearby New York Botanical Garden.
Murrill rushed over to the park, looked over the infected trees, and concluded that Merkel had been correct to doubt the USDA’s conclusion. It was definitely not a Cytospora, he assured, but what it was he couldn’t say. Murrill began to collect specimens and then spent much of the next year growing fungus cultures and studying their behavior under laboratory conditions.
In June 1906, Murrill published his findings in the Journal of the New York Botanical Garden. It was the first article to address the topic and, with minor exceptions, remarkably accurate in its conclusions. Murrill warned, “[T]his fungus may be classed with the most destructive parasites.” Once it infected a tree, it destroyed the host branch or trunk through a modified form of girdling, the process of removing a strip of bark all the way around a tree to interrupt the flow of water and nutrients. In the case of the fungus, this girdling occurred when the mycelium—the long, wispy, vegetative growth of the fungus—encircled a tree’s inner bark or cambium. Murrill found that mycelia injected directly into healthy trees caused the death of small branches within six weeks, a phenomenal speed. As the fungus killed its host, it also produced a huge quantity of spores. Murrill was uncertain exactly how these spores reached new chestnut trees, but speculated, correctly, that they were “liable to fall into even the slightest abrasions of the bark and germinate.” The article concluded that little could be done to save the trees already affected.
Reports soon began to appear of sightings beyond New York City. The fungus was spreading rapidly to surrounding counties in Connecticut, New Jersey, and New York. By the spring of 1907 infected trees had been recorded as far north as Poughkeepsie, New York, and as far south as Trenton, New Jersey. Two credible observers claimed that they had seen a similar fungus as early as 1893, suggesting that the threat had deeper and broader roots than initially thought. The issue finally gained coverage in the New York Times in May 1908 (though the front page was reserved for more important stories, like the birth of a Rocky Mountain goat at the Zoological Park). “Chestnut Trees Face Destruction,” read the headline: “Thousands of trees, amounting to millions of dollars in value, are dying, the victims of the most deadly plant parasite known, the chestnut canker, for which there is no known remedy.”
The potential scope of the threat put the fungus back on the radar of the USDA. Department scientists accepted that their initial analysis had been wrong and marshaled resources toward further study. Much of the initial work fell to the Bureau of Plant Industry, which had been created in 1901 to oversee a range of issues—it housed Fairchild’s Office of Seed and Plant Introduction but also would help to administer the Plant Quarantine Act after its passage in 1912. The bureau reached conclusions dishearteningly similar to Murrill’s, but took the attitude that the spread of the disease must be checked at all costs. In 1911, scientists at the bureau issued a report on methods to control the disease. Much of the advice was technical, but some language reflected the fight then raging over the passage of the Plant Quarantine Act and the need to strengthen federal control: “[I]t is essentially a national issue, but there is no law whereby the Federal Government can attempt to cope with the emergency. Each State must act on its own initiative and control the disease . . . [but] will be seriously handicapped if neighboring States do not.”
By the time this somewhat unhelpful pronouncement was made, the state of Pennsylvania had already heeded its message. The year before, the Main Line Citizens’ Association, a group of concerned and influential Philadelphians, had directed a campaign that ultimately produced state-level legislation to provide “efficient and practical means for the prevention, control, and eradication of a disease affecting chestnut trees, commonly called the chestnut-tree blight.” The new law created a Chestnut Blight Commission and formed the basis for a grant from the state legislature of $275,000, an enormous sum that almost equaled the amount provided for all other state forestry activities. Agents of the commission subsequently began traveling across the state inspecting trees and destroying any suspicious specimens. The law authorized them to proceed even if the property owners protested.
In early 1912, the Chestnut Blight Commission hosted a conference at Harrisburg, Pennsylvania, to bring together the leading minds in the field for the first time. The sentiment among many of the participants was Pollyannaish, patriotic, and contemptuous of anyone who questioned the Pennsylvania program. The state’s deputy commissioner of forestry declared to rousing applause: “The mere fact that somebody believes that something cannot be done is going to have mighty little weight in the work of this Commission. . . . [W]e do not care to join hands with those who see simply gloom and failure.” A participant from New York accused naysayers of being “un-American.” Murrill, who had spent more years studying the blight than anyone else, struggled to be heard above this dominant can-do spirit: “I do not believe in . . . wasting the public money uselessly. . . . I should say, keep in touch with the disease in every stage [but not] with reference to eradication, because I deem that impossible. Devote this year, at least, to scientific investigation.”
One of the most pressing scientific mysteries at the time of the conference concerned the disease’s origin. Some argued that knowing this information would help researchers devise strategies to limit its spread or possibly find a natural enemy to wipe it out altogether. The leading theory among pathologists at the Bureau of Plant Industry posited that it had come from somewhere in eastern Asia—the rationale was that Japanese and Chinese chestnut trees planted in America demonstrated resistance to the blight. In 1913, bureau researchers approached the nation’s preeminent plant explorer, David Fairchild, with a request for assistance. He quickly assigned the task to Frank Meyer, an FSPI agent already on a mission in China. Meyer’s skills in the field were legendary. He lived like an ascetic, covered incredible distances on foot, and helped introduce thousands of new plants to America (his name lives on in grocery stores across America with the Meyer lemon). Of the chestnut assignment, Fairchild explained, “Meyer was not a trained pathologist, but I felt confident that he would find the disease if it were common on the Chinese trees.” Meyer didn’t disappoint. Barely a month after receiving a sample of infected bark, he sent Fairchild a cablegram to announce his discovery of an identical fungus growing on Chinese trees. Bureau scientists analyzed a bark sample that Meyer sent soon thereafter and confirmed his claim. This discovery allowed agents to trace the likely source of the disease to Asian nursery stock imported in the late nineteenth century.
For a brief moment, it appeared to some that American scientists and forestry agents might get the upper hand on the outbreak. But the reality was stark. Dis
covering the source of the blight ultimately failed to produce new solutions. The existing control techniques continued to stumble along without slowing the spread of the disease. Federal quarantines, once they were introduced, did little to impede the blight’s progress. Each year the zone of infection swelled, sometimes by as much as thirty miles, an incomprehensible rate of expansion.
When the Pennsylvania Chestnut Blight Commission issued a new report in 1914, the confidence of two years before had faded. The earlier optimistic language had been replaced with the type of circumspection that formerly belonged to naysayers like Murrill. The report included a statement from the commission chairman that declared: “[I]t seems necessary to call sharp attention to the real lesson to be learned from the chestnut blight epidemic—viz: the necessity of more scientific research upon problems of this character; to be undertaken early enough to be of some value in comprehending, if not controlling, the situation.”
Americans used to a life dependent on chestnuts were slow to accept the idea of total defeat. It simply seemed impossible that a tree so central to American ecology and culture could actually disappear. There was no precedent for such a change. In 1920, Gifford Pinchot, still one of the nation’s leading authorities on forestry issues, said, “What happens as a rule is what I expect will happen in the case of the chestnut, . . . the plague itself will ultimately weaken, grow scarce, and disappear.”
Across the South, the nation’s great storehouse of chestnuts, residents hoped and prayed that Pinchot’s prediction was proved correct, that the fungus would peter out naturally before destroying their natural environment. But this was no less naïve than the early attitude of the Pennsylvania commission. The first sign of trouble for the southern chestnuts had come in 1912, when the disease crossed the Potomac River, which historian Susan Freinkel described as “a botanical Maginot line.” From there the fungus moved inexorably downward, infiltrating the Appalachians in the late 1920s and blanketing the entire region within fifteen years. The sight of dead chestnuts stretching off into the horizon was overwhelming. Fairchild wrote in 1938, “Last summer when I saw the hillsides in the Appalachians dotted with the tragic dead crowns of what had once been magnificent forest trees, . . . I regretted any feelings of impatience I may have had towards their quarantines and inspections.”