October/November 1986 | Volume 37, Issue 6
A HERITAGE PRESERVED
Since 1930, more than half of America’s splendid elm trees have succumbed to disease. But science is now fighting back and gaining ground.
They left behind great names —the Divine Elm, the Justice Elm, the Pride of the State, the Green Tree. In their dappled shade countless towns found repose, places like Elmhurst, Illinois; Elm Grove, Wisconsin; and New Haven, Connecticut, “City of Elms.” The trees carried the names of American heroes: the William Penn Treaty Elm, the Washington Elm, the Lincoln Elm. Under trees such as these, revolutions were pledged, treaties signed, oaths of office taken. But during the last fifty years, America’s big elms have disappeared, victims of Dutch elm disease.
To know why America loved and planted the elm, starting as early as 1646, one had only to walk under the soaring cathedral naves the trees formed. Helen Butler, a native of Syracuse, New York, remembers when that city, in the 1950s, was covered by one-hundred-year-old elms. “Oxford Street I can always remember. The elms made archways over the street and the sun would shine through and on a day that was very bright, especially in the fall when the leaves were beginning to turn yellow, it was almost golden going through the street. Just to look down it, just like gold.”
The elm is a storybook tree. “A great green cloud swelling on the horizon,” was how Oliver Wendell Holmes described it in The Autocrat of the Breakfast-Table . Thoreau in his journals thought the tree more noble than those who lived under it. The mature American elm ( Ulmus americana ) in its celebrated vase form, rises a hundred feet or so straight up, arching out to offer a dappled shade. The elm’s widely spaced leaves cast shifting shadows that admit enough light to allow a lawn to flourish and enough shade to cover half an acre.
The American elm, one of more than forty species of the tree, can stand the stress of a city environment. It has a wider range than any other American tree. An estimated seventy-seven million elms gave the nation’s towns and cities their characteristic look. But as a 1971 handbook for the U.S. Forest Service says, the elm “has a notorious pathology.” The handbook goes on to describe some fifty ailments, root rots, leaf wilts, stem cankers, bacterial wetwood, and various viruses and fungi. It was one of these diseases—Dutch elm disease—that changed the way America looks.
Dutch elm disease was first noticed in Holland in 1919. It spread through Europe and arrived in America in 1930 in logs imported for elm veneer. The disease is caused by a fungus that blocks the circulation of water and nutrients in elms, causing leaves to wilt and die. It is spread primarily by two beetles, one a native and one the devastatingly successful European bark beetle. Typically, the beetles, carrying spores of the fungus on their bodies, bore into a dead tree, breed there, and lay their eggs. In time the larvae mature and move on to a healthy elm to feed, carrying microscopic spores of the fungus with them. Having infected the healthy tree, they then return to a dying or dead one to lay their eggs and complete their life cycle. When the trees are set close together, as in cities, the disease can also spread through the roots.
The disease moved across the country like a wave, wiping out elms halfway across the continent before scientists began to understand how to control it. In 1933 the epidemic started out from the Atlantic ports of New York, New Jersey, and Connecticut. The first attempts to control the disease actually accelerated its spread by creating perfect breeding conditions for the beetles. WPA workers would pile up dead elm logs, or trees would be killed with copper sulfate and left standing, creating more deadwood. The idea was to set up a barrier, much like a firebreak, that the disease could not cross: experts believed the carrier beetles could not fly more than five hundred feet. It also was believed that by burning a dead elm, and thus destroying the beetles in its bark, adjacent trees would be made safe. Actually, the disease would have already beeri transmitted by then. As Dr. Gerald Lanier, professor of forest entomology at the State University of New York College of Environmental Science and Forestry in Syracuse, New York, tells it, the various misconceptions about the disease and the agility of the beetles that spread it were not finally resolved until the 1970s.
The country’s entry into World War II halted all efforts at control. By 1945 the disease had spread as far north as southern Quebec in Canada and as far south as Kentucky.
After the war the gray skeletons of elms were a familiar sight in numerous towns, and many people believed that all elms were doomed. There was no national program, but local groups who sought advice from the federal government were advised to spray their trees twice with DDT, at ninety-day intervals, as well as cleaning up deadwood. In the 1950s the epidemic continued to spread, reaching Kansas by 1957. To many Midwestern towns facing the death of their elms, DDT was a “miracle chemical.” It had been widely used in the war, and now, prescribed by the Department of Agriculture, it looked like the answer to their problem.
New York State, however, disagreed. With almost twenty years’ experience with the disease, New York environmental experts felt that DDT killed birds but had little impact on the destructive beeties carrying the fungus. There was, in fact, one New York city that never used DDT-Syracuse. Dr. Howard C. Miller, emeritus professor of forest entomology at the state forestry college in Syracuse, turned that city into his laboratory. Syracuse was losing close to a thousand trees a year, and Miller slowed the rate of loss to less than one percent, without DDT. Miller was a pioneer in the use of complete sanitation—the quick removal and destruction of all dead or dying elm trees, the breeding place of the beetle. Rachel Carson cited the scientist’s work in Silent Spring , published in 1962.
While DDT was new to many in the 1950s, Miller was already well acquainted with the pesticide by then. In 1946 he had worked with the forest service in the Adirondacks. They were then spraying two to five pounds of DDT an acre to control spruce budworm. The scientists had suspected it was harmful and had began to study its effects by forcefeeding birds the DDT-sprayed larvae of the budworm.
Based on that experience and other studies, Miller and his colleagues knew that DDT was not controlling Dutch elm disease. There was another way, a solution so straightforward that it is what scientists praise as “elegant”: control the beetle and you control the spread of the fungus it carries. So remove the breeding ground. And there was a large place, ignored in this country, that had set the precedent for doing this: Holland. Today, in the country that lent its name to the disease, the Dutch still retain most of their old elms. They did it by sanitation directed on a national level. In 1958 Miller decided to use sanitation in Syracuse, the fifth largest city in New York State, which had four hundred miles of streets planted with elms dating from the Civil War.
It was a demonstrably successful experiment. But towns and cities were not persistent enough in applying the sanitation method. A few towns in the Hudson River valley tried the program, but most continued spraying DDT and, in a lastditch effort, tried to reformulate the chemical or to apply it differently. Complete sanitation is an expensive program and politically unattractive. In a successful program, nothing appears to be happening.
In Syracuse, Miller saw his work undone. The city fathers faltered on continuing the sanitation program, and by the end of the sixties the city had lost almost all its elms. At one time Syracuse had eighteen thousand trees to remove. Limbs were falling on cars. “The thing just blew up,” Miller says, referring to the numbers of disease-spreading beetles. It looked as if a bomb had hit, removing all greenery and shade. “We lost a city of trees,” Miller says, “these big cathedral elms.” Just to clean up the trees and stumps, the mayor had to use extensive federal funds. In the end the crash program to remove the elms was much more costly than steady sanitation would have been.
Had Miller’s program been followed, the trees would have lived out their natural life-span, about seventy-five more years—plenty of time for younger trees to take their place. Against Dutch elm disease, DDT proved ineffective. It only served to give people the illusion they were doing something. “Most of the places you can find elms, they survived by use of a steady sanitation effort,” Lanier said.
By 1975 the immigrant that had arrived in New York only forty-five years earlier reached California. More than half of all the elms in the country were lost. Many cities lost their trees at the same time they were being ravaged by urban renewal, interstate highways, and suburban flight. The self-image of these cities changed, as Shady Avenue and Elm Street were now again as barren as when the settlers first cleared the land. In Syracuse the loss of elms led to the loss of most of the city’s twenty-two thousand maples, because with the elms gone, the streets heated up about fifteen to twenty degrees. The orioles that had nested in the elms also disappeared.
Many discouraged experts were writing the obituary of the American elm by the late 1960s. But there were a few elms in each community that had managed to survive and a few communities in which virtually all the trees had survived: Shaker Heights, Ohio; Fertile, Minnesota; Blue Hill, Maine; several North Shore suburbs of Chicago; and one of the country’s most elm-covered cities, Washington, D.C. Several other cities are now actively fighting for their trees: Grosse Pointe, Michigan; Minneapolis and St. Paul, Minnesota; and Bangor, Maine. The news from these cities today is that the American elm is not doomed and is in fact makine a comeback.
Some of these cities are following a program recommended by the Elm Research Institute, a nonprofit organization with headquarters in Harrisville, New Hampshire. In addition to the removal of deadwood, the institute’s procedure involves injecting elms with a fungicide. It is a preventive measure, carried out annually. After eleven years of this program, the rate of loss for treated elms has been less than one percent, says the assistant director, Barbara O’Brien. “There is no reason for a tree to be lost today,” she says. “It’s a crime when one goes.”
The Elm Research Institute has been fighting for elms since 1964. That was when the founder, John Hansel, a Connecticut businessman, saddened by the loss of his own elms, wrote a letter to find out what was being done. In time he wrote ten thousand letters to scientists, conservation groups, and foundations. He was alarmed that, while efforts were afoot to save the redwood, and the whooping crane, nothing was being done to save the elm. Dozens of universities, foundations, and corporations joined him, enabling the Elm Research Institute to fund almost a million dollars in research over the past two decades.
That research has led to some impressive successes and tantalizing leads. Barbara O’Brien predicts that “one-shot immunization against Dutch elm disease is around the corner.” But that is only one of the solutions scientists are studying. So diverse is the research on Dutch elm disease—there are now more than three thousand published scientific articles—and so different the tactics, that every three years the institute sequesters the experts at a New England inn to debate the direction new research should take.
Today the third generation of researchers is working on Dutch elm disease: the first identified it after World War I in Holland; the second, Miller’s generation, uncovered the mechanics of the epidemic; and today’s scientists hope to lead the revival.
Each generation of researchers has also come to some disappointing dead ends. In the late 1960s, attention focused on a small wasp from France that drilled through bark and whose larvae fed on the beetle grubs. But the American bark proved too tough for the visitor. Currently researchers are pursuing ways to divert the beetle from the tree. The National Park Service in Washington, along with Lanier, is studying pheromone traps—luring the male beetle to his doom with the scent of the female. The Elm Research Institute is funding work to find an olfactory disguise for the elm, the theory being that beetles are attracted to elms, of all trees, by a certain smell, and that if elms smelled like maples, or even like garlic, the beetle would fly on past with its harmful fungus.
Outside the laboratory, the elm, which some had marked for extinction, is thriving. Dr. Richard Campana, formerly the chairman of botany and plant pathology at the University of Maine, Orono, has spent much of his life studying Dutch elm disease, traveling across the country to visit regularly with about fifty “patients.” He recently finished a two-year study of areas where the disease first hit fifty years ago. He reports: “The elm is coming back and has been coming back every year. There are millions of elms coming up around the outskirts of the cities. It’s a weed. In New England you can’t keep it down. If you have a garden, you have to weed it out every year.”
In some forest somewhere a new strain of American elm resistant to Dutch elm disease may be evolving, but such evolution takes thousands of years. Arborists are trying to hurry the process by developing new disease-resistant hybrids. One such botanist is Dr. George Ware, who cross-fertilized a Japanese and a Chinese elm and produced a hybrid that seemed resistant to the disease. He has been growing generation after generation of seedlings at the Morton Arboretum outside Chicago in an effort to produce a tree as much like the beloved Ulmus americana as possible. Dr. Eugene Smalley, a plant pathologist, after twenty years of research, has created the first elm from American parents that is resistant to the disease. The Elm Research Institute in Harrisville now has ten thousand clones of Smalley’s hybrid under cultivation and already has thousands of orders. The institute is calling the tree the American Liberty Elm. However, it is not known if the hybrid will be resistant to other diseases, like elm phloem necrosis, a highly virulent virus now infecting trees in upstate New York.
The memory of elm-shaded childhoods, and trees that were landmarks in their time, does not fade easily. Many people are committed to restoring the American elm to the landscape. Standing in the Harrisville laboratory, O’Brien surveys the miniature forest-in-waiting —trees that may one day be one hundred feet tall. “The early settlers,” she says, “left us this beautiful country planted with the best of intentions in the world with this beautiful tree. And I think the very least we can do is to try to repair the damage, replant, and leave a legacy for the next generation that comes along.”