Why anyone would doubt, as some do, that Longfellow's village smithy stood under a spreading "American" chestnut tree is beyond me. New England was well within its natural range. Chestnuts were used as yard trees, partly because of their sweet nuts. And they surely grew to a size that would comfortably shade a smithy. The current "champion" American chestnut in the National Register of Big Trees is over six feet in diameter, 106 feet tall, with a crown spread of 101 feet. But, alas, although there were certainly big chestnut trees in Longfellow's New England, today there is no healthy American chestnut in the eastern hardwood region large enough to shade a smithy if, indeed, there were any to be shaded. The "champion" grows far away in Cicero, Washington.

After prospering for some 40 million years in the eastern United States, the American chestnuts were virtually eradicated in less than 50 years by a blight. Most of the remaining tree-size American chestnuts now grow as planted trees well outside the species' natural range. Within the natural range, the chestnut that once accounted for one-fourth of the eastern hardwood forest survives mostly as spindly sprouts from stumps of trees which may well have fallen half a century ago. In the deep forest one may still come across the rotting carcasses of the fallen giants.

The story of the American chestnut and the blight that devastated it carries some important lessons. Until a century ago the story of the chestnut might have been about the straight-grain wood and its sweet nuts used by American Indians and then waves of European settlers as they spread across the Appalachians to the Mississippi. A half-century later the story would have told of the deaths of billions of trees of this worthy species as the blight spread throughout its range. The story today is of the efforts to develop blight-resistant strains or a cure for the blight that will permit the American chestnut to reclaim its place in the eastern hardwood forest. But today's story should also tell about the need generally to protect our natural heritage against imported pests such as that which destroyed the American chestnut.

The fungus that causes the chestnut blight was, like most such deadly pests, unintentionally imported--presumably in a shipment of plant material imported from Japan to New York. The blight was first detected on chestnut trees in the Bronx Zoo in 1904. It spread quickly through New England and the Middle Atlantic states to the Midwest and ultimately down the Appalachian highlands to the Gulf states. By the early 1950s, practically all of the chestnut trees east of the Mississippi were infected or remained only as stark, whitened ghosts. Today, as if in a valiant effort to survive, sprouts grow from old stumps but after reaching fifteen feet or so, they, too, succumb to the blight and die. This cycle continues, with a scattering of new sprouts each year, but their prospects are dim.

Charles Sprague Sargent in his Manual of the Trees of North America published at the beginning of this century described the American chestnut as occasionally one hundred feet tall and three to four feet in diameter with a straight columnar trunk. When un-crowded by other trees, the trunk was occasionally ten to twelve feet in diameter and with crowns frequently one hundred feet across. The nuts were superior in sweetness to those of the "Old World chestnuts."

The tree was most common in the glacial drift areas from New England westward and in the Appalachians. Francois Andre Michaux, the French botanist, noted in his journals in 1802 that chestnut was one of the species--along with red oaks, black oaks, sassafras, and gums--used by Kentuckians to denote land of the second class for agricultural use. Chestnut was a tree neither of the deep, fertile coves of Appalachia nor of the bony mountain ridges. Rather, its niche was on generally well-drained soils of intermediate quality.

The loss of the American chestnut was sharply felt. Their nuts were an important food for both the people on the frontier and the animals that roamed the hardwood forests. The wood was somewhat like oak in appearance though not as strong or dense; but its lightness, workability, and stability made it valuable for building and furniture. Its resistance to decay was especially valued in uses such as railroad ties and utility poles. Because it was readily available and easily split, the split-rail snake fences of the Appalachians, which are now common in showy restorations of frontier settlements, were made of chestnut. Because of the tannin in its bark and wood, it was cut heavily to supply tanneries. No species now growing in the eastern forests fully replaces it either in its uses or as a component of the hardwood forest.

Chestnut was something of an ecological pioneer species in that it readily increased in numbers and dominance in areas that had recently been logged or burned. This, combined with its ability to sprout readily from cut stumps, contributed to its increased presence through much of its natural range during the post-settlement era. When given an opening and plenty of sunlight, it grew fast. Thus, its presence increased with settlement as forests were cut for wood and burned to create pasturage for cattle and sheep.

The Indians may have had some effect on the distribution of the trees. There may have been more chestnut in coastal plains areas where the influence of Indians on vegetation was greatest than in the relatively undisturbed forests of the interior.

During the first half of this century and following the spread of the blight, dead trees were still cut into lumber and posts. But it soon became evident that the chestnut would no longer be a source of wood, nuts and shade. The blight-carrying spores from the fruiting bodies of the fungus were everywhere in the air as new sprouts from old chestnut stumps were infected and spread more spores. The realization grew that the American chestnut was unlikely to regain its place in the eastern hardwood forest. The spaces in the forest that had been occupied by chestnut were taken by other species, most often red oaks and red maple on moist soils and chestnut oak on drier soils.

Despite the seemingly dim prospects for the revival of the American chestnut, nostalgia for days when these trees were a commonplace and their nuts were gathered by the bushel has prompted action. The American Chestnut Foundation (ACF) was founded in 1983 as a tax-exempt private organization devoted "toward the restoration of an American classic" as a viable part of the eastern hardwood forest. Both before and since 1983, research to improve understanding of the biology of the blight has been conducted at tax-supported research centers and universities. Today, with growing indications of success in these efforts and the knowledge provided by molecular biology, the prospects for the American chestnut are brighter.

Two main research and development approaches are being used in efforts to respond to the losses caused by the chestnut blight. One is to use plant-breeding techniques to develop strains of American chestnut that are resistant to the blight. This is the approach used by the ACF and is based on the successes in developing specialized agricultural crops. The other is to develop biological controls that can slow the spread of the blight.

The goal of the ACF's plant-breeding program is to combine the natural blight resistance of the Chinese chestnut with the favorable tree and nut-producing characteristics of the American chestnut. The two species are cross-bred and those progeny that show resistance to the blight are then successively back-crossed against American chestnut. The assumption is that a cross that is fifteen-sixteenths American chestnut will have characteristics very much like those of a pure American chestnut plus the resistance of the Chinese chestnut. Once the cross-breeding program develops a chestnut progeny that can once again prosper in forests to produce wood and in yards and orchards for shade and nuts, the program's goal will have been achieved.

This cross-breeding program is not quite as simple as it may appear. Unlike crops such as wheat or rice for which cross-breeding has had great successes, trees take several years before they produce the nuts used to grow the next generation of plants for the tests. Because of the considerable genetic diversity within a species such as chestnut, hitting on those strains of American chestnut that have the characteristics that are most desired is chancy at best. In any case, it may be years before it is clear that the initial crosses happened to contain the desired characteristics, whether for producing wood or nuts. And then there is the matter of finding strains that can accommodate to the differences in climate and growing conditions in the broad region within which American chestnuts originated. The ACF is addressing these difficulties in its cross-breeding program and has high hopes that will pay big dividends. In nine years they may have a blight-free American chestnut.

The other approach, biological control of the chestnut blight, seeks ways of attacking the fungus directly, either with viruses or naturally occurring hypovirulent strains of the fungus. The latter is based on the use of less virulent strains of the fungus to counter or weaken the effects of the virulent strains. Hypovirulent strains of the chestnut blight fungus attack American chestnut trees but do not kill them. Inoculation of these strains of the fungus into tree tissues around cankers caused by virulent fungus has been shown to retard or stop growth of the cankers. There is some evidence that suggests that naturally occurring hypovirulence can gain a foothold in slowing the growth and spread of the fungus without human intervention. A reasonable goal of research on hypovirulence is simply to improve an understanding of the mechanisms involved. But an important goal is also to find practical ways to reduce the effects of the blight. One such avenue of biological research focuses on how viruses function and how this understanding can be used to "engineer" hypovirulent strains of the blight fungus. Control of the blight could be achieved if the hypovirulence could be transmitted to the virulent strains of the fungus.

By the greatest good fortune, when the Asian blight reached Italy in 1938, a natural hypovirulence saved the forests. The eastern United States has not been so lucky yet. Whether this can be replicated with the more complex blight fungus populations in North America is, apparently, somewhat speculative. Nevertheless, hopes are high that genetically engineered hypovirulence will prove to be the key to combating the chestnut blight.

Among the optimists was Robert Frost who wrote:

Will the blight end the chestnut The farmers rather guess not, It keeps smoldering at the roots And sending up new shoots Till another parasite Shall come to end the blight.

We can hope Frost is prophet as well as poet.

The efforts to restore the American chestnut throughout its natural range are important in part for what can be learned about dealing with introduced pests. Obviously, the story of the chestnut blight is hardly unique. A clearly parallel case is that of the American elm, which has been practically destroyed by the Dutch elm disease, which is so widespread that some people actually believe the correct name for the tree is the Dutch elm. In view of the cost of cleaning up and then planting replacement trees, the economic loss of the elms as shade trees along the streets of America has been immense but does not compare with the economic loss of the American chestnut. Like the chestnut blight, the Dutch elm disease was caused by an introduced fungus that gradually spread through most of the country, leaving stark reminders of its destructive power.

The chestnut blight and the Dutch elm disease are not isolated cases of unwanted imported pests. There are others although few have attacked icons as familiar as the American chestnut and the American elm. And only some of them are killers. Many are pests because they take over ecological niches and simply drive out the natives. These include the English starling, which has become an urban pest; purple loosestrife, a pretty flowering plant from England that overruns wetlands here; Asian milfoil, an aquatic plant that is clogging lakes; the German carp, which has taken over warm water lakes in the Midwest; the gypsy moth, a defoliator of hardwood trees; and on and on. Many of these were introduced to North America because of perceived desirable features. For example, the gypsy moth was brought here to test its capacity as a substitute for the silkworm. But, in the absence here of the biological controls in their native habitat, the spread of these pests here has been largely unimpeded.

Efforts to restore the American chestnut to its place as a widespread forest tree show how difficult it is to deal with imported pests once they have become established. Federal rules restrict importing biological materials that may contain pests of various sorts. But the numerous ways in which such materials can come into the country make the task exceedingly difficult. Continuing increases in international movement of people and things point toward an almost inevitable homogenization of the world's biota. Coping with the problems this will bring will pose daunting challenges at least as great as the one posed by the chestnut blight.

These are challenges for which there are no easy solutions. International trade in unfinished wood products--logs, lumber, and chips--is already tightly regulated. But there are serious questions about the adequacy of such regulations in protecting against imports, or exports, of insect and disease pests. At the same time, trade in these products makes good economic sense and is a way to balance the uneven worldwide distribution of some of the many benefits of trees and forests.

Reasonably successful adjustments were made in the years after the blight struck the American chestnut. As the chestnuts died, other species took their place in the eastern forests. Substitutes were found for the wood, substitutes that were perhaps more costly and not as satisfactory, but nevertheless adequate. But the sense of loss is still great, great enough to bring about the American Chestnut Foundation and research on engineered hypovirulent strains of the chestnut blight. No one knows if their efforts will ever restore the chestnut to the place it once held in the eastern hardwood forest, but success in developing resistant strains of American chestnut is likely to the point where they will again provide shade for the modern equivalent of the village smithy and children can collect the nuts. The greater success will be in expanding our knowledge of the biology and ultimate control of similar blights.

Living American chestnut trees may be seen locally at the Accokeek Foundation in Piscataway Park (301-283-2113) where a chestnut research program has been under way since 1960 to develop a strain of American chestnut resistant to the blight.

To find more about the restoration of the American chestnut write:

The American Chestnut Foundation 
PO Box 4044
Bennington, VT 05201

Perry Hagenstein ('84), a forester and economist living in Massachusetts, is involved in forestry and natural resources policy issues. He has served the past two decades as a member of the Board of Directors of American Forests, the nation's oldest citizens conservation organization.