(FORTUNE Magazine) – The day that haunts the rubber industry will dawn like any other. The sun, rising the length of Asia, slowly burns away the haze from the plantations along the South China Sea that are the source of 93% of the world's natural rubber. In fields the size of nations, shadows merge with the silver trunks of millions of identical trees, the most recently domesticated of all the major crops, one vast genetic clone spawned but a century ago from a handful of seeds taken from the Amazon and sown in the pristine soil of Southeast Asia.

As Chinese and Tamil workers fan out among the plantings, the sea wind picks up, scattering foliage that falls unnaturally from the branches. The leaves, fresh and pliant a week ago, are withered and dry, blackened with lesions. The dark eruptions mean only one thing: The South American leaf blight, a fungal pestilence so virulent as to have thwarted all efforts to cultivate rubber in its native Amazonian homeland, has reached the shores of Asia.

In the ensuing weeks, growers try frantically to isolate and contain the outbreak. On the large estates, massive applications of fungicides provide some relief, but on the scattered family farms, source of 80% of the production, the disease proves impossible to control. In Kuala Lumpur, Malaysian officials hunt for the source of the infestation; so fearful have they been of this potential calamity that they have never permitted a commercial airline to fly directly to their country from any South American nation known to harbor the fungus. But it is too late; however the blight jumped the Pacific Ocean, the threat is the same: the end of the natural-rubber industry as we know it.

In America, consumers lulled into complacency by faith in synthetic chemistry wake to the realization that the world still moves on natural rubber. At least a third of the rubber in every tire comes from a tree, and for many critical applications there is no viable substitute. Without natural rubber, airplanes cannot land safely; the aircraft carrier is rendered obsolete. Trucking is crippled, interstate commerce severely compromised. Dismay sweeps the medical profession as doctors and hospital administrators learn that they, too, depend on natural rubber for a host of crucial products. Speculators make a killing as the price of rubber goes through the roof.

This nightmare, improbable as it may seem, is an open secret in the rubber industry. Ernie Imle, a retired pathologist, knows what could happen if the leaf blight crosses the Pacific: Decades ago in Central America, he witnessed an outbreak. "It moves like a blowtorch through the plantings," he says. A wiry, soft-spoken man who devoted much of his career at the Department of Agriculture to finding a way to cultivate rubber in the Americas, Imle adds, "We've had a period of grace for 50 years. But eventually every disease gets everywhere. It's only a matter of time before it reaches Asia. What has saved us until now is the thinness of the fungal spore wall. It can't survive a long ocean voyage. But with jet travel, it's an entirely different story."

Kevin Jones, secretary of the International Rubber Research and Development Board outside London, calls the leaf blight the "AIDS of the rubber industry." Concern is intense, research difficult. "You can hope to get on top of it early, if it breaks out," he says. While scientists can test fungicides in the lab, "you cannot test your controls in situ for fear of actually releasing the disease into the plantations."

Another world authority on rubber, Richard Evans Schultes, director emeritus of the Harvard Botanical Museum, believes that the blight would run through the Asian plantations in five years, reducing yields, killing trees, and compromising the entire industry.

That is not the worst part of the story. The worst is that we have endured such a crisis before, and forgotten it. In 1942 the fate of the Allies hinged on America's ability to find new sources of rubber, after Japan, at war, cut off supplies. Responding in spectacular fashion, the U.S. raced to develop synthetics, launched a mammoth recycling program, and sent scientists to risk their lives in the Amazon in a desperate search for latex-producing plants.

It was synthetic rubber that was decisive in the Allied victory, though the product was never as good as natural rubber. The plant explorers, meanwhile, after years of frantic effort, very nearly succeeded in giving America hardy strains that could be cultivated in the West. Yet after the war ended, Washington discarded their work through a combination of bureaucratic folly and 1950s-style technological hubris. So the nation has come full circle, and once again finds itself dependent on a natural product grown half a world away, threatened with disaster, and certain to be in short supply in the coming years.

In the Amazon it was known as the weeping tree, the white blood of the forest, and for generations Indians had slashed its bark, letting the latex drip onto leaves, where it could be molded by hand into vessels and sheets, impermeable to the rain. Columbus encountered Arawakans playing games with strange balls that bounced and flew. Thomas Jefferson and Benjamin Franklin found the material was ideal for erasing pencil notations. Because of a general belief that it came from the East Indies, the substance was called India rubber. In fact, the product came from Brazil, and there the King of Portugal had already established a fledgling industry that made rubber shoes, capes, and bags.

All these products, however, had a major flaw. In cold weather the rubber became so brittle that it cracked like porcelain. In summer heat a rubber cape was reduced to a sticky shroud. Then in 1839, quite by accident at his home in New Haven, Charles Goodyear invented vulcanization, a process that made rubber impervious to the elements, transforming it from a curiosity into an essential product of the Industrial Age. In 1888, John Dunlop invented inflatable rubber tires so that his son could win a tricycle race in Belfast. Seven years later the Michelin brothers stunned critics by successfully introducing removable tires in the Paris-Bordeaux car rally. Little more than a decade later, the first of 15 million Model T's rolled off Henry Ford's assembly line. Each needed rubber, and the only source was in the Amazon.

The flash of wealth was mesmerizing. In London and New York, men flipped coins to decide whether to go after gold in the Klondike or rubber in Brazil. In Pittsburgh, steel tycoon Andrew Carnegie lamented, "I should have chosen rubber."

Manaus, situated in Brazil at the heart of the trade, grew in a few years from a seedy riverside village into a thriving city where opulence reached bizarre heights. Rubber barons slaked their horses' thirst with silver buckets of chilled French champagne. Their wives, disdainful of the muddy waters of the Amazon, sent their linens to Portugal to be laundered. Prostitutes from Tangier and St. Petersburg earned as much as $8,000 for an evening's work, fees often paid in tiaras and jewels; the citizens of Manaus in 1907 were the highest per capita consumers of diamonds in the world.

All this wealth derived from the latex of a tree that grew scattered across two million square miles of rain forest. In that vast expanse, an area the size of the continental U.S., there were perhaps 300 million trees worth exploiting. Finding them was the challenge. In nature, rubber trees grow widely dispersed in the forest, an adaptation that insulates the species from the ravages of the leaf blight. This accident of biology forged the structure of the wild rubber trade, and in time determined the fate of entire nations.

To profit, merchants had to establish exclusive control over vast territories and secure to the yoke of the trade enormous numbers of workers. Impoverished peasants were imported by the thousands from Brazil's northeast and absorbed into an atrocious system of debt peonage. Throughout the Amazon the rubber trade unleashed a reign of terror the like of which had not been seen since the Spanish conquest. A Capuchin priest who witnessed the rubber boom recalled years later, "The best that could be said of a white man in that terrible time was that he did not kill his Indians for sport."

In the end, what saved the native population was an act of British imperial policy. In 1877 rubber seeds taken by the English from the forests of Brazil reached Malaya, a tropical land similar in climate to the Amazon but untainted by the leaf blight. Here there was no need for rubber trees to grow widely separated; dense, efficient plantations were possible. By 1909, Malaya (now part of Malaysia) had planted over 40 million trees, spaced just 20 feet apart in neat rows that enabled a single worker to tap 400 trees a day. Production doubled every 12 months. In a discovery that would later haunt the industry, growers learned to select high-yielding clones and propagate them by cuttings. Within a decade millions of rubber trees, all derived genetically from a handful of seeds, carpeted Asia's hillsides. With the plantations' success, the Amazon rubber boom imploded.

Dependence on plantations 13,000 miles away did not sit well with the leaders of American industry. With rubber by the 1920s accounting for an eighth of the value of all U.S. imports, breaking the Asian monopoly became an obsession.

Harvey Firestone tried growing rubber in Liberia. Thomas Edison surveyed 17,000 latex-bearing plants, exhausting his fortune as he sought new sources of rubber in North America. But the man most determined to smash the Asian growers was Henry Ford, who was by then making half the automobiles in the world. In 1927 he set in motion a multimillion-dollar scheme in the wilds of Brazil that came to be known as Fordlandia.

Unlike most Amazonian rivers, with their murky sloughs and impenetrable flood forests, the Rio Tapajos runs clear, its surface broken by the flash of pink dolphins and the shimmer of white-sand beaches that dominate the shore. It was here in 1876 that the Englishman Henry Wickham had gathered the rubber seeds that gave rise to the Asian industry. And it was here, 12 hours upriver by launch from the Brazilian city of Santarem, that Ford chased his dream of American rubber.

On a land grant four times the size of Rhode Island, he built a town complete with miles of roads and railroads, a modern port, a factory, schools, churches, hundreds of brick and stucco bungalows, and a fully equipped hospital that overlooked swimming pools, tennis courts, and a golf course carved from the jungle. Workers cleared thousands of acres and planted over five million rubber seeds. Botanists sent to Malaya and the Dutch East Indies secured the finest, highest-yielding clones, products of 50 years of plant breeding and horticultural ingenuity. By 1934, 1.5 million rubber saplings grew at Fordlandia. All went well initially. Then, as the growing foliage began to form a continuous canopy over the fields, the leaf blight struck. Within a year it had ravaged the plantation.

Ford ordered his agronomists to try again, on an even larger scale. A second concession was secured, another town built, more land cleared, and more rubber planted. The outcome was the same: dead and withered trees, bare limbs, and leaves black with blight.

Today little remains of Ford's dream. A few bungalows still stand, their leprous facades broken and abandoned. A handful of families scratch a living from tired soil and the gnarled trunks of remnant trees. Fire hydrants stamped by a Michigan manufacturer poke incongruously from dense undergrowth. Yet despite the decay, the plantation's legacy resonates in a manner Ford would never have imagined. From Fordlandia emerged a sobering lesson: By far the most sensitive and the first to die of the rubber trees were the high-yielding strains from the Far East. In selecting for yield, the breeders in Asia had inadvertently produced strains that were especially susceptible to the blight. After Fordlandia, everyone knew that if the disease ever reached Asia, it could mean the end of the industry.

The Asian monopoly took on an entirely new meaning on the morning of December 7, 1941, the day America went to war. Within three months of Pearl Harbor, the Japanese, as desperate for rubber as the Allies, seized Malaya and the Dutch East Indies, taking control of 95% of the world's supply and plunging the U.S. into crisis. Every Sherman tank had 20 tons of steel and half a ton of rubber. Every battleship had 20,000 rubber parts. Rubber was wrapped around every inch of wiring in every factory, home, office, and military installation in America. There was no synthetic alternative. With every conceivable source taken into account, the nation had, at normal rates of consumption, roughly a year's supply. Out of this it had to fuel the largest and most critical industrial expansion in history, the arming of the Allied cause.

Washington's response was swift and dramatic. Four days after Pearl Harbor, the use of rubber in any product not essential to the war effort was outlawed. The speed limit dropped to 35 miles per hour not to conserve gas but to reduce wear and tear on the nation's tires. Scrap rubber fetched a penny a pound at more than 400,000 depots across the country. Even Fala, President Roosevelt's dog, had his toy bones melted down. It was the most extensive recycling campaign in history, and it got the Allies through 1942.

The order went out to chemists and engineers to create a synthetic industry. In 1941 total production of synthetic rubber was just over 8,000 tons, mostly specialty products useless for tires. The nation's survival depended on its ability to manufacture over 800,000 tons of a product that had barely entered development. No blueprints existed for factories to process this immense tonnage. No facilities had been built even to produce the feedstocks from which the rubber would be made. American industry had never been called upon to handle such a task, to accomplish so much in such a short time. The engineers had two years. If the synthetic program did not succeed, America's capacity to wage war would collapse.

There was a third initiative besides recycling and synthetics: a desperate attempt to secure natural rubber from any conceivable source. When word reached Washington that the Russians were extracting latex from dandelions, orders went out to plant them in 41 states. The USDA dispatched plant explorers to every corner of the Free World, many to the Amazon. They were charged with securing raw supplies of latex, and also with a far greater challenge: finding out how to cultivate rubber in the Americas. That way the nation would never again be vulnerable to a foreign power's seizing control of the Far Eastern plantations.

Out of the disaster at Fordlandia had come a stunning possibility. Among the millions of trees that died, a handful survived, all wild and native to the Amazon. This raised the prospect that in nature there might exist trees with inherent resistance to the disease. It was to locate such trees that the USDA in 1943 sent explorers into the basin.

Traveling by dugout canoe hundreds of miles down unknown rivers, living for months at a time in lands inhabited only by Indians, their bodies wracked with disease, their crews dying in rapids and consumed by the jungle, this small cadre of botanists did the impossible. They not only found trees with marked resistance but also introduced them into cultivation at Turrialba, a USDA experiment station in Costa Rica. By the war's end, horticultural breakthroughs, mostly the work of Ernie Imle, had solved many of the technical problems related to establishing high-yielding, disease-resistant plantations in the Americas.

"There was still much to be done," Imle cautions. "It might have taken 20 years, and 40 might not have been enough. Such work never ends. Man has been improving wheat and corn for thousands of years. But with rubber we had made tremendous progress."

Yet shortly after the war's end, that work was wrecked by a single act of bureaucratic foolishness. In February 1952 the financing of the rubber research was taken over by the State Department. Rey Hill, director of the agency that controlled the program, knew little about science but much about politics. He decided on political grounds that rubber was not for Latin America. The British in Malaya were fighting a communist insurgency, and American plantations would undermine the colony's economic mainstay. Over the protests of every major rubber executive--Harvey Firestone Jr., Paul Litchfield of Goodyear, G.M. Tisdale of U.S. Rubber (now Uniroyal)--the research program was shut down. In Costa Rica all records of the project were lost or destroyed. The clonal gardens at Turrialba that preserved the invaluable germ plasm of an entire continent were abandoned, and in time were cut to the ground.

Recently declassified documents at the National Archives reveal that in this disastrous decision, shortsightedness was abetted by blind faith in the potential of synthetic rubber. The wartime synthetic program had been enormously successful. At a cost of nearly $700 million (about $5.6 billion in today's dollars), the U.S. had pulled off one of the most outstanding scientific and engineering achievements of all time. By 1945, production of serviceable synthetic rubber surpassed 800,000 tons a year and accounted for 85% of U.S. consumption. In the fall of 1953, when the rubber program was canceled, many people believed that the technical innovations would continue indefinitely. Federal officials declared brashly that natural rubber had no future and was no longer of strategic importance.

They were wrong. Of the dozens of synthetic rubbers that have since been developed, only one comes close to replicating the complex polymer created by nature. Introduced commercially in 1960 and sold by Goodyear under the trade name Natsyn, it has the identical chemical formula (1-4 cis-polyisoprene) and nearly the same molecular structure as natural rubber. Therein lies Natsyn's limitation, explains Bill Schloman, a rubber chemist at the University of Akron: "It is the same but different. Natsyn is not a perfect structure. There is some branching [in the molecule], and this manifests itself in subtle differences in performance."

Cost and capacity are even bigger problems. Isoprene, Natsyn's basic building block, is expensive and difficult to make. Goodyear operates the only plant in North America capable of transforming it into polyisoprene, and produces roughly 60,000 tons a year--less than a 16th of the tonnage of natural rubber consumed. As Schloman puts it, "If we needed to replace natural rubber with synthetic polyisoprene, Goodyear would have to clone its plants, as opposed to cloning its trees."

All the same, for nearly three decades after the war it looked as though the world would get along just fine using mainly lesser, cheaper synthetics. Each year synthetics captured a larger share of the market, and economists projected that natural rubber would be reduced to a historical footnote. Then came a double shock. First, the 1973 OPEC oil embargo quadrupled the price of raw materials for synthetics. Soaring oil prices also made Americans far more conscious of gas mileage, leading to a second and far more serious challenge to synthetic rubber: the rapid and widespread adoption of the radial tire.

Until 1968 over 90% of vehicles in America ran on bias-ply tires, the same technology that had been in place since 1900. The radial tire was a radical departure. By placing the cords within the fabric of the tire at 90 degrees to the direction traveled, and later adding a steel belt for strength, engineers at Michelin created a tire that performed better, saved gas (because of its greater rigidity), and lasted twice as long. Once radials caught on in America, they swept the market, and by 1993 they accounted for 95% of sales. This provided an immense boost for the plantation industry, for only natural rubber has the strength required for the sidewalls, and the adhesive qualities necessary for the steel belt of radial tires. Here was a technological breakthrough no one had predicted.

By 1996 natural rubber had reclaimed some 40% of the international elastomer market, and synthetic rubber's share had declined for ten consecutive years. The U.S., importing more than a million tons a year at a cost of $1.7 billion, was more dependent on natural rubber than at any time in the previous 40 years.

Washington had become concerned. Already in 1985, the National Defense Stockpile policy office commissioned a study from Smithers Scientific Services of Akron, the largest and most highly regarded independent testing and consulting laboratory dedicated to the tire and rubber industry, on what would happen if the supply of natural rubber were cut off once again. The Smithers report reached several disturbing conclusions. The natural rubber in a car tire could conceivably be replaced, provided the consumer was prepared to sacrifice performance and purchase tires more often. But as demand on a tire increased, so did the importance of natural rubber. A pickup-truck tire is 50% natural. The enormous tires of industrial machines are 90%. So are the truck tires that carry half of America's freight. Every semi rolling down the interstate does so on rubber scraped from a tree.

The tires of every commercial and military aircraft, from the 747 to the B-2 bomber and the space shuttle, are made almost entirely of natural rubber. There is no viable substitute, no product that can match the resilience, tensile strength, and resistance to abrasion and impact. Only natural rubber can withstand the rapid transition from the freezing temperatures of high altitude to the sudden heat of touchdown on the runway. Peter Roman, director of the Defense National Stockpile Center (as it is now called), summed up the importance of natural rubber in a recent interview: "All I can tell you is this--I sure as hell wouldn't want to be in a 747 about to land on synthetic tires."

Transportation is just the beginning. There are a score of other critical needs, the most dramatic being sex and health. In the last decade, with the AIDS epidemic and the increased demand for surgical gloves and condoms, consumption of natural rubber in the medical sector has doubled. Rubber's ability to adhere to steel and glass, and withstand heat and steam in sterilization, also makes it vital for the production of surgical tubing, blood stoppers, catheters, syringe tips, and other pharmaceutical products. According to the Smithers report, there is no viable substitute.

In the post-Cold War boom, demand for natural rubber is growing. Economists forecast shortages and anticipate dramatic increases in price--even assuming the leaf blight can be kept at bay. Asia is the source of virtually all the world's supply, and the region's industrialization is causing it to consume more and export less. In Malaysia land values have soared, and many planters have converted to the more lucrative oil palm. Competition for labor is intense. Rubber is associated with the colonial past, and few workers want to collect latex if given the option, say, to build cars. Since 1988 rubber production has dropped nearly 40%, and the trend is expected to continue.

Thailand, now the world's largest producer, has its own problems. Much of the surge in natural rubber production in recent years has been fueled by Thailand's spectacular success in replanting high-yielding clones. But most of that work has been done. The best rubber growing is in the southern peninsula, where land is limited and expensive and tourism is booming, and where many Thais would rather work in a resort than on a plantation. There is room for growth in Indonesia, but with its history of corruption and failed economic schemes, no one is holding his breath. Rubber production is expanding in Cambodia and Vietnam, and the Chinese now have 650 square miles of plantations in Yunnan. New sources of supply could emerge outside Asia--in West Africa, for example--but it would be a decade at least before production could begin, even if the trees were planted tomorrow.

Demand, meanwhile, is only increasing. The shift to radials is still under way. Vast markets are opening up as China and India industrialize. Add to this Russia and Eastern Europe, which became major consumers of natural rubber only with the fall of the Soviet Union. (Until then they got by with limited supplies from Vietnam and Soviet-made synthetics, which may be one reason, rubber experts suggest, for Aeroflot's abysmal safety record.)

Looming over everything is the specter of disease. A 1991 Smithers report put the matter succinctly: "If the leaf blight were to affect the crops in Southeast Asia and Africa, the world's supply of natural rubber could be devastated."

The danger from leaf blight is well known to the rubber industry, though rarely talked about. Goodyear executives declined to be interviewed for this story. Gary Miller, vice president for purchasing, said, "We buy a lot of rubber, and an article like this could seriously affect the price. So we have to be careful." Molded by the success of synthetic rubber that is the legacy of World War II, Goodyear and other large companies have focused most of their R&D spending on chemistry. Except for a fledgling effort to develop a replacement called guayule, a latex-producing plant native to the American Southwest, the industry is doing little research to reduce the risk of a botanical collapse.

If rubber trees in Asia started to die, history would repeat itself. The industry would scramble to build up production capacity for polyisoprene and other synthetic stopgaps. It would try to salvage some of the crop: If the price of natural rubber became high enough, large quantities of costly fungicides would be used, overriding environmental concerns. Price increases would also encourage efforts to find areas in Latin America that are naturally free of the blight. The concept of such "escape zones" is controversial. Many agronomists believe that the blight will ultimately reach anywhere rubber trees are found.

But common sense would argue for the development of blight-resistant strains of rubber, the dream of the plant explorers who during and after the war came so close to providing Latin America with a plantation industry. "There is still time," Ernie Imle notes. "The world cannot afford to give up on a plant that produces millions of tons of superior rubber, a crop benign to soils and the environment, a tree that at the end of its life furnishes a fine lumber to help finance the replanting of even higher-yielding selections."

Scattered across the country, living out the final years of their lives, are men once dispatched into the Amazon to do the impossible. Their field notes are deposited in archives, their collections rest in herbariums. It is not too late to rekindle their work, to apply the genius of agricultural science to developing high-yielding, blight-resistant rubber trees for the Americas. This alone will end the nightmare that has lingered since the rubber industry's inception, and ensure that the world will have a supply of natural rubber adequate to meet the growing needs of the 21st century.

REPORTER ASSOCIATE Alicia Hills Moore

WADE DAVIS is the author of One River (Simon & Schuster), a chronicle of Amazon exploration and the search for wild rubber during World War II.