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CHAPTER 3

The Epicenter

Ceylon

THE GLOBAL rust epidemic began, without fanfare, on a coffee farm in a small corner of Ceylon. Early in 1869, a farmer in the Madulsima district noticed some orange spots on the leaves of a few of his coffee trees. By mid-1869, the fungus had spread from a few trees to several acres. Over the next two years, the fungus engulfed the island’s coffee farms. “The rapidity with which this coffee leaf disease has spread throughout the coffee districts on the Island,” wrote George H. K. Thwaites, the director of the Royal Botanical Garden at Peradeniya, “has been perfectly marvelous.” “It is probable,” he continued, “that not a single estate has quite escaped, though it appeared in a very slight degree on some.”¹ In the years that followed, the rust gradually wreaked havoc on Ceylon’s coffee production. The photograph below (fig. 3.1) shows the Madulsima district just a few years after the rust was first reported. It shows some planters and laborers walking through a field of young coffee; the plants are waist high. Looking closely at the photo, the trunks and branches of the coffee plants are visible, suggesting that the plants may have been heavily defoliated.

Figure 3.1. Planters and laborers walking through a coffee estate, Ceylon. (Samuel Bourne and Charles Shepherd, View from Mr. Jenkins’ Coffee Estate, Madoolseema, Ceylon, 1872, Hume Collection, Photographs of Southern India and Ceylon, the British Library, Archives and Manuscripts. © Granger)

Farmers in Ceylon had been cultivating and exporting coffee for global markets since the eighteenth century, when the island was under Dutch rule. Ironically, most coffee produced in Ceylon under Dutch rule came from the one part of the island that was not directly under Dutch control: the highland Kingdom of Kandy. Under Dutch rule, Sinhalese farmers exported between 37,000 and 100,000 pounds of coffee per year. Coffee production boomed after the British took control of the island after the Napoleonic Wars. Between 1830 and 1880, Ceylon was the world’s third-largest producer of coffee. The colonial government eliminated export duties on coffee and exempted coffeelands from tax. They built roads, and later railroads, that linked the highlands of Kandy with the coast.²

At first, this sparked a boom in Sinhalese coffee production. At least some of this was produced using traditional farming techniques. Sinhalese farmers tended to farm coffee under shade and at lower altitudes, sometimes as low as sea level. “In these cases,” wrote Hull, “the plants will invariably be found growing under the shade of the jack, cocoa-nut, or other suitable trees, without which protection all chance of their thriving permanently would be out of the question.” These farms were also “limited in extent, and are generally richly manured and often well watered during the dry season.”³ According to some accounts, they also cultivated coffee in small patches around their villages. James Webb persuasively argues that during the 1820s and 1830s, some Sinhalese farmers adopted more intensive production techniques, supported by a series of policy changes by the colonial government to encourage local production. This intensification involved clearing highland chena lands and forests to take advantage of their rich soils. Webb estimates that they must have cleared some 60,000 acres of forest for coffee production, sometimes bringing them into conflict with British coffee planters.⁴

Although the earliest British estates were established in the 1820s, the estate boom did not began in earnest until the 1840s. Spurred by rising coffee prices in Europe and North America, Europeans (mostly Britons) started aggressively clearing the steep slopes of Ceylon’s highland forests. In 1840, the colonial government decreed that Ceylon’s highland forests belonged to the Crown. Over the next several decades, much of this land was sold to settlers for coffee production. Most of the colonists had little previous experience with farming coffee, or indeed, farming of any kind. Like estate coffee producers in other parts the world, they sought to maximize productivity and profitability. “It is generally admitted,” observed the planter William Sabonadière, “that nothing equals virgin forest land for the cultivation of coffee.” The trees were cleared so that coffee could be cultivated on the rich forest soils. At first, farmers often obtained arabica seeds and seedlings from neighboring Sinhalese farms. The estates were usually planted without shade, since shade reduced yields. By the late 1880s, 600,000 acres of forest had been cleared for coffee. “The lovely sloping forests are going,” wrote the novelist Anthony Trollope on a visit to Ceylon, “and the very regular but ugly coffee plantations are taking their place.” Between 1849 and 1868, annual coffee exports tripled, from roughly 330,000 hundredweight to 1,000,000 hundredweight (16,700 metric tons to 50,800 metric tons).⁵

The “most fruitful coffee districts,” according to Edmund Hull, were in the highlands between 2,500 and 3,500 feet (roughly 750–1,050 meters), although estates could be found at altitudes between 50 and 1,500 meters. Like coffee planters everywhere in the early nineteenth century, farmers on Ceylon (both Sinhalese and European) pushed arabica coffee to its ecological limits. They managed the plant as best they could by manipulating the conditions under which it was cultivated. In these respects, Ceylon was just as vulnerable to the rust as other coffee zones around the world. In another respect, however, it was even more vulnerable. Ceylon’s climate was unusually wet and windy. The summer monsoon (May–September) and the winter monsoon (December–February) showered the island with rain and exposed it to winds that could exceed 100 kilometers per hour. Rain also fell regularly during the intermonsoonal period. Ceylon’s wet climate, then, turned its coffee farms into a vast incubator for the coffee rust. And the strong and regular winds ensured that when the rust appeared, it would spread rapidly through the island and beyond.⁶

The Search for Origins

The early history of the rust in Ceylon remains murky. Some observers contended that the rust fungus was native to Ceylon, arguing that the epidemic had been triggered by the introduction of C. arabica. The rust’s supposed wild host was a plant then known as Coffea travancorensis (now classified as Psilanthus travancorensis), a plant closely related to coffee and indigenous to Ceylon and Southern India. Thwaites, who had been studying Ceylon’s fungi for almost a decade, argued that this was unlikely because he only found the rust on C. travancorensis after the epidemic had already broken out. It was more likely that C. travancorensis was infected from C. arabica, not the other way around. The naturalist John Nietner, along with several others, suggested that the rust had likely been present on coffee farms for several years before the epidemic broke out. Thwaites countered that if the rust had been present, “it is somewhat remarkable that the somewhat conspicuous orange-coloured spores on the underside of the leaves did not attract attention; and it is equally remarkable that the disease should so suddenly have assumed so very malignant a character.”⁷ Thwaites could not have known this, but as the rust later spread around the world, it often did pass unnoticed for several years before attracting attention—even when people were specifically looking for it.

This last objection is the most compelling one against an early introduction of the rust to Ceylon: if the fungus had been present on the island for any significant length of time, why didn’t the epidemic break out sooner? All the ecological conditions for a large-scale rust epidemic had existed since at least the coffee craze of the 1840s. One possibility is that the fungus had been present in Ceylon for some time, but the arabica plants cultivated in Ceylon were resistant to the strain of H. vastatrix that was initially introduced. After a time, a new, more virulent strain of the fungus evolved that could overcome that resistance. Later in the story, we shall see examples of this pattern. But as far as we know, most cultivated arabica is susceptible (to a greater or lesser degree) to all strains of H. vastatrix, and many, if not most, plants would surely have shown at least some lesions. It is hard to understand how it could have escaped notice altogether before 1869.

The location and pattern of the early rust outbreak in Ceylon strongly suggest that the rust was introduced. It began at a single point—Madulsima—in the interior of the island and spread outward from there. This pattern is characteristic of what plant pathologists now call a “focal epidemic,” which typically begins with a low level of inoculum (in this case, spores) at a well-defined location. The fungus then spreads outward from the focus in waves, like ripples in a quiet pond after a stone is dropped in.⁸ Had the fungus already been widespread in Ceylon’s forests, it is highly unlikely that the disease would have appeared at such a well-defined location; the epidemic would have been generalized across Ceylon’s coffee farms from the very beginning. But if we accept that the fungus was introduced, then we need to ask how.

In the mid-nineteenth century, pathogens of all kinds were traveling farther and faster than ever before. The historian David Arnold has aptly described the Indian Ocean basin in those years as a “disease zone” in which pathogens of all kinds followed the ebbs and flows of empire and found new host populations on which to survive and reproduce.⁹ Ceylon was tightly linked into a global network of steamships that regularly and swiftly moved goods and people between Asia, Africa, the Pacific, and beyond. New innovations like the Wardian case—essentially a portable greenhouse—made it possible for people to ship live plants anywhere in the world.¹⁰ This increased the risk of accidentally moving diseases and pests that fed on those plants. Newly empowered public institutions, such as the Royal Botanic Gardens at Kew, helped broker the movement of plants and seeds across the global tropics. Private nurseries, such as William Bull and Sons in London and the Horticole Coloniale in Brussels, also supported a global trade in tropical seeds and plants. The geographic and economic barriers that had for several centuries kept the coffee rust contained in Africa had begun to erode.

In the 1980s, the biologist Gordon Wrigley speculated that the spore might have been brought to Ceylon by the Napier expedition, a military expedition that sent troops from India to Ethiopia early in 1868. While in Ethiopia, the expedition passed through a number of minor coffee-growing areas where the rust may have been present. A number of people on the expedition, including Napier himself, had close connections with Ceylon. Wrigley speculates that they “might have returned with some live or pressed coffee plant material carrying viable spores.”¹¹ This is one possible explanation. But the fungus need not have come from Ethiopia; it was also present on wild coffees in the Great Lakes region of East Africa and in the upper reaches of the Congo. Trade routes for slaves and ivory passed through these regions. These routes linked the East African interior to maritime trade networks spanning the Indian Ocean and beyond. They were heavily traveled by many people, including African slaves, Arab traders, and European missionaries and explorers, among others. Perhaps one of these travelers brushed up against some infected coffee plants and inadvertently picked up some spores on his or her clothing. Then, that person may have gone to Ceylon and inadvertently brushed up against an arabica plant, leaving some spores on the susceptible arabicas. The specifics of how the fungus got from eastern Africa to Ceylon are unknown, and likely unknowable. But the circumstantial case is clear: one way or another, the rust epidemic was triggered by intensifying connections between the interior of East Africa and the Indian Ocean.¹² Taken individually, any given transfer between East Africa and Ceylon was unlikely. But taken together, as ever more people and goods were moving from Africa to Ceylon, there was a greater likelihood that some rust spores stowed away on a journey.

Of course, the spore was just one part of the story. The epidemic in Ceylon was devastating because the island’s coffee estates provided the fungus with the ideal conditions in which to reproduce. The outbreak was abetted by Ceylon’s climate. The rains that accompanied Ceylon’s two annual monsoons showered the coffee plants, providing ample supplies of the water droplets that the fungus needed to germinate. Ceylon’s comparatively warm temperatures, especially at lower elevations, also helped the spores reproduce. During a single crop season, the fungus could easily complete several infection cycles. In Ceylon’s warm and wet landscapes, much of inoculum survived from one crop season to the next, reinfecting each new crop of coffee. The coffee estates presented few physical or genetic barriers to prevent rust spores from dispersing and reproducing. The intense monsoonal winds—largely unchecked by forest trees or shelter belts—dispersed spores widely across the island. In this context, a vastly greater proportion of the spores released by each lesion landed on susceptible coffee plants, colonized their leaf tissue, and produced new lesions that, in turn, liberated countless new spores of their own.¹³ The outbreak in Ceylon was the fungal equivalent of nuclear fission. Just fifteen years after the rust was first detected in Ceylon, the island’s once-vibrant coffee industry had collapsed.

Competing Models of Crop Disease

Farmers and scientists alike struggled to make sense of the disease. Crop diseases on this scale were new; the potato blight in Ireland, for instance, had taken place just two decades before. And the coffee rust developed in complicated ways, making it difficult to read. In some years, it seemed far less severe than in others. During the initial attack, “the trees were denuded of their leaves altogether, and the site is then so pitiable that during the early years of the attack experienced planters recommended the abandonment of fields.”¹⁴ But the defoliation was not permanent. A few months after the initial defoliation, the trees “had put on a fresh flush of leaves and were bearing several hundredweights of crop per acre.”¹⁵ It seemed, at least initially, that the disease afflicted European estates more severely than the farms of Sinhalese coffee planters. “The coffee and plantations and gardens cultivated on the European system seemed likely to suffer most,” wrote one government official, “while much of the unpruned coffee surrounding the villagers’ huts and houses presented a fair show of berry.”¹⁶

Scientists quickly started searching for explanations and solutions. The farmer who first encountered the disease took some infected coffee leaves to the director of the Royal Botanical Gardens at Peradeniya, George Thwaites. The garden, located near Kandy in the heart of Ceylon’s coffee country, was then one of the world’s leading tropical botanical gardens. Nonetheless, naturalists at the garden had conducted little research on coffee agriculture. The garden’s applied research focused on acclimating exotic crops such as cinchona and tea.¹⁷ Thwaites had spent more than two decades studying Ceylon’s flora, but he had never encountered anything like the rust. So he sent the leaves back to Joseph Hooker at the Royal Botanic Gardens of Kew in England.

Hooker immediately forwarded the infected leaves to Miles Berkeley, Great Britain’s leading plant pathologist. Two decades earlier, Berkeley had participated in the commission to study the causes of the Irish potato blight (Phytophthora infestans). His research on the potato blight convinced him of fungal pathogenicity, a view of plant diseases that was, for the time, quite new. In the 1850s, he had published extensively on crop diseases.¹⁸ Berkeley had begun his scientific career as a specialist on the fungi of Great Britain, but he also developed an expertise in tropical fungi collections from British expeditions around the world, including the voyages of Darwin’s Beagle. He had previously analyzed the thousands of fungi that Thwaites collected in Ceylon.¹⁹ Given his expertise on crop diseases and his deep knowledge of Ceylon’s fungi, it is difficult to imagine anyone better suited to study the coffee rust. Berkeley’s collaborator, the microscopist C. E. Broome, created detailed drawings of the fungus.

After seeing the drawings, Berkeley concluded that the fungus appeared to be a completely new species. “The most curious circumstance,” he observed, “is that amongst more than a thousand species of Fungi received from Ceylon, this does not occur.” The fungus looked like no other, and Berkeley concluded that “it is not only quite new, but with difficulty referable to any recognized section of the fungi.” Berkeley concluded it was not only a new species, but also an entirely new genus, which he baptized Hemileia (Latin for “half-smooth,” reflecting the shape of the spores). He named the species, aptly as it turned out, vastatrix—the Latin word for “devastator” or “destroyer.” His description and drawings of the new fungus were published in The Gardeners’ Chronicle, a leading publication on pure and applied botany, on November 6, 1869. Just six months after this fungus had been discovered in a remote corner of Ceylon, it had been classified and described in Europe. Its image was published and circulated in one of Europe’s leading botanical journals—warning farmers and scientists about this new disease just as “most wanted” posters alerted citizenry and law enforcement officers about fugitive criminals.²⁰ Berkeley’s publication marked the beginning of scientific research into the coffee rust epidemic, but describing the fungus from dried spores was just a start.

As the epidemic in Ceylon became more severe, some of Britain’s leading scientists became alarmed. In February 1875, Joseph Hooker surveyed the world’s coffee farms to measure the extent of the rust. He sent a circular to all the world’s major centers of coffee cultivation.²¹ The circular described the nature of the rust infections and their impact on the coffee plants, then asked the local informants to report back to Kew if they had seen such a disease. By the end of 1875, responses had returned to Kew from informants as far afield as Jamaica, Brazil, Réunion, and the Dutch East Indies, all of whom answered in the negative. It appears that in mid-1875 the coffee rust was unknown anywhere beyond Ceylon and Southern India. The reports do, incidentally, indicate that coffee farms around the globe suffered from many local diseases and pests, but nothing on the scale of the leaf rust.²² In an article in The Gardeners’ Chronicle discussing the global rust survey, Hooker warned that “unless measures are taken to prevent the introduction of Coffee plants from infected countries into others at present free from it, [the rust] may be expected to spread eventually to wherever Coffee is cultivated.”²³

Hooker also lucidly explained why plantation monocultures were inherently vulnerable to epidemics such as the rust. Wherever large concentrations of crop plants were found, Hooker argued, the conditions would be “extremely favourable for the rapid extension and development of parasitic plants and insects.” In the wild, these parasitic organisms did not cause much of a problem since they had “only native plants in small quantities to prey upon.” Hooker expected diseases such as the rust to become a regular feature of tropical agriculture, characterizing them as “one of the penalties which man must expect to pay for such an enormous disturbance of natural conditions as implied in replacing a tropical forest of the most varied and mixed vegetation by a plantation of a single economic plant.” The problem was not limited to tropical crops; he pointed to the potato blight, the phylloxera of the vine, and the potato beetle as comparable infestations in the temperate zones. Based on this fundamental vulnerability, he predicted that Ceylon’s coffee planters would have to bear “the constant loss of a certain percentage in every year, with occasionally the loss of an entire crop,” just as the potato farmers in Europe did once the potato blight had become endemic in their fields. Still, Hooker hoped that some measure of control would be possible in order to keep coffee production economically viable.²⁴

Some coffee planters did not accept this kind of explanation. In retrospect, it is easy to characterize these planters as intellectually conservative, but at the time, the connections between the fungus and the decline in coffee production were not at all evident. Coffee production, especially estate coffee production, was volatile even without the rust. Intensively cultivated arabica farms follow a biennial production cycle, in which a year of high production is followed by a year of lower production. During high-bearing years, the trees devote so many resources to production that the next year they produce a much smaller crop. The coffee rust exacerbated this biennial cycle. Coffee trees that had been completely defoliated one year—often with the branches left dry, brittle, and seemingly dead—would recover the following year. In good years, coffee production remained high, although perhaps not as high as it would have been without the disease. In the off years, the defoliated trees produced even fewer cherries than they would have in disease-free off years. Production dropped by a quarter in 1869 and 1870 and then dropped precipitously over the next two years. Between 1873 and 1878, coffee production seemed to settle into the biennial cycle that planters were familiar with. During the peak years of the early 1870s, Ceylon produced about 950,000 hundredweight of coffee, just short of the pre-rust production. During the low-yielding years, it produced between 650,000 and 750,000 hundredweight. This stability, or seeming stability, may have given the planters the sense that they had reached some sort of equilibrium with the disease. But there were certainly still causes for concern. While the island’s total production had remained stable on average, the yield per acre had declined significantly. The total acreage under coffee cultivation actually increased by 50 percent between 1870 and 1878, from 185,000 acres to 275,000 acres.²⁵

Planters did recognize a correlation between the fungus and the drops in production but did not necessarily see the fungus as the cause. Rather, they argued that the fungus and the drop in production were both the consequences of a deeper disease inside the plant. “The leaf disease is not the ‘disease’ but an effect arising upon and from a diseased condition already contracted by the coffee trees,” argued one planter. “Fungus, blight, mouldiness, appear only upon already diseased subjects. Wherefore surely we are less concerned as to inquiring into how the evil operates … than in ascertaining the cause of it.”²⁶ The planters had no single theory to explain the disease; most invoked some sort of physiological or environmental explanation. Some argued that the disease was caused by a “poisoning of the juices” of the coffee tree. They suggested that the disease was the result of poor cultivation, inadequate manuring, or climatic disturbances. Some planters argued that the disease was just temporary and that sooner or later it would “wear itself out,” as earlier outbreaks of diseases and pests appear to have done.²⁷ In the end, planters were primarily interested in finding a practical way to manage the disease, however it was caused.

Managing the Coffee Rust

Farmers fought back against the rust, both individually and collectively. Some planters thought that high cultivation could help control the rust and perhaps even cure it. High cultivation involved a holistic approach to farming. The planter Edmund Hull succinctly described it as “careful pruning, manuring, shade, where required, the entire suppression of weeds, [etc.].” He found “a great unanimity of opinion” among planters, who agreed that while the coffee rust might not be “altogether prevented by high cultivation, [the disease] may be at least checked by it.”²⁸ The discourse of high cultivation had a strong moral undercurrent. Some European farmers used the concept to distinguish their farming practices from those of the—supposedly inferior—local farmers. In this view, any planter who failed to practice high cultivation, who neglected his farm, was letting his peers down—and also allowing the disease to spread.

Estate farmers tried a range of solutions, many of which drew on ideas and technologies imported from abroad. For example, one key component of high cultivation was manuring—the use of fertilizers. Coffee planters in Ceylon had been interested in fertilizers even before the coffee rust broke out. This was one area in which the planters had learned from scientific innovations and adopted science into their farming practice. The German chemist Justus von Liebig had revolutionized the fertilizer industry in the 1820s and 1830s. Liebig, a professor of chemistry at the University of Giessen, had developed the field of agricultural chemistry. His laboratory produced the earliest chemical fertilizers. Still, the scientists did not have a monopoly on the study of manures, and coffee planters used chemical and organic, local and imported fertilizers alike, choosing whichever they thought would work best. Ceylon planters, for example, used cattle dung, pig dung, dead animals, bones, castor-oil cake, and wood ashes (among others) as fertilizers, in addition to the chemical fertilizers then gaining prominence. Imported fertilizers were clearly important: between 1874 and 1877—as the rust made serious inroads into coffee production—the value of fertilizer imports to Ceylon quadrupled.²⁹

In the early years of the outbreak, it seemed that manuring did mitigate the coffee rust, if not cure it outright. Coffee growers who applied manure to their farms found that coffee yields recovered, at least partially. They concluded, therefore, that the crop losses were caused by soil exhaustion and that manuring could cure it. Thwaites, for example, claimed that “high cultivation, with judicious manuring, enables the tree to better sustain the attacks of the fungus, and to retain strength and vigour enough to produce a fair yield of berry.” But he worried—correctly, as it turned out—that the manure might not be a permanent cure for the disease.³⁰ Recent research has shown that the relationship between manuring and the epidemic is complicated. While manuring can offset some of the losses from the rust, its effectiveness depends on which fertilizers are used, how often they are applied, and the broader structure of the farm.³¹

Other planters experimented with chemical sprays. They used ideas and technologies imported from Europe. In his initial publication on the coffee rust, Miles Berkeley recommended that planters use sulfur, then the most widely used fungicide, to control the rust. Sulfur—in various compounds—had been used as a fungicide in Europe since the early nineteenth century. Farmers had used it to control mildew on grape vines and fruit trees, so it seemed reasonable to assume that it could also control the leaf rust. Sulfur sprays functioned primarily as preventives rather than curatives. Properly applied, they could prevent spores from germinating but could not cure a plant that was already infected. Berkeley recommended that farmers spray the coffee plants or use syringes to apply the sulfur directly to the infected parts of the leaves. It proved to be difficult, however, to use this imported technology to control the rust. To be effective, sulfur had to be applied at the specific moment the rust was germinating, and scientists had not yet established when this moment occurred. The rust’s life cycle had not yet been worked out. A second challenge was physical: Berkeley noted that the disease would be difficult to control since “the fungus is confined to the underside of the leaves, and the mycelium is not superficial.”³² This meant that the fungicide would have to be sprayed upward to be effective. Finally, fungicides were also expensive; they required significant investments in labor, chemicals, and equipment.

Farmers and researchers alike began searching for rust-resistant arabicas. They imported coffee plants from around the globe, through public and private institutional networks. The Royal Botanic Gardens at Kew helped facilitate a number of these global transfers, as they did with other crops such as tea, cinchona, and rubber.³³ Private institutions and individual planters also moved live planting material over great distances, often with unprecedented speed. Coffee planters could purchase coffee seeds and plants from newly established British nurseries that specialized in exotic crops, such as William Bull in London and Veitch in Liverpool. Some planters conducted bioprospecting expeditions of their own. The many non-Europeans who traveled to Ceylon as laborers, traders, or migrants of other sorts may have also circulated their own planting materials, as they had done for centuries before the age of European hegemony. Unfortunately, the surviving documents remain frustratingly vague about this possibility. In the end, however, all the imported arabicas promptly succumbed to the rust.³⁴

For the first time, coffee farmers also tried to cultivate other plants of the Coffea genus. In the early 1870s, some planters experimented with Liberian coffee, a coffee species native to West Africa. Unlike arabica coffee, Liberian coffee was a lowland plant, better adapted to warm and humid temperatures. The first seeds and seedlings of Liberian coffee were shipped to Kew and to William Bull’s nursery in 1872. From there, the plant was disseminated around the world through parallel state and commercial networks. By the mid-1870s, Liberian coffee plants were being “sent safely, in Wardian cases, to any country without removing the native earth from their roots.”³⁵ By 1873 at the latest, Liberian coffee had been introduced in Ceylon.³⁶ Coffee planters there hoped that the plant’s broad and thick leaves would be better able than arabica’s to resist attacks of the rust. In 1875–76, some coffee planters from Ceylon traveled directly to Liberia to observe how the coffee plant was being cultivated there, and to collect seeds for themselves. This movement of live plants, seeds, and soil in Wardian cases could have hastened the spread of the rust, although most commentators argue (compellingly) that any crop diseases carried in the cases would have likely made themselves apparent during the voyage itself.

Introducing the plant to Ceylon was just the beginning; farmers also had to determine how well it performed in the field. The initial trials were discouraging: “The Wardian cases had scarcely been opened,” noted one report, “when the Liberian plants were attacked by the prevalent plague, Hemileia vastatrix.” Undaunted, farmers continued to experiment with the plant and discovered that if the young plants were given proper care, “after 18 months or two years, they seem to be strong enough to withstand the disease and become healthy trees.”³⁷ And even if Liberian coffee plants were susceptible to H. vastatrix, they suffered less than arabica. They were not defoliated to the same extent, and “the greater part of the leaf area is left intact and it is enabled in spite of the leaf disease to discharge its functions as an essential part in the economy of the plant.”³⁸ By 1877, on some lowland coffee farms Liberian coffee produced as much as 2 tons per acre.

Even so, however, the crop faced other challenges. The fruit of Liberian coffee had a thicker skin than arabica coffee, so planters had to get special depulping machinery to process it. And there were also broader challenges with the market; Liberian beans had a different flavor from the arabica coffee that traders and consumers were then used to. The market for Liberian coffee remained uncertain through the 1870s, although global demand for coffee was expanding quickly enough that Liberian coffee usually found buyers.³⁹ In the end, in spite of continued advocacy from its many boosters, Liberian coffee remained little more than an experimental crop. European planters and Sinhalese smallholders alike showed little interest in Liberian coffee. In 1878, at the height of the coffee boom, only about 440 acres of Liberian coffee were under cultivation in Ceylon.⁴⁰

Still, in spite of the rust outbreak, owners of coffee estates remained generally optimistic about their crop through the 1870s. The outbreak coincided with a global spike in coffee prices after 1873, which for several years more than offset the losses in production. Between 1875 and 1881, the price for Ceylon plantation coffee fluctuated between 100 and 107 shillings per hundredweight, almost double what it had been a decade before. In 1877, the best year ever for Ceylon coffee planters, the total value of Ceylon plantation coffee exports exceeded £4,600,000. Profits increased even as production declined. In 1874, for example, when exports were 30 percent lower than they had been in 1870, the total value of coffee exports was 17 percent greater.⁴¹ “This great access of value to [one’s] returns,” wrote the Ferguson brothers, “more than sufficed to compensate the Ceylon planter for any diminution of his crop.”⁴² In fact, the high prices triggered a land rush; between 1869 and 1879—as the rust was wreaking havoc on coffee farms—some 100,000 acres of new coffee estates were brought into production, supported enthusiastically by Ceylon’s government. Even in the face of such losses, the planters continued to be optimistic. In short, as Thwaites observed, the planters were confident in the fact “there is little, if any, diminution in the anxiety to invest in the cultivation of coffee.”⁴³

The New Botany and the Origins of Coffee Rust Science

Estate coffee remained profitable though the 1870s, but by the end of the decade, planters began to express some concern. Total production declined steadily during the trough years of each biennial cycle. The editors of Ceylon’s Planting Directory predicted (accurately) that the coffee harvest of 1878 would be “less by 40% than that of 1869, although the area cultivated has increased to nearly 100,000 acres since that time.”⁴⁴ In 1879, which should have been a peak year in the biennial cycle, production was 170,000 hundredweight (about 8,600 metric tons) lower than the previous peak year. Planters finally began to panic. They asked the colonial government to hire a scientist who would devote himself exclusively to studying the epidemic. The planter G. A. Talbot wrote that the planters needed “a scientific man to make what researches he can and to give us information from a scientific point of view, so as to help us carry on the experiments. From a practical point of view we know our business, but from a scientific point of view we can get valuable assistance, by investigations with the microscope for instance.”⁴⁵ Talbot’s reference to a microscope is significant. Scientists had, of course, used microscopes to study the coffee rust since it was first reported in 1869. But the scientists who had done so—Berkeley and Broome, principally—lived and worked in England. Their research was important, but they didn’t work on living plant material and therefore could only see part of the fungus’s life cycle. Talbot was asking for a scientist who could bring the techniques of the laboratory—scientific instruments and experimental protocols—to study living coffee rust in the field.⁴⁶ They expected, or hoped, that this innovative kind of fieldwork would uncover some means to control the disease.

The coffee rust outbreak had, in fact, coincided with important innovations in botanical research, known in the English-speaking world as the “new botany.” The new botany could equally well have been coined the “German botany” since the discipline was largely developed in German institutions (just as Liebig’s agricultural chemistry had been) and then taken by eager students to the rest of the world.⁴⁷ Practitioners of the new botany emphasized the study of living plants, in contrast to traditional botany, whose practitioners usually worked with dried herbarium specimens. The new botany emphasized studying the life cycle of plants, both in the laboratory and in the field. The emergent discipline of phytopathology—the study of plant diseases—built on the methodologies and approaches of the new botany. In the 1840s and 1850s, German naturalist Anton de Bary conducted pioneering research on crop diseases, particularly on the potato blight and the rusts and smuts of wheat. Through meticulous research in the laboratory and the field, he reconstructed the entire life cycle of fungi, from spores to mature organisms. He cultivated spores in the laboratory and on plants, and he tried to reproduce disease by systematically inoculating healthy plants with fungal spores. He produced convincing evidence that the fungi were independent organisms, that they had a life cycle, and that they were the cause of plant diseases rather than the consequence. De Bary’s approach offered a new way of understanding the coffee rust.⁴⁸

In 1879, Ceylon’s planters enlisted the colony’s government to hire a scientist to study the rust. William Thiselton-Dyer, the assistant director at the Royal Botanic Gardens in Kew, recommended one of his former students, a young biologist named Daniel Morris. Thiselton-Dyer had previously trained Morris in the techniques of the new botany at the Normal School of Science in London. Morris had been in Ceylon since 1877 as an assistant at the Peradeniya Botanic Gardens. Using de Bary’s techniques, Morris carefully studied the rust in the field and reconstructed the fungus’s life history. He concluded that the rust had an external “filamentous” stage that lasted several months. He argued that attempts to control the fungus should focus on this external stage because the rust would be exposed and amenable to chemical control.⁴⁹ Morris worked directly with the coffee farmers in ways that the other scientists at Peradeniya had never done. He enlisted the help of coffee planters to conduct experimental sprayings of working coffee farms in the Dimbula district using “some of the specifics that have proved so successful in the treatment of the hop and vine mildew.” The sprays included mixtures of sulfur, including black sulfur, flowers of sulfur, sulfur and coral lime, and Grison’s mixture (sulfur and slaked lime). Morris found that a “mixture of sulphur and lime dusted by hand onto the tree has been found, by experiment, to be the most suitable remedy,” at a cost of 16.5 rupees per acre for materials.⁵⁰ Although the trials lasted just a single season, the preliminary results seemed to satisfy the planters.⁵¹

Morris’s decision to involve planters paid institutional and political dividends. Before his arrival, coffee planters had doubted whether botany had anything useful to offer them. Thwaites had not done any experimental work on the rust and had offered planters little hope. Morris quickly gained their support by enlisting them in his programs and offering them a compelling explanation for the disease and recommendations for control strategies. “Mr. Morris has been in this country for over a year, Dr. Thwaites more than thirty,” observed one coffee planter. “Who has told us the most about leaf disease?”⁵² Morris wrote that “there are plenty of good, practical, and hard-headed planters who have been convinced by the logic of facts and who intend to take up the cure most thoroughly.”⁵³ The editors of The Gardeners’ Chronicle in England celebrated “the progress made in ten—we may say for all practical purposes, in three years. It is a justification for the existence of scientific committees, scientific lectures, and practical experiments, and we are heartily pleased to see that Ceylon planters fully appreciate the import of what has been done.”⁵⁴

Just as Morris seemed to have established the value of agricultural research, he left his post. In mid-1879, the Colonial Office appointed him as the new director of the botanical garden in Jamaica, leaving the planters once again without the support of a scientist. At first, the island’s governor, Sir James Robert Longden, balked at hiring a replacement. He cited Morris’s success as a reason for not appointing a replacement. Morris, argued Longden, “had exhausted the history of the Hemileia.” The planters, he continued, “knew what they had to do and the mode of carrying it out.” That work “belonged to the practical planters rather than scientific men.”⁵⁵

Even as some planters celebrated Morris’s achievements, others voiced caution. Morris himself had argued that the results of his experiments could only be confirmed after a full growing season. He had left for Jamaica before this, and over the remainder of the season, it became apparent that the chemical treatments Morris had recommended did not, in fact, control the rust. This did not destroy the planters’ newfound faith in science, though. Ceylon’s chamber of commerce requested that the home government appoint “another gentleman of possible equal qualifications and attainments to Mr. Morris.” The Colonial Office once again asked Thiselton-Dyer at Kew to recommend a suitable candidate. He recommended another young scientist named Harry Marshall Ward, who had studied natural science at Cambridge (where he graduated with a first-class degree in 1879) and Würzburg, where he had studied under Anton de Bary and Julius von Sachs, two leading proponents of the new botany. When he returned to the UK, he worked at the Jodrell Laboratory at the newly founded center for experimental plant biology at Kew.⁵⁶ Thiselton-Dyer and Hooker recommended that Ward be sent to Ceylon on a two-year contract. This was enough time, they felt, for Ward to study coffee over several growing seasons. That would allow him to establish where Morris had gone wrong and—they hoped—to find an effective cure.

Ward brought the new botany to bear on solving the problems of the coffee rust. Over 1880 and 1881, he conducted a wide range of systematic and comparative observations and experiments aimed at understanding the fungus’s life cycle, its epidemiology, its impact on the coffee tree, and potential control measures. In these two years, he produced three important reports for the government of Ceylon detailing the experiments and his findings. He also produced two scientific papers for the Quarterly Journal of Microscopical Science and the Journal of the Linnean Society. Although the reports are written in dry, official language, they nonetheless reveal Ward’s creativity and energy. He conducted meticulous microscopical studies on the life history of the fungus, isolating the spores and exploring how they germinated and developed through the living leaf tissue. He placed potted coffee trees around the veranda of his house so that he could observe how the disease developed on coffee plants with different exposures to the wind and rain. He hung glass slides from coffee trees to trap airborne rust spores; he deliberately infected coffee plants placed in Wardian cases. He carefully observed how rust epidemics developed in the field. He also partnered with several coffee growers to conduct experiments on chemical control. Few cultivated plants had been subjected to this kind of systematic field work, and certainly no other tropical crop had received this kind of attention. Ward’s experimental rigor matters, then and now, because he transformed scientific and popular understandings of the rust.

The central puzzle was, as it had been with Morris, to determine the full life cycle of H. vastatrix. The phases internal to the coffee leaf were, by that point, reasonably well understood, but the phases external to the leaf had still not been settled. Morris had argued that the fungus’s life cycle included an external phase in which the fungus covered the surface of the coffee plants in a microscopic mycelial web for several months. Ward quickly cast doubt on Morris’s model. He collected samples of these mycelial threads in the field and studied them under a microscope. He concluded that these filaments were produced by four species of fungi, none of which bore any relation to H. vastatrix.⁵⁷ Furthermore, none of these external mycelia connected with the internal mycelia that were definitely H. vastatrix. Based on this, Ward discarded Morris’s model and the control methods on which it was based.

To clarify the rust’s life cycle, Ward conducted experiments on living plants under tightly controlled conditions. He collected rust spores from a lesion on an infected leaf. He then placed them in droplets of water on the leaf of a healthy coffee plant housed in a Wardian case. This glass case reduced the risk that the plant could be contaminated by other fungi. He found that the spores germinated in as little as twelve hours after contact with water, and the mycelium started forming inside the leaf two or three days after that. Within two weeks, this mycelium would produce a lesion visible to the naked eye. Roughly a week after that point—three weeks after the initial infection—the lesion would start producing and releasing new spores. Under ideal conditions, the lesion could continue producing spores for five to six weeks.⁵⁸ He calculated that a single lesion, produced by a single spore, could produce 150,000 new spores at a time. And a badly infected leaf could contain many lesions, which could cause the leaves to drop prematurely. Each individual spore thus carried the potential to cause tremendous damage.⁵⁹ As Darwin had done on a much larger scale, Ward demonstrated the tremendous cumulative power of small biological events.

Ward’s field research shed new light on the rust’s ecology. He showed how all the seemingly mysterious phenomena of the disease could be explained by the fungus’s life cycle. To determine how the spores spread in the field, he placed sterile glass slides in various parts of the farm, on the ground and attached to trees. In a single water droplet collected this way, he found spores of fifty-one species of fungi (including H. vastatrix). His experiments with slides suggested that spores could travel up to 50 feet in a single journey. He carried out other experiments that showed how outbreaks of the rust were connected to wind and rain patterns. He had placed potted coffee trees around the veranda of his house and noted that “the plants placed on the side of the house more exposed to the wind suffered more than those that had been sheltered”⁶⁰ Extending these observations to the coffee estates, he argued that “a sudden appearance of the disease is closely connected with the wind and this connection is of exactly the same nature as what we should expect if the wind blows spores about.”⁶¹ Similarly, the veranda experiment showed that water was also important to the development of the disease: plants “placed on the edges of the verandah, and kept wetter on the whole (from drip, driving rain, etc) appeared to become more diseased than the sheltered ones,” an observation that he later confirmed experimentally using coffee plants in Wardian cases.⁶²

Using the pathogenic model of disease, Ward explained the patterns of rust outbreaks in Ceylon. He described a field that had been apparently free of the rust in April but was badly infected by June. Using temperature and rainfall records, Ward showed how rains in mid-May would have caused spores across the farm to start germinating. As expected, the first lesions in the field were observed two weeks after the rain. Ward’s report discussed a number of real-life examples, showing how each outbreak could be explained mainly in terms of how wind and water shaped the fungus’s dispersal and development. He argued that the connection between the fungus and its conditions of existence “were no more mysterious than that between the life of any organism and its environment: sow the spores of Hemileia on a proper nidus, and give them air, water, and warmth, and they germinate and flourish as do the seeds of coffee or an similar plant in damp, warm, aerated soil.”⁶³

Based on this, Ward’s recommendations for rust control differed from the ones Morris had made. Ward argued that chemical control would only be effective under limited circumstances. The fungus was only vulnerable during the few hours after it had germinated but before it had penetrated the leaf tissues. To control the rust, then, the chemical had to be applied before the spores germinated. It needed to coat the leaf and stick to it. It had to be soluble so that it could be sprayed, yet it also had stick to the leaf during the heavy monsoon rains. It would need to be toxic to the fungus but not to the coffee plant or the soil. These stringent criteria eliminated most of the chemicals that planters had been trying. Ward enlisted a number of eminent planters in a series of spraying experiments, using various measures (weight of leaves and fruit produced) to assess how farms treated with chemicals fared in comparison to untreated farms. At the time, only sulfur compounds and particularly sulfur of lime met the criteria. In fact, planters found that the lime also acted as a manure, improving the life of the tree. Ward struggled to quantify the amount of benefit that applications of sulfur would give, but most experiments suggested that it offered planters at least some benefit if it was applied at the right time.⁶⁴

Ward argued that the rust could best be controlled through preventive measures. “The problem of combating this disease,” he argued, “is not a mere matter of quantity of chemicals and their efficacy in killing the fungus, but also in maintaining the strength of the tree and preventing reinfection.”⁶⁵ Like some planters, Ward called for the careful cultivation of coffee—judicious pruning and manuring as well as the systematic elimination of infected leaves and trees. A few years before, planters had argued that manuring actually cured the rust. Ward argued that it did not; in fact, paradoxically, “of every basket of manure placed at the foot of the tree, a certain proportion must be looked upon as serving the mycelium of Hemileia for food.”⁶⁶ Even so, careful manuring was still worthwhile because it would help the trees produce their leaves sooner and retain them longer, allowing the fruit and branches to develop more fully, which would mitigate the rust’s effects. Outbreaks could also be controlled by planting windbreaks that would slow the dispersal of spores.

Ward’s research was a scientific success, but it was a practical failure—at least as far as Ceylon’s planters were concerned. The planters accepted the basic premise of fungal pathogenicity and Ward’s account of the epidemic; most quietly abandoned their earlier models of disease. But from their perspective, Ward had failed to accomplish his main purpose: he did not offer them any tools to effectively manage the rust. He had shown them why most of their treatments would not work, but he had given little guidance as to what would. So the planters continued to innovate on their own. “We have now,” wrote the planter G. A. Talbot, “all that can be taught us by scientific men about Hemileia, and it is for practical planters, in working their coffee, to study the disease. I must say, I think there is a good deal to be found out yet.”⁶⁷

In 1880, the planters of Ceylon founded a horticultural journal, the Tropical Agriculturist, that published reports summaries of horticultural research as well as reports from European planters across the tropics. In this sense, the Tropical Agriculturist was a tropical version of The Gardeners’ Chronicle, which published horticultural pieces from both professionals and amateurs.⁶⁸ In the field, some planters continued to experiment with new methods of controlling the disease. One of the most widely reported of these involved the experiments of a planter named Eugene Schrottky who developed what he described as a “vaporization” technique that involved covering his coffee plants with a powder containing carbolic acid. In the local press, however, coffee planters argued heatedly about whether or not Schrottky’s method did much to control the disease. In the end, it was never adopted on a large scale.⁶⁹