Coffee Is Not Forever - Stuart McCook Series in Ecology and History

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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

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