and germplasm. This has been true ever since 1869, when the naturalist George Thwaites first sent samples of rust-infected leaves from Ceylon to the Royal Botanic Garden at Kew for analysis. Each contributed something to the growing global pool of knowledge about the rust, and in turn each benefited from the knowledge developed elsewhere. This openness may seem surprisingly altruistic—and it was—but it was also pragmatic. Most coffee research institutions were, and remain, small and inadequately funded. It was in their interest to share as much as they could and to learn how other communities were responding to the rust.9
Scientists have, from the very beginning, sought to understand the fungus and how it behaved in the field. In the 1880s, Harry Marshall Ward used the latest techniques in laboratory and field biology to demonstrate that the disease was caused by the fungus and to explain how cropping practices shaped rust outbreaks. Over the twentieth century, scientists have continued to refine and complicate our understanding of the rust’s ecology in wild and cultivated ecosystems. They have also shed new light on the biology of the fungus and the genetics of rust resistance and virulence. They collected and circulated new varieties and species of coffee around the world; botanical gardens across the tropics built collections of coffee varieties, which formed the raw material for selection and breeding programs. Breeding was a long-term process that involved brute-force, large-scale systematic trial and error over years and sometimes decades. Researchers in the Dutch East Indies, for example, developed commercially viable selections of robusta. Starting in the 1960s, Portuguese researchers developed the Timor hybrid, a rust-resistant coffee that was the foundation for research. More recently, a network of researchers at the US-based World Coffee Research has been developing new F1 hybrid coffees by blending classical breeding and selection with some of the latest biotechnologies. Scientific research is also vital to localizing tools and technologies developed elsewhere. For example, chemical fungicides have to be applied at just the right moment in the fungus’s life cycle, which is shaped by local conditions. So the optimal time for spraying in Kenya, for example, is not necessarily the same as that in Costa Rica. In these ways and others, science has helped farmers around the world sustain production in the face of the rust.
Even so, science alone has seldom been a panacea, and relations between scientists and farmers have not always worked smoothly. Over the nineteenth century, scientists learned a lot about the rust but could not offer coffee farmers effective ways of controlling it. Some of the disease-control strategies they later developed did not meet the farmers’ needs in other respects. In the 1970s and 1980s, scientists, backed by national coffee institutes and international research organizations, encouraged farmers to technify their farms by eliminating shade, planting high-yielding cultivars, and using fertilizers and fungicides. This technical package would, in principle, both control the rust and boost yields. But in most places only a minority of farmers adopted the full package. Others only adapted parts, or they continued farming coffee as they had done before. The package was simply not suitable for many of the region’s smaller farmers, who did not have access to capital, expertise, and technology to transform their farms. Some were reluctant to give up the traditional arabica cultivars that produced the high-quality coffees for which the region was famous. Farmers were not opposed to scientific innovation in general; they readily adopted cultivars and technologies that fit well in their economic and ecological niches. Since the 1990s, scientists have paid more attention to developing rust-control strategies that are both economically and ecologically sustainable, for farmers large and small.
The rust’s effects have rippled along the commodity chain—from coffee mills to roasters to consumers. According to one apocryphal story, the coffee rust outbreak in Ceylon explains why British consumers abandoned coffee for tea.10 This is a compelling story about the power of commodity diseases. But there is no evidence to support it, and plenty to contradict it. The collapse of Ceylon’s coffee industry caused barely a ripple in British consumption; any shortfalls from Ceylon could have easily been offset by imports from other sources. The most recent outbreaks in Central and South America may mark a change to this pattern, however, as this region produces most of the world’s high-quality mild arabicas, which are difficult to replace with coffees produced elsewhere. This helps explain the coffee industry’s growing interest in rust research and mitigation.
While the rust has not significantly reduced the global supply of coffee (to date), it has changed the global coffee trade in other ways. The Dutch developed the low-quality robusta coffee as a commercial species after 1900 because it was resistant to the rust. It has since transformed the global coffee trade, now typically accounting for between 30 and 40 percent of global coffee production. It is widely used in blended and instant coffees. And although it is typically associated with low-quality coffees, some Italian coffee aficionados argue that a little bit of robusta is an essential component of espresso blends since it helps the coffee develop its characteristic crema. The specialty coffee industry, which has long disdained robusta coffee, is now slowly starting to accept hybrid coffees that contain some robusta genes, like Colombia’s Castillo coffee.11
The heaviest burdens of the coffee rust, like the burdens of most commodity diseases, have been borne by the producers. The rust has disrupted livelihoods and landscapes. In myriad ways, the global coffeelands bear the imprint of the rust. It has transformed coffee farming, forcing farmers to either find strategies to coexist with the disease or abandon coffee cultivation altogether. It has driven farmers and laborers out of the countryside, to seek their livelihoods elsewhere. The imprint of the rust is visible in places where farmers use chemical control or have switched to resistant varieties to keep the rust levels down. The rust has changed the economics of coffee farming; rust control has made coffee production more expensive. Farmers have to pay for the supplies, labor, and technology necessary to carry out effective programs of rust control. Still other farmers cope with the rust by cultivating coffee in complex agroforestry ecosystems, which are ecologically resilient but typically produce far less coffee and, therefore, less income. Farmers can bear these costs if the price of coffee is high enough to offset them. The rust alone does not devastate coffee farms; the combination of disease and low coffee prices does.
While this study is organized around the coffee rust, it is also about the environmental history of coffee writ large. The rust is acutely sensitive to the broader conditions in which coffee is cultivated. Small changes in the conditions can trigger larger changes in the disease. The rust epidemic allows us to do the environmental equivalent of atom smashing. Physicists explore the behavior of subatomic particles by smashing particles into atoms and seeing what happens. The results shed light on the structure and function of atoms. A rust epidemic does the same thing: it sheds light on how the coffee ecosystem functions by disrupting it. Viewed as a time lapse, global coffee frontiers have been in constant motion, expanding in some places while contracting in others. The rust opens a window into these forces, showing the complex reasons why some regions survived the epidemic while others did not. The story of the rust embodies the broader environmental challenges that coffee producers face, including climate change. As we try to make sense of climate change, which in many respects is without precedent, the history of the coffee rust can offer some insight into how farmers have adapted to other permanent, large-scale changes to their ecosystems.
The Story, in Brief
The story begins with a prehistory of the coffee rust, before it became legible in the mid-nineteenth century. There is no evidence of any significant outbreaks before about 1870. Nor, based on what we know of the disease, is there any reason to believe that there were any major outbreaks that went unrecorded. The fungus was present in the forests of southwestern Ethiopia, the wild home of arabica coffee. But the structure of coffee production in Ethiopia likely kept any potential outbreaks in check.
The early global migrations of arabica coffee accidentally kept the rust contained to this small area. Arabica coffee was first cultivated on a large scale across the Red Sea in Yemen, on landscapes so hot and dry that the coffee plants had to be irrigated and cultivated under shade. These landscapes were singularly hostile to the development of the rust fungus, which requires water droplets on the leaves in order to germinate. Yemen’s coffeelands were an ecological filter against
