History prof's interest in tropical crops leads to study of coffee and its relationship with coffee rust, a destructive fungal disease
BY REBECCA KENDALL
When Prof. Stuart McCook, History, is in the middle of a grocery store, he is captivated by the products of global exchange and commerce that surround him. From the bananas that top our morning breakfast cereal to the chocolate, sugar, tea and coffee that have become regular parts of our diet, tropical crops are all around us, he says. The tropical products we consume are at the core of the research that consumes him.
“Being in a supermarket is almost a magical experience as I think about standing in the middle of a web that touches every part of the world — a web that is shaped by political, environmental and economic relationships,” says McCook, who arrived at U of G in 2003 and holds a BA from the University of Toronto, an MS from Rensselaer Polytechnic Institute in Troy, N.Y., and an MA and PhD from Princeton.
“I think it's important as a historian to remind people how strange it is that we consume the products of so many plants from halfway around the world, yet very few from our own backyards. It's a good idea to be aware that what we consume comes from somewhere and is grown by someone. These things are not born on supermarket shelves.”
McCook is intrigued by topics related to the environmental history of tropical commodities and the societies that produce them. Although it took him 28 years to become a coffee drinker, much of his time is now spent poring over literature and research related to the popular beverage. That's because his latest undertaking is a 150-year history of coffee and its relationship with coffee rust, a fungal disease that has plagued coffee plants in many areas of the world and has had dramatic effects on national economies.
This year, his work has taken him to Costa Rica, Guatemala, Portugal, Spain, the United Kingdom and Venezuela, the country where in 1993 he started to drink coffee, learned to speak Spanish and met his wife, Alicia.
Coffee rust is commonly found in the regions where coffee plants are native, namely southwest Ethiopia and northern Kenya, says McCook. A single tiny rust pustule on a coffee tree leaf can produce more than 100,000 spores, and a single leaf can contain hundreds of pustules. The pustules cause damage to the leaf and, in severe cases, can cause the leaves to fall off and compromise the health of the entire tree and the livelihood of coffee growers.
“The disease is a huge stress on the trees, and even if they're alive, they're very sick. Over the course of successive outbreaks, production starts to collapse. In some cases, it could be 100 per cent.”
McCook, who has studied other tropical crop epidemics, including sugar cane mosaic disease in Puerto Rico and Cuba and the impact of witches' broom disease in the cacao plantations of Ecuador and Brazil, says coffee rust is at the root of the destruction of many coffee plantations. Coffee rust co-evolved with coffee plants and was never a problem in the wild, he says, but it started to become a serious problem soon after coffee became a major global commodity.
In the wild, coffee rust was kept in check by the biological diversity of the forests, the genetic resistance of the coffee plants, the climate and the parasites that attacked the rust fungus, says McCook, who notes that coffee consumption in pre-colonial Africa did little to alter the relationship between the plant and the disease because most coffee was harvested from wild plants.
“Tropical crop epidemics have become frequent, widespread and devastating since the early 19th century. These epidemics were not simply ‘natural' events. They were also the accidental result of large-scale transformations in rural environments during this period.”
Although there are nearly 100 species of coffee plants, the main commercial species is arabica, which grows in the cool, dry mountain environments of southwestern Ethiopia and northern Kenya.
The popularity of coffee drinking began to skyrocket in the Islamic world and Europe in the 1500s, and this led to the increase in coffee cultivation in new locales, says McCook. The first coffee rust epidemic broke out in Ceylon (now Sri Lanka) at the same time that European colonies were expanding. Imperialism brought an influx of travellers and more transportation and shipping. People began to have more disposable income and could now afford products such as coffee and bananas. These factors, along with the invention of the Wardian case, a portable terrarium-like unit used to ship the difficult-to-transport coffee plants around the world, led to the increase in coffee rust, he says.
“Imperial expansion provoked epidemics — human, animal and plant — because it accelerated the spread of pathogens and it altered colonial environments in ways that favoured epidemics. With respect to coffee rust, British activity in the Arabian Sea accelerated the direct movement of goods and people and — by extension — people and pathogens among eastern Africa, India and Ceylon. British settlers in Ceylon and southern India created the ecological conditions that allowed coffee rust to flourish.”
One of the first countries to see an influx of coffee plantations was Ceylon. “In the 1840s and 1850s, Ceylon was sort of like the wild west,” he says. “British settlers were coming in and clearing land and planting coffee on a very large scale. Coffee went from being an intercropped plant to a monoculture. This made it highly productive, but vulnerable to disease.”
When coffee rust first reached the tiny island nation in 1869, nearly 400,000 acres of land were invested in coffee trees and coffee production, and the island nation was exporting some 45 million kilograms of coffee a year. Twenty years later, production was down by 95 per cent. By the mid-1920s, the disease had become globally widespread and decimated coffee operations in a number of countries, including Indonesia, Madagascar, Fiji, South Africa and the Philippines. The Philippines, which had been the world's fourth-largest exporter of coffee in 1889, the year rust was first detected there, had dropped its coffee exports from 16 millions pounds to virtually nothing by 1892.
Efforts to combat coffee rust and its chances of destroying modern coffee plantations have increased over the past few decades. Millions of dollars have gone into developing new varieties of rust-resistant hybrid coffee plants, modifying planting methods and developing chemical interventions as ways to control the spread of the fungus without compromising the taste or quality of the coffee that's produced. These efforts are ongoing and have met with mixed response, says McCook, who notes that no one has found a coffee that's resistant to the rust and still meets the highest quality in terms of taste and marketability. “It's a trade-off.”
