As mass crop failures of the 19th century go, it doesn’t get bigger than the blight that devastated Irish potatoes in 1845. Estimates vary on how much the disease impacted the harvest of the Irish staple, the blight destroying somewhere between one-third to as much as half of the crop. One million people died of the Great Famine that followed, and the devastation contributed to the migration of another million residents of Erin, bringing a massive Irish diaspora to the United States.
Thirty years later, the 400,000 acres of coffee grown in Ceylon began to be infected by a different kind of blight, a fungal disease known as coffee rust. The disease took a slower course than potato blight, but by 1889, exports had dropped to five million pounds a year, down from 100 million just before the rust arrived; the colonial coffee industry was all but dead, and the British put their energy into cultivating tea on the South Asian island.
Similar diseases have been impacting potato farms and coffee plantations ever since, although they have yet to strike quite as dramatically as they did in Ireland and Ceylon.
This week, both blights are back in the news. As the BBC reports, researchers studying dried potato leaves from the Kew Royal Botanical Gardens in the U.K. and Germany’s Botanische Staatssammlung Muchen have sequenced the DNA of the pathogen that caused the Great Famine. The results show that, “the strain that changed history is different from modern day epidemics, and is probably now extinct.”
Coffee rust, for its part, may be gearing up for Ceylon-like levels of destruction, according to a new article from The Atlantic. “Spurred by unusually high rainfall over the last few years, it currently threatens to ruin as much as 40 percent of the 2013/14 Central American harvest,” writes James McWilliams. Stepping into similar territory that TakePart reported on in the case of antibiotics being used to combat bacterial disease in organic orchards, McWilliams (who wrote, its worth noting, Just Food: Where Locavores Get It Wrong and How We Can Truly Eat Responsibly) seems to suggest that the regulations of organic farming are contributing to the problem. Copper sulfate, organic farmers’ only defense against fungal infections like rust, he explains, is less effective than conventional fungicides—and is environmentally problematic too. Instead of sticking with that ineffective treatment for the sake of a label, McWilliams wonders, “Why not allow a one-time application of a synthetic fungicide in an emergency situation?”
The discovery that the Great Famine strain of potato blight is likely extinct suggests that the more effective approach to combating such problematic diseases lies in breeding, not chemical applications. The potato blight research shows that introducing new disease-resistant varieties may have a profound effect on the development of pathogens—and perhaps their demise too. Researcher Kentaro Yoshida told the BBC, “Perhaps this strain became extinct when the first resistant potato varieties were bred at the beginning of the 20th Century.”
Indeed, McWilliams found that introducing rust-resistant varieties was one of the most effective means of controlling the disease. He notes “one mustn’t dismiss the preventive role of fungal-resistant coffee varieties”—but writing a story about addressing rust via selective breeding wouldn’t give him the opportunity to troll organic-loving consumers. McWilliams takes his own advice, pointing out that,
In Colombia, farmers benefiting from extensive state-funded research planted rust resistant varieties in 2008 and, in so doing, effectively exterminated the fungus from the countryside (though experts claim that taste is compromised when heirloom beans aren't grown).
Descendants and relatives of the newly identified potato-killing pathogen are still a source of frustration for many spud farmers. But after more than a century of breeding for resistance, there are plenty of varieties with names that are associated with the “heirloom,” farm-to-table realm of the food world—like Yukon Gold, for example—that deliver in terms of flavor and can withstand blight too.
Despite much hyperbole that suggests the contrary, no one would actually die if they didn’t have that very particular cup of coffee in the morning. And if you’re reading this thinking that breeding for rust resistance would involve Monsanto-ing up the coffee-gene equivalent of stainless steel and injecting them into your beloved heirloom plants, consider this: Biodiversity is incredibly limited in the global coffee trade. When the first modern case of rust was discovered in Brazil, in the 1970s, the majority of the coffee planted around the world was, according to the American Phytopathological Society, descendant from “a single tree planted in the conservatory of King Louis XIV in 1713.” As was the case in 19th-century Ireland, where one type of potato, the lumper, accounted for the majority of the crop, commercial coffee depends on a very narrow segment of the gene pool—which makes it susceptible to catastrophic crop failure. And where has naturally occurring rust resistance been discovered? In wild varieties—which may hold intriguing new (old) flavors too.