S8 Ep1038: Phytophthora Infestans: The Science of the Blight. Guest: Patrick Scanlan. The discussion turns to the biological cause of the famine: Phytophthora infestans, or the potato blight. Scanlan explains that Irish potatoes were grown from cuttings (clones), an

Phytophthora Infestans: The Science of the Blight. Guest: Patrick Scanlan. The discussion turns to the biological cause of the famine: Phytophthora infestans, or the potato blight. Scanlan explains that Irish potatoes were grown from cuttings (clones), and this lack of genetic diversity made them uniquely vulnerable to pathogens. While Ireland had experienced localized crop failures before, the blight was a "novel pathogen" originating from Mexico. It traveled through the Americas before crossing the Atlantic to Europe in 1844–45. As a "water mold" that reproduces through spores, it spread rapidly on the wind across Ireland's dense monocrops. While the blight struck across Europe, the impact was most catastrophic in Ireland due to the population's profound dependence on the crop and a lack of alternative food sources. The organism encountered fields that had been separated from such pathogens for centuries, allowing it to sweep across every field it reached and destroy crops with unprecedented speed. 7 1873 QUEENSTOWN