Plant Pathogen Identified in 19th-Century Potato Leaves

NORWICH, ENGLAND—An international team of scientists has examined preserved nineteenth-century plant leaves and collected DNA from the fungus-like infection that wiped out Ireland’s potato crop in 1845. They found that this particular strain of Phytophthora infestans is genetically different from strains that cause infections in potato and tomato crops today. “Perhaps this strain became extinct when the first resistant potato varieties were bred at the beginning of the 20^th century,” said Kentaro Yoshida of The Sainsbury Laboratory. The failure of Ireland’s potato crop led to the deaths of an estimated one million people between 1846 and 1851.