Large-scale DNA sequencing of samples of foliage collected in the 19th century from plants infected with late blight has shown that the potato famines of the 1840s were triggered by a single clonal lineage of Phytophthora infestans, called HERB-1, which persisted for at least 50 years.
Keywords: Herbarium; Other; Phytophthora infestans; Solanum tuberosum; ancient DNA.