The oomycete responsible for the highly destructive downy mildew or “late blight” of potatoes. This disease was the cause of Irish potato famine, 1843–1847, which was a principal reason for the waves of Irish immigration to the United States. P. infestans is incorrectly called a fungus in the earlier literature. See Classification, Protoctista, Oomycota.
Subjects: Genetics and Genomics.