Phytophthora infestans

Phytophthora infestans is an oomycete, a fungus-like water mold more closely related to algae and diatoms than to true fungi, that causes late blight, a serious disease of potatoes and tomatoes in the family Solanaceae. It thrives in moist, cool conditions, sporulating best between 12 and 18 degrees Celsius in water-saturated environments. The pathogen was a major cause of the European and Irish potato famines of the 1840s and the 1846 Highland potato famine in Scotland; Ireland's near-total dependence on a single susceptible variety, the Irish Lumper, made the outbreak catastrophic, contributing to more than a million deaths and the emigration of roughly two million people during the Great Famine of 1845 to 1852. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/