Late blight of potatoes is caused by the fungus-like oomycete pathogen Phytophthora infestans. It can infect and destroy the leaves, stems and tubers of potato plants. Severe late blight epidemics occur when P. infestans grows and reproduces rapidly on the host crop. Reproduction occurs via spores that are produced from infected plant tissues and is most rapid during conditions of high moisture and moderate temperatures. Spores disperse to healthy tissues via rain splash or on wind currents.