Pythium
Pythium is a genus of parasitic oomycotes. Most species are plant parasites, but Pythium insidiosum is an important pathogen of animals. They were formerly classified as fungi; the feet of the fungus gnat are frequently a vector for their transmission.
Morphology
Ecological importance
Pythium-induced root rot is a common crop disease. When the organism kills newly emerged or emerging seedlings it is known as damping off, and is a very common problem in fields and greenhouses. This disease complex usually involves other pathogens such as Phytophthora and Rhizoctonia. Pythium wilt is caused by zoospore infection of older plants leading to biotrophic infections that become necrotrophic in response to colonization/reinfection pressures or environmental stress, leading to minor or severe wilting caused by impeded root functioning.
Many Pythium species, along with their close relatives Phytophthora, are plant pathogens of economic importance in agriculture. Pythium spp. tend to be very generalistic and unspecific in their host range. They infect a large range of hosts, while Phytophthora spp. are generally more host-specific.