Pythiaceae

Pythiaceae is a family of oomycetes. The family includes serious plant and animal pathogens in the genus Pythium. The family was circumscribed by German mycologist Joseph Schröter in 1893.

Lifecycle

Live on land, and in water, or a combination of the two.
Most are deadly parasites, causing root rot and damping off on plants and pythiosis on animals.
The diploid life stage predominates, with a short haplophase initiated during sexual reproduction before the fusion of the gametes. Most species are homothallic.

The sporangia may germinate via a germ tube or by release of motile zoospores, depending on the species and the environmental conditions.

Some Pythium species cause "damping off" diseases in young plants.