Phytophthora is a genus of water mould, and a pathogen of considerable economic importance.
There are numerous species, including:
Phytophthora cactorum - Collar rot
Phytophthora cinnamomi - commonly known as "dieback" (as many Phytophthora species are), this affects as many as 2000 of the 9000 native plant species in the south-west of Western Australia, most notably jarrah (Eucalyptus marginata).
