Abstract A description is provided for Phytophthora katsurae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Chestnut, coconut. DISEASE: Trunk rot of chestnut. GEOGRAPHICAL DISTRIBUTION: Asia (Japan, Taiwan), Oceania (Hawaii), Africa (Ivory Coast), Australasia (Australia (Queensland), Papua New Guinea). TRANSMISSION: Soil-borne, isolated from forest soils in Taiwan (59, 2349), Queensland and Papua New Guinea and from chestnut orchard soils in Japan (58, 2951).