Homothallic Phytophthora infestans was found in China.

Out of 84 strains isolated in 1964, a strain of Phytophthora infestans forming oospores with typical amphigynous antheridium and oogonium on culture medium without pairing with opposite mating type was isolated from diseased potato tuber of cultivar “Long An Yang Yu” collected from Min Xian, Gansu Province. Its homothallic character was maintained in single sporangium or single zoospore isolates. Pathogenic experiments proved that this strain is a typical P.infestans. This suggests that proper attention should be paid to the existence of the homothallic strain of P.infestans though it is not so widespread as the already known heterothallic strains.