Occurrence of the A2 mating type of Phytophthora infestans on potato in Yunnan

A great number of strains of Phytophthora infestans were isolated from different potato production areas of Chuxiong,Dali,Kunming,Qujing and Xuanwei which were determined for their mating type with the standard A1 strain on the Lima bean V8 Juice agar medium. The result indicated that ten A2 mating type strains had been found in forty seven strains. A great abundant of sexual progeny were typically formed when two compatible strains were mated each other. The morphological character and size of oospore,amphigymius oogonium and artheridium were discribed respectively. It is firstly reported that there are A2 mating type strains of Phytophthora infestans in Yunnan province.