Further investigations on A2 mating type of Phytophthora infestans in China.
The occurrence and distribution of the A2 mating type of Phytophthora infestans in important potato producing areas of China were studied. Mating types of 142 isolates were determined on white kidney bean media. These isolates were collected from Hebei, Inner Mongolia [Nei Menggu], Shanxi, Yunnan, Sichuan, Chongqing and Beijing during 1995-98. Results showed that 28 isolates of the A2 mating type covered 19.7% of all, and great differences existed between the occurrence frequency of the A2 mating type in different provinces. A2 mating type occurred more often in Hebei, Shanxi and Inner Mongolia than in Yunnan, Sichuan and Chongqing. Two self-fertile isolates were also found, covering 1.4% of all tested isolates.