Preliminary Study Of Biological Characters And Mating Type Of Phytophthora Infestans Population In Gansu Province, China

Late blight caused by the Phytophthora infestans (Mont.)De Bary is a disastrous disease in the potato growing areas all over the word. Gansu is one of the potato production areas in china.Along with the potato transport becoming more frequently and the potato production's fast development. The structure of Phytophthora infestans population are changed. But the change of the structure Phytophthora infestans population have lead to meny diffcult in the prevention of this disease,the experimental results are as follow:1.149 isolates were isolated and purified from the samples of potato late blight which collected from 17 counties of Gansu province.Among them 12 isolates from the samples of infected tubers, 137 isolates from the samples of infected leaves. 10 isolates from kangle Caotan. 5 isolates from Hezhen Diaotan. 19 isolates from Dongxiang Zhuangping. 8 isolates from Lingxia Tuqiao. 8 isolates from Anding Tuanjie. 9 isolates from Pengyuan. 2 isolates from Longxi Caizi. 4 isolates from Zhuanglang Zhenghe. 9 isolates from Yongdeng Qinchuan. 4 isolates from Lingtao Taoyang. 7 isolates Lintao from Xiakou. 18 isolates from Qinan Wangpu. 12 isolates from Qinan Guojia. 9 isolates from Yuzhong Xinglong. 10 isolates from Weiyuan Huichuan. 3 isolates from Yongjin Wangping. 12 isolates from Longxi Fuxing.2. The results showed that CT-5 growed most quickly from the temperature of 18℃to 20℃; the conidia growed most quickly from the temperature of 20℃to 22℃. The results showed that TY-19 growed most quickly from the temperature of 18℃to 20℃; the conidia growed most quickly from the temperature of 20℃to 22℃.TY-19 and CT-5 growed and conidia growed most quickly in the rye media.3. Fifteen isolates of Phytophthora infestans collected from Gansu Province in 2009 used to test Sensitivities to Cymoxanil. The results showed that the frequencies of sensitive, intermediate and resistant isolates to Cymoxanil were 13.3%, 86.7% and 0, respectively, Their EC50 values for Cymoxanil ranged from 0.0766μg/mL to 0.4063μg/mL. The frequencies of resistant isolates to Metalaxyl was 78.3%. There was no cross-resistance between metalaxyl and cymoxanil in field populations of P. infestans. 4.72.The mating type of Phytophthora infestans isolates collected from Gansu were tested.59 isolates presented mating type A1 and 13 isolates presented mating type A2, the proportion of A2 mating type in Gansu province is about 18%.