马铃薯晚疫病菌抗甲霜灵菌株和敏感菌株在种薯上越冬能力的比较

The comparison of the overwintering ability of metalaxyl-resistance and metalaxyl-sensitive isolates of Phytophthora infestans in seed potato

应用浸泡法接种和越冬后薯片培养法测定了抗性菌株、敏感菌株和混合菌株在种薯上的越冬能力。结果表明 ,用抗性菌株和敏感菌株混合接种 ,病原菌存活率最高 ,其存活率为 10 0 % ;抗性菌株接种的病原菌存活率居中 ,存活率为 80 0 % ;敏感菌株接种的病原菌存活率最低 ,存活率为 4 7%。从晚疫病菌混合菌株接种的种薯上 ,共分离得到 39个分离物 ,测定其对甲霜灵的抗性。测定结果表明 ,抗性分离物的出现频率为 97 4 % ,敏感分离物的出现频率为 2 6 %。

The ability of metalaxyl resistance, metalaxyl sensitive and mixed isolates in P. infestans to overwinter in infected potato seed tuber was studied with immersing inoculation and culturing potato piece method.The survival rate of pathogen in the seed potato inoculated with mixed isolates was the highest(100%).The survival rates of pathogen in the seed potato inoculated with metalaxyl resistant isolates were 80 0%.The survival rate of pathogen, however, in the seed potato inoculated with metalaxyl sensitive isolates was the lowest(46 7%).Pathogen was isolated and assayed metalaxyl resistance by an in vitro radical growth assay on fungicide amended agar media 39 cultures were isolated from seed potato inoculated by mixed isolates.Among 39 cultures, 38 were metalaxyl resistant ones and the frequencies were 97 4%,only 1 was metalaxyl sensitive and the frequency was 2 6%. It showed that the abilities of overwintering and competition of metalaxyl resistant isolates in the seed potato were stronger than that of metalaxyl sensitive ones.