黄瓜霜霉病菌对甲霜灵的抗药性

Study on Resistance of Pseudoperonospora cubensis to Metalaxyl

本研究采用叶盘漂浮法测定了来自黑龙江省、吉林省、辽宁省、北京、山东省、江苏省、湖北省和广东省8个省份13个黄瓜主产区的36个黄瓜霜霉病菌株对甲霜灵的抗药性。结果表明，黄瓜霜霉菌对甲霜灵的EC50值为1．3277—171．5480μg／mL，平均EC50值为64．6782μg/mL；36株菌株中，有3个中抗菌株，占总菌株数的8．3％；33个高抗菌株，占91．7％，为优势群体，无敏感菌株和低抗菌株。各地区采集的黄瓜霜霉菌对甲霜灵抗性水平范围28．25～3649．96倍，平均抗性水平为1376．13倍；除黑龙江省齐齐哈尔检测到1株中抗菌株和辽宁省海城检测到2株中抗菌株外，其余菌株对甲霜灵的抗性水平均超过100倍，表明多数菌株对甲霜灵已经产生很强的抗药性。

36 strains of cucumber downy mildew in cucumber which were collected from 13 main producing areas in China were investigated to study their resistance to the metalaxyl, the toxicity of metalaxyl to P. cubcnsis was determined with leaf disk floating method. The result showed that ECs0 of P. cubens/s to metalaxyl was 1. 3277 - 171. 5480 pyo/mL, with the average ECs0 of 64.6782 μg/mL. There were 3 moderate resistant isolates, accounting for 8.3 % of 36 isolates,33 high resistance isolates, accounting for 91.7 %, were dominant group, and there was non-sensitivity isolate and low resistance isolate. Fungicides sensitivity of Pseudoperonospora cubertsis in all areas to metalaxyl was 28.25 -3649.96 times, and the mean res.stance was 1376.13 times. Except one in Heilongjiang and two isolates in Liaoning were mod- erately resistant, other isolates were more than 100 times, which indicated that most of the isolates had a very strong resistance to metalaxyl.