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为明确山西省黄瓜白粉病菌对甲基硫菌灵的抗药性现状,采用叶盘漂浮法测定了不同地区119株菌株对甲基硫菌灵的敏感性,用紫外线照射和药剂驯化方式诱导获得了甲基硫菌灵抗性突变体,并比较了亲本菌株与突变体的生物学性状。结果表明,119株菌株的EC50在0.48~14.37μg/m L之间,平均EC50为2.89±2.69μg/m L。不同地区菌株敏感性差异较大,采自未使用过任何杀菌剂的忻州市菌株敏感性最高,平均EC50为1.03±0.27μg/m L,可作为黄瓜白粉病菌对甲基硫菌灵的敏感基线;运城市菌株敏感性最低,平均EC50为7.02±3.12μg/m L,其中菌株YC01的EC50是敏感基线的13.98倍。3株室内诱导突变体均为高抗,突变体XZ11-2的抗性倍数达到94.96倍,抗性突变频率为1.5×10-3。无药剂处理条件下,突变体的侵染频率、病情指数、产孢量和孢子萌发率均显著低于亲本敏感菌株;抗∶感菌株分生孢子以80∶20混合培养7代后,抗性菌株频率变化不明显;以20∶80混合培养7代后,抗性频率降低甚至消失。表明黄瓜白粉病菌对甲基硫菌灵的抗性在选择压力低的情况下有可能丧失。
In order to clarify the drug resistance status of powdery mildew of cucumber in Shanxi Province to thiophanate-methyl, the sensitivity of 119 strains of thiophanate-methyl in different areas was determined by leaf disc floating method. The results showed that Thiophanate-methyl resistant mutants, and compared the biological characteristics of the parental strains and mutants. The results showed that the EC50 of 119 isolates ranged from 0.48 to 14.37 μg / m L with an average EC50 of 2.89 ± 2.69 μg / m L. The sensitivity of strains in different regions is quite different. Xinzhou strain collected from no fungicide has the highest sensitivity with the average EC50 of 1.03 ± 0.27μg / m L, which can be used as the sensitive baseline for thiophanate-methyl ; Yuncheng strains had the lowest sensitivity with the average EC50 of 7.02 ± 3.12μg / m L, of which strain EC50 of YC01 was 13.98 times of the sensitive baseline. The three inducible mutants were highly resistant, the resistance of mutant XZ11-2 was 94.96 fold, and the frequency of resistance mutation was 1.5 × 10-3. The infection frequency, disease index, sporulation rate and spore germination rate of the mutants were significantly lower than those of the parental sensitive strains under the condition of no drug treatment. The resistance: the conidia of the susceptible strains were mixed and cultured for 7 generations after 80:20, The frequency of the strains did not change obviously. The frequency of resistance decreased or even disappeared after mixed for 7 generations at 20:80. Show that cucumber powdery mildew resistance to thiophanate-methyl in the case of low selection pressure may be lost.