摘要:
为明确致病疫霉菌甲霜灵抗性菌株对氟吗啉、嘧菌酯、吡唑醚菌酯、烯酰吗啉和霜脲氰的敏感性,采用菌丝生长速度法,并用叶盘漂浮法加以比较,测定了致病疫霉菌甲霜灵抗性菌株和敏感性菌株对供试杀菌剂的敏感性。试验结果表明,供试5种杀菌剂对致病疫霉菌甲霜灵抗性和敏感菌株的菌丝生长、孢子囊的形成都具有明显的抑制作用。对致病疫霉菌甲霜灵抗性菌株毒力最强的杀菌剂是氟吗啉,其平均EC50值为0.037 6 gmL-1,致病疫霉菌间对霜脲氰的敏感性差异显著,EC50值在0.008 4~0.868 1 gmL-1之间,其中甲霜灵抗性菌株平均EC50值为0.386 6 gmL-1。菌丝生长速率法离体测定表现出与叶盘漂浮法结果具有较高的相关性,供试杀菌剂与甲霜灵不存在交互抗性,可作为甲霜灵的替代药剂防治番茄和马铃薯晚疫病。
Abstract:
In order to determine the sensitivity of metalaxyl-resistant strains of Phytophthora infestans to fungicides flumorph, azoxystrobin, pyraclostrobin, dimethomorph and cymoxanil, the toxicity of fungicides to metalaxyl- sensitive and metalaxyl-resistant strains of P.infestans were tested by measuring radial growth on agar medium amended with fungicides. The results showed that the five tested fungicides had high inhibitory activity against mycelium growth and sporangia formation of metalaxyl-resistant and metalaxyl-sensitive isolates of P.infestans. Flumorph exhibited the strongest toxicity to metalaxyl-resistant strains with the mean EC50 of 0.037 6 gmL-1.There was obvious difference in sensitivity of tested isolates to cymoxanil, which EC50 values ranged from 0.008 4 gmL-1 to 0.868 1 gmL-1,the mean EC50 value was 0.386 6 gmL-1 in inhibiting the mycelium growth of metalaxyl-resistant strains. There is high correlation of tested results between in vitro method and the floating-leaf-disk method, and showed that the tested fungicides had no cross-resistance with metalaxyl. These fungicides maybe substitute metalaxyl for controlling potato and tomato late blight disease.
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