海南淮山茎腐病菌对戊唑醇的敏感性测定

Sensitivity of Pathogen of Dioscorea opposita Stem Rot Disease to Tebuconazole in Hainan

研究海南淮山茎腐病菌株对戊唑醇的敏感性,以期为该病害的综合防治提供实践和理论依据。通过单孢分离获得32株茎腐病菌,分别采用菌丝生长速率法和孢子萌发法测定戊唑醇对各菌株的毒力,并进行毒力回归和敏感性分析。结果表明:戊唑醇对菌丝生长具有较强的抑制作用,其抑制中质量浓度(EC50)最小值、最大值、平均值分别为0.063 797、0.407 005、(0.228 3±0.080 5)μg/mL;该药对孢子萌发的抑制效果更明显,其EC50最小值、最大值、平均值分别为0.002 550、0.104 858、(0.031 8±0.024 2)μg/mL。正态分析表明:菌丝生长对戊唑醇的敏感性呈正态分布;而孢子萌发的敏感性呈非正态分布,其最大EC50和最小EC50之间的跨度较大,EC50表现不连续,在高质量浓度区仍有不敏感菌株存在,这表明在自然界中存在个别抗药性较强的淮山茎腐病菌株。

In order to provide practical and theoretical basis for the prevention and control of Dioscorea opposita stem rot disease,the bioassay method of baseline sensitivity was developed on the basis of the effect of tebuconazole on the mycelium growth and spore germination of Fusarium oxysporurn f. sp. dioscorea. Thirty-two strains were obtained by single spore isolation. Virulence of tebuconazole on all of the strains was tested by the methods of mycelium growth and spore germination. Then virulence regression equation was constructed and the sensitive distribution was analysed. The results showed that mycelium growth of the pathogen was affected by tebueonazole,with the maximal ECso of 0. 407 005 μg/mL,minimum EC50 of 0. 063 797 μg/mL, and mean EC50 of （0. 228 3±0. 008 5） μg/mL,respectively. And spore germination was inhibited by tebueonazole to a greater extent,with the mean EC50 as （0. 031 8±0. 024 2） μg/mL,ranging from 0. 002 550 μg/mL to 0. 104 858 μg/mL. Normal distribution analysis showed that the sensitivity of mycelium growth to tebuconazole fitted well with a normal distribution function, but that of spore germination did not, for which the span between the maximal EC50 and the minimum EC50 was big. In high concentration area, there were still insensitive strains. This may be related to the change of environment, and thus a few strains possessed a certain resistance.