烟草赤星病菌对菌核净和苯醚甲环唑的抗药性检测

为了解吉林省和黑龙江省烟草赤星病菌对菌核净和苯醚甲环唑的抗性水平，采用菌丝生长速率法，测定了318株烟草赤星病菌对菌核净和苯醚甲环唑的药剂敏感性，建立敏感基线。运用最低抑制浓度法确定抗性菌株及频率，并比较不同采样地点的抗性水平。结果表明，供试敏感菌株对菌核净的敏感性频率分布呈连续的单峰曲线，接近正态分布，其EC₅₀均值2.916 μg/mL可作为两省烟草赤星病菌对菌核净的敏感基线，抗性频率为21.38%；烟草赤星病菌对苯醚甲环唑的敏感基线为1.198 μg/mL，抗性频率为18.24%。吉林省和黑龙江省烟草赤星病菌对菌核净和苯醚甲环唑产生了不同程度的抗性，不同地点抗性水平存在差异。本研究为烟草赤星病菌的抗药风险评估奠定了基础，为制定吉林和黑龙江两省烟草赤星病科学防治策略和科学用药提供了依据。

Resistance Assessment of Alternaria alternata Causing Tobacco Brown Spot to Dimethachlon and Difenoconazole

To understand the resistance level of Alternaria alternata to dimethachlon and difenoconazole in Jilin and Heilongjiang Provinces,the sensitivity of 318 isolates of A.alternate to the two fungicides was determined by the method of mycelial growth rate and the sensitivity baseline to dimethachlom and difenoconazole were established.The resistant isolates and frequency were determined using the method of minimum inhibitory concentration and the levels of resistance risk of different locations were also evaluated.The results showed that the distribution of sensitivity frequency of isolates was a continuous single peak curve,which was close to the normal distribution.Therefore,the average value of EC50 with 2.916μg/mL could be used as the sensitivity baseline of A.alternata to dimethachlon in both provinces and the resistance frequency was 21.38%.The sensitivity baseline of A.alternata to difenoconazole was 1.198μg/mL and its resistance frequency was 18.24%.There was different resistance for the isolates to dimethachlon and difenoconazole between Jilin Province and Heilongjiang Province,and the resistance level in each regions was different.This study would lay the foundation of the resistance risk assessment and provide evidence to develop a scientific strategy to control tobacco brown spot disease in Jilin and Heilongjiang Provinces.