烟草赤星病菌对嘧菌酯及其添加水杨肟酸后的敏感性检测

为了解烟草赤星病菌对嘧菌酯的敏感性现状，采用菌丝生长速率法，检测了采自山东和湖北烟区的33株烟草赤星病菌对嘧菌酯的敏感性，分析了水杨肟酸协同下烟草赤星病菌对嘧菌酯敏感性的影响。结果表明:嘧菌酯对所有供试烟草赤星病菌的EC₅₀介于60.5230~111.7918 mg·L-1，平均为83.9068±2.4339 mg·L-1；嘧菌酯对采自山东烟区和湖北烟区的赤星病菌的平均EC₅₀分别为82.7986±2.5515 mg·L-1和88.0230±6.6785 mg·L-1。在水杨肟酸协同作用下，嘧菌酯对所有供试烟草赤星病菌毒力的EC₅₀介于19.9090~35.6684 mg·L-1，平均为29.2007±0.7801 mg·L-1，比嘧菌酯单独作用毒力提高了0.70~2.98倍，平均提高了1.87倍；添加水杨肟酸的嘧菌酯对采自山东和湖北烟区的赤星病菌毒力的平均EC₅₀分别为28.5494±0.8914 mg·L-1和31.6197±1.3290 mg·L-1，与嘧菌酯单独作用相比，毒力分别提高了1.90和1.78倍。研究表明，嘧菌酯对烟草赤星病菌的菌丝生长具有一定的抑制作用，添加水杨肟酸能够显著提高嘧菌酯对烟草赤星病菌的毒力，但不同菌株之间的提高倍数有差异。 

Determination of susceptibility of Alternaria alternata to azoxystrobin and to azoxystrobin added with salicylhydroxamic acid

In order to investigate the sensitivity level of A. alternata to azoxystrobin, EC₅₀ values of 33 isolates of A. alternata, collected from Shandong province and Hubei province, to azoxystrobin were determined using mycelium growth rate method. The sensitivity of 33 isolates to azoxystrobin with added salicylhydroxamic acid (SHAM) was also analyzed. Results showed that the EC₅₀ values of 33 isolates to azoxystrobin varied from 60.5230 to 111.7918 mg·L-1, with an average of 83.9068±2.4339 mg·L-1. The mean EC₅₀ value was 82.7986±2.5515 mg·L-1 for A. alternata collected from Shandong and 88.0230±6.6785 mg·L-1 for A. alternate colle cted from Hubei, respectively. However, the EC₅₀ values of 33 isolates to azoxystrobin with added SHAM varied from 19.9090 to 35.6684 mg·L-1, with an average of 29.2007±0.7801mg·L-1. The toxicities under SHAM were enhanced by 0.70-2.98 times (with an average of 1.87 times)compared to that under azoxystrobin alone. The mean EC₅₀ value of A. alternata to azoxystrobin with added SHAM was 28.5494±0.8914 mg·L-1 for Shandong and 31.6197±1.3290 mg·L-1 for Hubei, respectively. The toxicities were increased 1.90 and 1.78 times, respectively.Results also showed that azoxystrobin could inhibit mycelial growth of A. alternate. The toxicity of azoxystrobin to A. alternata could be significantly enchenced by adding SHAM, while the increase level of toxicity varied depending on different bacterial strains.