番茄早疫病菌对啶菌噁唑敏感基线建立及药剂作用方式初探

从中国山西、内蒙古、山东、海南、江苏、福建和陕西省 (自治区) 不同市、县从未使用过啶菌噁唑的露地或保护地采集并经单孢分离获得 166 株番茄早疫病菌，采用菌丝生长速率法测定了病原菌群体对啶菌噁唑的敏感性。结果表明:啶菌噁唑对番茄早疫病菌的 EC50 值范围在 0.11~2.29 mg/L 之间，敏感性频率呈正态分布，其均值 (0.56 ± 0.39) mg/L 可作为番茄早疫病菌对啶菌噁唑田间抗性监测的敏感基线；不同采集地菌株对啶菌噁唑的敏感性存在差异，其中采自福建省的菌株敏感性最高，而山西省大同、晋中和长治市的菌株敏感性最低。200 mg/L啶菌噁唑对番茄早疫病防治具有优异的保护和治疗作用，且接菌前 4 d 内施药和接菌后 1~2 d内施药防效最佳。研究表明，啶菌噁唑对番茄早疫病防治具有良好的实际应用前景。

Sensitivity baseline of Alternaria solani to pyrisoxazole and the mode of action of pyrisoxazole

To study the sensitivity of Alternaria solani to pyrisoxazole, 166 single-spore isolates were collected from tomato fruits or leaves infected by A. solani without exposure to pyrisoxazole in open field or greenhouse in Shanxi province, Inner Mongolia Autonomous Region, Shandong province, Hainan province, Jiangsu province, Fujian province and Shaanxi province. The sensitivity of each isolate to pyrisoxazole was determined by mycelial growth inhibition rate. The range of EC₅₀ values were from 0.11 mg/L to 2.29 mg/L, and the sensitivity frequency was normally distributed. Thus, the sensitivity baseline was established with the mean EC₅₀ value (0.56 ±0.39) mg/L of pyrisoxazole. There were significant differences in the mean EC₅₀ value of each collected district. The isolates from Fujian province were the most sensitive, while the isolates from Shanxi province (Datong, Jinzhong and Changzhi) were the least sensitive to pyrisoxazole. Pyrisoxazole provided excellent protective and curative activity on A. solani when applied at 200 mg/L, and it showed the best control efficacy before the artificial inoculation in 4 days and after inoculation in 2 days. Consequently, there is a good application prospect to pyrisoxazole for controlling tomato early blight.