10种杀菌剂及其复配剂对小麦纹枯病菌的室内毒力

Laboratory Toxicity Determination of Ten Fungicides and Their Mixtures to Rhizoctonia cerealis

小麦纹枯病是由禾谷丝核菌(Rhizoctonia cerealis)引起的冬小麦种植区的一种重要土传真菌病害.为筛选防治小麦纹枯病的高效低毒杀菌剂,缓解和治理生产中病原菌对药剂的抗性,在室内离体条件下采用菌丝生长速率法测定了10种杀菌剂(原药)对禾谷丝核菌的毒力.结果表明:98%戊唑醇原粉、95%氟环唑原粉、96%烯唑醇原粉、96%三唑醇原粉、97%吡唑醚菌酯原粉、95%丙环唑原油的EC 50分别为0.115,0.158,0.237,0.432,0.652和1.426 mg/L,表明小麦纹枯病菌对上述杀菌剂比较敏感;95%苯菌灵原粉、97%咪鲜胺原油和98%噻菌灵原粉的EC 50分别为8.034,9.225和14.894 mg/L,病菌对药剂的敏感程度相对较低;97.56%甲基硫菌灵原粉的EC 50为587.362 mg/L,抑菌活性较差.将不同作用机理的杀菌剂吡唑醚菌酯分别与烯唑醇、三唑醇、噻菌灵和甲基硫菌灵按照有效成分1∶1的比例复配,联合毒力测定和评价结果表明,上述复配药剂对抑制小麦纹枯病菌具有明显增效作用.

Wheat sharp eyespot(Rhizoctonia cerealis)is an important soil-borne fungal disease in winter wheat growing regions of China.In order to select high-efficiency and low-toxicity fungicides against wheat sharp eyespot and to delay the emergence of drug resistance in the pathogen,ten fungicides and their mixtures were used for determination of their toxicity to Rh.cerealis in laboratory with the mycelium growth rate method.The results showed that the EC 50 values of tebuconazole,epoxiconazole,diniconazole,triadimenol,pyraclostrobin and propiconazole were 0.115,0.158,0.237,0.432,0.652 and 1.426 mg/L,respectively,thus indicating that the above fungicides had significant inhibitory activity on mycelium growth.The EC 50 of benomyl,prochloraz and thiabendazole were 8.034,9.225 and 14.894 mg/L,respectively,which indicated that the susceptibility of pathogen to these agents was relatively low.Thiophanate-methyl was least effective for wheat sharp eyespot control,its EC 50 value being 587.362 mg/L.In addition,pyraclostrobin was mixed with diniconazole,triadimenol,thiabendazole and thiophanate-methyl at an active ingredient(a.i.)ratio of 1∶1,respectively,and these fungicide mixtures showed an obvious synergistic effect.