嘧菌酯对马铃薯早疫病菌Alternaria solani的毒力及防效

Toxicity and Control Efficacy of Azoxystrobin against Potato Early Blight Alternaria solani

采用组织分离法从西南北部马铃薯主产区的马铃薯罹病叶片分离得到63株早疫病菌,并通过分生孢子萌发法测定了其中30株早疫病菌对嘧菌酯的敏感性。结果显示,测试的30株马铃薯早疫病均对嘧菌酯保持高度敏感,陕西安康、湖北恩施和四川西昌马铃薯早疫病菌对嘧菌酯的平均EC50值分别为0.024 4、0.025 6和0.037 6 mg/L,3地总菌株的平均EC50值为0.029 0 mg/L。在田间药效试验中,25%嘧菌酯悬浮剂用量为450 g/hm2,对马铃薯早疫病的防效为84.71%,与43%戊唑醇悬浮剂300 g/hm2的防效之间差异不显著,但显著高于50%多菌灵可湿性粉剂1 500 g/hm2和80%代森锰锌可湿性粉剂3 000 g/hm2的防效,且增产效果显著。以上结果表明,嘧菌酯可作为该区域内生产上防治马铃薯早疫病的优选药剂。

Sixty-three strains of Alternaria solani, a causal agent of potato early blight, were isolated from leaves of potato plants growing in major regions of potato production in northern southwest China with tissue isolation method. The sensitivity of thirty isolates among them to azoxystrobin was detected by conidial germination method. The results showed that all of them were highly sensitive to azoxystrobin, mean ECs0 values of A. solani strains from Ankang in Shaanxi, Enshi in Hubei, Xichang in Siehuan to azoxystrobin were 0.024 4, 0.025 6 and 0.037 6 mg/L respectively, and the average ECso value of all these strains was 0.029 0mg/L. In the field trial, the control efficacy of azoxystrobin 25% SC applied at the rate of 450 g/hm^2 against potato early blight was 84.71% and compared with that of tebuconazole 43% SC applied at the rate of 300g/hm^2, the difference was not significant; however, its control efficacy was significantly higher than those of the fungicides carbendazim 50% WP applied at the rate of 1500 g/hm^2 and mancozeb 80% WP applied at the rate of 3000 g/hm^2. Moreover, its application increased the yield markedly. So azoxystrobin could be used as a preferred pharmaceutical for controlling potato early blight in the region.