烟草赤星病菌对苯醚甲环唑和氟环唑敏感性测定及田间防效试验

为明确山东省主要烟草产区烟草赤星病菌Alternaria alternata对苯醚甲环唑和氟环唑的敏感性,采用菌丝生长速率法检测苯醚甲环唑和氟环唑对86株烟草赤星病菌菌株的EC_(50),用Spearman’s秩相关系数法分析供试菌株对2种杀菌剂敏感性的相关性,并评价其对烟草赤星病的田间防效。结果表明,苯醚甲环唑对烟草赤星病菌菌丝生长EC_(50)值介于5.3883～8.0316 mg/L之间,平均值为6.9594 mg/L,敏感性频率分布呈连续性偏正态分布,田间烟草赤星病菌对苯醚甲环唑仍然较为敏感,可建立田间烟草赤星病菌对苯醚甲环唑的敏感基线。氟环唑对烟草赤星病菌菌丝生长的EC_(50)值介于0.1253～0.2517 mg/L,平均值为0.1773 mg/L,敏感性频率分布呈连续性偏正态分布,可建立田间烟草赤星病菌对氟环唑的敏感基线。相关性分析结果表明,烟草赤星病菌对苯醚甲环唑和氟环唑敏感性之间不存在明显的相关性。田间试验结果表明,30%苯醚甲环唑悬浮剂对烟草赤星病具有较好的防效,其有效成分150 g/hm~2处理的防效最高,为73.99%;12.5%氟环唑悬浮剂对烟草赤星病的最高防效为70.57%。表明2种三唑类杀菌剂对烟草赤星病防效较好。

The sensitivity of leaf spot pathogen Alternaria alternata to fungicides difenoconazole and epoxiconazole and control efficacy on tobacco brown spot

To clarify the sensitivity of leaf spot pathogen Alternaria alternata to difenoconazole and epoxiconazole and control efficacy for tobacco brown spot, the 86 isolates of A. alternata were collected in Shandong Province, the inhibition of mycelial growth of these isolates were detected and the control efficacy of two fungicides to tobacco brown spot were also evaluated in the tobacco field. The sensitivities of two fungicides were analyzed with Spearman''s rank correlation coefficient method. The results showed that the EC₅₀ values of 86 isolates to difenoconazole varied from 5.3883 to 8.0316 mg/L, with an average of 6.9594 mg / L. The EC₅₀ values of all isolates to epoxiconazole varied from 0.1253 to 0.2517 mg/L, with an average of 0.1773 mg/L. The sensitivity frequency distribution showed a continuous partial normal distribution, which could establish the sensitive baseline for A. alternata in the field. The correlation analysis showed that there was no correlation between two fungicides. The test results in field showed that 30% difenoconazole SC had better control effect on tobacco scab, and the control effect of 150 g/hm² was the highest (73.99%); the highest control effect of 12.5% epoxiconazole SC was 70.57%. The results indicated that two fungicides had good control effect against tobacco brown spot.