六种杀菌剂对烟草赤星病菌菌丝生长和分生孢子萌发的抑制作用

采用菌丝生长速率法和孢子萌发法测定了烟草赤星病菌Alternaria alternata对6种杀菌剂(氟硅唑、异菌脲、菌核净、嘧菌酯、醚菌酯及多菌灵)的敏感性。结果表明:6种杀菌剂对烟草赤星病菌菌丝生长和分生孢子萌发均表现出了不同程度的抑制活性。其中,对菌丝生长抑制活性最强的是氟硅唑,EC50平均值为(0.34±0.11)mg/L,其次为菌核净(1.13±0.68)mg/L]和异菌脲(2.08±0.24)mg/L];对分生孢子萌发抑制活性最强的是嘧菌酯协同100 mg/L水杨肟酸,EC50平均值为(0.28±0.09)mg/L,其次分别为单独处理的嘧菌酯(5.79±2.76)mg/L]、醚菌酯(11.93±3.93)mg/L]、菌核净(19.95±15.94)mg/L]和异菌脲(23.33±11.33)mg/L]。多菌灵对烟草赤星病菌菌丝生长和分生孢子萌发的抑制活性均最差,不宜用于烟草赤星病的防治,而异菌脲、氟硅唑、嘧菌酯和醚菌酯均有必要进一步针对烟草赤星病进行田间防效试验。

Inhibitory activities of six fungicides against mycelial growth and conidial germination of Alternaria alternata

Activities of six different fungicides(flusilazole, iprodione, dimethachlon, azoxystrobin, kresoxim-methyl, carbendazim) to Alternaria alternata were determined by mycelial growth rate method and conidial germination assay. The results showed that the six fungicides showed different inhibitory activities against A. alternata on mycelial growth and conidial germination. The most effective fungicide against the mycelial growth of A. alternata was flusilazole, with average EC₅₀ value of(0.34±0.11) mg/L, followed by dimethachlon (1.13±0.68) mg/L] and iprodione (2.08±0.24) mg/L]. The most effective fungicide against theconidial germination of A. alternata was azoxystrobin in combination with 100 mg/L SHAM, with average EC₅₀ value of(0.28±0.09) mg/L, followed by azoxystrobin (5.79±2.76) mg/L], kresoxim-methyl (11.93±3.93) mg/L], dimethachlon (19.95±15.94) mg/L] and iprodione (23.33±11.33) mg/L] when used alone. Carbendazim showed the lowest inhibition on both mycelial growth and conidial germination of A. alternata, suggesting it should not be used for controlling tobacco brown spot. Further study is needed to investigate the field control efficacy of iprodione, flusilazole, azoxystrobin and kresoxim-methyl against tobacco brown spot.