五种杀菌剂对烟草立枯病菌的生物活性

Bioactivities of five fungicides against Rhizoctonia solani,the causal agent of tobacco sore shin

由立枯病丝核菌引起的烟草立枯病是我国烟草苗床上危害最严重的病害之一。本研究评价了5种杀菌剂(嘧菌酯、啶酰菌胺、氟啶胺、丙环唑和嘧霉胺)对立枯丝核菌菌丝生长、菌核形成和萌发的影响,以及其对烟草立枯病的防治效果。结果表明:立枯丝核菌菌丝对氟啶胺和嘧菌酯的敏感性高于丙环唑和啶酰菌胺,而对嘧霉胺的敏感性较低;嘧菌酯对菌核形成的抑制作用强于丙环唑、氟啶胺、啶酰菌胺和嘧霉胺;5种杀菌剂对立枯丝核菌菌核萌发均无抑制作用。在离体烟叶的保护活性方面,12.5和50 mg/L的嘧菌酯和啶酰菌胺对立枯病的保护作用优于氟啶胺、丙环唑和嘧霉胺;在治疗活性方面,50和200 mg/L的嘧菌酯的治疗作用优于其他4种杀菌剂。因此,供试的5种杀菌剂中嘧菌酯最适合用于烟草立枯病的防治。

Tobacco sore shin caused by Rhizoctonia solani is one of the most destructive diseases in the seedbed suffered by tobacco in China.This study evaluated the activities of the fungicides azoxystrobin,boscalid,fluazinam,propiconazole,and pyrimethanil against mycelial growth,sclerotia formation and germination of R.solani,and also their protective and curative efficacies against tobacco sore shin.The mycelial growth of R.solani was more sensitive to fluazinam and azoxystrobin than to propiconazole and boscalid,and least sensitive to pyrimethanil.Azoxystrobin showed stronger inhibition of sclerotia production than propiconazole,fluazinam,pyrimethanil,and boscalid.None of the five fungicides inhibited the sclerotia germination of R.solani.In terms of the protective activity of detached tobacco leaves,azoxystrobin and boscalid at 12.5 and 50 mg/L were superior to fluazinam,propiconazole,and pyrimethanil in reducing sore shin.For curative activity,azoxystrobin at 50 and 200 mg/L was superior to the other four fungicides in reducing disease.Therefore,among the five fungicides,azoxystrobin is most suitable for the control of tobacco sore shin.