Antifungal activity of Brassica napus water extract on some phytopathogenic fungi

Some plant extracts have been reported to exhibit antimicrobial properties. Plant based pesticides appear to be an alternative for the synthetic pesticides because of their less dangerous impacts. The objective of this study was to assess the inhibitory activity of Brassica napus water extract on mycelial growth of six phytopathogenic fungi Rhizoctonia solani, Phythophtora drechseleri, Pythium aphanidermatum, Verticellium dahliae, Fusarium oxysporum, and Gaeumannomyces graminis. Antifungal activity test was performed by disc diffusion method. Concentrations of 100 and 50 ppm had the highest and the lowest inhibitory effects on all studied species respectively. The shoot extract (SE) was significantly exerted higher antifungal activity than root extract (RE). At 100 ppm, V. dahliae (17.02% inhibition by RE) and F. oxysporum (50% inhibition by SE) were the most sensitive species however, R. solani (1.8 and 15%) was the most resistant fungus to both extracts. Active compounds of B. napus extract were determined by high performance liquid chromatography (HPLC). Phenolic compounds had the highest concentrations in extracts and are probably the main cause of the mycelial growth inhibition. Application of canola aqueous extract or incorporation of canola in crop rotation program can be considered as a method for management of some soil-borne phytopathogenic fungi.