Evaluation of antifungal effect of some essential oils on mycelial growth of Sclerotinia sclerotiorum causal agent of white stem rot of rapeseed

Use of some essential oils as antimicrobial agents has increased during the past decade. In this study the antifungal activity of essential oils of peppermint (Mentha piperita)، fennel (Foeniculum vulgare) and thyme (Thymus vulgaris) was examined for inhibition of mycelia growrh of Sclerotinia sclerotiorum on PDA amended with ethanolic extracts of the 3 medicinal plants at five concentrations (75، 150،300، 600 and 1200 microliter/l.). Results showed that the essential oil of peppermint did not have sufficient effects on mycelial growth of Sclerotinia sclerotiorum because it exhibited no significant difference with control at 99% confidence level. The essential oil of fennel had high antifungal activity and suppressed fungal growth at minimum inhibitory concentration of 150 µl/l. Thyme oil reduced mycelial growth at relatively higher concentration. Findings from this study showed that essential oils of fennel could be considered as a candidate for further investigations towards its application as natural fungicide to control S. sclerotiorum. Results suggest that the kind and concentration of essential oil can affect pathogenic fungi differently.