Bioactivity of essential oils on the fungus Didymella bryoniae of the cucumber culture

Abstract

The objective of this study was to evaluate the in vitro antifungal activity of the essential oil of five plant species in the inhibition of mycelial growth of the fungus Didymella bryoniae causer of the gummy stem blight of cucumber ( Cucumis sativa ). In the inhibition of the mycelial growth of the fungus D. bryoniae was used five concentrations (250, 500, 750, 1000 and 1250 ppm) of essential oil of citronella grass (Cymbopogon nardus) , lemon grass (Cymbopogon citratus) , peppermint (Mentha piperita) , lemongrass (Lippia alba) and eucalipto citriodora (Eucalyptus citriodora) , in five times of assessment (2, 4, 6, 8 and 10 days after transplanting). Another experiment was performed with lower concentrations of essential oil of citronella grass (150, 300, 450 and 600 ppm) in four times of assessment (3, 5, 7 and 9 days after transplanting). The essential oils were distributed on the surface of the PDA meium crop (potato-dextrose-agar) for assessment of mycelial growth in different concentrations. The experiments were conducted in a completely randomized design with four replications. The essential oil of lemongrass provided the highest effect of inhibition of mycelial growth of D. bryoniae, 100% of inhibition at all tested concentrations. The essential oil of eucalipto citriodora ( Eucalyptus citriodora) provided the smaller effect of inhibition.