Antimicrobial activity of essential oils against early blight of tomato under in vitro conditions

Fungal diseases limit tomato production, particularly the early blight caused by Alternaria solani. Disease control is usually done with synthetic fungicides, which have long-term residual effects and also contribute to environmental pollution. In this study, the effectiveness of essential oils from lemongrass (Andropogon citratus), citronella oil (Cymbopogon nardus), clove oil (Syzygium aromaticum), peppermint oil (Mentha piperita) and patchouli oil (Pogostemon cablin) were tested in vitro in suppressing the radial growth of A. solani. The suppression of fungal growth was determined by measuring the radial growth of the examined pathogen. The oils have shown a certain effectiveness against the pathogen in question. Lemongrass oil was found to be the best oil for disease suppression at concentrations of 0.02%, 0.06%, 0.1% (59.37%, 73.12% and 84.32%, respectively). Essential oils were equally effective as synthetic fungicides in limiting pathogen growth. However, for these products to be used effectively in agricultural fields, an industrial formulation may be required to increase their effectiveness.