In vitro antifungal activity of commercial essential oils in vapor phase against Monilinia fructicola and Botrytis cinerea

Gray mold and brown rot, caused respectively by Botrytis cinerea and Monilinia spp., are fungal diseases responsible for significant losses during the storage of fruits and vegetables. Nowadays, the focus in the control of postharvest diseases is shifting toward more sustainable strategies, including the use of plant secondary metabolites. In this study, the antifungal effect of essential oils (EOs) from Origanum vulgare, Thymus vulgaris, Thymus serpyllum, Melaleuca alternifolia, Lavandula officinalis, Lavandula hybrida, Citrus bergamia, and Rosmarinus officinalis in vapor phase was tested in vitro against Monilinia fructicola and B. cinerea. Volatile organic compound chambers (VOC chambers) were used to perform the experiments, growing the fungal strains in the upper plate, and placing the EOs in the lower one. Three concentrations were tested per treatment, radial growth was measured, and minimum inhibitory concentration (MIC) was calculated. B. cinerea showed MIC of 22.73 mu L-1 for O. vulgare and T serpyllum, 45.45 mu L-1 for T vulgaris, and between 136.36 and 363.64 mu L-1 for the other EOs. M. fructicola MIC was 5.64 mu L-1 for 0. vulgare, 11.36 mu L-1 for T vulgaris, and T serpyllum, 181.82 mu L-1 for M. alternifolia, L. officinalis, and L. hybrida, and 363.64 mu L-1 when using C. bergamia and 12. officinalis. No fungicidal activity was exerted within the applied concentrations. M. fructicola appeared more sensitive to the tested EOs than B. cinerea. These results highlight the potential of some of the tested EOs for the control of postharvest gray mold and brown rot, although in vivo studies are needed to assess their use in storage conditions.