Evaluation of antifungal activity of essential oils against aflatoxigenic Aspergillus flavus and their allelopathic activity from fumigation to protect maize seeds during storage

Four essential oils were evaluated for antifungal activities against ten isolates of Aspergillus flavus. All strains, except A. flavus PSRDC-2, were strongly inhibited by clove (Syzygium aromaticum (L.) Merr. & L.M. Perry) and vatica (Vatica diospyroides Symington) oil. The oils contained 14 and 24 compounds, respectively, with eugenol (62.4%) as the main component of clove oil and benzyl acetate (48.8%) as the main component of vatica oil. Clove oil showed 84.7% inhibition on conidial germination of A. flavus PSRDC-2 at 100 μL L−1, while complete inhibition of disease infection on maize seeds occurred at 10 μL L−1. Vatica oil at 50 μL L−1 exhibited strong antifungal activity as it completely inhibited growth, sporulation, conidial germination, and disease infection of A. flavus PSRDC-2 both in vitro and on maize seeds. Fumigation of vatica oil for 6 h could protect and cure the infected maize seed. Both clove and vatica oils exhibited dose-dependent allelopathic activity on maize germination, stem length, and root length, with vatica oil being more phytotoxic than clove oil.