Initial screening for inhibitory activity of essential oils on growth of Fusarium verticillioides, F. proliferatum and F. graminearum on maize-based agar media

An in vitro initial screening of a range of 37 essential oils on inhibition of mycelial growth of Fusarium verticillioides, F. proliferatum and F. graminearum under different temperature (20–30°C) and water activity (a_w) (0.95–0.995) conditions was made. The basic medium was a 3% maize meal extract agar. The maize meal agar was modified with glycerol to a range of water activity conditions and the essential oils were incorporated at different concentrations (0, 500, 1000 μg ml⁻¹). Cinnamon leaf, clove, lemongrass, oregano and palmarosa oils were the products tested suitable for being used as novel preservatives in the control of the three Fusarium species studied. Although water activity was determinant for the growth of the isolates, in general, the preservative effects of the oils were not linked to a_w. However, a trend to a higher inhibition by the oils when a_w was low was observed. Temperature had a minor importance in the inhibitory effect of the preservatives. In vivo studies may be required to confirm the usefulness of the results obtained.