In vitro antifungal activity of essential oils of Ocotea quixos (Lam.) Kosterm. and Piper aduncum L.

The phytopathogenic fungi cause relevant crop losses, both under field and post-harvest conditions. The use of essential oils extracted from Amazonian plants, at different concentrations, was investigated, in order to evaluate in vitro properties against those fungi. Essential oils were obtained by steam distillation, from two plant species (Ocotea quixos and Piper aduncum) collected in the Amazonian province of Pastaza, Ecuador. The antifungal activity was evaluated through the agar diffusion method against the Aspergillus oryzae, Cladosporium cladosporioides, Fusarium solani, Rhyzopus stolonifer, Moniliophthora roreri and Phytophthora sp. The O. quixos essential oil, in its maximum concentration (500 mu L.mL(-1)), inhibited the growth of all strains, reaching an average of 94 % inhibition rate, similar to the essential oil of thyme (Thymus vulgaris), which was used as standard. The P. aduncum essential oil, also in the maximum concentration, showed the best inhibition percentage against F. solani (94 %) and Phytophthora sp. (91 %). These results suggest the use of both essential oils as agents of biological control of phytopathogenic fungi.