Antagonistic activity of fungi of Olea europaea L. against Colletotrichum acutatum

Fungi naturally present in olive trees were identified and tested for their antagonistic potential against Colletotrichum acutatum. A total of 14 isolates were identified, 12 belonged to genera Alternaria, Epicoc-cum, Fusarium, Aspergillus, Anthrinium, Chaetomium, Diaporthe, Nigrospora, one to family Xylariaceae andone was unclassified. All fungal isolates showed some inhibitory action over the growth of C. acutatumduring dual culture growth, however, when agar-diffusible tests were performed only five fungal isolatescaused C. acutatum growth inhibition: Alternaria sp. isolate 2 (26.8%), the fungus from Xylariaceae family(14.3%), Alternaria sp. isolate 1 (10.7%); Diaporthe sp. (10.7%), Nigrospora oryzae (3.5%). Volatile substancesproduced by these isolates were identified through gas-chromatography techniques, as phenylethyl alco-hol, 4-methylquinazoline, benzothiazole, benzyl alcohol, lilial, galaxolide, among others. These inhibitoryvolatiles could play a significant role in reduction of C. acutatum expansion in olive and their study aspotential biocontrol agents should be further explored.