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, Epicoccum, Fusarium, Aspergillus, Anthrinium, Chaetomium, Diaporthe, Nigrospora, one to family Xylariaceae and one was unclassified. All fungal isolates showed some inhibitory action over the growth of C. acutatum during dual culture growth, however, when agar-diffusible tests were performed only five fungal isolates caused 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 substances produced by these isolates were identified through gas-chromatography techniques, as phenylethyl alcohol, 4-methylquinazoline, benzothiazole, benzyl alcohol, lilial, galaxolide, among others. These inhibitory volatiles could play a significant role in reduction of C. acutatum expansion in olive and their study as potential biocontrol agents should be further explored.Inalentejo ALENT-07-0324- FEDER-001747, OPERAC¸ ÃO: Gestão Integrada da Protec¸ ão do Olival Alentejano. Contributos para o seu desenvolvimento e implementac¸ ão. Carla Marisa R. Varanda is recipient of a PhD fellowship from Fundac¸ ão para a Ciência e a Tecnologia (FCT), SFRH/BPD/76194/2011, financed by QREN – POPH – Typology 4.1—co-financed by MES national funding and the European Social Fund. This work has been supported by FEDER and National funds, through the Programa Operacional Regional do Alentejo (InAlentejo) Operation ALENT-07-0262-FEDER-001871/Laboratório de Biotecnologia Aplicada e Tecnologias Agro-Ambientais