Antifungal Activity of Three Essential Oils against Colletotrichum acutatum, the Causal Agent of Strawberry Anthracnose

Abstract

The antifungal effects of thyme, cinnamon bark and clove bud essential oils (EOs) were investigated in vitro on Colletotrichum acutatum mycelial growth, conidial germination, appressoria formation, and in vivo on strawberry fruit disease incidence. All tested EOs, incorporated in potato-dextrose agar, inhibitedC. acutatum mycelial growth, and had a fungistatic effect at concentration 667 mu l/l of medium. Volatiles of cinnamon bark, thyme and clove bud EOs completely prevented conidial germination at the lowest concentrations of 1.53, 15.3 and 76.5 mu l/l of air, respectively, and disabled appressoria formation at concentration of 1.53 mu l/l of air. On inoculated strawberry fruit, thyme and cinnamon bark EO volatiles reduced anthracnose incidence at concentrations above 15.3 and 76.5 mu l/l of air, respectively. GC-FID and GC-MS analysis showed that major components of thyme EO were p-cymene, thymol, alpha-terpineol, carvacrol; cinnamon bark EO: trans- cinnameldehyde, trans-cinnamyl acetate; clove bud EO: eugenol and beta-caryophyllene. Our results suggest thatvolatiles of thyme and cinnamon bark EOs are effective against C. acutatum both in vitro and in vivo.