Action of thymol, carvacrol and eugenol on <i>Penicillium</i> and <i>Geotrichum</i> isolates resistant to commercial fungicides and causing postharvest citrus decay
Hakima Moussa, Bouchra El Omari, Hanane Chefchaou, Mariam Tanghort, Aouatef Mzabi, Najat Chami, Adnane Remmal
Abstract
This study aimed to evaluate the antifungal activity of oregano and clove essential oils and their main components (thymol, carvacrol and eugenol) against Penicillium digitatum, as well as against isolates of Penicillium italicum and Geotrichum candidum resistant to imazalil or guazatine, respectively. In vitro tests were conducted by a direct contact method on potato dextrose agar medium. The results indicated that the essential oils and their main components were effective in inhibiting fungal growth, with thymol displaying the highest efficacy. The antifungal activity of thymol was evaluated further on orange fruit infected experimentally with a suspension of spores of P. digitatum, G. candidum or a mixture of both fungi, using isolates resistant to chemical fungicides. Treatment of the oranges with the thymol solutions reduced or totally inhibited the development of fruit decay, depending on the thymol concentration used. These essential oils and their main components demonstrated a strong antifungal effect against Penicillium spp. and G. candidum resistant to chemical fungicides. They may have potential as active compounds for the formulation of natural preparations to use as alternatives to synthetic fungicides for the management of green, blue and sour rot in citrus fruit.