Anti-phytopathogenic fungal agents from essential oil

Abstract

The antifungal activity of twenty-five essential oils was evaluated on three phytopathogenic fungi Fusarium oxysporum 43-68, Alternaria sp. 43-89 and Phytophthora sp. 572. Essential oils from kitchen mint (Mentha cordifolia Opiz.), cinnamon (Cinnamomum bejolghota Sweet.), litsea (Litsea cubeba Pers.) and clove (Eugenia caryophyllus Bullock & Harrison.) exhibited complete inhibition for all tested microorganisms at 1000 ppm. Crude clove oil and cinnamon oil exhibited conidial germination inhibition for F. oxysporum 43-68 at 54 and 51% and for Alternaria sp. 43-89 at 52 and 46%, respectively. The presence of active compounds in crude essential oils from kitchen mint, cinnamon, litsea, clove and ginger (Zingiber Officinale Roseoe.) was confirmed by bioautographic assay. All crude essential oils except that from Z. officinale showed fungal growth inhibition zone. The relationship between chemical structure and the antifungal activity was also studied. The phenolic compounds showed the highest antifungal activity followed by aldehyde, alcohol, carboxylic acid and hydrocarbon, respectively. The possibility of using clove oil and cinnamon oil as postharvest disease control agent was examined. The results showed that the essential oils from clove and cinnamon reduced F. oxysporum infection on inoculated banana (Musa spp.) at 94 and 87%, respectively when dipped in 1000 ppm solution for 15 min. The phytotoxicity on inoculated banana was observed. It was found that the heterogeneous solution caused the physiological damage occurred as the browning on peel, but those compounds had no effect on the ripening and the smell of the product.