Essential oil vapours control some common postharvest fungal pathogens

Abstract

Diseases caused by fungal pathogens cause substantial postharvest losses to most perishable food crops. Fungal diseases are currently controlled with fungicides; however, reliance on this single control strategy leads to problems such as environmental damage and fungal resistance to fungicides. There is increasing pressure from consumers to find more natural methods of disease control. A possible alternative to fungicides may be essential oils, which have been shown to inhibit the growth of several fungi and are seen as natural compounds. The present study examined the effect of the vapour phase of spearmint, tea tree, pine and cinnamon oils and an antifungal blend on the growth of eight common postharvest fungal pathogens growing in vitro. It was found that the antifungal, spearmint and tea tree oils controlled the growth of Botrytis cinerea, Fusarium solani, Colletotrichum sp., Geotrichum candidum, Rhizopus oryzae, Aspergillus niger and Cladosporium cladosporiodes more effectively than pine or cinnamon oil but were less effective against Penicillium digitatum. Antifungal, spearmint and tea tree oils appeared to reduce sporulation in P. digitatum, A. niger and R. oryzae and inhibited spore germination by A. niger. This work shows that the antifungal, spearmint and tea tree oil vapours may provide an alternative means of controlling postharvest pathogens. All of the oils had a fungistatic mode of action and their use would require the development of commercial treatment methods applicable throughout the postharvest handling chain.