Potential use of thymol to control anthracnose development in mango

Abstract

Anthracnose is the main postharvest disease that affects mango production on Reunion Island. It is caused by a pathogenic fungus called Colletotrichum gloeosporioides. Fruit produced for the export market are always treated with chemicals such as fludioxonil, benomyl and prochloraz. This type of postharvest treatment is not in line with consumer expectations, as consumers prefer fruits treated with nonharmful and natural products. The objective of this work was to study alternative postharvest treatments using the fungitoxic properties of thymol, a natural molecule synthesized by thyme (Thymus vulgaris L. thymoliferum). Thymol, prepared in a terpene solvent that acts as a penetrating agent, was effective on quiescent and wound mango anthracnose. When diluted to a final concentration of 0.1%, no necrosis development due to pathogens during storage was observed on fruits. The thymol-based treatment also made it possible to stimulate some of the metabolic pathways involved in the resistance of the fruit to the development of Colletotrichum gloeosporioides, particularly the stimulation of gallic acid biosynthesis. However, the treatment significantly affected fruit maturation and quality, especially the peel colour and sugar content. Additional studies must be carried out to determine the optimal thymol concentration for controlling storage disease without impacting fruit quality.