Effect of Essential Oils and GRAS Compounds on Postharvest Disease Control in Mango (Mangifera indica L.cv Tom EJC)

Abstract

Purpose : Mango (Mangifera indica L. cv. Tom EJC) has a high economic value due to its unique qualities. Postharvest diseases such as anthracnose cause considerable loss of fruits in the market. Applications of synthetic fungicides are the common practice for controlling postharvest diseases, which could lead to hazardous effects on health. Therefore, search for alternative measures for the control of anthracnose are in demand. Research Method : Different fungal species have been described as causative agents of above disease. To determine the causative agent, fungal isolations were done from symptomatic fruits and identified by morphological and molecular techniques. Sodium bicarbonate, and sodium metabisulphite were used as GRAS (Generally Recognized as Safe) compounds and clove, cinnamon and citronella oils were used as essential oils during in-vitro studies to evaluate their potential to control the pathogen. The mycelial inhibitory capacity of five concentrations (1µLplate-1- 5µLplate-1) of each essential oil was evaluated in-vitro disc volatilization method. Compounds with minimum inhibitory concentrations were selected for in-vivo studies. Essential oil treatments for mango comprised of fumigation and application of GRAS compounds by dipping 15 and 30 minute time intervals. Physiochemical properties (pH, titrable acidity and total soluble solid content) of treated and non-treated mango fruits were evaluated. Findings : The identified causative agent of anthracnose was Colletotrichum siamense. Sodium bicarbonate (80000ppm), sodium metabisulphite (1500ppm) showed 100% inhibition of radial mycelia growth against the pathogen through in-vitro poison food method.100% inhibition of radial mycelia growth was reported with clove and cinnamon oil at all the concentrations tested (1-5µLplate-1). The citronella oil showed the lowest inhibitory activity. 15 minute and 30 minute dipping in sodium bicarbonate and fumigation with clove oil and cinnamon oil treatments effectively controlled anthracnose disease in mango, in comparison to the recommended fungicide Chlorothalonil (3mL/L). Physiochemical properties of mango were not altered by any of the treatments in comparison to no-treated fruits. Originality / Value : These results suggest that Sodium bicarbonate, Clove oil and Cinnamon oil could be used as alternatives to control the anthracnose disease in mango.