In vitro antifungal effi cacy of selected essential oils in controlling fungi associated with the stem-end rot disease of mango (cv. Karutha Colomban) fruits and characterisation of antifungal components

Abstract

Karutha Colomban is one of the most delightful mango varieties popular among Sri Lankan consumers. A signifi cant postharvest loss of mango takes place every season due to diseases including stem-end rot (SER), which is caused by a group of endophytic fungal pathogens. In this research, in vitro antifungal effi cacy of diff erent concentrations of essential oils of basil, clove, and cinnamon were evaluated for their ability to control SER causing fungal pathogens of mango (cv. Karutha Colomban) as bio-safe alternatives to conventional fungicides, by conducting liquid and disc volatilisation bioassays. Major bioactive compounds of the selected essential oils were identifi ed by gas chromatography-mass spectroscopy (GC-MS). Basil and cinnamon bark oils (0.20 – 0.30 μL/mL) in liquid bioassay showed high effi cacy against Lasiodiplodia theobromae, while basil and cinnamon leaf oils (0.40 – 0.60 μL/mL) successfully inhibited Pestalotiopsis sp. Cinnamon bark oil (0.60 μL/mL) was identifi ed as the most eff ective oil against Phomopsis sp. According to disc volatilisation bioassay, vapour of cinnamon oils (0.20 – 0.40 μL/mL) was the most eff ective in controlling L. theobromae. Pestalotiopsis sp. was effi ciently controlled by clove and cinnamon bark oil (0.20 – 0.60 μL/mL) vapour. In vapour phase, clove and cinnamon oils (0.40 μL/mL) were the most eff ective against Phomopsis sp. According to GC-MS characterisation, methyl chavicol was the most abundant antifungal component in basil oil while it was (E)-cinnamaldehyde in cinnamon bark oil. Moreover, eugenol displayed the highest abundance in clove and cinnamon leaf oils. Based on in vitro studies, it could be concluded that cinnamon bark oil in liquid and vapour phases demonstrated a higher antifungal effi cacy among the tested essential oils in controlling fungal pathogens causing SER of mango.