In vitro antifungal efficacy 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.

In vitro and in vivo Application of Eco-friendly Treatments to Control Postharvest Stem-end Rot of Naturally Infected Avocado (cv. Pollock)

“…Contrary to Sukatta et al (2008), the present study showed that clove oil was successful in inhibiting growth of L. theobromae at concentrations lower than 10 μL/plate. According to a similar in vitro disc volatilization assay carried out by Kodituwakku et al (2020b), clove and cinnamon oils inhibited the growth of SER pathogen L. theobromae isolated from mango at a concentration of 2 μL/plate, which is comparatively lower than the inhibitory concentrations reported in the present study. This might be due to differences in composition of the same oil, depending on its origin.…”

“…GC-MS conducted by Kodituwakku et al (2020b) revealed that eugenol (79.11%), β-caryophyllene (9.07%), caryophyllene oxide (0.40%) and eugenyl acetate (0.20%) are the major bioactive components of clove oil. Eugenol, which is the dominant component of clove oil as reported in many studies, varies from 30 -95% depending on the plant part used for extraction.…”

“…28%) was found in the oil isolated from growing clove leaves (Nowak et al, 2012). Similarly, some of the major components of cinnamon leaf oil such as eugenol (63.76%), cinnamaldehyde (1.37%) and linalool (1.27%) are found to be antifungal against SER causing fungal pathogens of mango (Kodituwakku et al, 2020b). The two main antifungal components present in cinnamon oils are eugenol and cinnamaldehyde.…”

Dip treatment of <em>Aloe vera</em> gel and <em>Aloe vera</em> in combination with cinnamon essential oils on stem-end rot of mango cv. ‘Karthakolomban’

“…The antifungal efficacy of cinnamon oils is mainly due to the presence of eugenol and cinnamaldehyde as major constituents in cinnamon leaf and bark oils respectively (Abeywickrama, 2009). According to a recent gas chromatography-mass spectroscopy (GC-MS) analysis, cinnamon leaf oil mainly consisted of eugenol (63.76%), benzyl benzoate (3.61%), β-caryophyllene (2.48%), eugenol acetate (2.27%), (E)-cinnamaldehyde (1.37%), linalool (1.27%), and cinnamyl acetate (1.08%) (Kodituwakku et al, 2020a). GC-MS analysis of cinnamon bark oil showed a higher percentage of (E)-cinnamaldehyde (72.18%) followed by cinnamyl acetate (5.16%), eugenol (4.82%), β-caryophyllene (3.95%), linalool (3.69%), and benzyl benzoate (1.51%) as major constituents (Kodituwakku et al, 2020a).…”

“…Different studies on essential oils of Cinnamomum verum J.Presl (cinnamon) have revealed that it has fungistatic and fungicidal properties against pathogenic fungi. Kodituwakku et al (2020a) reported that cinnamon leaf and bark oils effectively inhibited SER causing fungal pathogens of mango cv. 'Karthakolomban'.…”