EVALUATION OF THE ANTAGONISTIC POTENTIAL OF Terminalia catappa L. LEAF EXTRACT AGAINST Colletotrichum spp. CAUSING ANTHRACNOSE ON MANGO (Mangifera indica L.)

Abstract

The study was conducted to evaluate the antifungal activity of Terminalia catappa L. leaf extract against Colletotrichum spp., the causal agents of anthracnose on postharvest mango (Mangifera indica L.), with the aim of proposing a biological alternative to chemical fungicides in fruit preservation. Pathogenic fungi were isolated from diseased mangoes collected in Kien Giang province (currently An Giang province) and identified using DNA sequencing techniques. Leaf extracts were prepared using distilled water and 50% ethanol. Antifungal efficacy was assessed through two experiments: (1) on PDA medium, by monitoring fungal colony diameters at 3 – 17 days after inoculation and (2) on mango fruit under storage conditions, by treating samples with extract concentrations of 0.5; 2.0; 5.0 mg/mL and evaluating disease incidence and severity after 7 days of artificial inoculation. Two fungal isolates, X1 and X4, were successfully obtained and showed high virulence. Molecular identification revealed that isolate X1 was Colletotrichum acutatum, while X4 was Colletotrichum gloeosporioides. The 50% ethanol extract exhibited strong antifungal activity in a dose-dependent manner. On PDA medium, the colony growth of both fungal species was nearly completely inhibited after 13 - 15 days. On mango fruit, treatment with 5 mg/mL ethanol extract reduced disease incidence of C. acutatum to 0% and C. gloeosporioides to 30%; corresponding disease severity values were 0% and 7.33%, respectively.