Antifungal Activity of Neem (Azadirachta indica) Leaf Extract against Pathogens Associated with Tomato (Solanum lycopersicum L.) Fruit Spoilage

Abstract

The study was conducted to evaluate the antimicrobial activity of neem (Azadirachta indica) leaf extract against fungal phytopathogens isolated from diseased tomato (Lycopersicum esculentum) fruit. Diseased tomato fruits were obtained and to establish a mixed culture. Two distinctive fungi were identified on the mixed cultures and subculture into freshly prepared potato dextrose agar medium. The fungal isolates were identified using the cultural characterization. Neem (Azadirachta indica) leaves were obtained and used to prepare water extract. The antifungal activity of the neem leaf extract was evaluated using the poison plate method. Mycelial growth was measured and recorded. The results showed that two fungal pathogens were isolated from the diseased tomato fruit. The cultural characterization of the two isolates revealed the identity of the fungal isolates to be Diaporthe and Xylaria species. There was a significant reduction in the mycelia growth of Diaporthe species with values of 2.210±0.34, 1.42±0.37, and 0.61±0.16 cm for the 25, 50, and 100% neem leaf extract, respectively, compared to the control (3.67±0.34 cm), indicating antifungal activity of the neem leaf extract. Conversely, only the 25 and 50% neem extract showed antifungal activity against Xylaria species. The findings of the present study suggest that neem leaf extract could be used to preserve tomato fruits from fungal pathogens causing spoilage.