Evaluation of Stem Bark Extracts of Azadiratcha indica (A. Juss) and Vernonia amygdalina (Del.) for the Management of Aspergillus flavus on Tomato

Abstract

This study investigated the antifungal effects of three concentrations of the stem bark extract of neem (Azadiratcha indica A. Juss) and bitter leaf (Vernonia amygdalina Del.) on Aspergillus flavus causal agent of rot in tomato fruits.  Five, ten and fifteen percent concentration of the plant extracts  were prepared by weighing 25 g, 50 g and 75 g and infusing each in 500 ml sterile cold water for 48 hours (weight by volume w/v). Potato dextrose agar (PDA) media was amended with the plant extracts and inoculated at the centre with 1 mm diameter mycelia discs taken from a advancing edges of a pure culture of seven days old A. flavus. Healthy tomato fruits were dipped in 5% w/v, 10% w/v and 15% w/v concentrations of the stem bark extracts for five minutes and the tomato fruits inoculated with 7 day old pure cultures of A. flavus. All the plant extracts tested at all concentrations significantly reduced the mycelia growth of A. flavus compared with the control. The tomato fruits treated with 5% w/v of A. indica had the lowest firmness decrease of 1.67 and was considered marketable. Tomato fruits treated with 15% w/v of A. indica had significantly (P≤ 0.05) lower weight loss of 20.30% compared with the control (61.73%). The study suggests that             V. amygdalina can be used for the preservation of tomato fruits while A. indica can be used to improve tomato fruit quality in storage.