Comparative Analysis of the Phytochemical and Antifungal Properties of Lemon and Lime Peels in Preventing Rot Fungi in Irish and Sweet Potatoes

Background and Objective: The use of plant extracts in treating plant diseases is gaining acceptance due to the adverse effect of chemical fungicides on plants, animals, humans, and the environment. The study was conducted to assess the phytochemical compounds and in vitro antimicrobial potential of the ethanol and methanol leaf extracts of lemon and lime peels. Materials and Methods: The study investigated the antifungal efficacy of plant extracts against the causative agent of dry rot in sweet and Irish potatoes. Diseased potato samples were collected, and the fungal pathogen was cultured using Potato Dextrose Agar (PDA) which was prepared according to the manufacturer’s instructions and isolated. The organisms were identified using standard microbiological techniques. Plant extracts were obtained through Soxhlet extraction using aqueous and methanol solvents. The antifungal susceptibility assay was conducted using the agar well diffusion method, with inhibition zones measured to determine effectiveness. Data were analyzed using appropriate statistical tests to compare antifungal activity across treatments at the significance level 0.05. Results: Methanolic and ethanolic extracts of lemon and lime peels tested positive for tannins, alkaloids, and glycosides, with stronger reactivity in methanolic lemon peel extracts (24.16% yield). Methanol extract of lime peel had the highest concentration of steroids (++), while flavonoids and cardiac glycosides were the most abundant (+++). Fusarium oxysporum had the highest occurrence (50%) across isolates. Methanolic lemon peel extract showed inhibition zones of 77.90 mm (200 mg/mL) and 69.10 mm (150 mg/mL), while lime extract had 83.21 mm and 76.33 mm, respectively. Fluconazole exhibited the highest inhibition (100.0 mm) at all concentrations, with statistical significance varying (p>0.05 and p<0.05). Conclusion: The result showed that lime peel extract is more effective against the fungi causing dry rot of sweet and Irish potatoes compared to lemon peel extract.