Abstract
Pythium aphanidermatum, a highly aggressive soil-borne oomycete, is a major pathogen causing root and stem rot, leading to substantial crop losses in warm and humid environments. Given the growing concerns regarding the environmental hazards and resistance associated with synthetic fungicides, the exploration of botanical extracts as sustainable, eco-friendly alternatives is gaining traction. In this study, methanolic extracts from five plants—Ginger (rhizome), Bitter kola (seeds), Neem (leaves), Aloe vera (leaves), and Moringa (leaves)—were evaluated for their antifungal efficacy against P. aphanidermatum. Pathogen isolation was conducted using serial dilution and direct methods, with culture media including Potato Dextrose Agar (PDA), Malt Extract Agar (MEA), and Czapek Dox Agar (CDA). Pathogenicity was confirmed via Koch’s postulates, establishing P. aphanidermatum as the causal agent of root and stem rot. Growth assessments revealed that PDA supported the highest pathogen growth rate (2.85 cm/day), followed by CDA (2.38 cm/day) and MEA (1.78 cm/day). In vitro assays demonstrated that botanical extracts, tested at concentrations ranging from 40,000 to 80,000 ppm, significantly inhibited P. aphanidermatum growth, with Bitter kola exhibiting the highest inhibition (85.9%), followed by Ginger (83.6%), Neem (80.7%), Moringa (73.1%), and Aloe vera (67.6%). Synthetic fungicides, Benlate and Mancozeb, showed higher inhibition at 150 ppm (89.7% and 88.5%, respectively), but the botanical extracts provide a viable, lower-risk alternative. Phytochemical analysis of the extracts revealed the presence of alkaloids (2.09-5.45%), saponins (0.40-2.92%), flavonoids (0.83-4.70%), and tannins (0.28-5.09%), except for tannins in Moringa oleifera, while proximate analysis indicated variations in ash (1.91%–3.39%), protein (0.53%–3.19%), fibre (2.84%–9.60%), moisture (6.40%–27.0%), and carbohydrate content (75.21%–80.60%). These findings suggest that botanical extracts, with their rich phytochemical profiles, offer significant potential as sustainable biocontrol agents for P. aphanidermatum, contributing to safer and more environmentally friendly crop protection strategies.