Antagonistic Activity of Ginger Extract and Bacillus Subtilis Against Bacterial Wilt in Tomato

Background: Solanum lycopersicum L. (Tomato) is a major global food crop but is highly susceptible to bacterial wilt caused by Ralstonia solanacearum. This disease leads to significant yield and postharvest losses under both field and storage conditions. Objectives: This study evaluated the antibacterial and biocontrol effects of of ginger (Zingiber officinale) extract and Bacillus subtilis, applied individually and in combination, against R. solanacearum causing tomato wilt. Methods: In vitro assays were conducted to assess the inhibitory effects of turmeric extract at different concentrations, while dual culture assays were used to determine the antagonistic activity of B. subtilis. In vivo experiments on tomato tubers evaluated disease incidence, lesion diameter, and percentage wilt reduction. Treatments included turmeric extract, B. subtilis, and their combination. Data were statistically analyzed using ANOVA. Results: Both turmeric extract and B. subtilis significantly inhibited the growth of R. solanacearum. The inhibitory effect of turmeric extract was dose-dependent, while higher inoculum levels of B. subtilis enhanced pathogen suppression. The combined treatment was the most effective, producing the lowest wilt incidence and lesion development, suggesting a synergistic interaction between plant-derived phytochemicals and microbial antagonism. Conclusions: Turmeric extract and B. subtilis demonstrated strong potential as eco-friendly biocontrol agents against tomato wilt caused by R. solanacearum. Their integration offers a sustainable alternative to chemical bactericides and may be adopted within integrated disease management systems. Further field validation is recommended to confirm efficacy under natural growth conditions.