Formulation of calcium-based nutrition for mitigating bacterial wilt (Ralstonia solanacearum) in tomato

Bacterial wilt, caused by Ralstonia solanacearum, is a major constraint in tomato (Solanum lycopersicum L.) production, especially in tropical and subtropical regions where favourable soil and climatic conditions support pathogen survival and spread. Conventional management practices have shown limited effectiveness, emphasizing the need for sustainable alternatives. Calcium is an essential nutrient that strengthens cell walls, stabilizes membranes and enhances plant defenses against soil-borne pathogens. This study evaluated calcium-based nutrient formulations for their effectiveness in suppressing bacterial wilt and improving tomato growth and fruit quality as part of a sustainable disease management strategy. In vitro assays using a virulent R. solanacearum isolate from the Eastern Dry Zone of Karnataka showed strong antagonistic activity, producing inhibition zones of 26.00–29.30 mm after 48 hr. The most effective formulation was further tested in a pot experiment arranged in a completely randomized design with six treatments and four replications, using two tomato varieties: Baaho (wilt-susceptible) and Abhinava (wilt-resistant). The calcium-enriched formulation containing calcium, magnesium, sulfur and potassium significantly improved plant growth, yield and fruit quality in wilt-susceptible Baaho while delaying wilt onset up to 60 days after transplanting. At harvest, calcium-based nutrition to plants recorded a height of 84.61 cm, chlorophyll content of 34.52 (SPAD), 42 fruits plant-1, fruit weight of 71.49 g, diameter of 4.14 cm, firmness of 1.44 kg cm-2 and a shelf life of 10.75 days. Abhinava remained resistant and performed better across all treatments. These results demonstrate that calcium-enriched nutrient formulations can effectively suppress bacterial wilt while enhancing yield and fruit quality in tomato.