Resistance of tomato genotypes to Ralstonia solanacearum in Ghana

Introduction Bacterial wilt of tomato, caused by the Ralstonia solanacearum species complex (RSSC), is a major constraint to tomato production in the Upper East Region of Ghana. The deployment of resistant cultivars remains the most effective and sustainable management strategy. Despite this, there is limited information on the diversity of RSSC populations and the availability of resistant germplasm in Ghana. Methods In this study, RSSC isolates from two identified disease hotspots in the Upper East Region (Soogo and Teshie communities) were characterized, and selected tomato genotypes were evaluated for resistance to representative virulent strains under greenhouse conditions. Twenty isolates recovered from symptomatic plants were all identified as biovar 3, with thirteen belonging to phylotype I and seven to phylotype III. Fifteen tomato genotypes were evaluated using a 2 × 15 factorial arrangement in a randomized complete block design with three replications. Results Significant differences (p < 0.05) in disease response among tomato genotypes were observed, while the genotype × strain interaction was not significant, indicating consistent performance across strains. Mean plant survival across strains ranged from 0.0 to 83.3%. Two genotypes, CRA66 (WorldVeg) and TmL114-42-N-H.T.P Early, demonstrated stable resistance, characterized by high plant survival and lower AUDPC values. Most genotypes were moderately resistant, while two were susceptible. Discussion The absence of significant strain-specific effects under the tested conditions indicates that these resistant genotypes may provide broad-based protection. These findings identify promising sources of resistance for breeding and provide a foundation for developing tomato cultivars with durable resistance to bacterial wilt in Ghana and similar tropical tomato-growing environments.