In Vitro and Screenhouse Evaluation of Trichoderma harzianum T22 and Bacillus subtilis BS01 for Management of Tomato Bacterial Wilt

Abstract

Bacterial wilt, caused by the Ralstonia solanacearum species complex, severely constrains tomato production in warm production environments. This study evaluated the compatibility and efficacy of Trichoderma harzianum T22 and Bacillus subtilis BS01, applied individually or together, for suppression of tomato bacterial wilt. T22 and BS01 were compatible in dual culture. In the quantitative T22 antagonism assay, inhibition of R. solanacearum increased from 11.45 ± 3.77% at 24 h to 46.48 ± 2.56% at 96 h (p < 0.001). A screenhouse experiment comprised five treatments: pathogen + T22, pathogen + BS01, pathogen + T22 + BS01, pathogen-only control, and an uninoculated control. Treatment, assessment week, and their interaction influenced disease incidence and severity (p < 0.05). At the final assessment, the pathogen-only control recorded 94.4% incidence, 100.0% severity, and a severity area under the disease progress curve of 251.7 %-weeks. The combined treatment recorded the lowest numerical final incidence (33.3%) and severity (38.3%) among inoculated treatments, although it did not differ significantly from either single-agent treatment. Treatment also affected plant height (p = 0.010) and stem girth (p = 0.002). The combined treatment produced the greatest numerical plant height (117.4 cm) and stem girth (2.13 mm). Thus, individual and combined applications suppressed bacterial wilt under screenhouse conditions, but the combination did not demonstrate statistical superiority over the single agents. Field validation is required. Int. J. Appl. Sci. Biotechnol. Vol 14(3): 131-140.