Efficacy of Bacillus subtilis and Trichoderma asperellum against Pythium aphanidermatum in tomatoes

- Coating seeds with B. subtilis and T. asperellum offers protection of the seedlings against damping off disease.
- Coating of tomato seeds with B. subtilis and T. asperellum results in improved growth.
- The interaction between the seeds coated with B. subtilis and T. asperellum fertilizers leads to improved growth.

Seedling damping-off disease caused by Pythium aphanidermatum is the most important seedling disease in tomato production in Kenya. The disease causes seedling losses of up to 30%. Greenhouse trials were conducted to evaluate the application of Bacillus subtilis and Trichoderma asperellum, as seed coating for management of damping-off in tomato from April 2011 to August 2014. Tomato seeds (var. Rio Grande) were coated with either B. subtilis or T. asperellum at a concentration of 106 CFU/ml. The interaction between the two biocontrol agents and NPK fertilizer was assessed. To simulate the effect of high disease pressure, the coated seeds were planted in P. aphanidermatum inoculated media. The post-emergence seedling damping-off on seeds coated with B. subtilis and T. asperellum was 20.19% and 24.07% respectively while the control (non-coated) had 65.89% seedling mortality. A combination of NPK fertilizer and biocontrols in seedling management resulted to a significantly higher dry mass compared to the use of either biocontrol agent or fertilizer alone (P ⩽ 0.001). This study indicates that coating of tomato seeds with B. subtilis and T. asperellum may be useful in the management of damping-off disease.