Abstract

Damping-off disease, caused by Pythium aphanidermatum, significantly impacts tomato production. This study explored the potential of a two-pronged approach for enhanced biocontrol: combining two antagonistic Trichoderma asperellum strains (CB-Pin-01 and NST-009) with a plant immune stimulant (CaCO<inf>3</inf>). Laboratory assays demonstrated strong individual efficacy of both Trichoderma strains against P. aphanidermatum, with significant growth inhibition and overgrowth capabilities. Importantly, scanning electron microscopy confirmed their compatibility. Greenhouse experiments revealed that the combined application of Trichoderma strains and CaCO<inf>3</inf> achieved the most significant reduction in disease incidence (17.78%) compared to the control (66.55%). Furthermore, this treatment resulted in 100% root colonization by Trichoderma and the highest population density in the soil (6.17 × 10⁷ CFU g⁻¹), suggesting the immune stimulant’s role in promoting beneficial microbe establishment. These findings highlight the potential of this combined strategy as a sustainable and effective approach for managing damping-off disease in tomatoes.