The study was carried out during winter (rabi) season of 2022–2023 at Dharmapuri and Cuddalore districts of Tamil Nadu to formulate an integrated strategy for managing tomato collar rot, a major disease caused by Sclerotium rolfsii Sacc. The survey identified Keerapatti village as a hotspot with 47.53% incidence. Among fifteen isolates, Sr10 was the most virulent, causing 62.30% disease incidence in pot experiments. Molecular characterisation confirmed the pathogen as S. rolfsii and antagonists as B. subtilis showing 98.8–99.0% nucleotide identity with reference sequences. A native antagonist, B. subtilis isolate Bs3, exhibited strong antifungal activity with 78.94% inhibition in vitro, significantly suppressing mycelial growth (77.41%) and sclerotial formation (84.40%) through secondary metabolites. Molecular docking analysis further demonstrated that key antifungal compounds from B. subtilis showed strong binding affinity with pathogen target proteins, suggesting disruption of pathogenicity-related mechanisms. In pot trial, the integrated treatment (T7), combining B. subtilis with neem cake, was most effective, reducing collar rot incidence by 78.29%. Additionally, treated plants exhibited enhanced vigour, with maximum plant height, germination rate, and fruit yield. Collectively, these findings highlighted that integrating B. subtilis and neem cake, supported by docking-based mechanistic evidence, offers a sustainable and eco-friendly alternative to chemical fungicides for collar rot management in tomato (Solanum lycopersicum L.).
A et al. (Fri,) studied this question.