Antagonistic Potential of trichoderma spp. and pseudomonas fluorescens against sclerotinia sclerotiorum in Mustard

Sclerotinia sclerotiorum, a fungal pathogen, causes stem rot in mustard (Brassica juncea), significantly reducing yields. The study tested the efficacy of Trichoderma species (T. atroviride, T. viride, T. harzianum) and Pseudomonas fluorescens in controlling this pathogen through lab, greenhouse, and field experiments. In vitro tests showed T. atroviride inhibited pathogen growth by 72.9% ± 1.9, followed by T. harzianum (71.1% ± 1.8), T. viride (69.1% ± 1.7), and P. fluorescens (64.4% ± 1.5). P. fluorescens produced the largest clear zones (19.7 mm ± 1.1) in antibiosis tests, indicating strong chemical inhibition. Greenhouse trials revealed T. atroviride reduced disease incidence to 11.5% ± 0.9 and maintained 89.0% ± 2.0 plant survival. Field trials demonstrated T. harzianum lowered disease to 12.8% ± 0.9 and increased yield to 1475 kg ha^-1. Strong correlations (r = -0.89 to -0.94, p < 0.01) between lab and field results confirmed the predictive value of in vitro tests. Trichoderma species employed mycoparasitism, while P. fluorescens utilized antibiosis, offering sustainable strategies for stem rot management.