Vol. 7, Issue 9, Part E (2025)

dBroccoli (Brassica oleracea L. var. italica) is a nutritionally rich crop with increasing global demand, yet its productivity is severely constrained by soil-borne pathogens such as Rhizoctonia solani, the causal agent of foot and root rot. Chemical fungicides, while widely used, face limitations due to resistance development, environmental risks, and regulatory concerns, highlighting the need for sustainable alternatives. The present study evaluated the antagonistic potential of Trichoderma harzianum, T. viride, and Bacillus subtilis against seven isolates of R. solani under in vitro conditions. Antagonists were isolated from broccoli field soils and tested using dual culture and paper disc methods on Czapek’s sucrose nitrate agar medium. Results revealed significant variability in pathogen inhibition across isolates and antagonists. T. harzianum demonstrated the highest mean mycelial growth inhibition (63.04%), followed by T. viride (57.66%) and B. subtilis (49.78%). Maximum inhibition was recorded in R Isolate-006, where T. harzianum achieved 69.42% suppression and T. viride 67.28%. Conversely, the lowest inhibition was observed in R Isolate-005, with B. subtilis showing only 42.35% suppression. The findings confirm that T. harzianum consistently exhibited superior antagonistic activity, suggesting its potential as a promising biocontrol agent against R. solani. These results align with earlier reports of Trichoderma spp. exhibiting mechanisms such as mycoparasitism, antibiosis, and competition, thereby supporting their integration into eco-friendly disease management strategies. Further research on formulation development and field-level validation is essential to translate these laboratory findings into practical applications for sustainable broccoli production.