Antagonestic activity of Trichoderma viride against legume plant field soil associated pathogens

Soilborne pathogens such as Fusarium spp. cause significant yield losses in legume crops, and biological control using fungal antagonists offers an effective alternative to chemical fungicides. The present study evaluated the antagonistic potential of Trichoderma viride isolated from the rhizosphere soil of Arachis hypogaea. Soil mycoflora enumeration revealed a high fungal load, with dominant isolates identified as Fusarium sp. (pathogen) and T. viride (antagonist). Antagonism was assessed using T-streak and agar cake plate methods. In both assays, T. viride exhibited rapid radial growth and strongly inhibited the pathogen. In the T-streak method, the pathogen’s growth remained restricted to 3.0 cm after 72 hours, whereas T. viride expanded to 7.3 cm by 120 hours. Similarly, in the cake plate assay, T. viride reached 5.0 cm by 120 hours, while Fusarium growth was suppressed to 2.8 cm. The antagonist outcompeted the pathogen through fast colonization, nutrient competition, mycoparasitism, and secretion of diffusible antifungal metabolites. Extracts of T. viride demonstrated strong antimicrobial activity, surpassing standard antifungal antibiotics. Early inhibition of Fusarium reached 100%, gradually decreasing to 60.96% and 54.96% by the 7th and 8th days due to metabolite diffusion and stability dynamics. These results highlight T. viride as an effective biocontrol agent capable of suppressing soilborne Fusarium in legume cropping systems and improving overall soil health.