Naga Hari Chandana Kilaru, Johnson Iruthayasamy, Shajith Basha Jaffer, Parthiban V Kumaresan, Manikanda Boopathi Narayanan, Anandham Rangasamy, Saranya Nallusamy, Karthikeyan Muthusamy
Blast disease incited by Pyricularia grisea is a major biotic constraint in pearl millet leading to significant yield losses. In the present study, thirty Pyricularia isolates were obtained from infected leaf samples collected across different locations of which MgPM1 was identified as the most virulent based on pathogenicity assays. A total of fifty-four Bacillus spp. (B1- B54) and ten Trichoderma spp. (T1-T10) isolated from the rhizosphere were screened for antagonistic activity, wherein Bacillus stercoris B51 showed the highest mycelial inhibition (72.16 %) against MgPM1 under in vitro conditions. Isolate B51 demonstrated multiple plant growth-promoting and biocontrol traits including indole-3-acetic acid production, siderophore production, ammonia synthesis, citrate utilization and the secretion of hydrolytic enzymes (amylase, cellulase, xylanase and lipase). The presence of antimicrobial peptide genes (ituD, srfA, β-1,3-glucanase) and GC–MS-identified metabolites such as 2,4-di-tert-butylphenol, butylated hydroxytoluene, hexadecanoic acid, 9,12-octadecadienoic acid and squalene, suggest strong antifungal potential. Consistent with these functional attributes, application of B51 as a talc-based formulation (seed treatment at 10 g kg −1 plus soil application at 2.5 kg ha −1 ) significantly reduced blast disease incidence to 22.47% under pot culture conditions, along with enhanced activity of plant defense-related enzymes. This study provides the first detailed investigations into the biocontrol potential of B. stercoris against P. grisea in pearl millet under controlled condition.