Abstract: To develop an effective strategy for controlling peanut pod spot (PPS), a newly emerging soil-borne disease of peanut, antagonistic microorganisms were isolated from the peanut rhizosphere using a dual-culture assay. The isolates were identified based on morphological, physiological and biochemical characteristics, together with molecular analyses. A soil amendment containing the selected biocontrol strain was subsequently formulated, and its efficacy against PPS and its effects on peanut yield were evaluated in pot and field experiments. One biocontrol strain, designated SW-1, exhibited strong antagonistic activity against the pathogen of PPS and was identified as Bacillus velezensis. Strain SW-1 also showed antagonistic activity against multiple plant pathogens, including Fusarium neocosmosporiellum and Alternaria tenuissima. Based on the soil microecological characteristics associated with PPS occurrence, a powder-form biological soil amendment, Siami25, containing B. velezensis SW-1 at 2.0×10⁸ CFU/g was developed. In pot experiments, Siami25 achieved a control efficacy of 67.36% against PPS and increased peanut yield by 26.82%. In two field trials, application of Siami25 at 2,250 kg/hm² before sowing resulted in control efficacies of 69.02% and 73.77%, respectively, and increased peanut yield by 17.59% and 36.44%, respectively. These results demonstrate that the powder-form biological soil amendment containing B. velezensis SW-1 has substantial potential for controlling PPS and promoting peanut yield. This study provides an effective biocontrol strategy for controlling PPS and offers a practical basis for the management of this emerging soil-borne peanut disease.

Key words: Bacillus velezensis, peanut pod spot, Fusarium neocosmosporiellum, biological control, microbial soil amendment