The Combination of a <i>Bacillus velezensis</i> <scp>CHEP5</scp> ‐Based Bioinput With Synthetic Fungicide Applications as a Sustainable Strategy for Peanut Cultivation

ABSTRACT This study aimed to optimise the application of a Bacillus velezensis CHEP5‐based bioinput within an integrated pest management (IPM) framework. Dose–response experiments were conducted under controlled conditions to determine the minimum effective concentrations for seed and foliar applications that control fungal disease caused by Sclerotium rolfsii . The compatibility of CHEP5 with commonly used fungicides was assessed, and field trials were performed to evaluate its performance under agricultural conditions. Soluble phenolic compounds (PC) were quantified as markers of plant defence induction. Under controlled conditions, seed and leaf application of CHEP5 at 2 and 4 L ha −1 , respectively, protected peanut against S. rolfsii , correlating with an early increase in the PC content. CHEP5 remained viable in the presence of conventional fungicides. In field trials, seed treatment with CHEP5 reduced the incidence and/or severity of diseases caused by Thecaphora frezzii and the Sclerotinia sclerotiorum – S. minor complex. Foliar spray of CHEP5, replacing the first fungicide spray, provided protection against Nothopassalora personata , and also reduced T. frezzii incidence. This response was linked to early PC accumulation, suggesting a primed defence state. These results demonstrate the effectiveness of CHEP5 in controlling multiple fungal pathogens and activating plant defence responses. Its compatibility with chemical fungicides and its field efficacy support its integration into sustainable peanut disease management programmes.