Optimizing prochloraz timing for curative control of <scp> <i>Fusarium</i> </scp> wilt in chili: a multi‐target strategy targeting early root infection

Abstract BACKGROUND Soil‐borne Fusarium oxysporum causes destructive wilt in chili ( Capsicum annuum L.), yet the critical window for curative chemical intervention remains undefined. This study elucidates early pathogenic mechanisms and optimizes prochloraz application timing for precision disease management. RESULTS Fusarium oxysporum secreted polygalacturonase (PG) and pectin methyl galacturonase (PMG) to compromise root cell integrity, elicit reactive oxygen species (ROS) burst, and reduce root vitality by 78.17% versus healthy controls. Scanning electron microscopy confirmed extensive hyphal colonization. In vivo therapeutic assays demonstrated that prochloraz (80 μg mL −1 ) at 2 days post‐inoculation (dpi) achieved 73.08% disease control (disease index 29.53), significantly outperforming 4 dpi treatment (44.36% control, disease index 54.81). Mechanistically, prochloraz inhibited conidial germination by 79.15%, suppressed PG and PMG activities by 54.42% and 59.35%, respectively, and attenuated hydrogen peroxide accumulation by 75% in infected roots. CONCLUSION Early‐stage prochloraz intervention provides multi‐target, mechanism‐based curative control of Fusarium wilt by disrupting pathogen establishment and restoring root physiological function. These findings establish a precision timing strategy for integrated disease management in chili production. © 2026 Society of Chemical Industry.