Synergistic Janus nanocarrier enables high-deposition fungicide emulsion delivery for enhanced and sustainable control of wheat crown rot.

INTRODUCTION: The escalating incidence and severity of wheat crown rot poses a profound threat to global wheat yields and food security. Despite widespread fungicide application, the spatial mismatch between deposition sites and pathogen infection loci limits the precision and sufficiency of delivery, thereby reducing disease control efficacy and utilization efficiency, resulting in resource waste and environmental pollution. OBJECTIVES: This study aimed to develop a multifunctional fungicidal nano-formulation with high leaf deposition and long-distance transport of active ingredients, in order to enhance the utilization efficiency of the active components. METHODS: A functional difenoconazole Pickering emulsion (DIF-PE) with high deposition and delivery efficacy was successfully developed using mesoporous amphiphilic Janus nanoparticles. These nanoparticles (PEG@PDA@CaP) composed of hydrophobic calcium phosphate (CaP) integrated with hydrophilic polydopamine modified with methoxy poly (ethylene glycol) thiol, served as both solid emulsifiers and functional carriers. Interface behavior and transport performance were characterized using theoretical calculations, HPLC-MS/MS, SEM, TEM, CLMS, and ICP‑OES. RESULTS: Electrostatic interaction (E =  - 64.24 kcal/mol) between PEG@PDA@CaP and wheat leaves imparts DIF-PE with exceptional foliar deposition and adhesion. Compared to commercialized difenoconazole emulsion (DIF-EW), DIF-PE achieved 79.73% greater foliar deposition and 63.84% higher rainfastness. Enhanced deposition and penetration, together with the synergistic transport facilitated by PEG@PDA@CaP, collectively promoted more efficient downward delivery of difenoconazole, root and stem difenoconazole concentrations in treated plants were 6.95-fold and 2.34-fold higher than in controls at 24 h, respectively. Ultimately, DIF-PE improved the control efficacy against wheat crown rot by 19.15% relative to DIF-EW, with no adverse effects on plant growth. CONCLUSION: This nanocarrier-formulation system significantly improved the efficacy of conventional formulations, and broadened the applicability of nanocarriers, providing a powerful strategy for green management of crop diseases.