An eco‐friendly alkaline lignin/sodium alginate/β‐cyclodextrin composite hydrogel for enhanced foliar deposition and sustained control of Botrytis cinerea with azoxystrobin

BACKGROUND: Conventional pesticide formulations often suffer from limitations such as large particle sizes, poor adhesion, and susceptibility to environmental losses through volatilization and drift, leading to low utilization efficiency and potential ecological risks. RESULTS: To address these challenges, we developed a novel composite hydrogel system (AZO@βASCa) through the integration of alkali lignin (AL), sodium alginate (SA), and β-cyclodextrin (β-CD) via physical cross-linking and ion gelation. This system is designed for the efficient encapsulation and environmentally responsive release of the fungicide azoxystrobin (AZO). By systematically optimizing the mass ratio of SA to AL, we identified a 2:1 ratio as optimal, yielding a hydrogel with a uniform porous network structure, an impressive encapsulation efficiency of 94.99%, and a loading capacity of 24.75%. The AZO@βASCa hydrogel exhibited notable temperature-responsive release behavior and significantly enhanced photostability. Adhesion assessments revealed superior wetting and adhesion performance on both osmanthus and poplar leaves, characterized by lower contact angles, higher adhesion work, and resistance to runoff even at vertical inclination. In vitro and in vivo antifungal studies demonstrated that AZO@βASCa provided sustained inhibition of Botrytis cinerea, outperforming commercial AZO in long-term efficacy. Importantly, acute toxicity assays in zebrafish indicated that AZO@βASCa reduced toxicity by 4.77-fold compared to its commercial counterpart. CONCLUSIONS: This study successfully developed a highly efficient, low-toxicity, and environmentally friendly nanopesticide delivery system. This approach provides a viable material strategy and technical pathway for achieving pesticide reduction while enhancing efficacy, thereby advancing green and sustainable agriculture. © 2026 Society of Chemical Industry.