Transforming agricultural waste into intelligent biopesticide delivery: soil‐disintegrable tea saponin microcapsules for sustainable crop protection

Abstract BACKGROUND In order to achieve intelligent and sustainable delivery of tea tree oil (TTO) for tea pest control, we developed a soil‐disintegrable, pH‐responsive microcapsule system (TMS) with an average particle size of 2.05 μm using 15.6% tea saponin as the shell precursor via interfacial polymerization. RESULTS Optimized TMS (1–2 μm) achieved 97.4% encapsulation efficiency. The system exhibited accelerated TTO release under acidic conditions (78.8% at pH 5.0), enabling targeted delivery to fungal infection sites. It demonstrated superior foliar adhesion and rainfastness (84.5% retention) compared to free TTO. Biological evaluations revealed potent dual bioactivity: antifungal efficacy against Colletotrichum camelliae [median effective concentration (EC 50 ) = 0.87 mg mL −1 ] and Phyllosticta theaefolia (EC 50 = 2.3 mg mL −1 ), alongside significant insecticidal activity against Ectropis obliqua larvae (90.0% mortality at 3 mg mL −1 ). CONCLUSIONS This work demonstrates substantial macroscopic disintegration and no apparent phytotoxicity, with the potential to reduce persistent microplastic accumulation, providing a potential strategy to improve its formulation and delivery while retaining its biological activity. © 2026 Society of Chemical Industry.