Construction of a pH-responsive nanopesticide Pro@ZnS@CMCS and its triple synergistic mechanism against sclerotinia stem rot

Sclerotinia sclerotiorum threatens crop production worldwide. Conventional prochloraz (Pro) suffers from photolysis, low utilization, and pollution. We developed a pH-responsive nanopesticide, Pro@ZnS@CMCS (PZC), using mesoporous ZnS to load Pro and coating it with carboxymethyl chitosan (CMCS). In the acidic microenvironment (pH ≈ 3) formed during fungal infection, the CMCS shell protonates and decomposes, enabling precise Pro release. Concurrently, the decomposition process consumes H + to modulate the pH of the infection microenvironment and disrupts the homeostasis of fungal oxalate metabolism. The exposed ZnS and residual CMCS synergistically enhance antibacterial activity, resulting in a triple mechanism of drug release, pH regulation, and multi-component action. PZC released 3.7-fold more Pro at pH 3 than pH 7. It improved leaf adhesion and rainfastness, with higher retention than free Pro. PZC exhibited an inhibition rate of 98.16% against Sclerotinia sclerotiorum , which was significantly higher than that of free Pro (30.23%). Transcriptomic analysis revealed that PZC treatment inhibits Sclerotinia sclerotiorum by inducing a “synergistic multiple stress” mechanism. This mechanism involves the simultaneous activation of stress responses, including catabolism, and the systemic inhibition of fundamental growth functions such as ribosome biogenesis, ultimately resulting in the collapse of its metabolic homeostasis. PZC also exhibited excellent biocompatibility with non-target organisms. This work offers a strategy for intelligent nanopesticides enabling targeted delivery, reduced dosage, higher efficacy, and environmental compatibility.