Pectin-modified pyraclostrobin nanocapsules: Targeted delivery of pesticides for improved control of stem base rot of wheat

Traditional agrochemicals suffer from low utilization rates and high environmental exposure levels, posing threats to ecosystem security and limiting their practical application. Wheat stem rot is one of the world's major agricultural diseases caused by Fusarium pseudograminearum , which mainly affects the stem base of wheat. Improving the agent's deposition distribution and duration of action in the wheat rhizome is critical when applied through foliar spray or root application.to control this disease. Stimuli-responsive delivery systems can provide more effective crop protection while improving the safety of pesticides for non-target organisms and the environment. In this study, we developed pectin-modified pyraclostrobin nanocapsules (NCS@Pec) exhibiting dual responsiveness to pH and pectinase. Compared to conventional nanoemulsion (NEW), NCS@Pec demonstrated superior adhesion to wheat surfaces with 2.86-fold enhanced rainfastness. Root application reduced pyraclostrobin translocation to leaves while prolonging rhizosphere activity. At 14 days post-treatment, NCS@Pec maintained approximately 68% control efficacy. In addition, the selectivity coefficients of NCS@Pec between F. pseudograminearum and zebrafish were 2.67 and 7.09, significantly reducing environmental risks to aquatic life while maintaining fungicidal activity. These findings advance the application of carbohydrate polymers such as pectin in nanopesticide development and contribute to novel bioactive agent design and food security enhancement.