Agrochemical mixture compatibility for UAV and conventional sprayers in maize: bridging precision and practicality

Eficient pesticide delivery in maize (Zea mays L.) using Unmanned Aerial Vehicles (UAVs) necessitates a comprehensive assessment of agrochemical compatibility under diverse ield conditions. This study investigated the physical and chemical compatibility of commonly used insecticides Chlorantraniliprole 18.5% SC, Spinetoram 11.7% SC, and Emamectin benzoate 5% SG and fungicides Azoxystrobin 18.2% + Difenoconazole 11.4% SC and Tebuconazole 50% + Triloxystrobin 25% WG applied alone and in binary mixtures using UAV-based ultra-low volume (ULV) and Taiwan sprayer-based high-volume protocols. Compatibility was evaluated across four water sources: deionized distilled water (DDW), tap, canal, and bore water. Over 90% of treatment combinations exhibited excellent physical stability with minimal coagulation, sedimentation, or foam formation. Emamectin benzoate showed moderate sedimentation under UAV concentrations (2.2–3.1 mL/L) but was redispersible upon agitation. Chemical proiling of spray solutions revealed that water quality signiicantly inluenced pH stability. Chlorantraniliprole displayed consistent buffering (pH 7.10–7.62), maintaining formulation integrity. Spinetoram demonstrated a mildly alkaline proile (7.40–7.91), while Emamectin benzoate preserved an acidic environment (6.28–6.72), potentially minimizing hydrolytic degradation. Notably, mixtures containing Tebuconazole + Triloxystrobin occasionally surpassed pH 8.5, indicating the need for pH modulation. These results underscore the importance of water chemistry and formulation interactions in UAV-enabled pesticide delivery. The study offers a strategic framework for selecting UAV-compatible agrochemical mixtures, contributing to precision application, reduced formulation failure, and enhanced sustainability in crop protection systems