A variable-rate spraying method fusing canopy volume and disease detection to reduce pesticide dosage

Variable-rate spraying technology based on plant canopy volume is widely applied during precision agricultural practices. However, field observations indicate that larger canopies typically correlate with healthier trees, exhibiting reduced disease risk and severity. Therefore, the integration of canopy health information into variable-rate pesticide application is imperative. This study developed a variable-rate spraying system that addresses the critical limitations of conventional variable-rate spraying systems by employing a multisensory fusion methodology, which integrates real-time spot detection with plant canopy volumetry. Dual-modality sensing system achieves concurrent canopy volume measurement (4.34% error) and spot detection (82.6% accuracy), enabling adaptive pesticide dosage optimization through integrated decision-making that synergizes disease severity with canopy volumetry. Experimental tests demonstrated a 74.0% reduction in chemical usage compared to conventional spraying, while maintaining the required deposition parameters for low-severity diseases, and a 42.7% reduction for high-severity diseases. When targeting pear rust disease, the system attained 86.53% control efficacy with 66.4% and 22.2% dosage savings over traditional and volume-only variable-rate spraying approaches, respectively. The newly developed variable-rate spraying system can perform as a precise variable-rate spraying system using fused information on fruit-tree canopy volumes and disease, which significantly reduces the use of pesticides without affecting the control effect, further enabling a reduction in pesticide quantity and an increase in efficiency.