Evaluation of Spatial Distribution and Residue Safety of Lambda-Cyhalothrin and Triadimefon Sprayed by UAV on Wheat

With the rapid advancement of unmanned aerial vehicle (UAV) technology, its application in crop pest management has become increasingly prevalent. However, further research is still required to elucidate pesticide deposition patterns and residue risks. This study developed a validated LC-MS/MS method to compare UAV and electric backpack sprayer (EBS) applications of lambda-cyhalothrin and triadimefon in wheat. The method showed satisfactory performance (recoveries: 73–108%; RSDs: 0.6–14.7%), meeting pesticide residue analysis requirements. UAV spraying significantly altered pesticide distribution, reducing deposition in the upper canopy (50–60 cm) by 6.4–32.8% while increasing the middle-lower layer (10–40 cm) coverage. The UAV delivered 1.01–4.36 times higher lambda-cyhalothrin deposition across different parts of the wheat plant than the EBS, but only 0.73–2.09 times that for triadimefon. Both application methods yielded residues below the maximum limits in edible parts, confirming food safety compliance. These findings demonstrate the UAV’s potential for optimized pesticide application in wheat pest management, as it improves deposition efficiency while maintaining residue safety standards.