UAV-applied fluopyram enables rapid translocation and long-lasting efficacy for control of pine wilt disease

The pinewood nematode Bursaphelenchus xylophilus is the causal agent of pine wilt disease (PWD), a devastating disease that threatens pine forest ecosystems globally. Conventional control methods are often limited by their inefficiency, high cost, and operational challenges in complex terrain. This study developed an integrated chemical control strategy that combines unmanned aerial vehicle (UAV) spraying technology with the systemic nematicide fluopyram to improve PWD management.

Using an L9 (3³) orthogonal experimental design, key operational parameters, including spray volume, flight speed, and adjuvant concentration, were systematically tested and optimized (at 3.0 L/min spray volume, 5.0 m/s flight speed, and 1.0% adjuvant, respectively). In field applications, fluopyram exhibited remarkable systemic mobility, showing full translocation throughout the tree via needles and branches within 1 day, with detectable residues persisting for 360 days. The degradation kinetics followed a first-order model, with half-lives ranging from 177.73 to 315.07 days. Environmental monitoring confirmed rapid dissipation in the soil, with residue levels declining to negligible concentrations within 90 days. UAV-applied fluopyram achieved 82.46% efficacy at 540 g/ha, which was comparable with trunk injection (78.95%) and significantly higher than that of vector-targeted cypermethrin spraying (43.86%).

The integration of UAV spraying with fluopyram provides an effective and operationally feasible strategy for PWD management. This approach offers improved control efficacy and environmental compatibility, highlighting its potential for large-scale and sustainable protection of pine forest ecosystems against the notorious PWD. © 2026 Society of Chemical Industry.