Does the self-developed fatty acid esters-based aerial spray adjuvant really work on improving the targetability of pesticide liquid sprayed by unmanned aerial vehicles (UAVs)?

BACKGROUND

Low pesticide utilization, particularly in high-concentration aerial spraying via an unmanned aerial vehicle (UAV), poses a severe risk in terms of pesticide waste and environmental damage. We conducted a new trial to improve the properties of a spray liquid by the addition of customized spray adjuvants, thereby facilitating droplet deposition and reducing drift of UAV-sprayed pesticides.

RESULTS

Our self-developed mango tree special pesticide diffusing agent (PDA) altered both the value and components of the liquid surface tension toward that of the mango leaf surface free energy; thereby, apparently reducing the contact angles of liquid droplets on the leaf surface by more than 70.00%. The retention ability (R) of pesticide diluents on the leaf surface was enhanced by 0.75-1.24 times, but no pesticide injury was induced. Moreover, the PDA endowed the spray liquid with strong anti-drift performance under ambient temperature and humidity levels typical of tropical areas, and substantially decreased the cumulative drift rate by 31.09-67.08%. The spray drift buffer zone distance was shortened from more than 8.19-8.62 m to around 4.61-5.79 m.

CONCLUSION

Customized development of a spray adjuvant (PDA) based on the properties of the mango tree canopy and leaf surface, together with the operation characteristics of UAV sprayers, was an efficient way to achieve optimization of the spray solution system in terms of promoting its targeting delivery to the crop surface. Our findings provide inspiration and references for the selection, development and application of spray adjuvants, to increase pesticide efficiency and curb agricultural non-point source pollution. © 2025 Society of Chemical Industry.