Evaluation of an unmanned aerial vehicle as a new method of pesticide application for almond crop protection

BACKGROUND Unmanned Aerial Vehicles (UAVs), a new method of application to deliver pesticides, is rapidly being adopted for commercial use in crop protection in East Asia with increasing worldwide interest. Pest control in mature almond orchards with dense foliar canopies presents greater coverage challenges than field crops and smaller orchard or vineyard crops. We investigated the use of an electric hexacopter to provide acceptable spray deposition and canopy penetration to be considered credible for use in an almond pest control program. RESULTS The performance of the aerial and ground methods at different spray volumes were compared by analyzing spray deposition on water sensitive papers, insecticide residues on filter papers and residues on whole unhulled almonds at three canopy elevations. Overall residue levels of chlorantraniliprole insecticide on whole unhulled almonds across all pooled canopy strata were similar between UAV applied at 46.8 L/ha and 93.5 L/ha and the comparative air blast sprayer treatments applied at 935 L/ha. However, significant interactions between canopy elevation and spray method showed distinct residue patterns between the two application methods. Penetration and spray deposition at the lower canopy were observed and validated for the UAV application. Pest efficacy was evaluated by measuring nut damage at harvest. CONCLUSION This study presents promising data that support the potential innovative integration of UAV's into crop protection programs for large canopy crops such as almonds and may guide future research for developing relevant label recommendations.

Automated summary

The study compared the performance of UAV and ground methods at different spray volumes, analyzing spray deposition on water sensitive papers, insecticide residues on filter papers, and residues on whole unhulled almonds. Although overall residue levels of chlorantraniliprole insecticide on whole unhulled almonds were similar between UAV and air blast sprayer treatments, there were significant interactions between canopy elevation and spray method, indicating distinct residue patterns. Penetration and spray deposition at the lower canopy were observed and validated for the UAV application.