Comparison of UAV and fixed-wing aerial application for alfalfa insect pest control: evaluating efficacy, residues, and spray quality.

BACKGROUND: Integrating unmanned aerial vehicles (UAV) as a new method of pesticide application into existing commercial crop protection systems requires extensive research and comparison to conventional, proven application technology. Pest control expressed as efficacy against target pests, and spray quality expressed as coverage and chemical residue are three key criteria. We investigated and compared these quantitative parameters between a multi-rotor UAV and conventional piloted airplanes in two commercial alfalfa production systems. RESULTS: Effective and equivalent control of leaf-feeding insect pests was achieved by both methods of aerial application when delivering chlorantraniliprole at the same labeled use rate in different spray volumes (46.8 and 93.5 L ha-1 ) on commercially grown alfalfa in California. Residue levels and spray coverage were also comparable and consistent between the UAV and airplane applications across three sampling techniques, specifically residue levels on alfalfa, insecticide recovery from filter paper, and spray coverage on water sensitive cards. Differences in droplet size and deposit characteristics were more variable for the UAV than airplanes based on analysis of deposition images. CONCLUSION: The results of this study provide confidence supporting the use of small-scale multi-rotor UAVs for pesticide application on agricultural crops. According to the parameters tested, UAV application quality and crop protection performance were comparable to that of the conventional fixed wing airplane application. However, the droplet spectrum and the short-term fate of droplets from unmanned aerial spray system require further optimization for effective and efficient crop protection with minimal risk to the environment.

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.