Spot Spraying of Rice Weeds from Remotely Piloted Aircraft, 2017


Project Leader

Ken Giles, professor, Dept. of Biological and Agricultural Engineering, UC Davis

The objective of this new project is to assess the performance and feasibility of using remotely piloted aircraft—drones—to treat patches of weeds with herbicides.

Global Positioning System (GPS) technology provides the capability to map target weed patches down to the centimeter. Coupled with remotely piloted aircraft, this strategy seeks to test the spot application of control materials with extraordinary accuracy.

Research was conducted at the Rice Experiment Station in September 2017. Weedy red rice was not present in these initial experiments.

The research focused on the physical process of treating small patches of weeds. Simulated target maps were used to guide a DJI Agras MG-1 S multi-rotor drone helicopter fitted with a spray system for spot treatment. Delays in obtaining regulatory approval for chemical dispersion necessitated the application of water onto water-sensitive paper for visual assessment of spray deposition performance.

The feasibility results from 2017 testing were extremely positive. The MG-1S, fitted with GPS and operated from a base station, successfully hit a number of target locations in rice plots. This exercise simulated mapped weed locations, such as would be the case with a weedy red rice infestation.

The aircraft was fitted with four flat-fan nozzles, each under a rotor. A 36-inch “bull’s-eye” target was fabricated to secure the water-sensitive paper for recording spray deposition and positioned at the center of the mapped target location. Results were consistently encouraging. The pilot was successful in positioning the aircraft and spraying the target with good deposition across the target area.

Another remotely operated aircraft, Yamaha’s RMAX, holds potential for broadcast applications, not precision spraying. Other manufacturers are developing similar spray system products.

The success of this initial experiment demonstrates the potential for a new, flexible, and low cost method of controlling patchy weeds (as well as insect and disease pests) in rice fields. Efficacy and drift studies are planned for 2018.