Abstract
Small, unmanned aircraft systems (UAS) provide an opportunity for pesticide spray application in which the applicator can be displaced from close proximity of the spray discharge and in which the spray application can be made with highly targeted spatial resolution, particularly in challenging geographic terrain. In this project, a commercially manufactured UAS-mounted spray system was deployed in high-value specialty crops in California. The UAS used in this project was a unmanned aerial vehicle (UAV) and an associated ground control station that provided a means for remote piloting of the aircraft. The aircraft was a petrol-powered helicopter (RMAX, Yamaha Motor Co. USA, Cypress, CA USA) originally developed for spraying of rice fields in Asia. In this test, the primary experimental areas for spray deposition and performance assessment included a 0.61 ha block of Cabernet Sauvignon wine grapes located at the University of California Oakville Field Station in Napa County, CA USA. The block consisted of 42 rows, each 61 m long with a row spacing of2.4 m. Depending on the spray method deployed, specifically, the swath width used and the flight pattern flown, the UAS spray application could achieve 2.0 to 4.5 ha/h work rates while applying volume rates of 14.0 to 39.0 L/ha. Spray deposition on the grape foliage increased with applied volume rate. In comparisons to ground-based sprays at 935 L/hr, deposition in the grape canopy from the UAS at 47 L/ha was similar.
