Evaluation of flight directions and other canopy coverage characteristics from aerial spraying, using Remotely Piloted Aerial Application Systems (RPAAS aka drones), in a high-density linear olive grove

Abstract

The use of Remotely Piloted Aerial Application System (RPAAS, aka drones) for applications of various plant protection products, fertilizers, biostimulants, air seeding and air-fertilization is becoming the most effective way for to provide sustainable solutions in all crop species. It is also the faster developing agricultural technology and very much accepted and used by farmers and other stake holders. However, few studies exist to evaluate precisely the overall effectiveness and efficacy of these systems. The RPAAS. Currently used mainly in field crops and not much on tree production systems. This study was established to specifically evaluate the flight direction (parallel vs. perpendicular to planted lines) in a linear and highdensity olive grove, at the premises of the Perrotis College/American Farm School, Thessaloniki. The olive grove adapted for mechanical harvesting, was established in 2011 and consists of two varieties used in these systems (Arbequina and Koroneiki), three planting densities a Super high Density (SHD), a High Density (HD) and a Medium Density (MD) with 1670, 1000 and 500 trees/ha, respectively, spaced at 4 m between the rows. The traditional olive systems use ca. 250-350 trees/ha spaced in orthogonal systems. These density systems represent a much more dense plant canopy than the traditional olive groves and it is a unique case to evaluate penetration studies with aerial spraying systems. The drone used two Flight Directions (FD), a parallel (Par FD) and a perpendicular (Per FD) to the planted lines, using various flight settings (volume, height and speed). The percent Canopy coverage (PC%) and other droplet characteristics were recorder with Water Sensitive Papers (WSP) in all three planting Densities and in three heights (low –medium – high) within each olive tree replicated. The overall results indicated that the Perpendicular flight (Per FD) provided a better coverage and also planting densities and tree profile, were not shown to significantly vary among all three densities These results can be used by users of RPAAS to achieve better canopy coverage in foliar applications. Therefore, using the same volume of spraying, a higher coverage can be achieved. The results presented in this study are only applicable to the specific type of high-density olive linear systems and should not be extrapolated directly to other linear systems such as vineyards, fruit trees, due to the differences in plant canopy, geometry and density and to traditional olive groves. Comparative aerial spraying studies between high and traditional olive densities and in vineyards are in progress at Perrotis College/American Farm School.