Field validation of a variable rate application sprayer equipped with ultrasonic sensors in apple tree plantations

In recent years, there has been a significant progress in technologies used in 3D crop spraying. The inherent goal of applying these technologies has been to reduce drift, improve efficacy in the use of Plant Protection Products (PPP) and, consequently, reduce the amount of chemicals in fruit production, thus minimizing environmental impact and enhancing human health. In order to assess the study of this impact, deposition trials were conducted in an apple orchard at two different growth stages (BBCH72 and BBCH99). Three typical sprayers were used to perform these trials: the reference sprayer, representing the most popular one used by local farmers; the Best Management Practices (BMP) sprayer, symbolizing well-adjusted equipment according the target; and the VRA sprayer, a newly developed machine provided with ultrasonic sensors and the corresponding developed hardware to achieve an on-line pesticide rate adaption, according to the canopy dimensions. This VRA sprayer has been developed within OPTIMA H2020 EU project (www.optima-h2020.eu). The VRA sprayer effectively achieved similar or better values of deposition and coverage in the whole canopy target, using up to 35% less PPP rate, compared to the reference sprayer. Additionally, the developed VRA machine has demonstrated its ability to adapt the applied PPP rate to fundamental canopy parameters such as width and density, allowing to implement alternative pesticide rates, based on canopy characteristics (i.e. Leaf Wall Area), as a new method proposed by European and Mediterranean Plant Protection Organization (EPPO).