Evaluation of an electrostatic spray charge system implemented in three conventional orchard sprayers used on a commercial apple trees plantation

Authors: SALCEDO, RAMON - Technical University Of Catalonia; SANCHEZ, ELENA - Technical University Of Catalonia; Zhu, Heping; FABREGAS, XAVIER - Technical University Of Catalonia; GARCIA-RUIZ, FRANCISCO - Technical University Of Catalonia; GIL, EMILIO - Technical University Of Catalonia

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2023
Publication Date: 5/1/2023
Citation: Salcedo, R., Sanchez, E., Zhu, H., Fabregas, X., Garcia-Ruiz, F., Gil, E. 2023. Evaluation of an electrostatic spray charge system implemented in three conventional orchard sprayers used on a commercial apple trees plantation. Crop Protection. 167: Article #106212. https://doi.org/10.1016/j.cropro.2023.106212.
DOI: https://doi.org/10.1016/j.cropro.2023.106212

Interpretive Summary: The European Union is establishing a large and innovative program to ensure sustainable and quality food production without negative impacts on the human health and environment. One of the goals is to reach a 50% reduction in the use of pesticide in crop production by 2030. Advancement of pesticide application technologies is essential to achieve the goal because there are few economically effective alternatives. In this research, three different designs of air-assisted spraying systems equipped with an electrostatically charged technology were evaluated for spray deposition distributions in a commercial orchard in Spain. The three spraying systems were a multi-fan sprayer, a vertical boom orchard sprayer, and a pneumatic tower sprayer. Test results illustrated that there were no significant differences in spray deposition distributions on leaves among the three spraying systems; however, the multi-fan sprayer, consisting of three moving axial fans on each side, discharged the most uniform air velocity distribution to the crops. In addition, the three electrostatically charged spraying systems provided comparable spray deposition quality as the conventional spraying system. Even though electrostatic spray technology has potential to improve spray deposition efficiency and reduce pesticide use, this research suggested that it would be necessary to include additional factors such as off-target loss, pest control efficacy, energy consumption, and technical maintenance in future field investigations.

Technical Abstract: Electrostatic sprayers can be an option for increasing the effectiveness of treatments and reducing pesticide consumption, but it still requires more verifications, especially in orchards. The spray deposition performances of three different electrostatic sprayers design were compared for apple tree pesticide application, all of them used with the electrostatic system activated and disactivated, as conventional spray application. Despite designs of particular type sprayers were unique, no significant differences were observed in the normalized deposition and droplets density between the conventional and electrostatic spray methods of the same sprayer, but differences were found between the vertical boom and the pneumatic sprayer in terms of coverage. The normalized deposition values of the three sprayers were very similar, ranging between 1.0 and 1.5 µg cm-2. However, the vertical boom sprayer produced the highest spray coverage, followed by the multi-fan sprayer. In general, the measured values of coverage and deposit obtained were in the three cases similar, independently on the use or not of the electrostatic device, being the sprayer type more affecting parameter rather than the electrostatic charging system. Differences in spray deposition qualities on apple trees were observed among three types of sprayers, but were not for the same sprayer with and without activation of the electrostatic charging system. Appropriate design of orchard sprayers according to the canopy structure seems to be more effective rather than the implementation of electrostatic spray charge system to achieve the European challenge of 50% reduction of pesticides by 2030.