Deposição de calda no cafeeiro promovida pela aplicação aérea com aeronave remotamente pilotada empregando diferentes pontas, adjuvantes e volumes de calda

Abstract

Brazil is a major global producer of coffee. Like in other important crops, coffee farming faces significant challenges in achieving high yields, especially concerning pest and disease control, which are limiting factors for productivity growth. Currently, new application technologies are increasingly focused on addressing these issues, and in this context, the use of Remotely Piloted Aircraft (RPA), also known as drones, has become increasingly common. This study aimed to analyze the spray deposition on coffee plants promoted by aerial application using an RPA employing different nozzles, adjuvants, and spray volumes. The research was conducted in the Coffee Sector of the Experimental Farm of Glória (Federal University of Uberlândia – UFU, Uberlândia, MG). The RPA employed was an octocopter AGRAS MG-1P (DJI, China), with a 10 L spray tank, 4 spray nozzles, and 8 motors. Spray deposition studies were carried out in an area of Topázio coffee cultivar. The experiment consisted of 8 treatments and 4 repetitions. A completely randomized design was used in a 2x2x2 factorial scheme: two spray compositions (spray with spreading adjuvant and mineral oil), two spray nozzles (standard flat jet XR 11001 and flat jet with air induction Airmix 11001), and two spray volumes (10 and 20 L.ha-1). Deposition of tracer, coverage, droplet density, median volumetric diameter, and relative amplitude of the spectrum of drops generated during application were evaluated. For deposition analysis, a tracer was applied to the coffee plant to be detected by spectrophotometry, considering deposition on the upper and lower parts. The study of the droplet spectrum was performed by analyzing water- sensitive papers. Air induction nozzles were found to be more suitable for RPA application than standard flat jet nozzles, as they provided higher spray deposition on the coffee canopy. The use of mineral oil proved advantageous in improving spray deposition on coffee leaves, although the adjuvant had a greater capacity to reduce the surface tension of the spray. The higher spray volume (20 L.ha-1) provided greater density of droplets deposited on the target, as well as greater coverage, which is particularly relevant when using contact agricultural pesticides. The Airmix nozzle produced larger droplets compared to XR, which is an important strategy for drift reduction, especially in field situations with wind presence.