Abstract
ABSTRACT Farmers are seeking pesticide treatments with lower application rates and higher travel speeds. However, this can lead to a poor quality of the application. The aim of this study was to evaluate the spray deposition on soybean crop and the droplet spectra using different application rates and speeds. The experiment was conducted in soybean (R5 stage), M 6410 IPRO variety. Six treatments involving two application rates (80 and 150 L ha-1) and three speeds (10, 15 and 20 km h-1) were evaluated through a self-propelled sprayer. A characterization study of the spray droplets was conducted through the evaluation of water sensitive papers. The spray deposition study was carried out. For this, a marker was added to the application to be detected by absorbance in spectrophotometry. The use of spray nozzles with higher nominal flow, as well as lower pressures, produced droplets of larger sizes. The application rate of 80 L ha-1 provided equal and higher spray retention in the lower and upper leaves of the plants, respectively. The three speeds did not influence the deposition on soybean plants.
Highlights
Despite the high production potential and high availability of soybean varieties (Glycine max (L.) Merrill) with characteristics that allow their adaptation to the different regions, it is sometimes observed low and irregular production
Due to the different application rates, this study aimed to characterize only the droplet spectrum and not the deposition of the spray, which was evaluated through a tracer
In Figure 1, there are the results of the volumetric median diameter (VMD)
Summary
Despite the high production potential and high availability of soybean varieties (Glycine max (L.) Merrill) with characteristics that allow their adaptation to the different regions, it is sometimes observed low and irregular production. This is attributed, among other factors, to the occurrence of weeds and the constant cycles of pests and pathogens during the development of the crop (Yokomizo et al, 2013). In this context, chemical control has become a fundamental tool for the protection of the genetic potential of plants. Received in: 12-20-2016 Accepted in: 6-30-2017 other hand, may compromise canopy cover and reduce the effectiveness of disease and pest control when used improperly (Cunha et al, 2014). Berger-Neto et al (2017) showed that air induction nozzles were efficient to control soybean diseases. Baio et al (2016) obtained good results of spray deposition in different extracts of soybean plants with this type of nozzles
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