Navegando por Autor "Tavares, Antonio Augusto Corrêa"

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    Influência de fatores operacionais nas perdas das aplicações da mistura em tanque de Dicamba + Glyphosate
    (Universidade Estadual do Norte do Paraná, 2021-04-30) Tavares, Antonio Augusto Corrêa; Oliveira, Rone Batista de; https://orcid.org/0000-0002-3071-4827; http://lattes.cnpq.br/2379804514613050; Oliveira, Rone Batista de; https://orcid.org/0000-0002-3071-4827; http://lattes.cnpq.br/2379804514613050; Souto, Ana Carolina; http://lattes.cnpq.br/4909756168282078; Kruger, Greg R.; https://orcid.org/0000-0002-8975-0507
    The use of herbicides such as glyphosate and synthetic auxins in tank mixtures is a viable and effective alternative in weed management practices. However, drift reduction techniques are necessary to avoid damage to susceptible crops and preservation areas close to applications of these herbicides. The objective of this research was to evaluate the influence of operational factors and wind direction on the drift potential of dicamba + glyphosate tank mixture applications. For this, two different experiments were carried out. In the first experiment, the collected drift and the damage to soybean plants caused by the herbicide tank-mix application with different spray nozzles at different pressures and boom heights were determined. The treatments were arranged in a completely randomized design in a 3 × 2 × 4 factorial (nozzle × operational pressure × boom height) with four replications. The spray solution used was a tank mixture of dicamba (480 g a.i. ha⁻¹) and glyphosate (1440 g a.e. ha⁻¹) prepared to simulate a carrier volume of 130 L ha⁻¹. For the collected drift analysis test, the bright blue dye at 6% v/v was added to the spray solution as a tracer. The applications were carried out using the AIXR11003, MUG11003, and TTI11003 nozzles at 400 and 700 kPa in a wind tunnel (Universidade Estadual do Norte do Paraná, Brazil). The wind tunnel is 20 m long, with a 2.0 m square section and a 0.90 m diameter double axial fan. The boom heights used were 0.50, 0.75, 1.00, and 1.50 m above the tunnel floor. The airspeed was 3.0 m s⁻¹, measured and monitored by a hot wire anemometer. For tests using plants as drift indicators, soybean plants at stage V3 were positioned at five downwind distances (2, 5, 8, 10, and 15 m) from the nozzles during applications. Each repetition was sprayed for 30 seconds, with the ventilation on for another 2 minutes. For the collected drift test, nylon strings were positioned on metallic supports at a height of 0.3 m from the tunnel floor. The supports were positioned at the same distances used in the plant test. Each repetition consisted of spraying for 2 minutes. The climatic conditions during the tests were temperature of 23.4 ± 1.7 °C and 51.3 ± 5.0% relative humidity. After the applications, the soybean plants were kept in a greenhouse and evaluated for visual damage estimates at 28 days after application (DAA). For the nylon strings, the spray solution deposited on each string was extracted by washing with distilled water, and the resulting solution was read through the spectrophotometry method. The analysis of the droplet spectra was performed using a particle analyzer (Sympatec GmbH, Clausthal-Zellerfeld, Germany) with an R7 lens (range from 18 to 3,500 µm in diameter). The droplet spectra of the MUG11003, TTI11003, and AIXR11003 nozzles at pressures of 137, 275, 414, 552, 689, and 827 kPa were compared. The DV50, the relative span (RS), and the percentage of droplets smaller than 200 µm (driftable fines) were reported. The data obtained indicate that the increase in boom height results in an increase in drift and damage to plants for all distances, as well as the results for the different nozzle models. The greatest damage to plants was observed when they were closer to the nozzle. For the analysis of droplet spectra, a reduction in DV0.5 values and an increase in the percentage of driftable droplets were observed when the working pressure was increased.