The influence of three types of commercial formulation of insecticides and fungicides, emulsifiable concentrate (EC) formulation, suspension concentrate (SC) formulation and water dispersible granule (WG) formulation on the surface tension, viscosity and the droplet size spectra of sprays was evaluated using thirty commercial insecticide and fungicide products. The concentration of sprays was based on application water spray volume of 50 L ha À1 using an XR 8003VS flat fan nozzle, operated at 200 kPa pressure. The lowest surface tensions were obtained with EC formulations, while the SCs had the highest viscosities. Emulsions were the most effective at decreasing the percentage of droplets smaller than 100 mm and relative span, while increasing the DV 0.1 and DV 0.5 values than the dispersion-type formulations, represented by WG and SC formulations. These factors should be considered for planning spray applications and reducing drift.

RESUMO -O uso inadequado da tecnologia de aplicação de agrotóxicos, relacionados ao uso de pontas de pulverização e adição de adjuvantes, resulta diretamente em um maior risco de deriva. Objetivou-se como trabalho quantificar a deriva gerada por pontas de pulverização com e sem indução de ar, em aplicações de glyphosate e adjuvantes. O experimento foi realizado em túnel de vento, com o herbicida glyphosate isolado ou em mistura com ureia ou adjuvante redutor de deriva (LI700). As coletas foram realizadas, com fios de polietileno, nas distâncias de 5,0; 10,0 e 15,0 m em relação à barra e nas alturas de 0,2; 0,4; 0,6; 0,8 e 1,0 m em relação ao piso do túnel, a deriva foi aferida por meio do processo de condutividade elétrica. Os resultados apresentaram maior deriva nas menores alturas, tendo igual comportamento para todas as caldas e em todas as distâncias. A ponta de jato plano com indução de ar (AVI 110-015) proporcionou menor deriva em relação à ponta jato plano padrão (AXI 110-015), para todas as caldas avaliadas. Para a ponta de jato plano padrão o acréscimo de adjuvante reduziu a deriva para as três distâncias avaliadas em relação à calda contendo somente o herbicida. Já para a ponta de jato plano com indução de ar a ureia elevou a deriva para todas as distâncias em relação às outras caldas. A ureia pode ser utilizada em aplicações com o modelo de ponta jato plano padrão, por diminuir os riscos de deriva.Palavras-chave: Tecnologia de aplicação. Agrotóxicos. Ureia. Plantas-efeito dos herbicida. Túnel de vento. ABSTRACT -The improper use of pesticide-application technology, related to the use of spray nozzles and the addition of adjuvants, is directly related to a greater risk of drift. This study aimed to quantify the spray drift generated by nozzles, both with and without air induction, in applications of glyphosate and adjuvants. The experiment was conducted in a wind tunnel, using the herbicide, glyphosate, either pure or in combination with urea or a drift-reducing adjuvant (LI700). Collections were made on polyethylene strings, at distances of 5.0, 10.0 and 15.0 m from the spray-boom, and at heights of 0.2, 0.4, 0.6, 0.8 and 1.0 m from the floor of the tunnel; the drift was measured using a process of electrical conductivity. The results showed greater drift at the lower heights, giving the same results for all solutions and at all distances. The flat nozzle with air induction (AVI 110-015) gave a smaller drift relative to the standard flat nozzle (AXI 110-015) for all solutions tested. With the standard flat nozzle, adding an adjuvant reduced the drift at the three distances tested, for the solution containing pure herbicide. For the flat fan nozzle with air induction however, the urea increased drift at all distances compared to other the spray solutions. Urea can be employed in applications where the standard flat tip model is used, as it reduces the risk of drift.

ResumoA deriva está diretamente ligada ao uso inadequado da tecnologia de aplicação de agrotóxicos, sendo a correta seleção das pontas de pulverização e adjuvantes importantes variáveis para auxiliar em sua redução. O objetivo deste trabalho foi estimar o potencial de deriva em túnel de vento com diferentes pontas de pulverização e diferentes concentrações de adjuvantes. O ensaio foi composto por seis caldas (óleo vegetal (em três concentrações), óleo mineral, surfatante e redutor de deriva), aplicadas com pontas de pulverização anti-deriva, jato plano com pré-orifício (DG 8003 VS) e indução de ar (AI 8003 VS). O equipamento utilizado foi um túnel de vento, onde as coletas de deriva foram realizadas em diferentes pontos. As médias dos tratamentos foram comparadas pelo Intervalo de Confiança, a 95% de probabilidade. A análise da porcentagem de deriva demonstrou que os tratamentos tiveram comportamentos distintos. O adjuvante nonil fenol etoxilado apresentou a maior deriva quando aplicado com a ponta de pré-orifício e a menor deriva quando aplicado com a indução de ar. Porém, comportamento contrário foi observado quando o adjuvante a base de óleo foi utilizado para as mesmas pontas. Para a ponta DG o menor percentual de deriva em todas as distâncias analisadas foi para o tratamento óleo vegetal (1,0%) e para a ponta AI a menor deriva foi encontrada no tratamento com o adjuvante nonil fenol etoxilado (0,0625%) nas quatro distâncias de coleta. Pode-se concluir que as pontas de pulverização e os adjuvantes testados alteram diretamente o potencial de deriva. Não houve proporcionalidade entre as concentrações do adjuvante a base de óleo vegetal testadas com a porcentagem de deriva. Palavras-chave: Tecnologia de aplicação, surfatante, óleo vegetal, óleo mineral AbstractThe drift is intimately linked to inappropriate use of pesticides and an important factor for reducing it, is the correct selection of spray nozzles and adjuvants. The objective of this work was to evaluate the drift potential in wind tunnel with different spray nozzles and different concentrations of adjuvants. The experiment was composed by six spray solutions (vegetable oil (in three concentrations), mineral

Abstract. Drift is one of the most hazardous consequences of an improper aerial application of glyphosate. Wind, droplet size, application height, and distance to sensitive areas are the most important factors for drift. Droplet size is affected by nozzle, operating pressure, flight speed, deflection angle, and physicochemical properties of the spray solution. The objective of this study was to evaluate the effect of flight speed and the use of adjuvants on droplet size spectra in aerial applications of glyphosate. The study was conducted in a high-speed wind tunnel at the Pesticide Application Technology Laboratory (University of Nebraska-Lincoln, West Central Research and Extension Center, North Platte, Neb.). Aerial applications were simulated with four different airspeeds (44.4, 52.8, 61.1, and 69.4 m/s) and glyphosate combined with adjuvants (high surfactant oil concentrate, microemulsion drift reduction agent, nonionic and acidifier surfactant, polyvinyl polymer, and glyphosate alone). Droplet size spectra were evaluated using a Sympatec Helos laser diffraction instrument measuring 90 cm from the nozzle tip (CP11-4015). The volumetric droplet size distribution parameters (VMD, DV0.1, and DV0.9) and the percentage of droplets smaller than 100 µm were reported. The relative span was calculated to indicate the droplet size homogeneity [(DV0.9 - DV0.1) / DV0.5]. Glyphosate solutions with adjuvants had a larger VMD than the glyphosate alone solution at 44.4 m/s wind speed. At 69.4 m/s only the glyphosate solution with polymer had a larger VMD. Conversely, the glyphosate with polymer had the smallest DV0.1, and the greatest relative span and percentage of droplets smaller than 100 µm. Generally, adjuvants influence on droplet size was diminished or muted as the airspeed was increased. The polymer tested in this study failed as a drift agent reduction agent, especially at higher airspeeds. While not all polymers were tested, cautions should be taken if using these types of adjuvants in aerial applications. The interaction of airspeed and adjuvants influencing droplet size distribution in aerial applications of glyphosate should be considered by applicators in order to mitigate glyphosate drift to the surrounding environment. Further studies are necessary to better understand the interaction between solution viscosity and air shear effect on the atomization process and droplet size distribution, as well as confirm that trends hold true for other adjuvants in the polymer class. Although applicators tend to operate aircrafts with increased flight speeds in order to optimize the application time efficiency, this practice can reduce or mute adjuvants effects, decrease the droplet size distribution, and increase drift potential in aerial applications of glyphosate. Keywords: Drift reduction technologies, Flight speed, High-speed wind tunnel, Laser diffraction.

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