Influência de pontas de pulverização e adjuvantes na deriva em caldas com glyphosate

Abstract

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.

Spectrum, Velocity and Drift of Droplets Sprayed by Nozzles With and Without Air Induction and Mineral Oil

“…This dye has low toxicity and is a highly water soluble product, and it is used in several studies with satisfactory results as tracer in the respective experiments for deposition measures (CHECHETTO et al, 2013;MOREIRA JÚNIOR & ANTUNIASSI, 2010).…”

“…The drift is considered one of the biggest problems of agriculture, and it can be defined as the trajectory deviation that prevents the produced droplets to hit the target, a fact that is mainly related to the droplet size and wind speed (CHECHETTO et al, 2013;ALVES & CUNHA, 2014).…”

“…In addition to reducing the environmental contamination risk, spray nozzles with air induction provide droplets with air induced in its interior in the form of air bubbles (GANDOLFO et al, 2013) due to the Venturi system, thereby reducing the droplets rebound effect when hitting the target.…”

“…Agríc., Jaboticabal, v.37, n.3, p.502-509, maio/jun. 2017 503 mixture, consequently reducing the drift (GANDOLFO et al, 2013;HILZ & VERMEER, 2013). Among the many types of adjuvants available in the market, the widespread use of mineral oils is highlighted because it acts reducing the surface tension and increasing the wettability, spreading and absorption of the products (BAYER et al, 2011).They may also have drift reduction action by increasing the diameter of the spray droplets (OLIVEIRA et al, 2013).…”

Spray adjuvant characteristics affecting agricultural spraying drift

“…Although real drift conditions might only be obtained in field experiments, the wind tunnel experiments have a great advantage over those, once wind tunnels determine the potential drift risk of different application systems. These experiments could not be repeated and compared under field conditions due to weather variations (NUYTTENS et al, 2009;CHECHETTO et al, 2013;GANDOLFO et al, 2013;FRITZ et al, 2014;GANDOLFO et al, 2014).…”