ABSTRACT Agricultural spray adjuvants (ASA) are widely used in pesticide applications to enhance the performance of pesticides. The aim of this research was to investigate the effects of ASA on static surface tension (SST) and foliar spray retention on coffee leaves. The SST of ASA at different concentrations was determined by the drop weight method. Spray retention on adaxial and abaxial coffee leaf surfaces was performed using a micro-sprayer at solution concentrations of 0, 0.01, 0.1, 0.5, and 1.0% v v−1. The ASA assessed were: polyether-polymethylsiloxane-copolymer (PPC); Nonylphenol ethoxylate; nonyl polyethylene glycol ether; mineral oil; nonylphenoxy polyethoxy ethanol; carboxyl copolymer of styrene and butadiene; primary aliphatic oxyalkylated alcohol plus carboxyl copolymer of styrene and butadiene; and soyal phospholipids and propionic acid. All ASA reduced the SST of the aqueous solutions. PPC provided the best performance in decreasing SST, reaching values below 20 mN m−1 at a concentration of 0.05% v v−1. Spray retention on leaves was influenced by adjuvant type as well as concentration. A very strong positive correlation between SST and spray retention on coffee leaves was observed. Decreasing the SST of the solution provided a reduction of spray retention when spraying was performed until run-off point.

ABSTRACT The effect of blade angle on droplet size spectrum of five rotary cage atomizers and one rotary disc atomizer used in Brazil was evaluated in a high speed wind tunnel, with an air speed of 180 km h−1. This study included the characterization of the droplet size spectrum, via laser diffraction instrument, generated by three blades angles, of 45, 60 and 75 degrees. The spray solution was composed of Picoxystrobin+ Cyproconazole fungicide (SC), at 20 mL c.p. L−1, and at a flow rate of 6 L min−1. As the angle decreased from 75 to 45 degrees, the rotational speed of the atomizers increased and the volume median diameter (VMD) decreased. However, increasing the rotational speed also increased the percentage of droplets smaller than 100 µm (% < 100 µm). At the blade angles of 45 and 60 degrees the atomizers showed that % < 100 µm was higher than 20% and VMD was smaller than 198 µm. The disc type atomizer resulted in the lower values of relative span (RS). The use of 75 degrees blade angle produced the highest values of VMD and the lowest values of % < 100 µm; these parameters were also affected by atomizer model and brand.

RESUMO O objetivo deste trabalho foi investigar o nível de conhecimento de trabalhadores ligados à atividade de aplicação de defensivos agrícolas sobre as funções de adjuvantes de calda e coletar informações sobre os locais de descarte dos resíduos provenientes da lavagem interna do reservatório de calda de pulverizadores, ocorrência e motivos da deriva, nas aplicações de defensivos agrícolas, no Estado do Mato Grosso. As informações foram coletadas por meio das respostas de um questionário entregue aos participantes de um programa de extensão rural, em tecnologia de aplicação, em dezenove municípios produtores de grãos e fibras do Estado. Ao todo, 49,0% dos adjuvantes citados pertenciam à classe dos óleos minerais e 17,9% dos participantes declararam não saber as funções desempenhadas pelos adjuvantes. Os resíduos eram descartados nas lavouras por 58,5% dos participantes. Dentre os participantes que responderam sobre as causas da ocorrência de deriva nas aplicações, 54,1% indicaram problemas relativos às condições climáticas inadequadas. Conclui-se que há carência de conhecimento sobre as funções desempenhas pelos adjuvantes, bem como a ocorrência de descarte de resíduos em locais inadequados no Estado do Mato Grosso. A deriva foi reconhecida como um problema, mas a maioria dos participantes não se propôs a discutir as causas deste tipo de perda.

ABSTRACT This paper aimed at investigating the knowledge level of people working on pesticide spraying activities concerning spray adjuvant properties, as well as collecting information on disposal locations for residues from internal spray tank cleaning, and finally the understanding of pesticide spray drift occurrence in the state of Mato Grosso, Brazil. The information was gathered through a questionnaire answered by participants of a rural extension program in application technology located in nineteen grain and fiber producing regions of Mato Grosso state. Among the mentioned adjuvants, 49.0% belonged to the mineral oil class and 17.9% of participants did not know the functions performed by such products. In addition, 58.5% of the participants discarded residues into the field. Among the participants who answered the question about spray drift occurrence causes, 54.1% indicated problems relating to inadequate weather conditions. In conclusion, there is a lack of knowledge on adjuvant functions, besides of inappropriate residue disposal in the state of Mato Grosso. Spray drift was referred as a problem; however, most of participants were not able to discuss the causes of these losses.

A cada ano, há um aumento no consumo e na importância do uso de agrotóxicos na produção agrícola em alta escala, sendo fundamental o conhecimento da tecnologia de aplicação para o sucesso da atividade. O objetivo deste trabalho foi avaliar a influência da pressão de trabalho sobre a deriva gerada por diferentes pontas de pulverização, avaliada em túnel de vento. Os tratamentos foram compostos por duas pontas de pulverização: AXI 110015 e AXI 11002, nas pressões de 276 e 414 kPa. A calda de pulverização foi composta por água e NaCl a 10%. As aplicações foram realizadas com velocidade de vento de 2,0 m s-1, sendo a deriva coletada a 5,0; 10,0 e 15,0 m de distância da barra de pulverização e nas alturas de 0,2; 0,4; 0,6; 0,8 e 1,0 m em relação ao piso do túnel. Para as duas pontas de pulverização, a maior deriva coletada ocorreu na menor distância em relação à barra de pulverização e na menor altura em relação ao piso do túnel. O modelo de ponta AXI 11002 apresenta menor porcentagem de deriva coletada em relação ao modelo AXI 110015, para as duas pressões testadas e em todos os pontos de coleta. Independentemente da ponta, o aumento da pressão de trabalho aumenta a porcentagem de deriva em todas as distâncias de coleta realizadas no túnel de vento.

Each year, there is an increase in pesticide consumption and in its importance of use in the large-scale agricultural production, being fundamental the knowledge of application technology to the activity success. The objective of the present study was to evaluate the influence of working pressure on the drift generated by different spray nozzles, assessed in wind tunnel. The treatments were composed of two spray nozzles AXI 110015 and AXI 11002 with pressure levels of 276 and 414 kPa. The spray solution was composed by water and NaCl at 10%. The applications were conducted at wind speed of 2.0 m s-1, being the drift collected at 5.0; 10.0 and 15.0 m away from the spray boom and at heights of 0.2; 0.4; 0.6; 0.8 e 1.0 m from the tunnel floor. To both spray nozzles, the greatest drift was collected at the smallest distance to the spray-boom and at the lowest height. The AXI 11002 nozzle gave a smaller drift relative to the AXI 110015 nozzle for the two tested pressures and for all the collection points. Regardless of the nozzle, a rise in the working pressure increases the spray drift percentage at all distances in the wind tunnel.