Vertical volumetric distribution of an axial fan sprayer on the Brevipalpus phoenicis control

ABSTRACT Spray distribution generated by axial fan sprayer, among other factors, should be critically analyzed, in order to prevent unnecessary costs and environmental contamination. This study aimed at evaluating the effect of the vertical volumetric distribution of an axial fan sprayer on the Brevipalpus phoenicis control efficiency. First, an assay was performed to evaluate the vertical volume distribution uniformity of the sprayer, assessing different spray nozzles configurations on the spray arcs, sides of the sprayer and spray heights. Afterwards, another experiment was carried out to analyze the relationship between the distribution of the Fenpyroximate acaricide on Coffea arabica L. and the B. phoenicis control efficiency. The treatments were arranged in a 4 x 2 factorial + 1 additional control, consisting of four spray volumes (200 L ha-1, 400 L ha-1, 600 L ha-1 and 800 L ha-1) and two spray nozzles configurations (1: 100 % of MAG1.5 nozzles; 2: upper extension with 5 MAG3.0 nozzles, middle extension with 9 MAG1.5 nozzles and lower extension with 4 MAG3.0 nozzles). Configuration 2 provided the smallest coefficient of variation (28 %). Nozzle configurations had no effect on the incidence of B. phoenicis. The use of nozzles with different flow rates on the spraying arc improves the vertical volumetric distribution uniformity of axial fan sprayers, but does not affect the B. phoenicis control efficiency. RESUMO A distribuição de calda proporcionada por pulverizadores hidropneumáticos, dentre outros fatores, deve ser analisada com critério, sob pena de elevar custos de produção e causar contaminação ambiental. Objetivou-se avaliar o efeito da distribuição volumétrica vertical de pulverizador hidropneumático na eficácia de controle de Brevipalpus phoenicis. Primeiramente, realizou-se ensaio visando a avaliar a uniformidade de distribuição volumétrica vertical do pulverizador, considerando-se diferentes configurações de pontas nos arcos de pulverização, lados e altura de pulverização. Em seguida, realizou-se outro experimento, com o intuito de analisar a relação entre a distribuição do acaricida Fenpiroximato, aplicado a lavoura de Coffea arabica L., e o controle de B. phoenicis. Os tratamentos foram dispostos em esquema fatorial 4 x 2 + 1 testemunha adicional, sendo eles: quatro volumes de calda (200 L ha-1, 400 L ha-1, 600 L ha-1 e 800 L ha-1) e duas configurações de pontas (1: 100 % das pontas MAG1,5; 2: parte superior com 5 pontas MAG3,0, parte medi