COBERTURA DAS FOLHAS DE SOJA UTILIZANDO PONTAS DE PULVERIZAÇÃO COM DIFERENTES FORMATOS DOS JATOS*

Abstract

For efficient and safe spraying, parameters such as spray nozzles model, droplet spectrum and application volumes rates are very important. The aim of this research was to evaluate interaction between the spray nozzles shape and the application volume rate, in the coverage in soybean leaves. The treatments consisted of three spray nozzles (pre-orifice low drift flat fan, pre-orifice low drift double flat fan and angled flat fan) and two application volumes rates (100 and 200 L ha^-1). The spray solutions were prepared using the mixture with Sphere Max^® fungicide, Aureo^® and Luxcor LRM 100 dye. The analysis of coverage was perform through the visual evaluation, comparing each leaf with a scale of grades, in a dark room with fluorescent lighting. In the upper portion of canopy had 27.59% more coverage in the 200 L ha^-1 than 100 L ha^-1. There were no significant difference between the nozzles, in the upper portion. In the medium/lower portion of canopy, the application volumes rates of 200 L ha^-1 had 52.32% more coverage than 100 L ha^-1 and there were no significant difference between the nozzles. When applying fungicides at the beginning of soybean flowering, the shape of spray nozzles does not change the leaf coverage in any canopy portion. The change in application volume rates from 100 to 200 L ha^-1 increased the leaf coverage, for both portions of the canopy analyzed.