Effect of wind intensity, pressure and nozzles on spray drift from preemergence herbicide applications

摘要

The aim of this work was to evaluate the effect of nozzles, spray pressure and wind intensity on spray drift generated in simulated preemergence herbicide applications. The nozzle designs and respective pressures tested were: SF 11002 (207 and 310 kPa), JA-2 (345 and 655 kPa) and AVI 11002 (207and 414 kPa). The applications were performed during two periods, on days with different wind conditions, in an area with 1,200 m2, in the Experimental Farm of the FCA/UNESP. A sprayer with a 12 m boom, 24 nozzles and tank with 600 L was used for the applications. The spray liquid was composed by water and the food dye FDC-1 as a tracer. The spray drift was sampled by active collectors fixed on the spray boom. The minimum, mean and maximum wind velocity values registered in the first and second spraying period were 7, 14 and 23 km h-1 and 1, 5 and 18 km h-1, respectively. The air induction flat fan nozzle AVI 11002 and the hollow cone JA-2 at 655 kPa resulted in the lowest and highest amounts of deposit detected, respectively, for both applications. The higher wind intensity increased the drift. Reductions on the spray pressure can be used to control the drift, but adequate nozzle selection was found to be more important for this purpose.