Publicação on-line; 27 ref.; 5 tables; 2 illus.; Summary (En)

ABSTRACT
Background: The study of the interactions between equipment,
application methods, and spray mixtures is fundamental to optimize the
application of pesticides. The determination of the best combination of
these factors can reduce the drift during the application of the herbicide
2,4-dichlorophenoxyacetic acid (2,4-D).
Objective: The objective this paper is to study the influence of nozzle
models, working pressures, and surfactant adjuvant in reducing the drift
of 2,4-D.
Methods: The spectrum of nozzle drops was determined for a
conventional flat jet; flat jet with air induction; double plane jet with air
induction; deflector flat jet with air induction; and an empty cone with air
induction at pressures of 200, 300, 400, and 500 kPa. This was quantified
in a wind tunnel with four drifts: water; water + surfactant adjuvant; water
+ 2,4-D; and water + 2,4-D + surfactant adjuvant, applied by the five
nozzle models at four working pressures. The data was evaluated by
analysis of variance and, when significant, by the Tukey test and
regression at 5% significance level.
Results: The interactions between the nozzle models, working pressure,
and spray mixture directly influenced the 2,4-D drift.
Conclusions: The use of surfactant adjuvant must be carried out
carefully, according to the nozzle model, working pressure, and spray
mixture. The conventional single fan jet nozzle is more sensitive to
increased working pressure and has a high potential to cause drift
compared with the models with air induction.

Keywords:
agricultural mechanization
application technology
quality control
air induction
droplet size
wind tunnel