Publicação on-line; 28 ref.; 7 illus.; Summary (En)

ABSTRACT
Background: The use of pre-emergent herbicides is an important tool to
control weeds, however the tolerance of soybean to these herbicides can
vary according to the type of soil.
Objective: The aim of this study was to evaluate sulfentrazone and
diclosulam soybean selectivity in a sandy soil, in order to establish these
herbicides as supporting tools in weed control.
Methods: The treatments consisted of six doses of sulfentrazone (150 to
400 g ha-1) and diclosulam (25.2 to 75.6 g ha-1), and an untreated control.
A field study was repeated in two growing seasons (2013/14 and
2014/15) in a sandy soil.
Results: The occurrence of injury depended on the growing season. The
first season presented lower rainfall rates during the crop cycle. The
recommended dose of sulfentrazone (200 g ha-1) caused 26% and 10%
of plant injury at 15 days after the treatment for the first and second
season, respectively. For diclosulam, the recommended dose of
35.3 g ha-1 caused 20% and 8% of plant injury, respectively, for the first
and second season. However, at the recommended doses, only for
diclosulam and in the rainy season there was a reduction in soybean
productivity.
Conclusions: The herbicide sulfentrazone, although causing visual
soybean plant injury, present satisfactory selectivity at recommended
doses and can be used as an important tool on weed control on sandy
soils. Similar response was observed for diclosulam in 2013/14.
However, in a rainfall season diclosulam impacted on soybean yield at
the recommended dose for sandy soils, with selectivity depending of the
growth season.

Keywords:
Glycine max
plant injury
pre-emergence herbicides
weed management