Publicação on-line; 32 ref.; 8 tables; Summary (En)

ABSTRACT
Background: Competition with weeds and the lack of selective
herbicides registered for birdsfoot trefoil crops affect their development
and limit their productivity.
Objective: This study aimed to evaluate selectivity of post-emergent
herbicides for weed control in birdsfoot trefoil crops.
Methods: Experiments were carried out in a greenhouse and on a field,
in both vegetative and reproductive development stages of birdsfoot
trefoil crops. Treatments were composed of post-emergent herbicides
recommended for soybean, corn and garlic cultivation. Phytotoxicity
(PHYTO), plant height (HEI), shoot dry matter (SDM) and root dry matter
(RDM) were evaluated. Data were submitted to the analysis of variance
and when means were significant, they were compared by the Duncan’s
Test (p≤0.05). In order to determine post-emergent herbicides which were
selective to the crop, those that provided PHYTO below or equal to 15%
were recommended, since they did not significantly interfere with
morphological variables HEI, SDM and RDM, by comparison with the
control.
Results: Unlike results found in the vegetative stage, birdsfoot trefoil
plants were more tolerant to phytotoxic effects of herbicides imazethapyr,
chlorimuron-ethyl, cloransulam-methyl and fomesafen in the reproductive
stage. The variables were negatively affected by the herbicides bentazon,
glyphosate and carfentrazone-ethyl, with PHYTO higher than 40% at
20 days after treatment in the vegetative stage.
Conclusions: Herbicides imazethapyr, chlorimuron-ethyl and
flumetsulam, when applied as post-emergent ones, regardless of the
development stage of the species, are selective to birdsfoot trefoil crops,
without affecting crop development, whereas herbicides cloransulammethyl and fomesafen are not selective to them.

Keywords:
Lotus corniculatus
management
efficiency