Glyphosate applied with different concentrations of urea or ammonium sulfate for weed desiccation

Abstract

^{This work was developed with the objective of evaluating glyphosate efficacy for Bengal dayflower (Commelina benghalensis) and other weeds desiccation, when combined to different concentrations of ammonium sulfate or urea. Three experiments were carried out with similar treatments: two in field conditions and one in greenhouse. Treatments applied in field conditions were: glyphosate at 360 g ha-1 a.e., isolated or combined to four concentrations of ammonium sulfate (2.5, 5, 10, and 20 g L-1) or urea (1.5, 3, 6, and 12 g L-1); glyphosate at 720 g ha-1 a.e., applied isolately; and checks without application. In greenhouse, for the specific control on Bengal dayflower, glyphosate rates were increased to 720 (isolated or in combination) and to 1,440 g ha-1 a.e. Ammonium sulfate addition to glyphosate spray solution increased field weed control, when concentrations up to 10 g L-1 were used. None of the glyphosate rates were efficient to control Bengal dayflower. Urea addition to spray solution did not improve weed control in field conditions; however, it increased Bengal dayflower control for concentrations up to 6 g L-1, at the evaluation after 28 days of application.}