The objective of this work was to evaluate the agronomic efficacy and selectivity of the phytotoxic effects of post-emergent herbicides, applied in pre-planting, in the control of Euphorbia heterophylla and Bidens pilosa under no tillage system of soybean. The experiment was conducted during the growing season of the crop 2000/2001, in FEP-UNESP, in Selvíria-MS, Brazil. The soybean variety used was 'Conquista', and the experimental design was a randomized block, with seven treatments, and four replications, with eight rows, totaling 20 m², for each replication. The treatments were the following: glyphosate (720 and 960 g ha-1), chlorimuron-ethyl + glyphosate (10 g + 720 and 960 g ha-1), glyphosate + 2,4-D (960 + 868 g ha-1), and control with and without weeds. The applications were accomplished with a pulverizer of constant pressure (CO2) of 45 lb pol-2, with a bar equipped with four beaks of the fan type Teejet 110.03 XR, 0.5 m spaced and 250 L ha-1 volume. It was observed that the treatments were efficient in the control of E. heterophylla and B. pilosa and are selective to the soybean plants. The herbicide chlorimuron-ethyl (10 g ha-1) applied together with the glyphosate, provides to the treatment a significant residual effect for E. heterophyllaheterophylla and B. pilosa, reducing weed infestations during the soybean crop cycle.
herbicide; weeds; control; residual; Glycine max; chlorimuron; glyphosate; 2,4-D
