The objective of this work was to evaluate the s-metolachlor efficiency, in the control of Brachiaria plantaginea in the bean crop, under two irrigation conditions associated to the herbicide application. The work was conducted in the field, from September to December 1998, in a Cambic Podzolic soil, terrace phase, with 35.0 dag kg-1 of clay and 3.6 dag kg-1 of organic matter. Two experiments were accomplished, differing only in the methodology used by cach, i.e., in the first, a 20 mm water lamina was applied immediately before herbicide treatment and, in the second the same water lamina was applied immediately after herbicide application. Six doses of s-metolachlor (0; 0.48; 0.72; 0.96; 1.20; and 1.92 kg ha-1) were evaluated associated to two evaluation times (20 and 35 days after emergence). The control efficiency of B. plantaginea was not influenced by the initial of the irrigation management, which was superior to 81.0% for doses starting from 0.96 kg ha-1. The s-metolachlor gave a good B. plantaginea control up to 35 DAE, when there was sufficient for a complete covering of the soil by the bean crop.
soil moisture; weed; Phaseolus vulgaris
