This work aimed to carry out an experiment under greenhouse conditions to eva luate the effect of humidity conditions and germination depth of Brachiaria plantaginea and Digitaria spp. on the efficacy of tebuthiuron. The treatments were constituted by five germina tion depths of the weeds and different herbicide application conditions (1; 2; 3; 4 and 5 cm) and four humidity conditions. The following treatments were applied: treatment 1: 15 mm of rainfall, followed by herbicide application; treatment 2: 15 mm of rainfall, followed by herbicide appli cation and 15 mm of rainfall after 7 days; treatment 3: 15 mm of rainfall, followed by herbicide application and 15 mm of rainfall after 14 days; and treatment 4: herbicide application on dry soil and 15 mm of rainfall after 14 days, and a control without application. The treatments were arranged in a 5 x 5 factorial scheme, with four repetitions. The weeds were seeded in vases at the different depths. Tebuthiuron promoted an effective control of the plants of B. plantaginea at all depths tested and application conditions, with a significant flaw in the control of the plants that germinated at 5 cm depth where the herbicide was applied to wet soil and without rainfall. For Digitaria spp., excellent plant control levels were initially observed, with flaws in the control for wet soil application, followed by rainfall occurrence at 14 DAA at depths of 2 and 3 cm, indicating possible leaching of this herbicide for layers below 3 cm in the soil.
weed; leaching; mobility
