The aim of this research was to evaluate the control of Egeria densa and Egeria najas, using the herbicide diquat. The herbicide doses used for both species were: 0.1; 0.25; 0.5; 1.0; and 1.5ppm. Tanks with 0.60x1.10m dimension constituted the plots. Visual evaluation at 5, 7, 10, 14, 26, 31, 38, and 45 days after herbicide application was performed through percentage score scale, with 100% corresponding to total plant control. For Egeria najas, 0.5 ppm of diquat was sufficient to determine total plant control, with no posterior occurrence of sprouts. For Egeria densa, sprouts occurred 45 days after herbicide application with highest intensity at the lowest doses. Reapplication doses of 0.5ppm also determined death of the plants.
herbicide; immersed plant; aquatic plant
