Aquatic weeds, especially macrophytes, are a serious problem in hydroelectric plant systems, affecting the multiple use of water, such as fish production and fishing activities, water losses by evapotranspiration, aquatic sports, boating, irrigation and hydroelectric power production. An experiment using boxes filled with water was carried out to analyze the potential use of carfentrazone-ethyl in the control of the main aquatic weeds in Brazil. The following herbicide treatments (g i.a. ha-1) were used: carfentrazone-ethyl at 15, 30 and 60; glyphosate at 4,536; 2,4D at 4,690; imazapyr at 1,250, and no herbicide. These treatments were tested on the species: Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes, Myriophyllum aquaticum, Brachiaria arrecta, Hydrocotyle umbellata, Typha sp. and Echinochloa polystachya. The evaluations were conducted at 7, 14, 21 and 28 days after treatments. The results showed that carfentrazone-ethyl is efficient in the control of E. crassipes (higher rate), P. stratiotes (the two highest rates) having a suppressive effect on S. auriculata. No efficacy was observed on the other weeds studied.
herbicide; aquatic weed control; macrophytes
