This work aimed to evaluate the efficacy and selectivity of the herbicide carfentrazone-ethyl applied in post-emergence to control weeds in sugarcane crop and to evaluate dose-response curves of this herbicide in four species of Ipomoea spp. and Commelina benghalensis. Field experiment was carried out in post-emergence of weeds and sugarcane (cv. RB72-454).The experimental design adopted was a completely randomized block with the following treatments: carfentrazone at 5, 10, 20, 30 and 50 g ha-1 and metribuzin at 2,400 g ha¹. The main weed species presented in the area were I. nil, I. grandifolia, I. quamoclit, Momordica charantia and C. benghalensis. The evaluations of percentage of weed control and selectivity to sugarcane crop were carried out at 15, 30 and 45 days after herbicide application. An experiment was carried out under greenhouse conditions to elaborate dose-response curves with the weeds I. nil, I. grandifolia, I hederifolia, I. quamoclit and C. benghalensis. The herbicide rates analyzed were: 10D, 4D, 2D, D, 0.5D, 0.25D, 0.125D, 0.1D and 0.01D; where D = 20 g ha-1. Results were analyzed by dose-response curves in visual control and fresh mass. In the field experiment, results showed efficient weed control and the rate of 50 g ha-1 was considered the best carfentrazone treatment. No chemical treatment caused visible injury in the sugarcane crop. The greenhouse experiment showed that decreasing susceptibility of Ipomoea species to carfentrazone-ethyl was: I. hederifolia > I. quamoclit > I. nil > I. grandifolia and that C. benghalensis is controlled by carfentrazone at 5 g ha-1.
morningglory; benghal dayflower; metribuzin; selectivity
