The effects of purple nutsedge densities and chemical control on sugarcane (var. SP 86042) yield were evaluated. Three densities were studied: low (58 to 246), medium (318 to 773) and high (675 to 1198 shoots m-2).Yield reductions were 13.5; 29.3 and 45.2% compared to the check, respectively. The importance of a good chemical control was evidenced in the second experiment with the herbicides sulfentrazone (0.8 kg ha-1), imazapic (0.105 kg ha-1) and flazasulfuron (0.150 kg ha-1), at pre-emergence,and trifloxysulfuron-sodium + ametryne and surfactant (1.5 kg ha-1 + 0.25%), halosulfuron + surfactant (0.105 kg ha-1 + 0.20%) and flazasulfuron + surfactant (0.150 kg ha-1 + 0.25%), at post-emergence. Density variation was from 66 to 154 shoots m². At 90 days after planting (DAP), shoot control was 79.6; 70.6; 30.3; 84.8; 89.1 and 61.1%, respectively, for the tested herbicides. Yield reduction of 16.4% was observed between the infested and weeded checks and of 11.9% and 6.0% in the plot with flazasulfuron applied at post and pre-emergence, respectively.
Cyperus rotundus; Saccharum ssp.; herbicides; selectivity
