To evaluate the efficacy of herbicides applied in pre and post-emergence, alone and in combination, during the dry and wet seasons, for the control of hairy woodrose (Merremia aegyptia) on sugarcane, an experiment was arranged in a randomized block design, in split-plots, with four replications, in a commercial production area in Pradópolis, São Paulo, Brazil, from July 2008 to May 2009. Three herbicide treatments [amicarbazone (1.4 kg ha-1 ), imazapic (0.147 kg ha-1 ) and clomazone plus hexazinone (0.8 kg ha-1 plus 0.2 kg ha-1 ) applied on July 16, 2008, after sugarcane harvest, and one treatment without herbicide were tested. To evaluate the need of herbicide application during the wet season, the combinations of four extra herbicide treatments and two treatments without herbicides were studied. The herbicides used at the second experimental stage were: mesotrione alone (0.192 kg ha-1 ), and in mixture (0.12 kg ha-1 ) with atrazine (1.5 kg ha-1 ), metribuzin (0.96 kg ha-1 ) or diuron plus hexazinone (0.702 plus 0.198 kg ha-1 ), applied in post-emergence on November 6, 2008. Amicarbazone presented the best M. aegyptia control among the herbicides applied during the dry season. However, anagement complementation with herbicide application during the wet season was found to be mandatory for all herbicides. In the second experimental stage, the association of mesotrione to atrazine, metribuzin and diuron plus hexazinone was more efficient for M. aegyptia control than when applied alone. None of the herbicide treatments affect stalk number, stalk diameter and stalk height in sugarcane (variety SP 81-3250).
hairy woodrose; weed; Saccharum spp
