Effect of herbicides on the initial growth of sweet sorghum

The presence of weeds may severely reduce yield of sweet sorghum (Sorghum bicolor), and due to the reduced number of herbicides registered, the objective of this work was to evaluate the effect of herbicides on the initial growth of this crop. The experimental design was completely randomized with five replicate, being, the herbicides haloxyfop-methyl, cyhalofop-butyl, fomesafem, imazaquim, lactofen, atrazine, 2,4-D and saflufenacil were applied at different initial post-emergence rates and herbicides atrazine, atrazine + simazine, hexazinone and s- metolachlor in pre-emergence of the culture. The phytointoxication evaluations were performed at 7, 14, 21 and 30 days after application (DAT) and the dry biomass of the aerial part evaluated at 30 DAT. In post-emergence, the herbicides haloxyfop-methyl and imazaquim caused high phytointoxication and impacts on plant biomass. 2,4-D and atrazine did not cause significant differences in relation to the control in both phytointoxication and biomass. The herbicide lactofen caused low phytointoxication, however, saflufenacil and fomesafen promoted phytointoxication at commercial dose close to 40% and changes in biomass. Of the herbicides used in pre-emergence, only hexazinone and s-metolachlor demonstrated phytointoxication and changes in biomass. It is concluded that the herbicides atrazine, lactofen and 2,4-D can be used in post-emergence applications, and pre-emergence atrazine and atrazine + simazine.