Abstract

The sorghum crop in Brazil has expanded substantially. Among the factors that interfere in sorghum yield is the interference imposed by the presence of weeds. The objective of this study was to assess the potential of different herbicide treatments applied in pre-emergence or post-emergence of sorghum in terms of selectivity and weed control. Two experiments were conducted, one for each application modality: experiment 1: pre-emergence; experiment 2: post-emergence. The experimental design was a randomized block design with four replications, in split plots. For experiment 1, the pre-emergence herbicides applied constituted the plots, and the different sorghum hybrids (50A10, 50A40, 50A50, 1G100, 1G233, SS318) constituted the subplots. For experiment 2, the post-emergence herbicides applied constituted the plots, and the different sorghum hybrids (50A10, 50A40, 50A50, 1G100, 1G233, SS318) constituted the subplots. Based on the results obtained, and on the discussion done, it is possible to conclude that herbicides and their respectively doses that had potential for use in sorghum crop in pre-emergence were: atrazine (1000 and 2000), mesotrione (100), tembotrione (75), atrazine + mesotrione (1000+100 and 2000+100) and atrazine + trifluralin (1000+1000 and 2000+1000). Meanwhile in post-emergence the best options were: atrazine (1000 and 2000), mesotrione (50 and 100), bentazon (720), fluroxypyr (100), mesotrione + atrazine (50+1000) and mesotrione + fluroxypyr (50+100). All of those treatments provided less than 25% of plant injury which means less potential to reduce the sorghum grain yield.

Key words: phytotoxicity, weed control, Sorghum bicolor, selectivity.