Evaluation of Four S-Triazine Herbicides for Early Weed Control in Grain Sorghum

Abstract

Four s-triazine herbicides were evaluated for weed control in grain sorghum (Sorghum bicolor L.) at the Lajas Research and Development Center farm in 1975. Preemergence herbicides were evaluated alone and in mixtures. The chemicals 2-chloro-4-(ethylamino)-6-(isopropylamino) s-triazine [Atrazine] at 3.36 kg a.i./ha, 2-chloro-4, 6-bis (isopropylamino)-s-triazine [Propazine] at 4.48 kg a.i./ha, and the mixture of Atrazine plus 2-(tert-butylamino)-4-(ethylamino)- 6-(methylthio)-s-triazine [Terbutryn) at 1.68 kg a.i./ha each resulted in significant grain yields (P = 0.05) similar to the hand-weeded plots. Atrazine alone was efficient in controlling grass weeds, and when mixed with Terbutryn in controlling broadleaves. Although the hand-weeded check was the highest grain yielder of all treatments there was no statistical difference among handweeding and the herbicide treatments, Atrazine, Propazine, and Atrazine plus Terbutryn. Johnson grass (Sorghum halepense L.) was an aggressive competitor weed and could not be controlled effectively with the chemicals evaluated.