Field studies were done to compare a wettable granular formulation (Authority 75 WG) and a suspension concentrate formulation (Authority 48 SC) of the herbicide sulfentrazone. A 6 x 2 factorial experiment was laid out in a split plot design to evaluate the effect of herbicide levels on phytotoxicity and residues in both leaves and the soil. One rate of the wettable granular formulation (0.225 kg/ha), four different rates of the suspension concentrate formulation (0.165 kg/ha, 0.205 kg/ha, 0.185 kg/ha, 0.225 kg/ha) and the control (0.00 kg/ha) were tested. Tobacco phytotoxicity at 27 days after transplanting (DAT) and soil residues at 12 WAT was measured. There was significantly higher (P<0.05) phytotoxicity in all treatments where herbicides were applied compared to the control. The WG formulation showed significantly higher phytotoxicity than the SC formulation. Residues in both the soil and leaves were significantly higher in the herbicide applied plots as compared to the control for both formulations. The SC formulation of sulfentrazone at a rate of 0.225 kg/ha was significantly less phytotoxic than the same rate of the WG formulation at 27 DAT. The SC formulation of sulfentrazone can replace the WG formulation for broad spectrum weed control in tobacco in Zimbabwe at a recommended rate of 0.225 kg/ha.


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