Herbicide Evaluation Studies with Nutsedge

Abstract

The herbicidal effectiveness of 16 chemicals on nutsedge control was studied at the Manoa Campus Farm and the Waimanalo Experiment Station. The studies consisted of five field experiments and two translocation greenhouse experiments which Included C14-labeled paraquat and MSMA. It was found that MSMA plus surfactant was the most promising herbicide to control nutsedge when compared to paraquat and aromatic oil. Five successive field applications of MSMA at 6#/A plus surfactant reduced tha nutsedge population by 30% over a period of eight months at the Manoa Campus Farm. DSMA and DMAA showed a similar response to MSMA. Paraquat and aromatic oil applications did not result in a significant reduction of the nutsedge population. The time of application was an important factor in the activity of the herbicides. Morning and noon applications gave better control with MSMA than paraquat if subsequent regrowth populations were considered. Paraquat applied in the early evening was more effective than the morning or noon applications for short term control. However, at six weeks after application there were no differences in stand between the morning, noon and evening treatments with paraquat. Post-emergence applications of bromacil and D-732 were more effective than D-767 and amitrole. Dichlobenil gave the most satisfactory control among the preplant and preemergence herbicides. R-1856 resulted in slightly better control than EPTC; however, good control of nutsedge was found with KPTC at 6#/A for a period of 5 to 6 weeks. CP 50144, R-7465 and U-22,326 were not effective in controlling nutsedge under the test conditions.