Behavior of Five Sulfonylurea Herbicides and a Low-Dose Glyphosate on Cynodon nlemfuensis Pasture

African star grass (Cynodon nlemfuensis Vanderyst) is an excellent forage for animal feed, especially in tropical and subtropical climates. However, there is little information on weed management in African star grass pastures. Two experiments were carried out in 2017 and 2018 to evaluate the response of African star grass to five herbicides of the sulfonylureas chemical group and glyphosate at a low dose. The treatments were as follows: metsulfuron-methyl (Ally®) (7.8 and 15.6 g ai ha-1 plus 0.1% v/v mineral oil); chlorimuron-ethyl (Staron®) (15.0 and 30.0 g ai ha-1 plus 0.05% v/v mineral oil); halosulfuron (Sempra ®) (112.5 and 225.0 g ai ha-1 plus 0.1% v/v surfactant); ethoxysulfuron (Gladium®) (150.0 and 300.0 g ai ha-1); nicosulfuron (Sanson®) (60.0 and 120.0 g ai ha-1); glyphosate (Roundup Original®) (360 g ae ha-1); and a control without herbicide application. The herbicides nicosulfuron (60.0 and 120.0 g ai ha-1) and glyphosate were the most phytotoxic treatments; however, none of the treatments caused the total death of African star grass plants. The herbicides metsulfuron-methyl, chlorimuron-ethyl, halosulfuron and ethoxysulfuron were selective and are potential products for use in African star grass pastures.