GlyStar Plus is a herbicide that is used to kill grass. The active ingredient in this herbicide is glyphosate, which is a broad-spectrum herbicide that kills grasses and weeds. GlyStar Plus also contains surfactants and other ingredients that help the glyphosate to penetrate the leaves of the plants and to kill them. The recommended amount of GlyStar Plus to use for killing grasses is 1 to 2 ounces per gallon of water.