Switchgrass (Panicum virgatum) is a native, warm-season perennial grass. It grows 3 to 6 feet tall in large clumps, and it has bluish-green, hairy leaves and tiny, purple flowers. Originally found along streams and creeks, switchgrass is used for livestock grazing, wildlife cover and as a crop for biofuel, according to the University of Wisconsin Extension. There are several herbicides that can be used to keep broadleaf weeds and weedy grasses out of the switchgrass crop.
Certainty, manufactured by Monsanto, has sulfosulfuron as its active ingredient. According to "Grounds Maintenance" magazine, it works well on sedge species like green kyllinga and yellow nutsedge, as well as some broadleaf weeds. This herbicide is first absorbed by the leaf surface and/or root system, then sent through the rest of the plant. It stops cell division, which cuts off plant growth.
Drive's main active ingredient is Quinclorac. It is a post-emergent herbicide manufactured by Monterey and used to control crabgrass and other annual grasses and weeds. According to RoseCare.com, it can control, prevent or suppress black medic, clover, crabgrass, dandelion, signalgrass, torpedograss and more. Drive is absorbed by a plant's foliage and roots. It interferes with cellulose production and plant growth, causing plants to die.
Plateau contains imazapic, an herbicide registered for weed control in native grass establishments and other non-crop areas, according to the Bonneville Power Administration. Plateau, manufactured by BASF, provides both pre- and post-emergent control of select annual and perennial grasses and broadleaf weeds. It kills plants by stopping the production of branched chain amino acids, which are key to cell growth and protein synthesis, according to the Washington State Department of Transportation.