It could be sedge. Here's how to control it.
Sedge Stop™ Nutsedge Weed Killer offers season-long control of sedges and kyllingas. Powered by Vexis®, a new proprietary active ingredient from PBI‑Gordon, Sedge Stop also controls select broadleaf weeds, and can be used on listed warm- and cool-season turfgrass species. The granular formulation reduces the potential for drift, and the shaker can makes application simple.
Here's how to use SedgeStop: