Brachiaria decumbens - Signal Grass is a low growing erect perennial grass with bright green hairy lanceolate leaves. It has growth through both rhizomes and stolons. It is usually grown as a pasture but can escape to colonise bare areas and become a weed.
Control: Check for any organic control methods first which could include removal by hand especially before seeding, digging up all the underground stem.
Chemical control would require a contact herbicide to kill the weeds. By careful not to spray or paint on other plants as it will kill them as well.
Check out the garden chemicals category in the information section of this website. Always read the label and safety directions before using any chemicals.