If the weed has invaded your vegetable garden then digging it out is the best way to safely remove the invader. You can use an herbicide like Roundup on this weed but shield other plants from the spray or it will damage them as well. You can also smother most weeds with a layer of cardboard, old carpet, or stacks of newspaper, all covered with a wood chip mulch. Keep growing - but not nut grass, Marianne Binetti