This weed looks like green foxtail.  It is an annual grass that is best controlled with pre emergence herbicides applied in late winter.  These would include products that contain the active ingredients pendimethalin, prodiamine, benefin, or oxidiazon.  If it is already up in your turf grass ( I am assuming this weed is in your lawn), there is nothing you can do other than pull it up or spot spray with Roundup.