In 2011, the Certainty label was updated to remove any uses in cool season grasses. Before 2011, Certainty was labeled for use in creeping bentgrass, Kentucky bluegrass, and KBG mistures with perennial ryegrass or fine fescues to suppress (not control) quackgrass, control roughstalk bluegrass, and remove tall fescue. The 2011 label revision removed those uses. If you want quackgrass controlled, I might suggest that you ask different applicators just that -- advertise that you want quackgrass controlled. If an applicator still has the old label product, he'll tell you. Just remember, Certainty isn't a silver bullet for quackgrass: it will only suppress it, not control it. Any professional applicator worth his salt will have a plan for controlling quackgrass and it won't rely on an overpromised off-label application.