He was suggesting a liquid over granular because most of us on here will agree that liquid pre-emerge does a better job at preventing weeds than a granular pre. You can purchase a pull behind sprayer for lawn mower for about $250.00
Your grasses spread and grow with stolons. Stolons run across the top of the ground and root down into the ground. With a pre like Barricade, the stolons try to root but can not because of the "barricade".