The idea of using corn gluten meal for weed control burst on the scene in the early 1990's after Dr. Nick Christians at Iowa State accidentally discovered its herbicidal properties while he was testing it for suppression of turf diseases. Corn gluten meal is not a registered pesticide because the U.S. EPA has granted an exemption for corn gluten meal as an herbicide. Corn gluten meal is a product of the wet milling process. It is a pre-emergent herbicide which inhibits root formation during germination.
Data suggest it has at least some activity on an even wider variety of plants.
It is safe to use on established turf. DO NOT use corn gluten meal in an area in which you are trying to establish turfgrass. Studies suggest that control is improved in successive years and as use rates increase. It is sold for the homeowner market in retail stores as Concern-Weed Prevention Plus. Until recently it was only offered in powder form.