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. Research shows 50-60 percent control can be achieved in the first year when applied at 20 lbs.
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. Now a granular form is available which can be more easily applied with Vikon spreaders, rotary and drop spreaders. Application rates vary from 12 to 20 lbs. Since the corn gluten meal is about 10 percent nitrogen, this catches two flushes of crabgrass and spreads out the nitrogen effect.