Corn gluten meal can be an environmentally friendly approach for pre-emergent weed control. It is a by- product of cornstarch production, that has shown promise as a natural pre-emergent herbicide by inhibiting the development of a plant seedling’s feeder roots. If conditions are right, a seedling plant treated with corn gluten meal cannot get enough moisture to survive, thereby causing the death of the newly emerged seedling. When used properly, corn gluten meal will not harm beneficial organisms or water sources, and it is safe for use around pets and children.
Corn gluten meal does not harm the established lawn, or perennial weeds such as dandelions, but it can prevent successful development of many plants from seed. The efficacy can last from 5 to 6 weeks. After this time, other desirable plants can then be established from seed.
To ensure the best results, applications should be made 3-5 weeks prior to the expected germination period of the target weeds ( s ). In the case of crabgrass, in Connecticut the product should be applied before forsythia is in full bloom. If no rain is expected, water the product in. A period of water stress is required to kill the weeds as they emerge. Therefore, it is critical that watering be restricted during this period. Provide sufficient amounts to keep established turf growing, but withhold water to introduce
some drying periods to improve corn gluten meal’s activity. If enough rain occurs, the plants will be able to survive and re-grow new roots.
The first year, control will probably be acceptable. Control should increase each successive year, with good control resulting by the fourth year.
Keep in mind that the weed control rate of 20 lbs. per 1,000 square feet of lawn will also be applying a rate of 2 lbs. of nitrogen per 1,000 sq. ft. Straight corn gluten is a 10-0-0 fertilizer, and other nutrients may have to be applied as needed.
Iowa State University Research Foundation, Inc. Office of Intellectual Property and Technology Transfer. 2003-2005
For more information contact: UConn Home and Garden Center: 860-486-6271 or your local
UConn Cooperative Extension System Office