Considerable discussion and a number of questions have been asked about the use of corn gluten as a herbicide. Corn gluten is a product of the wet milling process. It is labeled for preemergence control of crabgrass, barnyardgrass, foxtails, dandelion, lambsquarters, pigweed, purslane, and smartweed. That it can control weeds under certain situations is unquestioned. Applied twice per season.
Weed control is inconsistent.
Bob Parker solicited results on the national weed worker network. Responses ranged from effective weed control to zilch. It seems to me that the future of corn gluten as a herbicide is highly questionable except for true organic believers. Certain peptides have been identified as the active ingredients. They are degraded too quickly to be effective when applied alone, but studies are underway to prepare them to produce a usable product.