SWD and others: the main source of CGM info since later 80s has been IA State. Corn Gluten Meal Research Page
There's a better start page for overall corn meal as organic turf care, but can't find the link now.
I think the main question for all applicators is: "Can I use CGM in my state?" The EPA exempted CGM from pesticide registration requirement in the mid 90s. But since states also have to approve a pesticide also, does your state allow CGM? If they do, have they exempted licensed applicators, or unlicensed applicators for hire, from state pesticide laws for the application of CGM??? Doubtful, but you better get answer in writing from your own state.