I had previously reported that cornmeal was being tested for use as a fungicide, siting a study by researchers at Texas A&M Research Station in Stephenville, TX that was highlighted by Howard Garrett, the Dirt Doctor.
I tried it around a couple of tomato plants, but the results were very disappointing. The cornmeal first caked and later turned moldy - not an auspicious experiment. I was then notified by someone at Cooperative Extension in Washington State that the initial testing was for a specific problem under specific conditions, not for a general purpose fungicide. Even then, the cornmeal did not show any promise.
It would have been nice if something as available and safe as cornmeal turned out to be effective to, but that is not the case. Cornmeal is not an effective fungicide.