YC
Check out posts on the lawn forum. Do a search for posts from "Todd from Texas". He and others have posted a lot of good answers to the questions you are asking.
Matt

Have you talked with the knowledgable folks at your local Texas A & M Cooperative Extension Service office about what might be causing problems this year in St. Augustine grass in Texas? If not it would be a good idea.

Mellen,

I can't answer your question on how to use the corn meal, but I have a question for you: When and how often do you water?
All living things, plants and animals, have certain conditions in which they do best. Fungus likes moist conditions. You don't see a lot of it in deserts! If you normally water in the evenings, and frequently, you might be able to get rid of the fungus simply by watering as early in the morning as possible? That would give the sun, and any wind, time to dry out the lawn before nightime. Then if you didn't water again till the grass absolutely needed it, the area might simply stay too dry for the fungus' liking?
I once got into a conversation with a guy who runs one of those "storage facilities" not far from my house. He had a whole bunch of huge brown areas in his lawn. The first thing I asked him was when and how often he watered? (Since it virtually never rains during the summer here in Sacramento, we have complete control over watering.) Predictably, he told me they watered in the evening, and every single day!!! I suggested they start watering only early in the morning, and at most twice a week. Within a month, all the brown spots were green.
Oh, you can make a simple "water measuring device" form the bottom rung of a wire coat hanger. Cut it where it's straight on one end, but leave a bit of the curve on the other, so you wind up with something that looks like a tiny cane. After you've watered, stick the wire in the ground and it will tell you how deep the water's penetrated. It goes in easier as far as the soil's been wet.
Most lawn grasses, with Zoysia being an exception, have roots about 6 to 8 inches deep, so that's how deep you want to water. Then say the soil dries out an inch a day, you wouldn't need to water again for a week.
Oh, you could still use the corn meal, but just as a fertilizer. It's got a pretty good nitrogen content, as well as other nutrients.
I've always believed that "the simplest solutions are usually the best."

Cornmeal is a very effective method to treat fungus. You're not going to poison anything including yourself, you can use it anytime under any conditions (where chemicals has conditions for use), cornmeal is dirt cheap compared to chemicals and they work better than any chemical fungicide with very few exceptions. Plus they add protein to your soil which translates to nitrogen for your plants.

Corn Meal as a Fungicide
Cornmeal: Organic Fungus Control for Plants
Cornmeal is a natural fungal control
Cornmeal Fights Fungus on Roses and Toes

But keep in mind cornmeal probably won't work if you use it after you apply a chemical fungicide. Cornmeal feeds the soil microbes including a beneficial fungus called Trichoderma which will kill off the disease and bad fungus. If a chemical fungicide is used then the Trichoderma will probably also be killed and cornmeal may not work. If not, allow 2-3 weeks for the cornmeal to work.

I had a couple of black and grey fungus patches in my bermuda this past spring:

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I applied cornmeal by hand and watered in. In about 2 1/2 weeks the spots had disappeared. I get my cornmeal/ground corn from the local feed store. It goes for $8.95 for a 50lb bag.

Yes, by the way... just hand toss it then water it in. If you need to apply to to your whole yard you can use the broadcast spreader but it gets dusty and you have to bounce the hopper constantly to keep it flowing. I prefer tossing it by hand. Our daughter helps us as well:

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-Todd

Todd, your 'fungus' is a slime mold, a fairly common occurance on grasses. It is completely harmless and will go away on its own.

Best method of control for this is a broom!