What kind of fungal wilt? There are many different such diseases. What kind of plants are you talking about?

I believe it's called Sclerotium rolfsii fungus. The description matched exactly to what is happening to my plants. Which is; the lower leaves turn yellow, eventually brown, as the disease progresses and the roots fail; then the plant wilts and eventually collapses. I have had it on my liatris, dianthis and coriopsis. One coriopsis is allmost dead now. I am going to remove it and the dirt and sprinkle the cornmeal there. The dianthis I removed the dead portion and the rest of the plant is doing fine, but the liatris is dying also. Any suggestion's?

I would first put samples of the affected plants in a sealable plastic bag and take that to my local office of my state universities USDA Cooperative Extension Service for an accurate diagnoses.
Lots of compost may help the soil bacteria eventually control whatever disease you have in the soil, if any.

It's commonly called Southern Blight and is frequently seen in gardens in the heat of the summer. Though those symptoms you describe can be attributed to Southern Blight, they also match up with other fungal diseases, too. But look for the tell-tale white fuzzy stuff on the soil and stems (that's the sclerotia). That's something you can readily see with your own eyes. However, a laboratory test might be a good idea, if you are not certain.

A well-balanced soil containing plenty of organic compounds is very helpful in helping your plants fight off these ubiquitous diseases naturally. So, too, is providing good growing conditions for your plants, according to specific requirements. Air circulation is essential, careful monitoring of watering practices, good drainage, conservative fertilization practices, and tending to garden housekeeping tasks.

Corn meal has long been identified as helpful in preventing several fungal diseases, and yours is one of them. It doesn't work, however, by 'building up the soil' as you say, but by direct fungus against fungus action. Corn meal triggers a rapid growth of a Trichoderma fungus which devours some of the plant pathogens.

Wow, it's all very scientific and aggrivating!! I am an emaculate gardener, and was horrified to find this in my garden. I water only at the plants bases, never, ever on the foliage, but of course who can stop rain. I deadhead constantly, and I give my plants plenty of elbow room. And I use manure and nothing like pesticides, or chemicals. However I do use some on my roses, and do feel that may be the problem. This problem started in the spring with one plant, and then another one got it a little later on, and another, till now I have had it on around 6 plants. I threw away 3 plants now. They all had the same symptems, but only one had white worms in their roots. So I will make sure to throw away the plants in the fall and see how I make out next year. So thanks guys for all the advice.

What you see in your plants -- "the lower leaves turn yellow, eventually brown, as the disease progresses and the roots fail; then the plant wilts and eventually collapses" -- can also be explained by cultural glitches. Such as water, too much or too little.

As rhizo said, you should also see "the tell-tale white fuzzy stuff on the soil and stems." Do you? If not, I doubt you have Sclerotium.

Beyond that, where do you live?

Have you tried Physan 20? I swear that stuff will cure anything.... I've used it on plants with root rot from overwatering and they came back in time to sell for late summer.