I don't think the grass has anything to do with it. I think it is a soil issue. With healthy soil it doesn't matter which grass you are growing.

Someone wrote in on another forum and suggested putting sugar into your spreader and scattering it around. I would think that might work. I used sugar on individual dog spots years ago, and it worked like magic every place I tried it. The grass went from dead looking to 8 inches tall and very dark green in 3 weeks...in January.

The thing with st. augustine is it spreads rapidly and fills in bare spots. Bluegrass to some degree. Fescue is a goner.
Come to think of it I dont remember seeing st. ausustine burned ever.