Fertilize with nitrogen.

I have some dimension 19-0-0....will that work. I am not big on synthetic fert. But I assume I would need a fast release nitrogen,right? Any else besides nitrogen?

Yes, fast resease nitrogen (urea). It will push the grass to outgrow the rust. Other than the claims of some herbicides, I know of nothing better to cure it. Although it can kill turf, it is usually pretty bengn if the turf isn't otherwise stressed, but it's not good to just ignore it.. Bag the clippings and clean your mower after mowing to help reduce spreading the fungus.

Fertilize it and for Pete sake do not over water the grass. Rust is caused by low fertility with cool temps and wet conditions.

Ok I will fertilize w/ the 19-0-0. Unfortunely we are expecting rain all week. Should I mow a little lower the next week or two? Mowing now at 3.5"