There's an article on daylily rust controls from the Daylily Journal available as a pdf here:
http://www.daylilies.org/RustR...
For those thinking of using a detergent, a study on treatments for daylily rust included dish soap, the kind you get in your local supermarket, in their tests. You can read that study here (edited to add - skip to the pages numbered 51-52 and on if you don't want to read it all):
http://www.uoguelph.ca/%7Ethsi...
