Quoting from Toxicity of Fungicides to Urediniospores of Six Rust Fungi That Occur on Ornamental Crops (one of which was daylily rust):
"The strobilurin (azoxystrobin and trifloxystrobin), broad-spectrum protectant (chlorothalonil and mancozeb), and inorganic copper (copper sulfate pentahydrate) fungicides were fungicidal to urediniospores of the six rust fungi. However, the benzimidazole (thiophanate-methyl), dicarboximide (iprodione), hydroxyanilide (fenhexamid), and demethylation-inhibiting (myclobutanil, propiconazole, triadimefon, and triflumizole) fungicides were only fungistatic to rust urediniospores.
The full article is here: http://apsjournals.apsnet.org/...
"Fungicidal" means they killed the spores, "fungistatic" means those fungicides inhibited the spores but didn't completely kill them.
There's a Daylily Journal article by Dr. Patricia Crooks Henley on controlling daylily rust that may help, it's available from the AHS as a PDF here:
In the article she suggests that Compass is the most economical strobilurin fungicide for a smaller area. Compass is trifloxystrobin, considered fungicidal in the research above.
As Larry said, because of the higher potential for resistance with the systemics, you should also use, or rotate with, a contact fungicide. The contact fungicides kill external spores but won't do anything to the fungal body itself that is inside the leaves, that's what the systemics are for. Dr. Henley's article should give you some ideas. (Thanks for posting the link to my site, Larry).
An interesting study found that a single soil drench of the strobilurin azoxystrobin was effective for quite a long time: "One early-season drench of azoxystrobin at 0.12 g a.i‥/plant provided season-long reduction in disease incidence and disease progress that was comparable with foliar sprays with azoxystrobin or chlorothalonil applied at 14-day intervals. That one's here:
All the above are also linked to from my daylily rust info pages that Larry mentioned above.