RUST ON HOLLYHOCKS.
Hollyhock rust is a fungal disease of the foliage spread by airborne spores and will invariably develop on untreated hollyhocks although it is worse during wet summer weather-the leaves, stems and calyx of the flowers can all be affected. Control is not easy even with fungicides as the spores can travel long distances. Do remove and dispose of affected leaves or the entire plant if heavily infected. Once you have disposed of the worst infected try a fungicide.
Regular applications-even 2x a week when hollyhocks are in rapid growth-of a fungicide is recommended. It is ideal to begin in early spring when the first hollyhock leaves are expanding. Sulfur, myclobutanil and chlorothalonil are fungicides registered for use on hollyhocks. Follow the directions on the fungicide packaging for application instructions.
Virginia Tech has a publication on hollyhock rust: http://pubs.ext.vt.edu456-018
I do hope this answers your question and that you are able to get the hollyhock rust under control but if unable to do so, then do destroy the plants this year and begin with new seed and a fungicide program early next year.
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