Hello
I have had usually problems of slugs and snails but never had a problem like this with all my hollyhock the leafs are covered in like rust spots and under the leafs there are white pin heads also the some of them have blackspots on the stems is it all rain we have had or is it more serious and i have to remove the plants see photo's, My poor plants are now missing half of it's leafs.
(http://i30.photobucket.com/albums/c320/srs101/Veg/CRIM0128.jpg)
(http://i30.photobucket.com/albums/c320/srs101/Veg/CRIM0129.jpg)
Cheers
Brogusblue
Hollyhocks are notoriously prone to lots of different rusts, I'm guessing yours have got one of those. You can spray against it , I usually just pick off any affected leaves as soon as I see them.
You can also try plenty of dilute food to encourage them to outgrow the rust. Although it doesn't spread to other plants, you should get rid of the plants at the end of the season.
That is definately rust.