Hi my hollyhocks have suddenly developed yellow leaves with some of them looking like they have been eaten. On the underside of the leaves there are little yellowish orange bumps. Any advice to help clean them up. Thanks.
I'm assuming the flowers aren't affected. Though I'm no expert, I would suggest you remove any infected leaf and discard it in the trash (Don't compost!)
My hollyhocks also have a recurring disease (looks like some kind of rust) showing up every year and affecting only the leaves. Although the flowers are ok, it makes the plant unsightly. Since it's a biennial I haven't been as vigilant as I should in discarding the infected leaves, and so the problem re-surfaces every year.
The only other alternative for you would be to remove every infected plant and replace it next year with new ones.
Helene (canadian daisy)
This sounds like hollyhock rust which affects the leaves and not the flowers. (in my experience)
If it runs for you as it does for me you will see this every year unless you start new plants in a different location each year and don't allow them to continue to regrow in the same area. I don't like doing that so I just pull off the leaves and throw them in the trash. It's just a fact of life with hollyhocks, however I hear there are more resistant strains out there that aren't affected as much by this rust.