Perhaps the question I get asked the most about hollyhocks is what do I do to get rid of rust.
For me that’s not the way to approach hollyhocks. Manage your expectations and expect to get rust, and just think how you will manage it when it comes.
Using an anti fungal spray is one method that can help keep in in check – but I always use that more as a last resort given it can have an impact on pollinators. For me its about removing any infected foliage once you see the signs – and dispose of them, as opposed to putting on your compost pile which could just aid the spread,
There are of course rust resistant hollyhocks, but even those can and do get rust. Having removed any infected foliage some people think the plants look a tad strange – so why not just treat hollyhocks as a back of border plant, and add some under planting.
This way you are learning to live with what is an incurable disease as opposed to trying to totally cure it, which may leave you disappointed.