How to Prevent Rust Colored Spots on Hollyhocks | eHow 3" mulch of shredded leaves or grass clippings and 4. If rust does develop on your plants, remove the infected plant immediately and dispose of it in the trash to prevent the problem from spreading. In the fall, cut back the stalks of healthy plants and remove as much dead plant matter as possible from the plant, because the rust spores overwinter on stems and leaves. Burn or trash the stalks and clippings, don't put them in your compost.