If your plants do become infected, good garden sanitation practices are the best remedy. Remove affected leaves immediately and burn or dispose of them in the garbage. Don't place affected plants in your compost pile. Spores overwinter in infected leaves and stems. Most hollyhocks are biennial, which means that once they produce seed, they die. In late summer, when you see the rosettes of foliage that will provide next year's display, promptly pull up any finished stalks and dispose of them. At the end of the season, be sure to remove any dead plant matter remaining in the bed, because it harbors rust spores and perpetuates the problem. In spring, mulch around the base of the hollyhocks.