Answer: Hollyhock rust is a very common problem. It begins with yellow spots or orange spots with red centers on the top side of the leaf, along with brown pin-head sized dots on the underside of the leaf. Eventually gray pustules form on the underside of the leaf, and all the spots run together and kill big areas of leaf tissue.
Hollyhock rust is a fungus and it overwinters on the basal leaves and old stems of the plant. In the fall, after killing frosts, you should remove and destroy the old leaves and stems. During the growing season you can remove and destroy infected leaves. Work when the leaves are dry to reduce the risk of spreading it further. You might also use a fungicide labeled for hollyhock rust. Be sure to follow the instructions carefully.
Hollyhocks are very popular old-fashioned flowers, but they are known for their susceptibility to leaf diseases. Keeping the plants healthy by growing them in full sun, in rich moist soil and making sure they have good air circulation around them will help. Another tip is to grow them in the back of the garden with shorter plants in front of them to conceal the damage. Some gardeners grow them as biennials, starting new plants every year, and removing them after they flower in their second season. In this way, you have new flowers every year.
Q&A Library Searching Tips