Rose of Sharon Diseases

Leaf Spot

• Leaf spot is a circular spot on the leaves that causes them to drop off the rose of Sharon. Pick off the infected leaves, but don't add them to compost because this disease will continue to spread. Rake up any leaves that have fallen and destroy them.

Leaf Rust

• Leaf rust is a yellowing of the foliage and leaf spots. Check the underside of the leaves for a yellow-orange pustules. They will turn black in the fall. To treat the rose of Sharon for this disease, which can continue through the winter, spray with a fungicide every seven to 10 days.

Cankers

• Cankers can kill entire branches or even the entire plant if left untreated. Cankers are bright, reddish-orange fruiting bodies on the bark of the rose of Sharon. First, remove the infected branches. Be sure to disinfect the cutting tools to keep the disease from spreading. There is no treatment for canker. If the canker is on the main trunk, either remove the tree or allow it to decline. This disease will slowly kill the rose of Sharon, although the process may take several years.

Powdery Mildew

• Resembling white powder on stems and leaves, powdery mildew is a fungal disease that can attack the rose of Sharon. While it will not kill the tree, it will turn the leaves purple, causing them to curl up and fall. Powdery mildew, which can also deform the buds, spreads in the wind. To treat, spray with a fungicide.