Stem dieback affects the twigs and branches. Two fungi, Phytophthora and Botryosphaeria , are common causes of this problem. A canker develops and girdles the stem. Leaves and stems above the canker wilt and die while the rest of the plant looks normal. Labeled fungicides may be helpful.
Powdery mildew is a problem on some deciduous azaleas.
If ordering deciduous azaleas from a catalog, look for those specifically mentioning mildew resistance. Root weevils, particularly the black vine weevil, are the major insect pests in Ohio. Adult weevils feed at night and cause small, irregular or semicircular notches on the leaf edges that give the leaf a jagged appearance. The Fundamentals of Rhododendron and Azalea Culture . Published by the American Rhododendron Society.