Azaleas are generally very healthy plants when their basic cultural requirements are met. However, they are subject to a number of problems caused by infectious agents, insect pests, weather and nutrition deficiencies. Thorough descriptions of these problems and their control measures can be found in Compendium of Rhododendron and Azalea Diseases,  American Phytopathological Society, 1986, ISBN 0-89054-075-6. Its table of contents is shown here, with links to some excerpts and summaries by permission.

Introduction		34	Diseases Caused by Nematodes
2	Rhododendron and Azalea Diseases	35	Diseases Caused by Algae
2	Infectious Agents	35	Algal Leaf Spot and Stem Infection
3	Noninfectious Agents
3	Disease Control	Part II. Insect Pests
		37	Black Vine Weevil and Other Weevils
Part I. Diseases Caused		39	Rhododendron Borer
by Infectious Agents		40	Scale Insects and Relatives
4	Diseases Caused by Fungi	41	Other Sucking Arthropods
4	Phytophthora Root Rot	43	defoliators
8	Armillaria Root Rot	43	Establishing a Pest Management Program
9	Phymatotrichum Root Rot
10	Pythium and Rhizoctonia Damping-Off and Root Rot	Part III. Diseases Caused by Noninfectious Agents
10	Botryosphaeria Dieback	45	Moisture Stress, Heat Injury, and Winter Injury
11	Phomopsis Dieback	46	Mineral Nutrient Deficiencies and Toxicities
12	Phytophthora Dieback	48	Air Pollution Injury
15	Phytophthora syringae Blight	50	Pesticide Phytotoxicities
17	Other Twig Blights
17	Cylindrocladium Blight and Wilt	Part IV. Beneficial Organisms
20	Rhizoctonia Web Blight	52	Mycorrhizae
21	Leaf and Flower Gall
22	Ovulinia Petal Blight	53	Aid to Diagnosis
24	Powdery Mildew
25	Leaf Spots	54	Common Names of Rhododendron and Azalea Diseases
26	Rusts
29	Diseases Caused by Bacteria	57	Glossary
29	Crown Gall
30	Diseases Caused by Viruses	61	Index
31	Rhododendron Necrotic Ringspot	Color Plates (following page 30)
34	Mosaic and Leaf Spot
34	Diseases Caused by Higher Plants
34	Dodder