Answer: What you describe sounds like sooty mold and indicates that your azaleas have some sort of pest feeding on them. Aphids, scale insects, mealybugs and others feed on the fluids inside plant tissues. They suck up the fluid and eliminate the excess, which is sticky (called honeydew). As this sticky fluid ages it attracts fungal spores which turns it black. If it sticks to leaves, it looks shiny and black but can be easily scraped or washed off the leaves. So, the problem is not with the black sooty mold but with the insects causing it. Carefully inspect the undersides of the leaves of your plants, and the areas where the leaves meet the stems. I think you'll find some pests. Once you've identified the critters you can use the proper insecticide to control them - and to save your plants.
Best wishes with your azaleas!
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