looks like mites....try diazanon if you can buy it on the market anymore..
Always difficult to tell from an image - it could be Powdery Mildew Leaf Disease. If it is this guide should help you sort the problem - http://hometipster.com/how-to-deal-with-mildew-leaf-disease/ Really home that helps Tammy. Have a great day! Graham
Turn the leaves over and look for very small black insects. You may need to use a hand lens or to shake the leaves onto a piece of white paper. If you find them, along with black spots, you have azalea lace bugs. You could try starting out with an insecticidal soap, but if looks like you have a pretty widespread problem, so you may have to resort to a chemical control. For a list of suggestions, see this link:
It's important that you thoroughly drench the plants, especially the undersides of the leaves. And you will probably need to repeat the application a couple of times.
I notice you are from Georgia, so I guess the summers are fairly humid? Just like Sydney. Sometimes a plant can be in distress (ie not enough water or food), and that's when a fungus/mould or mites will attack the weakened plant. Are there other gardens in your neighbourhood that have Azaelas with the same problem? I always find it beneficial to take a sample to the local plant nursery. Where you will get the correct information. But keep it say in plastic film wrap, just to make sure that the problem with your plant will not spread to other plants. good luck.
How to cure powdery mildew
Here are 3 different remedies I have found. 1. One powdery mildew organic remedy is to use dilute solutions of hydrogen peroxide (9 parts water to 1 part hydrogen peroxide). Spray it on the plants thoroughly about once a week. Organic removal of powdery mildew is always preferable to using harsh chemicals on your plants. 2. Cow milk diluted with water is a common natural way to get rid of powdery mildew, and almost everyone has milk in their home. Milk may be especially effective for zucchini and other types of squash but will work on everything from melons to roses. Treat powdery mildew every week but alternate between methods 3. Potassium bicarbonate– Similar to baking soda, this has the unique advantage of actually eliminating powdery mildew once it's there. Potassium bicarbonate is a contact fungicide which kills the powdery mildew spores quickly. In addition, it's approved for use in organic growing. Spray on plants every one to two weeks.