The plants have been beautiful during the flowering season. Still had blooms but were fading. Did not notice that the leaves were turning whitish until today.
What Is the Black Mildew Look on the Back of Established Azaleas
It sounds like you might have scale on your plants. This article tells more about them and their control: https://www.gardeningknowhow.com/plant-problems/pests/scale-bug-how-to-control-plant-scale.htm Whatever control you use, make sure to apply it once a week for 4 weeks to break the life cycle of the bugs.
Also, here's an article on other possible problems that might affect azalea: https://www.gardeningknowhow.com/ornamental/shrubs/azalea/common-azalea-problems.htm