If azalea leaves show small white or cream-colored dots and flowers have rust-colored spots, the plant likely has petal blight. Spots on both leaves and flowers grow quickly; the flowers turn mushy and disintegrate into pieces when touched. Petal blight spreads rapidly, so one infected azalea could sicken others. The infected flowers will product fungal bodies that carry the disease spores; if not removed, they will pass on petal blight. Treat the plant with fungicides that target this disease.
Humid, cool or wet spring weather causes leaf gall, which affects only the leaves and not the flowers of your Encore azalea. Leaves develop large green galls, which take on a whitish mold over time. When they turn white, they develop fungal spores and can infect plants. Leaf gall is not a serious disease, but it does make the plants look ugly. Pluck off infected leaves before they turn white to stop the spread of this disease. Chemical control is not necessary.
If only some of the leaves on your Encore azalea appear sick, the plant could have a minor fungal infection called twig blight. This disease causes leaves to wilt and twigs to die on parts of the plant, but never the whole azalea. When a branch has infected tissue, the entire branch will slowly die. If you see wilted leaves and dead twigs, prune off the branch. You can slow twig blight with fungicide; however, since it won't affect the whole plant, it's not necessary.
Encore azaleas that get irrigated via sprinkler or that experience hot, humid summer can contract Rhizoctonia web blight. This fungal disease targets the interior branches, causing leaves to turn brown and fall off the branch. Neighboring leaves often display a web-like growth and remain stuck on the branch from the fungus. You can attempt to control the disease with fungicide, but you cannot prevent its spread altogether. Rake out infected leaves when they drop in the fall to remove fungal spores and switch to a soaker hose for irrigation to avoid wetting interior leaves.