Some of my azaleas have developed what I call a "blight" manifested by dead twigs at the end of branches and encrusted by a grayish matter. The blight was first noticed in the spring of 2014 in a plant which is about 50 yrs. old. The blight has spread through that plant and to others which are less that 40 yrs old. The plants are on the North, East and West sides of my house and are in sunlight and shade as the day progresses. The symptons have not changed. I have not used pesticides or fertilizer on or near the plants. However, a lawn service was used for about 4 yrs. ending in 2014. Except for the plant first affected [which is about 4' high and 6' in diameter], the plants are about 3' high and wide. If you need photos, I'll do my level best to provide them.. Your help is appreciated.
Without photos we cannot say for sure what you are dealing with. Here is some information. The grayish matter may be lichens on the branches. They grow harmlessly on tree trunks/branches and no control is necessary. They may grow on mature trees or shrubs and are not a reason for decline.
Azaleas can be susceptible to canker diseases ( Botryosphaeria Dieback). This is a common disease in the landscape. Symptoms are scattered dying branches on an otherwise healthy plant. Heat, drought stress, and winter injury can increase disease incidence. Plants should be grown in partial shade, with mulch and kept well watered during dry periods. All dying branches should be pruned out in dry weather and all discolored wood should be removed. back to healthy tissue. No chemical controls are recommended. Look at our azalea publication for more information http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG51_IPM_Azaleas_and...
If this is not what you are noticing, send us photos of the whole shrub, around the base, and affected branches.
Here are two photos of the "blight" affecting my azaleas. I apologize for poor focus on one. I'm too far from the azaleas to take another picture.
Based on your photo this looks like lichens on the branches. No control is necessary. The foliage looks good.
Thank you for your quick and informative responses. I'm impressed as always with your work. My most satisfactory experiences go back to the last century.