Hi. Thank you for your question. Lichen are on branches of the azalea photos you provided. They are not causing the azalea to die, they are actually a sign of good air quality. Here is a link to a great fact sheet and video explaining what lichen are and how they function. https://extension.umd.edu/hgic/topics/lichens
If you are experiencing problems with your azaleas, here is another fact sheet that may be helpful: https://extension.umd.edu/learn/ipm-series-azaleas-and-rhododendrons-hg51 . Feel free to call the New Castle County Garden Helpline if you need further assistance 302-831-8862.