Please help me save my rhododendron!
Good morning. Thank you for your question and good pictures.
What you are seeing is winter injury on the rhododendron, not a disease. Here is a good publication from University of MD extension on diseases of azaleas/rhododendrons: https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG51_IPM_.... It discusses winter injury on page 2. While unsightly, it is not a concern to the overall health of the plant. Once the new leaves fully emerge, they will cover the damaged leaves.