Answer: There are a number of diseases that can affect rhododendrons. You need to know what is causing the problem before you can recommend how to treat it. Based on your description I am unfortunately not able to diagnose the problem specifically. I would suggest you work with your local county extension and/or professionally certified nurseryman to get an identification of the problem and then based on knowing that, determine how to proceed. They may appreciate photos of the overall plant and close-up and/or samples enclosed in a clear plastic bag. I am sorry I can't be more specific for you long distance.
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