Old Rhododendron suddenly dying

[Howard Canning]

Hi there,
I have a mature rhododendron that's presenting with rolled up brown leaves and dried out dead looking branches for the first time. I'm in Massachusetts, USA and was wondering if anyone had any tips on identifying the issue and suggesting a solution. The rhododendron hasn't been moved and has sat untouched for years but bloomed marvellously
Images attached.
Thanks

 

[Howard Canning]

Bark jmage

 

[Howard Canning]

Brown patch on back of leaves

 

[Sabina515]

That looks like some kind of fungal/brown spot disease. Go to a garden nursery and see what they have for it and if it can be saved