Adult vine weevils chew small notches around the edges of leaves. I see a few holes but not much sign of notches on your plants. The grubs eat roots but don't usually bother established large shrubs. They're more of a problem with containers and indoor plants.

The wilt seems to be only on one branch. Have you traced that branch right back to the point it joins the main shrub? There could be some physical damage causing this. If it is VW the grubs should be visible if you dig round the root of the affected part. They're plump, curled, white larvae.

Hi Floral

Thank you,

Any guesses what this might be then?

Thank you,

Herman

As floral noted, that isolated damage looks like some sort of mechanical injury.....the branch was broken or damaged. Just trace it back to its source and cleanly prune it off. You and the rhody will never notice it has gone!

Looking again I see another wilted area in the top picture. (Bottom left front). After the drooping leaves the stem is brown and after that the leaves look healthy again. I don't know what is causing that but it's not vine weevil. Maybe something fungal. https://hyg.ipm.illinois.edu/article.php?id=407

Thank you very much for taking the time to provide comments, gardengal and floral

Floral - thank you for the link - that is a scary disease but there are no treatments.

And my patch has been there 35+ years, so not sure that is the same.

Below are some more pics, you can see that the lower area outside of this particular patch of rhodies are dying off, slowly, I guess it is possible that my lawnmower guy is doing something, but hard to believe as it is so extensive.

Also, FYI, I have 5 other rhody patches on my property - not exhibiting this.

Gardengal, is there somewhere the OP can send samples? Here it would be the RHS.

Depending on his location, the count extension service, a well staffed garden center (many have diagnosis/ID personnel available) or if here in the PNW, the Rhododendron Species Foundation.

Thanks for the suggestion, I am in New Jersey