It is neither a rhododendron nor an azalea. It is Viburnum davidii. Not much bothers this plant. When I was attending hort school, we used to refer to this as the "McDonald's plant" as it is adaptable, hardy and tough and able to withstand commercial plantings (like MD parking lots) with minimal care and attention.

I would suspect there is some issue going on with the root system but unable to say for sure without digging and examining. So phytophthora (specifically P. ramorum) could be a possibility, as V. davidii is prone but that normally involves poor drainage or infection by another, afflicted plant.

The shrub will tolerate some pretty severe pruning so I would suggest pruning out all affected branches. Be sure to disinfect your pruners between cuts and very thoroughly before using on another plant.

If the extension services offices were not closed, I'd suggest taking it (or at least the damaged portions) in for a diagnosis but you will just have muddle along without that at this time :-)

Thankyou for clarifying for me the kind of plant. I bought the house in October and the previous owners completed all of the landscaping. I'm very new to such, so I'm learning as I go.

I'll dig down to the root system today and take a look. It appears that the root of the leaf decay may be rotten roots, so we will see what's up. The plant is at the end of a rocked landscaped section, so perhaps water is not draining well at this point.

Actually, the point at which it is planted - just over the crest of the sloped portion of that planting bed - should offer excellent drainage.

previous owners completed

==>> not knowing the actual history .. i wonder if it was a new planting.. improperly planted ... with lack of proper followup care ...

roots rot after other injury ... so we have to avoid jumping on that bandwagon too fast ...

are the first and second pic even the same plant??? .. i dont see the brown leaves in the second pic ...

also look for a broken branch in regard to the all brown leaves... if found.. properly prune out.. back to live growth ...

ken

Rhododendrons and azaleas never produce berries. Sloping surface topography does not compensate fully when poor internal soil drainage is present.

It's Viburnum davidii for sure, perhaps not watered properly last summer? I've got Pieris showing random browning now likely from same....

Dead exterior branches on a heath family plant like Pieris will often be due to Phytophthora.