Some pathogen killed an azalea that we've had in a pot for over 10 years. It lost some branches over the last two years and finally died completely this spring. Another azalea in the ground near the potted one lost several branches last year and is losing more this year. I found some white, fleshy growths on quite a few leaves when I looked more closely at it this morning and thought they might be mushrooms from an internal fungal infection. However, a brief internet search showed that they were Azalea Leaf Galls, which are due to a fungus; but this is not something that will kill the whole plant. So, is anyone aware of something that is killing azalea plants in this area? There is no sign of any insect pests.
I found this thread from the forum from 20 years ago discussing dying Azaleas. One reply mentions Phytophera cinnamomi as a possible culprit. The Wikipedia link is not very encouraging as it is described as one of the most invasive alien species in the world! I believe that a variety of Phytophera is also to blame for the widespread dying off of cedar hedging in the Lower Mainland. Might be a possibility for your azaleas. azaleas-dying-one-by-one.2868 Phytophthora_cinnamomi
