Hello,
I have two identical rhododendrons two meters apart from each other, in the same flowerbed. One is blooming every year and looks healthy. The other looks sick and produces no flowers but much short growth on the top of every branch, three four new branches 10 - 15 cm long from every branch and doesn't do nothing else. The leaves look unhealthy. Can anyone suggest what may be wrong? A virus, a disease, lack of some nutrients? It is the one on the right and to the front, on this picture:
More closeups of the unhealthy one: