The soil compacts a bit. Phytopthora attacks leaves, as always. It enters the plant and produces a circular spot on infected leaves. Then it travels to the roots and begins to destroy them, as it does on most rhododendrons. If it finds an environment lacking in good aeration, strong acidity, and good drainage, the disease will attack the roots and eventually kill the plant.
Few treatments are effective against phytopthora.
A very large plant may require two or three people to move it or lift it. Once that's done, you may treat the plant with Subdue or similar product. Subdue enters the plant and fights the disease from the inside. Many rhododendrons offer profuse small flowers as does pink R. Carolinianum . Resign yourself to knowing that your plant may die despite your best efforts.