My rhododendrum plant is about 20 ft tall and about 35 ft wide it has not bloomed since we bought the house. The plant is said to be 75-100 years old. It had about 15 flowers last year and none this year. How do I prune it and help it to flower again. It also has spots on it with holes on its leaves. The local nursury said it was fungus and a tree service company said it was a bug attacking the tree so I do not know how to treat my plant.