The bush has been in my garden for over 30 years and always is beautiful. This year however, half of the plant seem to have died and the other half is looking very sorry for itself. The leaves are yellow and curling and the flowers although budding and trying to open are looking very wrinkled and unhealthy when they open, they do not last very long. Have you any advice.
I sounds like a pest or fertilizer problem. Have you done anything different with it than you would? If not then check it for bugs and pests. They may have affected it near the root system.