Hello. I have a rhododendron that appears to be dying from the top outward. I have other rhododendrons near it but they look fine. It started last fall and appears to be getting worse. It gets good sunlight but is shaded a little by a tall pine tree. Any idea what it could be and how I can save this plant? Thank you! Tracy Abbott
Van Buren County Michigan
I am sorry to hear about your Rhododendron. Rhodies thrive in acidic soil that is rich in organic matter. They are sensitive to salinity and winter injury. They require excellent drainage. High dappled shade is best, but tolerate full sun with moderate temperatures and adequate moisture. They have fine roots that grow close to the surface and should be mulched to keep the soil moist and cool. Perhaps the most limiting factor to their growth is inadequate drainage or watering. Because their roots form a thick fibrous mat and are so close to the surface, water may not penetrate to the roots. This may also be the case if there is competition from other plant roots, such as ground cover growing under the plant.
It is difficult to see exactly what disease or insect is infecting your plant by the picture. If the plant did not receive enough moisture last summer, it may have begun to be stressed by the fall. This could also lead to winter injury. Once the plant is stressed it may be attacked by any number of diseases and insects, including powdery mildew, crown rot and others. For an accurate diagnosis of what caused the problem, I suggest that you submit a sample to MSU Plant & Pest Diagnostics. Go to https://www.canr.msu.edu/pestid/ to obtain information about how to submit a sample. Once you have an idea of what is causing the damage, a method to improve its health can be reached.
Thank you for your question and good luck with your rhododendron.