Spots on Rhododendron - Ask Extension
Last summer my rhody was covered with spots. In the fall I trimmed it back and tried to get rid of most of the affected leaves. I only had one bloom t...
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Spots on Rhododendron #872781
Asked June 12, 2024, 11:40 AM EDT
Last summer my rhody was covered with spots. In the fall I trimmed it back and tried to get rid of most of the affected leaves. I only had one bloom this year which was expected since I cut it back so much. It was looking healthy with new growth. Now I see spots coming back. My other rhody which is about 500 feet away is very healthy and robust. Can you tell me what is going on and what I should do. Pictures attached.
Lane County Oregon
Expert Response
This could be some powdery mildew and/or a fungal leaf spot and the spores they produce can overwinter in plant debris (old leaves, etc.) under the shrubs. Then the spores can be splashed back up on the leaves where they can cause a new outbreak. So try to remove and destroy old leaves each fall if possible.
You can also try some fungicide to treat and prevent further infection - you might consider
You can also try some fungicide to treat and prevent further infection - you might consider
- Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. Group M5 fungicide. H
- Monterey Liqui-Cop at 3 Tbsp/gal water.
