Shrub disease - Ask Extension
Last year our lilacs died; there were grayish spots on the branches and also green spots. Now the same thing is happening to our big, beautiful rhodie...
Knowledgebase
Shrub disease #941627
Asked August 05, 2026, 2:16 PM EDT
Last year our lilacs died; there were grayish spots on the branches and also green spots. Now the same thing is happening to our big, beautiful rhodie. Some of the leave are curling like they do in the fall/winter and I'm afraid it's going to die as well. It's right next to our burning bush and I'm wondering if the disease will spread to that as well.
Your help is appreciated. Thank you
Ramsey County Minnesota
Expert Response
The gray and green spots are lichens. They are harmless and do not indicate the presence of pests or disease.
Compare here:
https://share.google/OLTSgyyE4alqktdGR
Learn more here:
https://site.extension.uga.edu/madison/2020/04/the-truth-about-lichens/
Rhododendron leaves roll when they are exposed to cold temperatures and/or drought. In any case, the roll indicates the leaves are short of water. Leaves may also roll when stem or root damage limits moisture transfer to twigs and branches. Water well during drought or dry spells.
Compare here:
https://share.google/OLTSgyyE4alqktdGR
Learn more here:
https://site.extension.uga.edu/madison/2020/04/the-truth-about-lichens/
Rhododendron leaves roll when they are exposed to cold temperatures and/or drought. In any case, the roll indicates the leaves are short of water. Leaves may also roll when stem or root damage limits moisture transfer to twigs and branches. Water well during drought or dry spells.
