How should we deal with powdery mildew on azaleas? - Ask Extension
I'm on a landscape committee for a large homeowner association. Our landscape includes over a hundred exbury azaleas most of which suffer from powder...
Knowledgebase
How should we deal with powdery mildew on azaleas? #164688
Asked January 20, 2014, 6:19 PM EST
I'm on a landscape committee for a large homeowner association. Our landscape includes over a hundred exbury azaleas most of which suffer from powdery mildew. We want to pass on to our landscaper the best method for dealing with it. We heard that strong pruning after the plant becomes dormant along with fertilizer will rejuvenate the plants. Is that what you recommend? If so, can you advise as to timing for both? If not, what would you recommend? Thanks!
Washington County Oregon
Expert Response
Thank you for your question to Ask an Expert.
Deciduous azaleas are prone to powdery mildew and pruning to provide for good air flow will hopefully minimize the conditions that favor the disease. It is a good time to prune from now until they break dormancy. If they are growing in the shade, you might consider thinning overhead trees to allow more light, if possible. Application of a lot of nitrogen fertilizer will favor the disease, and is not recommended.
Here is information about the disease which should be useful for your group and to pass onto the landscape company: http://pnwhandbooks.org/plantdisease/azalea-rhododendron-spp-powdery-mildew
Please let me know if you have any further questions.
Weston
Deciduous azaleas are prone to powdery mildew and pruning to provide for good air flow will hopefully minimize the conditions that favor the disease. It is a good time to prune from now until they break dormancy. If they are growing in the shade, you might consider thinning overhead trees to allow more light, if possible. Application of a lot of nitrogen fertilizer will favor the disease, and is not recommended.
Here is information about the disease which should be useful for your group and to pass onto the landscape company: http://pnwhandbooks.org/plantdisease/azalea-rhododendron-spp-powdery-mildew
Please let me know if you have any further questions.
Weston
