Leaf problem with rhododendron - Ask Extension
Leaves are desiccating and have a strange rust like growth beneath, but doesn’t have normal look of rust. The raised red rust like bodies on the und...
Knowledgebase
Leaf problem with rhododendron #872080
Asked June 07, 2024, 1:48 PM EDT
Leaves are desiccating and have a strange rust like growth beneath, but doesn’t have normal look of rust. The raised red rust like bodies on the underside of the leaf are in lines, not in spots.
Coos County Oregon
Expert Response
This looks like a fungal infection of some type, possibly gray blight. Recommend you remove and destroy infected leaves on the shrub. You should also clean up dead leaves beneath the rhododendron so spores will have one less place to overwinter and then possibly reinfect the shrub in the spring.
Here is some information about gray blight on rhododendrons - https://hortsense.cahnrs.wsu.edu/fact-sheet/rhododendron-gray-blight/#:~:text=Gray%20blight%20is%20a%20fungal,found%20on%20the%20leaf%20surface.
The only way to positively identify the disease would be to submit a plant sample for diagnosis. The Oregon State Plant Clinic conducts this disease diagnosis (for a fee). Here is a link to their site - https://bpp.oregonstate.edu/plant-clinic/submit-sample/services-and-fees
Here is some information about gray blight on rhododendrons - https://hortsense.cahnrs.wsu.edu/fact-sheet/rhododendron-gray-blight/#:~:text=Gray%20blight%20is%20a%20fungal,found%20on%20the%20leaf%20surface.
The only way to positively identify the disease would be to submit a plant sample for diagnosis. The Oregon State Plant Clinic conducts this disease diagnosis (for a fee). Here is a link to their site - https://bpp.oregonstate.edu/plant-clinic/submit-sample/services-and-fees
Thank you.
Adam
New Day Gardens
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Sent: Tuesday, June 11, 2024 11:33 AM
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Subject: Re: Leaf problem with rhododendron (#0141998)
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Subject: Re: Leaf problem with rhododendron (#0141998)
