Some common Rhododendron leaf problems are leaf gall, winter injury, fungal leaf spots, chlorosis and oedema. These have many causes, including fungi, mechanical injury and environmental factors.Continue Reading
Fungal leaf spots are dark on the outside and paler in the center and develop in mid-summer. They are caused by different fungi and usually don't require herbicide treatment. Leaf galls are caused by fungi and are succulent masses on the leaves that eventually turn white with the fungus's spores. Hand removal is the best treatment.
Winter injury occurs when leaves don't have enough water and dry up, turn brown, and shrivel or curl. Oedema occurs when leaves take in water quicker than they can transpire it and is characterized by dark blotches that usually go away when conditions improve. Chlorosis describes leaves that are pale green to yellow or white. They do not produce enough chlorophyll because the pH of the soil is too high.Learn more about Outdoor Plants & Flowers