|What can I do about brown spots on rhododendron leaves? It seems to get worse each year.|
|You didn't describe the symptoms very thoroughly, so I'll venture a couple of guesses. There's a fungus that attacks rhodie leaves called Botrytis. The symptoms include brown, water-saoked spots on leaves, which later produce a gray-brown mass of spores. If this sounds like what your rhodie has, remove the affected leaves and try to decrease humidity by increasing air circulation around the plant. Be sure to pick up any fallen leaves and remove spent flowers.
A different problem with similar symptoms is also a fungal leaf spot, caused by Phyllosticta. Spots are dark brown and frequently cover half the leaf area. Again, remove and destroy affected leaves and fallen leaves.
For a positive identification of your rhodie problem, take a sample into your local Cooperative Extension office. In your county contact Joel Flagler, County Agent, 327 Ridgewood Ave, Paramus, 07652. Phone (201) 599-6162