Answer: It's really difficult to diagnose plant disease problems without actually seeing the plant so I'm going to suggest you place some of the affected leaves in a plastic bag and seal it, then take it to your nursery, Cooperative Extension office or Master Garden Clinic for positive identification of the problem. Your magnolia could have fungal or bacterial leaf spot, which is easily treated. In the meantime, rake and destroy the fallen leaves to slow the spread of the disease. Best wishes with your magnolia!
Q&A Library Searching Tips