Answer: Sycamore (Platanus) is susceptible to several fungal diseases. Brown leaf spots are symptoms of these diseases, but entirely brown leaves are probably caused by some other sort of stress in the tree. Carefully inspect the foliage and look for black fruiting bodies (spores) on the undersides of affected leaves. If you find leaves with brown spots and black spores, it's a sign of a fungal disease. For positive identification of the disease, take a sample of the problem to your local Cooperative Extension office (phone 323-838-8330). The helpful folks at the Extension office will recommend some control measures. Good luck with your sycamore tree!
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