|I have black spots & yellowing on the leaves of my mandevilla. Please advise.
There are several fungal diseases that can cause such spots. You need to pick off the diseased leaves to reduce spreading of the fungus. Then spray the plant with a good fungicide for leaf spots. Some product examples include Zyban, Daconil (chlorothalonil), or anything containing thiophanate methyl. Your County Extension can also offer some control suggestions.
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