|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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