Answer: Unfortunately, based on your description it is difficult to make a specific recommendation. It might be a pest or disease problem, or the black spots might be sooty mold. If it is sooty mold, you could rinse it off with plain water. Then check the plant for insects such as aphids or scale -- these secrete honeydew and the mold grows on it. Aphids and scale can be treated using commercially formulated insecticidal soap. Read and follow all of the label directions. You could also consult with your local county extension for help in identifying the problem. Based on knowing that and knowing which plant it is, they should be able to give you more specific instructions.
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