Answer: The black may possibly be a fungal infection growing as a result of insect damage, possibly caused by aphids feeding at the tips of the new growth. It is difficult to diagnose this type of problem long distance, however. I would suggest she consult with her local county extension and/or a professionally trained, certified nurseryman for help in diagnosing the problem more specifically. Then once you know that, treat accordingly. They may appreciate an overall photo of the plant plus some samples. If it is something that requires a chemical control, the county extension will have the most up to date recommendations as to what to use and how/when is best to apply it. I hope this helps.
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