Try using a product with imidocloprid as the active ingredient on the palm. It is systemic and works on some types of scale. Other than this you will need to be treating periodically for scale as they do return and one treatment is seldom enough.
The crapes have aphids which produce honeydew on which the black mold grows. With winter coming I would not do anything at this time. When spring arrives you can try the imidocloprid product or just periodically (when aphids appear) use a insecticidal soap spray making sure to get good coverage of the aphids.
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