Answer: There are only two explanations for the black leaves - winter dieback or sooty mold. Sooty mold is a coating, usually on the tops of the leaves. See if you can scrape the black off the leaves. If so, look for aphids or other insect colonies on the leaves and stems directly above the black leaves. Sucking insects feed on the fluids in the leaves and excrete a sticky substance called honeydew. This substance eventually turns black. If you find these insect pests and control them with Insecticidal Soap, no more honeydew will fall on the leaves and no more sooty mold will develop. The sooty mold that is there now will eventually weather away.
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