what disease is black spots on Hibiscus leaves
Answer
Black spot is a fungal disease that can affect any plant with fleshy leaves. The black spot on the hibiscus leaves may be caused by leaves that are wet (and possibly cool) for an extended period of time. Try to avoid getting the leaves wet when watering. The leaves will probably fall on their own but badly spotted leaves may be removed or a branch removed if necessary.
Black scale is a possibility but before using a fungicide or neem oil, try to keep the leaves dry to see if that works.