Black spots can be mold growing on leaves, stems and buds damaged by feeding insects. Apply a pesticide for aphids, mealy bugs, scales, mites or whiteflies. Remove damaged leaves.
About this Author
Michael Logan is a writer, editor and web page designer. His professional background includes electrical, computer and test engineering, real estate investment, network engineering and management, programming and remodeling company owner. Logan has been writing professionally since he was first published in "Test & Measurement World" in 1989.