Help - some kind of black crud on leaves and spreading- what is it and how do I deal with it?
Indoors or outdoors? In a pot or the ground? What does the rest of the plant look like?
A guess: Sooty mold (not a disease) which is growing on honeydew (sticky stuff) excreted by insects on the leaves above those.
Look for aphids, mealybugs and the nearly invisible scale.
Thanks for responding- it's in a large pot- outside for the summer but spends Maine winters indoors. When it was inside it did have some scale but they seem to disappear when it's outside- and this has been true in the past. Last fall I cut it back to a small leafless stub ( it had been about 4 ft. tall and quite bushy) because of the black stuff. I was afraid I killed it but once inside it regrew almost to it's original size---and the scale returned. Solution???