I saw black spots on the top and bottom of my lilies on the leaves. Harmful?
It is related to the black spot you sometimes see on Roses though not quite the same nasty. While it won't kill the bulb it can kill the leaves. This may prevent enough food storage in the bulb for next spring. I have 1000 Lilies and never seen this on mine but have on others. I would use the same thing that is used to kill black spot on Roses.