black spots on leaves of black eye susans

by Dina
(Galloway, NJ)

why do the leaves of my black eye susans get black spots all over them.


Doug says that the Rudbeckia family is prone to 2 kinds of problems that appear as black spots. The first is powdery mildew that starts as a whitish powder (and sometimes isn't too visible) and progresses to killing off the leaf surfaces which is when you see the black spots (irregular and large).

The second is a spot fungus problem that creates small circles.

Both can be controlled (but not eliminated in this plant) by spraying with a lime sulphur or bordeaux mix. Check the labels for the how and when of spraying.