Don't know if my question went through before. This is my rudebeckia with yellowing leaves and shriveling and powdery white stuff on the underside. On a few, it looks like it starts toward the new growth at top. Rest of plant is thick and healthy. What is it and what do I do?
Looks like your Rudbeckia has downy mildew, which weakens the plant. There is no suitable cure for the garden. You might want to get rid of this plant and replace it with a Rudbeckia other than Goldstrum, which is extremely susceptible to downy mildew. vw