Chris,

This looks like a type of fungus. Remove all of the infected leaves and discard far away from your plants. Because leaf moisture is essential for infection to occur, increase air circulation around the foliage by properly spacing plants (and removing volunteer seedlings) to prevent over-crowding. As with other foliar disease problems, avoid overhead watering. Fungicides containing chlorothalonil or copper* may protect new growth and reduce the spread of the disease. Preventative applications of fungicides should begin in early to mid June prior to the onset of symptoms.

Thanks, EM

Thanks so much echinaceamaniac!!

I haven't done anything to them in the 5 years I've had them. I will remove some plants to give them some air, and remove the infected leaves.

Any recommendations for a "green" fungicide?

Thanks again!

There is one called Fertilome. I've never used that one, but it is green and contains the ingredient recommended for this problem.

What I use is called Daconcil. It is not green, however.

One thing to do is make sure you don't get water on the leaves when watering. I've been trying to do that this year and it seems to help a lot.

I've been having a problem with a fungus on the Phlox, Monarda, Asclepias, Veronicastrum, and some Rudbeckia. I've been spraying with an organic fungicide called Soap Shield by Gardens Alive. It is a copper fungicide without sulfur that breaks down into copper and fatty acids, which are nutrients for plants and the soil micro-organisms. For the most part it has stopped the progress of the fungus. It needs to be reapplied after a rain, which I haven't been 100% diligent about because it rains every 2 days and I get sick of the spraying.

Here is a link that might be useful: Soap-Shield® Fungicidal Soap