The leaves on some of my coneflowers get leathery, dry, and feel a little "gritty." They eventually dry up and fall off. It doesn't look like powdery mildew, and I don't see any insects. Sometimes pulling off the affected leaves helps the plant recover, but often the plant dies. It doesn't affect all of my coneflowers, just some. I regularly use Neem as a fungicide. Does anybody know what this is or what to do about it?
If you have more pictures it will be helpful.
anyway if you spray neem at day time - the interaction between neem and direct sun cause leaf burning.
Here's another photo. I ended up cutting it all down and I can see some regrowth starting. I always spray Neem in the evening, so it's not an interaction with the sun. It's quite befuddling.
