That looks like a fungus. Definitely separate it from your other plants. Copper sulfate is a folular spray that was effective in stopping something similar I had on some hydrangeas. Don't wait. Also send some pictures to your County extension agent for id and treatment. Is that container...
Mucho Gracias to all of you and thanks for the warm welcome. I hope to get to know all of you over time and share some thoughts on our love for the incendiary.