Leon, that article was very interesting and informative. So the pathogen is soil borne and thrives in moisture and warm temperatures. I'll look into getting some Terrachlor. Tim recommended that, too.
I must say that what Arlyn said about sun and airflow is really on. I have noticed among my big clumps where the rhizomes have grown close together there is some blemishes on the leaves and it is not leaf spot. I don't get perturbed about leaf spot. I think in the future I am going to thin the big clumps.
