This disease is becoming more and more common each year. The rings seem to start to appear in late August and are pronounce by mid October. I have been treating the lawns that have this disease each year in May. One year with Rubigan and the next with Heritage. On some lawn I am getting fairly good control. On others, very poor control. Some lawns I treated twice (again in July) and still poor control. My plan now is to try treating in late July rather than May and perhaps inter-seed this fall with a resistant grass species. All my lawns with this problem are predominantly Bluegrass lawns. Any help ?