I take care of alot of commercial property in Western NC. This year I have three separate properties develop what looks like a fertilizer line. These lines are large semi circle patterns that vary from 25' to one over 120' No one has been on the turf. And I have not fertilzed since spring. I can send pictures if needed. Lately, the oldest line is killing the grass just inside the dark line. What is this? I have never encountered this. Any help?