Ok... moved here in October of last year and lawn is spotted with fairy ring. Thatch is about 1/2" + Based on the what Purdue states in this publication http://www.ces.purdue.edu/extmedia/BP/BP-113-W.pdf re: decomposing thatch layer providing a habitat for the fairy ring to prosper I was considering doing an aggressive flail blade spot dethatch to completely get rid of any thatch layer in those spots? Waste of time? Just mask spot with fert? Live with it?