I have a beautiful centipede lawn or at least I did. All of a sudden dark green circles started to appear. They are anywhere from 6 inches in diameter to 25 or 30. The grasses seem to be a bit different than the centipede in that they may have a wider blade. I had one neighbor tell me it was different grass but I don't know how it could be when the circles are so perfect. Another said it was caused by dogs but I thought it would be brown spots if it were dogs. Any help would be appreciated
You might have been overfertilizing with a solution too high in nitrogen. Go to http://pubs.caes.uga.edu/caespubs/pubcd/L313-w.html for a thorough discussion of centipedegrass and its common problems, and how to solve them.