Fairy Ring on #6 Fairway - click to enlarge
Some people have asked me about the dark green rings seen on some of the greens this time of year. The circular pattern is caused by the Basidiomycete group of fungi that inhabit the soil. These fungi digest organic matter in the soil left behind by the turfgrass. As the fungi breaks down the organic matter, nitrogen is released. This nitrogen is taken up by the turf and results in a green up in the areas where the fungi are working. The pattern starts small and may grow to many yards across. I choose not to apply fungicides for this issue, since this pattern is primarily cosmetic. On occassion, severe drought can occur in the rings or the fruiting bodies of the fungus (mushrooms) pop up. It is a natural process and the turf normally recovers well in the middle of the rings.