Many people have seen the ubiquitous rings that appear in lawns in many parts of the country and here in Arizona. There are many interpretations as to what the rings actually are and what causes them. The ring is not an excessive problem unless the lawn is under fertilized. In this case, the ring will stand out like a sore thumb in contrast to the dying turf at the edge caused by an hydrophobic soil. At one time, it was believed that fairies from the woods would come out at night and dance in circles.
Science believes that there is another culprit.
Fairy rings are caused by a group of underground fungi that are related to the wood-rot fungus. The fungus starts as one tiny spore under the lawn. As it grows, it eats what little organic matter is in the soil. Fairy rings can occur on any type of lawn. In addition to the green ring, which may make the lawn look uneven, there is sometimes a bare area either on the outside or inside of the green ring itself.