They are the result of old tree stumps and roots, or construction debris rotting below the soil surface. The size varies from a few inches to several feet across. The stimulated zone is the result of the breakdown of organic matter, which releases nitrogen that stimulates the growth. Mushrooms of the fungus causing the type 1 ring are produced in the bare zone or at the junction of the bare and outer zones. The fairy ring may be broken when it encounters a barrier, such as a large rock, pathway, or unfavorable soil condition.
Rings get their start often as a cluster of mushrooms noted after heavy rains or an irrigation.
Thus, the grass dies not directly from the fungus killing it, but by keeping water from reaching the roots. In essence the grass plants are killed by droughty conditions in that zone. Suppression is the easiest and most practical approach. This involves the core aeration of the area to allow for better water penetration, the use of wetting agents in the bare areas, and the optimal maintenance of water and nitrogen in the affected zone. Antagonism is based on the premise that when fairy ring soil is mixed with other healthy soil, antagonistic organisms will suppress the pathogen.