Question

Very often people talk about the fairy rings they most commonly see in the forests. What are they? How do you account for their appearance?

Answer 1

They are often seen in a circular pattern and are related to the old belief that fairies danced inside this circle. They mainly are formed due to the growth of fungus and are formed as a result of the way certain types of fungi grow.

Complete answer:
The name 'fairy ring' originates from a very old folk-tale when people believed that mushrooms that grow in a circle follow the path made by fairies dancing in a ring. Fairy rings can be usually found in open grassy places and in forests. In grassy areas, the best-known fairy ring fungus has the scientific name Marasmius oreades. The body of this fungus includes mycelium which is underground and grows outward in a circular form. As it grows, the mycelium uses all of the nutrients from the soil and leaves the surrounding grass devoid of it. This is the reason a fairy ring has dead grass all around the growing edge of the mycelium. Umbrella-shaped fruiting bodies grow from the mycelium.
Larger rings are formed when the older mycelium in the center finally uses all the soil nutrients and degenerates. On the degeneration of the central mycelium, the nutrients get returned back to the soil and grass grows again. During this time the mycelium tries to grow outward and secretes chemicals into the ground. These chemicals break down the organic matter present in soil and release nutrients. This allows mycelium to have a food source when it reaches this area. These extra nutrients make the surrounding grass dark green, taller, and thicker than the rest of the lawn. This lush grass dies when the mycelium grows under it and takes away the nutrients. Fairy rings made by fungi named Marasmius oreades are called "free" rings.

Additional information:
Fairy rings mainly continue to grow outward until a barrier is reached. Sometimes the barrier can grow into another fairy ring. Rings can grow into each other's territory and pass away when they reach the other's "dead zone." If there are no barriers present, free rings can grow outward at up to 8 inches or 20 cm approximately per year. They can reach up to 30 feet in diameter. One ring formed by the fungus named Clitocybe geotropic in France is almost a half-mile in diameters. This ring is known to be 700 years old. Mycorrhizal fungi, which live in a symbiotic relationship with trees, also form the fairy rings. Their rings are given a special name called "tethered" rings. A tether is leash shaped. The fungus and its mycorrhizal partner tree need each other for survival. The mycelium of these specific fungi always remains joined to the tree's roots. Here the roots are the 'tether' that keeps or holds these fairy rings from growing too far from their tree.

Note:
Fungicides are most effective in controlling the fairy ring population when used on a preventative basis. Curative applications may have only little effect because the symptoms are caused by a variation in the soil environment, whereas fungicides do nothing to change the soil. A preventative fungicide program should be started in the spring season.