Buckeye Yard and Garden onLine

The rings are typically most obvious in the spring and fall when the hyper-stimulated fairy ring grass becomes darker and outgrows the surrounding grass.  However, certain environmental conditions may also make them obvious at other times of the year.  For example, the affected grass tends to take longer to turn brown under droughty conditions.  For unknown reasons, under extremely dry conditions the fairy ring grass may actually turn brown quicker.  This is called a "fairy ring collapse," and the affected area may fail to recover and die.

The exact causal agents and factors affecting the growth dynamics of fairy rings is poorly understood; however, it is known that ring formation is related to fungal growth in the soil beneath the turfgrass.  Indeed, research has shown that a complex of at least 54 species of fungi may be involved in their formation.  Most are basidiomycetes which mean that the rings occasionally sprout mushrooms in a circular pattern, thus the common name.  It is also known that fairy rings continually expand, getting larger year-after-year.

Controlling fairy rings is difficult and in most cases the cost of pursuing treatments is not justified by the marginal chances for successfully eliminating the ring.  For example, soil removal and replacement may be attempted; however, even a small area missed during removal will fire the formation of a new ring.  An "indirect" approach to fairy ring management is usually more cost-effective.  For example, following a consistent fertilization program will maintain the growth and color of surrounding grass to mask the fairy ring.  Irrigation will also mask the color contrast between the ring and surrounding drought-stressed turfgrass.  In the end, it should be remembered that the ring will continue to grow to eventually leave the affected lawn, and become the neighbor's problem.

For more information, see:

• University of Minnesota Fact Sheet