Symptoms
Circles or arcs of lush green grass in spring or early summer. Depending on the fungus responsible the circle may be zoned with a middle zone of dead grass or 'thatch', particularly obvious in dry weather.

In late summer and autumn toadstools may appear at the outer ring edge, encouraged by damp weather.

Cause
Fairy rings are caused by a number of fungi and are most common on poor light dry soils. The rings can expand and grow almost indefinitely, even into adjoining flower beds.

Control
Control of any kind is difficult. The best option is to keep the lawn well fed and watered so that the overall 'greening' effect will mask the ring.

The alternative is to dig out the infested turf. This means excavating a band of soil at least 20cm (8in) deep from 50cm (20in) in front of the inner circle to 50cm (20in) beyond the outer circle. Replace excavated soil with fresh topsoil and reseed.