Fairy rings can be caused by many different species of fungi but Maramius oreades, is the most common organism responsible for fairy rings in both turf grass and pasture. This fungus is usually present in most soils. It is more common in soils with a thick thatch layer or containing un-decomposed organic matter. Lawns with low fertility or which lack water tend to have more damage than healthy lawns.
- The first sign of fairy rings may be a ring of mushrooms followed by rings of darker green grass with an inside border of dead grass.
- The bands of affected grass can be 5 - 10 cm (2'"-4") wide and can form circles or arcs measuring 0.3 - 2 meters (1' - 6') in diameter.
- Small tan coloured mushrooms* usually develop on the outer border of the ring or arc especially during rainy weather or later in the season. These mushrooms are the fruiting body of a much larger fungal organism.
- The best prevention of fairy rings in the lawn is proper care and maintenance of the lawn so that it will be less susceptible to the fairy ring fungus, along with other diseases and weeds.
- There is no sure-fire cure for fairy ring. The following tips have mixed results:
- Use a garden fork, screwdriver, a piece of rebar or any other tool that can make a hole about 25 cm (10") deep and spaced 10 -15 cm (4" - 6") apart throughout the entire affected ring. These holes will allow water and fertilizer to infiltrate past the white mycelium growth which occurs anywhere from 2 - 20 cm (1" - 8") below the soil surface.
- Spray a gallon of water to which one teaspoon of liquid dish detergent has been added over the surface of the affected area before watering. This will act as a wetting agent against the hydrophobic mycelium, and help the water soak into the soil.
- Then, soak the area with plain water every day or every second day for at least a month, especially if the fairy ring has progressed to the dried grass stage.
- Apply nitrogen fertilizer to the area at the recommended rate to mask the symptoms of the fairy ring.
- Fungicides are not reliable for controlling fairy rings.
* Disclaimer: Gardeningatusask does not provide information about the edibility of mushrooms. Never eat any mushroom found in a lawn or in the wild. Many mushrooms contain toxins that can cause serious harm or even death.