According to European folklore, fairy rings appear on lawns to mark where fairies danced in the night. Believers of these tales avoid stepping inside those rings, as it could anger the fairies. Those ancient tales are fun to hear, but for gardeners, fairy ring lawn fungus poses more mundane problems.

What Is a Fairy Ring? 

A fairy ring is a turf disease characterized by a circular ring of toadstools appearing on the lawn. Some fairy rings are simply rings of fungus, while others cause the grass in the surrounding area to die.

The most severe form of fairy ring lawn disease is caused by the fungus Marasmius oreades. This fungus lives in the turf’s roots and thrives in summer and autumn. It spreads spores outward, causing the circle to grow slowly over time. As the circle grows, patches of grass may die off because they’re starved of water, especially if the weather is dry.

How to Identify Fairy Rings

Fairy rings come in a few different forms, but once you know what you’re looking for, it’s easy to identify them. The most well-known form is a ring of mushrooms that appears between spring and fall. However, some fairy rings don’t have visible mushrooms. Instead, they appear as a ring of dead grass that slowly grows in diameter.

Types of Fairy Rings

Fairy rings are classified into three broad types:

• Type 1: This type of fairy ring is a ring of brown, wilted or dead grass with dry soil that struggles to retain water. The fungal infection isn’t clearly visible. However, the fungus is hydrophobic, meaning it stops water from entering the soil. Type 1 fairy rings are the most damaging to your lawn.
• Type 2: If you notice a dark green ring of grass growing faster than the rest of your lawn, this indicates a Type 2 fairy ring infection. The cosmetic effects of a Type 2 infection can be managed with appropriate fertilizers.
• Type 3: A ring of mushrooms or toadstools is a sign of Type 3 fairy ring grass disease. The ring may grow in diameter at a rate of around 12 inches per year, with the center of the ring dying out each cycle. You may notice the grass surrounding the mushrooms appears dead or dried, whereas the grass a bit further away is lush and green. 

What Causes Fairy Rings in Grass? 

Fairy rings occur when fungi form colonies underground, below the turf’s roots. The fungi sprout mycelium, which spreads outwards, dying off in the center as they expand. During this phase, the fungi don’t usually damage the turf they’re growing under, although they might starve the grass’ roots of water.

Eventually, mushrooms pop out of the ground, producing the iconic fairy rings mentioned in folklore. Each year, the colony of fungi gets slightly larger, dying back and reappearing in a bigger circle. If left undisturbed on a large enough area of turf, the cycle could repeat hundreds of times over many centuries.

Most Common Plants or Grass Types Impacted

Fairy rings can affect all kinds of turfgrass, but Kentucky bluegrass, perennial ryegrass and creeping bentgrass are particularly susceptible. You’re more likely to see fairy rings in the western United States, but that doesn’t mean other parts of the country are immune to them. If you have a large lawn you tend to trim short, you might encounter fairy rings during your gardening journey.

How to Treat Fairy Rings 

The best method for treating fairy rings depends on the type of disease your lawn is showing symptoms of. For Type 1 fairy rings, the recommended treatment is to aerate the lawn and use a wetting agent, as previously discussed. This helps the soil absorb water, allowing the grass in the affected area to recover.

You can treat the cosmetic signs of Type 2 fairy rings by applying nitrogen fertilizer to your lawn. However, consider contacting a lawn care professional to determine the appropriate treatment dose to help prevent unwanted side effects.

Type 3 fairy rings are more difficult to treat. You can treat the cosmetic issue by carefully removing the visible fungi. If you choose to do this, it’s important to wear gloves because the fungi may be poisonous and unsafe to handle. For a more long-lasting solution, you can remove and replace infected turf. This can be effective in removing small patches of fairy rings but isn’t always practical for bigger circles.

Another way to treat Type 3 fairy rings is by applying a fungicide containing alkyl dimethyl benzyl ammonium chloride to the area where the mushrooms are visible and immediately surrounding the ring.

How to Prevent Fairy Ring Disease 

As with other lawn diseases, prevention is better than cure. Properly fertilizing and irrigating your soil can support the growth of healthy grass with strong roots. Removing dead roots, leaves and other organic matter can also help, as this deprives the fungi of the food sources they need to grow.

You should also aerate your soil regularly and keep the lawn at its proper length. If possible, avoid scalping your lawn, as this can weaken it and allow pests and diseases to take hold.

With proper care, you can revitalize a lawn that has succumbed to fairy ring disease and prevent it from coming back. If you’re having issues with your lawn’s health, contact Lawn Doctor today for expert lawn care services.