Fairy Rings and Fairy Tales

Fungi love water and here lately in North Carolina we've had plenty of water via record rainfall to help ensure they don't go extinct any time soon. The majority of fungi in this world are beneficial, because without these fungi we wouldn't have some of the finer things in life such as beer or Agaricus bisporus that adorns salads and pizzas as a topping. However, there are plenty of them that cause problems for us in the form of plant diseases.

You name a disease of turfgrass and we have likely observed it in the field or as a sample submitted to the NC State Turf Diagnostics Lab over the past 3-4 months. One that we rarely receive as a sample due to it's ease of identification is from a fairy ring. Most people associate fairy rings with mushrooms. To quote NC State alum Dr. Lee Miller, "not all fairy rings produce mushrooms and not all mushrooms produce fairy rings." This is important to remember, because if you observe mushrooms in your lawn, putting green, or croquet court, it doesn't necessarily mean you have a fairy ring problem.

A fairy ring in Raleigh, NC.

Fairy rings have likely peaked the interest of mankind since day one. This fascination has led to some crazy theories over the years such as fairies danced there the night before or that it was created by the fiery tail of a flying dragon. Whatever you do, don't step into the ring, collect the dew from the grass blades, or attempt to destroy it because bad luck is guaranteed to follow!

"Plucked from the Fairy Circle" - A man saves his friend from the grip of a fairy ring.

From British Goblins: Welsh Folklore, Fairy Mythology,Legends and Traditions (1880)

Fairy rings tend to form in circles, arcs, crescents, or broken rings. During their radial journey outward, fairy ring fungi decompose organic matter, which in turn releases nitrogen and other nutrients back into the soil for plants to take up. This is why the ring will often be darker green than the surrounding turf. The good news is that fairy ring fungi don't actually infect the turfgrass plant like brown patch, dollar spot, etc. The bad news is that they leave behind a coating on the soil particles that renders the soil hydrophobic (repels water) and may ultimately kill the turf. This is important to know when it comes to controlling the symptoms caused by fairy rings. For example, if you are treating fairy rings curatively in a home lawn situation, your best bet may be as simple as punching holes through the dead rings with something as fancy as an aerification machine or as simple as a pitchfork. Either way, you are instantly helping water penetrate the affected zone. If you are only observing green rings, then you may be able to mask them with a light fertilizer application. In severe cases or in high profile areas, you will likely want to use wetting agents and/or fungicides in addition to the aforementioned tips. 

For more information about fairy rings, including control recommendations, click here.

Type I fairy rings in warm-season grasses

Type I fairy ring symptoms on a bermudagrass fairway

This spring we've seen a tremendous amount of Type I fairy ring on bermudagrass fairways and landscapes established with zoysiagrass and centipedegrass.  Type I fairy ring symptoms are the most severe, causing decline or death of the affected turf. In most cases these symptoms appeared as soon as the turf began to green-up in the spring. The affected turf never greened-up, indicating that it had been killed over the winter.

Note how the symptoms stop near the drainage basin

How and why did this happen? I suspect that these rings began to develop last year during periods of wet weather in the spring. In fact, some people noted that these same areas had green (Type II) fairy ring symptoms last year. All of this fungal growth may have turned the soil hydrophobic, or water-repellent, and caused the turf to be killed by winter desiccation. Or maybe the extra nitrogen released into the soil profile by the fairy ring fungi caused the turf to be more prone to winter injury.

Either way, the important thing now is to take steps to encourage a rapid recovery. Wetting agents or soil surfactants should be used to re-wet the soil in affected areas, and spiking or aerification should be done to break up the mat of dead turf. Avoid application of DNA herbicides, like prodiamine, as these inhibit root growth and will slow recovery. Fungicides probably won't help to speed up the recovery, but they may help to prevent the problem from recurring next year. For a list of fungicides labeled for fairy ring control, please visit the Disease Management Utility on TurfFiles.

For more information on fairy ring, check out our fairy ring disease profile.