Demystify fairy ring

While folklore has many colorful explanations for fairy ring, Dr. Megan Kennelly, associate professor in Kansas State University’s Department of Plant Pathology shows how to take the hocus-pocus out of diagnosing and treating it.

What brings on fairy ring?

Most diseases, like dollar spot, brown patch, anthracnose, gray leaf spot, etc, are caused by a particular fungal species. Fairy ring is different because it can be caused by a number of different fungal species. That is one reason why fungicide efficacy could vary from one site to the next - it could be a different fungus involved. Broadly, they are all in the group of fungi known as basidiomycetes. Another unique characteristic of fairy rings is that they really aren't directly pathogens of the turf. The damage to plants is brought on primarily by changes that the fairy ring fungi cause to the soil environment.

Are certain turfgrasses more/less susceptible to fairy ring?

I have seen fairy rings in just about every kind of turfgrass. However, they are most problematic in sand-based putting greens.

In the lab, what has shown to work best in battling fairy ring?

There are a number of fungicide classes that can be effective for fairy rings. Some have been shown to work better in conjunction with the use of a wetting agent. There is new research out of North Carolina that shows that preventative DMI fungicides may have reduced efficacy when used with a wetting agent, however, which has been increasing in recent years.

When/how often should a superintendent treat?

For preventive applications, recent research in North Carolina demonstrated that spring soil temperatures of about 55 degrees are a good time to initiate applications. I have heard from several superintendents here in Kansas who have used that strategy successfully for a number of years. It may not work for every site, but it is a strategy worth trying.

What are two or three strong tips on preventing fairy ring?

Fairy ring tends to be more severe when nitrogen is low, so make sure to apply adequate fertility. Fairy rings can cause hydrophobic soils, so make sure you are on a good aerification program. If you have not had success with fungicides, you might try your own experiment to compare a few products. Be sure to include a non-fungicide-treated check. Finally, make sure that fungicides are applied in adequate water amounts or irrigated in so that they reach the zone in the thatch or soil where the ring is active.