Experts’ Insights: Fighting fairy ring

Fairy ring is caused by a fungus that in its most severe form causes turf and the surrounding soil to become hydrophobic. (Photo: Nufarm)

Fairy ring manifests as circular or arc-shaped patterns in turf that can vary from just a few feet to more than 20-25 feet in diameter. The patterns will look different, depending on which of the three types of fairy ring is affecting the turf.

Type one is the most severe type of fairy ring. The turf and soil around the ring become hydrophobic, so they repel water and become dry. Type two forms darker green rings or arcs in the turf that grow faster than the surrounding turf. Type three is the least severe. Its symptoms include a ring or arc of mushrooms or puffballs in the turf.

The symptoms of fairy ring are likely to recur in the same places every year, and it is most likely to see them once summer stress begins in warm- and cool-season grasses, says Karl Danneberger, Ph.D., professor at The Ohio State University.

According to Danneberger, treatment depends on the severity of the disease. “If it’s severe,” he says, “they’ll go in and core cultivate, usually with hollow tines, and apply a wetting agent because you want to get the water movement. Then you make a fungicide application.”

Mike Fidanza, Ph.D., professor of plant and soil sciences at Penn State Berks, recommends managing soil biometric water content by using wetting agents. Wet-dry cycles help the fungus flare up because it’s related to soil moisture content, he says.

Additionally, controlling organic matter helps control fairy ring, Danneberger adds.

Paul Giordano (Photo: Bayer)

Bayer

Paul Giordano
Green Solutions Team member, Bayer Turf and Ornamental Division

A key practice in mitigating fairy ring is to minimize thatch via core aerification, vertical mowing and frequent sand topdressing. Another best practice is using wetting agents, which help improve water movement and distribution in an otherwise hydrophobic soil profile. Seasonal timing of applications may differ, but the overall control strategy is similar for cool- and warm-season turfgrasses. Fungicide applications should be made when 2-inch soil temperatures average 55-60 degrees F for five consecutive days. Some of the telltale symptoms of fairy ring include rings, arcs or patches of green or dry-looking turf damage that can vary greatly in size. With more research dedicated to the turfgrass soil microbiome, I suspect our understanding of suppressive soils and microbial dynamics will improve immensely. This could lead to solutions tailored toward soil conditioning or biological control products that will ultimately disfavor the fairy ring fungi and remedy symptoms without a complete reliance on traditional fungicides.

Ian Rodriguez (Photo: Quali-Pro)

Quali-Pro

Ian Rodriguez
Technical Services Manager Control Solutions Inc.

Minimize or prevent the conditions favoring fairy ring such as poor fertility, thatch buildup and dramatic swings in soil moisture. Wetting agents can mitigate the severity of hydrophobic conditions and help move fungicides into the soil profile where the fungus is active. On a site with a history of issues, preventive use of fungicides may be successful if applied when soil temperatures are 55-65 degrees F. Regional differences in approach include the timing of fungicide applications along with the duration of occurrence. Sensitivity to DMI fungicides narrows the options of effective active ingredients for bermudagrass. I would expect to see increased use of wetting agents and additional fungicide combinations. We will also probably see increased focus on using irrigation to move fungicides down to the appropriate depth.

Rick Fletcher (Photo: Nufarm)

Nufarm

Rick Fletcher
Technical Services Manager – Turf and Ornamentals

One of the best practices for controlling fairy ring is understanding the life cycle of this group of fungi. There are more than 60 different species of fairy ring-causing fungi, so when someone says “I have fairy ring,” it could be a different organism in different places. That doesn’t mean a whole lot to management as far as chemical or agronomical, but it does explain why someone gets great results with product A, but only fair results with product A somewhere else. Fairy ring control typically does not differ regionally. The easily identifiable part of fairy ring is the green ring or the mushrooms. It is a highly concentrated group of fungi and treatment areas don’t have to go too far outside of the green symptomology of fairy ring, since that is where the colony is. The future is going to be whether or not we get additional classes of chemistry that show activity.

Tina Bond (Photo: FMC Professional Solutions)

FMC Professional Solutions

Tina Bond
Technical Service Manager

Fairy ring can be difficult to control as there are some species that produce mycelium 2 to 3 feet deep in the soil profile. In infested areas, core aerification and localized irrigation can help reduce dry areas associated with fairy ring. In general, preventative applications should begin once soil temperatures at 2 inches reach 55 degrees F. Depending on the season, it may require two to three applications for season-long management. Applying fungicides with a penetrant or wetting agent is highly recommended. Fairy ring is caused by a group of fungi classified as basidiomycetes. These are soil-borne fungi that colonize soil particles in the root zone as well as thatch layer. There are more than 50 species of fairy ring. Fairy ring control can be very difficult. What works for one turf manager may not work for another. Fungicides are an important tool when it comes to fairy ring control. Keeping abreast of research can help us understand control options and how to better manage fairy ring.