Ask the expert: Fairy ring

Fairy ring is one of the most difficult cool-season turf diseases to control. It is caused by any of 60 or more soilborne basidiomycete fungi. Fairy ring fungi do not directly attack plants but instead cause problems by stimulating turf and causing hydrophobic soils, which leads to localized dry spot (LDS). Fairy ring fungi use thatch and organic matter as a food source. All turf species and golf course locations can be affected by fairy ring. Greens are particularly susceptible to fairy ring given their low mowing height and sand-based rootzone.

Symptoms
Fairy ring occurs in rings, arcs or patches that can vary greatly in size. The size often ranges from several inches to several feet in diameter. Three types of fairy ring are used to describe symptoms and associated turf damage:
•    Type 1 = brown rings of dead turf
•    Type 2 = green rings of stimulated turf growth
•    Type 3 = presence of mushrooms or puffballs

Above ground mushrooms or puff balls are not always seen with fairy ring. Instead, a layer of white mycelia or a band of dry, brown-orange or yellowish material will be present in the thatch, mat or soil layers. Depth of fairy ring activity is important to know for fungicide applications.

Management solutions
Core aerification, vertical mowing and frequent topdressing reduce thatch and organic matter, minimizing fairy ring severity. Aerification by needle tining or spiking also improves water penetration.
 

Wetting agents are useful to address LDS associated with fairy ring activity. Apply wetting agents regularly, but space them a week apart from DMI fungicide applications to avoid potential turf injury. Wetting agents can be mixed with non-DMI fungicides.

Preventive fairy ring control is much more effective than curative control. Apply preventive fungicides when the 5-day average soil temperature (2-inch depth) reaches 55-60 degrees F. Solutions for fairy ring include Bayleton FLO, Chipco Triton FLO, ProStar and Tartan. These can be applied alone or in a multi-application program with proven effectiveness.

Preventive programs (rate per 1,000 sq ft)¹

¹ See product labels for complete information and additional use instructions.

² If no disease symptoms are present, the application interval can be extended from 14 to 28 days.

³Adjust application timing to a shorter interval under high disease pressure.

Make applications in 2-4 gallon spray volume with flat fan nozzles and water in within 10 hours of application to the depth of the fairy ring.

Bayleton, Triton FLO and Tartan provide early season control of dollar spot, as well as brown patch, anthracnose, and summer patch. Triton FLO is highly effective against Waitea patch, and ProStar is excellent for both Waitea patch and brown patch. Fungicides with StressGard Formulation Technology will reduce summer stresses on turfgrass, such as midday wilt caused by fairy ring and localized dry spot.

Dr. Rob Golembiewski is a member of the Bayer Green Solutions Team.