Optimizing Fairy Ring Control on Cool Season Turf

Fairy ring affects all turf species and is one of the most difficult diseases to control. It is caused by >40 species of basidiomycete fungi that can infest thatch, mat or soil. Fairy ring fungi does not directly attack plants; therefore, damage is caused indirectly by two factors:

• Formation of hydrophobic layers of soil or thatch
• Release of nitrogen from organic matter that stimulates or kills turf

Types of Fair Ring and Symptoms
Fairy ring symptoms are grouped into type I, II, and III symptoms.

• Type I: Hydrophobic areas of weak or dead turf
• Type II: Green stimulated areas
• Type III: Production of mushrooms

Symptoms can vary in appearance from rings, crescents or irregular patches.

Fairy Ring Control:  Cultural
Symptom management is best done preventively as both type I and II symptoms are considered the most troublesome.

• Type I symptoms must be managed by preventing areas from becoming hydrophobic.  Implementing a program approach such as aerification, wetting agents, and deep watering has been helpful for minimizing turf symptoms.
• Type II symptoms can be masked with foliar nutrients such as soluble nitrogen, iron, and/or magnesium sulfate.

Improving soil health such as aerification and regular use of wetting agents improves water infiltration and absorption as they will help in reducing the formation of hydrophobic layers.

Fairy Ring Control: Optimizing Chemical Control with Bayleton, Tartan, Mirage and/or Prostar. 

Preventative applications in the spring are being recommended to control basidiomycete population on turf.

WHEN to TREAT:
Start preventative fungicide applications when 5-day average daily soil temperatures taken at 2 inches are 55-60 degrees F. Follow up with a second fungicide application 28 days later. I am recommending the following Bayer products.

• First application: Treatment with 1.0 -1.5 oz./M with Bayleton® FLO or 2 oz./M of Tartan® Stressgard®.
• Second application: Same initial treatment as your first with the option to substitute Mirage® Stressgard® at 1.0 -2.0 oz./M.
• Apply Prostar 70 WDG at 2.2 oz./M up to sixty days after the 2nd initial applications should symptoms reoccur.

NOTE:
Do not tank mix with a wetting agent or PGR’s.
Apply fungicide at least one week before or after PGR applications to minimize growth regulation effects by DMI’s.

Optimizing Fungicide Penetration
Use an adequate application of water volume at 2-4 gallons per/M to target fairy ring fungi at different depths. Select the proper nozzle for maximizing the coverage with your fungicide and water volume.

In Summary
Identifying the past history of fairy ring pressure and understanding the various types will be a key part of implementing a successful program. Both cultural and chemical programs are necessary for maintaining quality turf conditions for optimizing fairy ring on cool season turf. Using Stressgard technology will also contribute to the overall plant heath care within your program.