Fairy Ring Lawn Fungus

Learn to recognize the symptoms of lawn diseases, specifically fairy ring lawn fungus: Circles approximately 3 to 8 feet wide of dark-green, fast-growing grass, surrounding an inner area of partially dead or thin grass. Sometimes the rings produce mushrooms. For the safety of children and pets, always remove these poisonous mushrooms immediately.

Cause of Fairy Ring Lawn Fungus

Feeding on organic matter, fungi that live in the soil release nitrogen causing the grass to turn dark green which interferes with the flow of water to the turf roots and causes thin or dead spots. Decomposing tree stumps buried under the lawn often cause fairy ring.

Aerating

Try hand-aerating which breaks up the fungus and allows the roots to receive the water and nutrients they need. To correct the color problem, feed the non-affected grass with a nitrogen fertilizer. You should see results in 10 to 14 days of the darkening turf masking the fairy ring. The fairy ring grass will thicken up with aeration in about two to three weeks. Follow the directions on the nitrogen fertilizer.

Replace the Sod

Replace the soil with new sod after removing one foot of soil around the entire fairy ring and extending beyond by two feet. Remove the soil carefully and place in a large plastic garden trash bag to avoid contaminating other grassy areas. Seal the bag and throw it in the trash can.

Kill the Sod

Kill the sod and till the infected area thoroughly to mix the soil. According to Curtis Swift Phd. at Colorado State University Extension, “This method of control takes advantage of the self-inhibiting metabolites produced by the fungi. It is thought that mixing these materials together will prevent the regrowth of the fairy ring. Success has been reported with this method.”

Fumigating Grass Fungus

Fumigating a particularly troublesome area involves digging down and removing two feet of the entire ring and beyond and turning 6 to 9 inches of dirt. Spray the fumigant on the fairy ring grass fungus and then cover with a plastic tarp. Use extreme care when applying the fumigant. It can burn through clothing, skin and damage the lungs. If you are not comfortable using the chemical, hire a professional.

Prevention of Fairy Ring Lawn Fungus

Maintain a healthy lawn with a balanced fertilizer to avoid the fairy ring from recurring. Every late April or early May apply 1/2 lb. for every 1,000 square feet of turf. Repeat this at the end of June or early July and repeat again at the end of October. During the winter the roots of store energy, making the lawn much healthier in the spring.

Resources

The Family Handyman: “First Aid for Your Lawn”; Ken Collier; 2009

Colorado State University Extension: “Fairy Ring: ” A Problem of Turfgrass