FAIRY RING

fairy ring puffballs	Characteristic	Description
	Host Grass Species	all
	Month(s) with symptoms	all
	Stand Symptoms	patches (1 to 3 feet), rings
	Foliar Symptoms - Location/Shape	dieback from leaf tip, no distinct leaf symptoms
	Foliar Symptoms - Color	tan, yellow, orange
	Root/Crown Symptoms	none
	Fungal Signs	mushrooms, puffballs, or none

 

Note: Still not sure if this is the right disease? The Turfgrass Disease Identification program may be helpful. Or consult the experts at the Turf Diagnostics Lab. Check the TurfFiles glossary for definitions of unfamiliar terms.

FACTORS AFFECTING DISEASE DEVELOPMENT

Fungi that cause fairy rings are common inhabitants of forested areas. These fungi begin growing on a source of organic matter, such as an old stump, waste lumber, or dead tree roots in the soil. Once established, the turf produces thatch and organic matter, which provides a source of food for continued expansion of the fairy ring.

On golf course putting greens, fairy rings are often observed spreading into the root zone mix from the surrounding native soil. Mushroom fungi are also prolific spore producers and may be spread into putting greens by wind, water, or other means.

Type I fairy rings are most damaging to turf and are encouraged by drought stress, inadequate irrigation, and infrequent aerification.

Type II fairy ring symptoms are a result of the release of nitrogen and other nutrients into the soil as organic matter is degraded by the fairy ring fungi. These symptoms are most evident in turf that is deficient of nutrients, especially nitrogen and iron.

Type III fairy rings are encouraged by over-irrigation or poor soil drainage.

CULTURAL CONTROL

The most effective means for control is to prevent the fairy ring fungi from becoming established in the turf. Remove large pieces of woody material (stumps, waste lumber, and dead tree roots) before turf is planted to prevent the establishment of fairy rings. Landscape contractors should remove this debris around new construction sites before seeding or sodding.

Installation of a plastic barrier between the root zone mix and surrounding native soil may limit the spread of fairy ring into golf course putting greens.

Power raking or vertical mowing to remove excessive thatch will help to minimize fairy ring problems. Golf course superintendents should regularly aerify and topdress putting greens to prevent thatch buildup and maintain soil aeration. Avoid extremes in soil moisture (too wet, too dry), apply nitrogen based on local University recommendations, and ensure balanced fertility through regular soil testing.

Once a fairy ring appears, the best management practices depend on the type of symptom that is observed. To control a Type I fairy ring, the water-repellent thatch and soil beneath the affected turf must be re-wet. Hollow-tine aerification, spiking, water-injection, application of soil surfactants, and heavy irrigation are effective strategies for re-wetting this hydrophobic layer. Affected areas should be hand-watered to prevent over-watering of the unaffected turf.

Symptoms of a Type II fairy ring can be masked with an application of nitrogen or iron. This will cause the surrounding turf to green-up, making the affected turf less evident. Collect soil or tissue samples for nutrient analysis from the turf immediately surrounding the Type II fairy rings, and correct any nutrient imbalances as recommended. Use caution when applying nitrogen to mask Type II fairy ring symptoms on cool-season grasses during the summer. Too much nitrogen may over-stimulate the grass and lead to the development of more serious diseases. In this case, iron should be used to increase turf color without causing excessive foliar growth.

Drastic methods for control of fairy rings, such as soil fumigation, removal of infested soil, or turf renovation by tilling and mixing the soil may be effective in the short-term, but the fairy rings usually become re-established over a period of years.

CHEMICAL CONTROL

Over 60 species of fungi have been associated with fairy ring symptoms in turfgrasses, and these species likely vary in their sensitivity to fungicides. Control of fairy rings with fungicides is a site-specific venture for this reason. Turfgrass managers should experiment with different products to identify those that will control the disease in their location.

Fungicides are most effective for fairy ring control when used on a preventative basis. Curative applications have little effect because the symptoms are caused by a change in the soil environment, and fungicides do nothing to change the soil. A preventative fungicide program should be initiated in the spring when mean daily soil temperatures are consistently above 55°F. Regular use of soil surfactants will help to maintain uniform soil moisture and may reduce the appearance of Type I fairy ring symptoms.

Because fairy ring fungi are in the thatch and soil, fungicides must be watered-in or applied in large volumes of water for best results. Applications in 2 gallons H₂O per 1000 ft² followed by 0.25” of irrigation have provided excellent results in research trials at NC State University. Irrigation must be applied immediately before the spray begins to dry on the turfgrass foliage. Tank-mixing some fungicides with a soil penetrant may also enhance movement into the soil and improve fairy ring control.

The DMI fungicides provide excellent preventative control of the puffball fungi Lycoperdon perlatum and Vascellum pratense in golf course putting greens. Two applications on a 30 day interval, beginning in spring when 5-day average soil temperatures reach 55°F, have provided season-long control in many cases. The DMI fungicides, however, should not be tank-mixed with soil surfactants as this may reduce their efficacy and increase the potential for phytotoxicity.

© North Carolina State University. This information sheet was prepared by Lane P. Tredway, Gail G. Wilkerson, Bridget R. Lassiter, Jenifer J. Reynolds, and Gregory S. Buol. Departments of Plant Pathology and Crop Science, College of Agriculture & Life Sciences, North Carolina State University. Prepared March 23, 2009. Available on-line at www.turffiles.ncsu.edu. This publication was made possible through a grant provided by the Center for Turfgrass Environmental Research & Education (CENTERE) whose purpose is to support worthwhile projects that will benefit both the private sector and the public, and protect the environment.