Natural methods for controlling fairy rings used to be just theory … until now
The unsightly appearance and often damaging effects of fairy rings on fine turf and grass playing surfaces has always been one of the more intractable problems faced by turf managers.
Although mainly a cosmetic problem, a fairy ring can affect the roll of a ball on fine turf and more dangerously, the bounce of a cricket wicket. More recently, fairy rings have been the curse of high - profile sporting events, where the trend for overhead camera shots reveals the livid rings as the only blot on an otherwise immaculate surface.
The increased prevalence of fairy rings in the last few years has coincided with bumper crops of mushrooms and toadstools in grassland and woodland and increased fungal activity generally. This suggests that environmental conditions are promoting fairy ring activity rather than the tailing - off effect of heavy metal based fungicide residues in the rootzone and that they are proliferating naturally.
A Basic Biology
Turf managers are familiar with the various 'types' of fairy ring although they are all caused by members of the basidiomycete family of fungi. These fungi grow out in a ring from a cental point obtaining nutrients via the degradtion of organic matter. The greatest level of fungal activity is at the leading edge of the ring and it is the release of inorganic nutrients from the breakdown of thatch and other organic matter that stimulates prominent circle of grass growth. Certain fungi also produce water repellent compounds at the leading edge of the ring which can result in the drought stress and death of the adjacent grass.
Historical Control Methods
Trying to control fairy rings or limit their impact has always been difficult due to the wide variety of fungi that are implicated in fairy ring formation and the depth within the soil that some of these fungi reside. Digging out the affected areas to remove the deep-seated mycelium was an early hit or miss operation as well as a highly impractical one.
The use of a broad - spectrum fungicide mixed with a suitable wetting agent as a penetrant can be an effective but aggressive option for those trying to encourage healthy mycorrhizal fungi populations in the soil and the establishment of fine grasses. The masking of rings by bringing surrounding grass up to a similar level of lushness is also effective but again does not sit well with those turf managers attempting to reduce nutrient inputs and to limit 'soft' grass growth, disease and thatch build up.
Fighting Fire with Fire
It has long been observed that where fairy rings merge or cross over, there may be no sign of lush grass growth and similarly one can often see incomplete fairy rings growing in natural grasslands. This led to the suggestion that natural competition between fungal species in the soil can suppress fairy ring activity and stimulated research into developing products based on natural fungi for fairy ring control.
Developments in this area have meant that natural fungal inoculants are now commercially available in a form that can be used simply and economically on amenity turf. Drenching the margins of fairy rings with a liquid fungal culture after treating with a suitable wetting agent has shown that fairy rings can be made to recede within a few days resulting in a stark contrast with any untreated rings. Turf managers who regularly use fungal rich Compost Teas have also reported an absence of fairy rings in areas where they have historically always been a problem. Both of these methods mimick the effects seen in nature.
This method of control has now been demonstrated on all types of amenity turf and fine lawns and could at last be the closing chapter of this particular fairy story.
David Ward, Senior Biochemist, Symbio. 01372 456 101