A fungus is spreading in the garden of our summer cottage. It forms a ring, which has grown year by year and is now about 8 metres in diameter. Large mushroom-like fungi spring up after each rainfall and then appear to take moisture from the lawn and the roots of bushes, drying them out. Why does it form a ring and why does the ring only spread outwards. And how do we get rid of it?
鈥� The lawn has 鈥渇airy-ring fungus鈥�, which could be one of many grassland species. The most common and troublesome, with a fondness for short turf, is , which sends up mushrooms at certain times of the year. These are the fruiting bodies of a hidden, filamentous fungus which may live for centuries. It feeds on dead vegetable matter and spreads out as it exhausts its food supply.
The most widely accepted explanation for the death of the grass is that the fungal filaments, or mycelia, form a dense mass preventing water soaking into the soil. Paradoxically, fairy-ring fungi may also feed neighbouring grasses by releasing nitrogen as they break down their food, and this causes the rank, dark-green growth described by Shakespeare as 鈥渢he green sour ringlets鈥� whereof the ewe not bites鈥�.
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Getting rid of a fairy ring is not easy. Weedkillers don鈥檛 work against the fungus, and there does not seem to be an effective anti-fungal treatment on the market. The fungus penetrates the soil to a depth of at least 30 centimetres, making physical removal hard work. The best answer gardening experts can come up with is to support the growth of grass by spiking affected areas and pouring in as much water as possible, mixed with a little washing-up liquid to attempt to damage the fungus.
It is worth noting that an attack on a ring may have unpleasant consequences. It is believed across Europe that the Little People do not like such interference.
Christine Warman, Saltburn-by-the-Sea, North Yorkshire, UK