‘Fairy rings’ are naturally occurring rings or arcs of mushrooms and we’ve been noticing a lot of ‘Fairy Rings’ on the lawns this past week. The mycelium in the soil needs a lot of moisture to flower (we had over 100mm just this past weekend in Victoria), the perfect conditions for fairy Rings to pop up.
Let’s start at the beginning. Think of the visible portion of a mushroom as a flower. Below it there’s a vast network of microscopic filaments, called hyphae. When hyphae bind together to form a mass of white or dark threadlike growth, that’s called a mycelium.
Just like a plant waits for the right conditions to flower, the mycelium waits for sufficient moisture to bloom (send up mushrooms). In dry years, the fungus simply waits under the soil for enough rain to fall.
The white mushrooms in your lawn are feeding off old thatch, buried bits of wood, and other assorted decaying matter around which the mycelium wraps itself.
Surface mushrooms are fruiting and their only goal in life is to spread spores. Try to pick them before they can do this, because each of the countless spores they release into the air will become hyphae of their own and will seek to build new underground infrastructure.
When you mow your lawn, you may want to use a bag if mushrooms are widespread. Collecting the shredded fungus bits in a bag will keep them, and the developing spores, off the lawn.
There’s no chemical treatment, and the only way to make sure they’re gone is to dig them out. You’ll need to dig up the entire yard deep enough that you can’t find any more white strands of mycelium. This often means digging several feet deep.
My advice is to learn to live with them.The good news is that most mushroom species won’t harm your grass and will disappear as moisture levels fall. The bad news is that other than snipping off the toadstools, there’s nothing you can do. The first thing to do is pick the mushrooms as soon as they appear; you don’t want them to go to spore.