Mushrooms in circle around tree.

[LRTS]

These mushrooms have appear in a circle around this tree (gleditsia triacanthos). Any ideas why they seem to like this patch? After the last mow they haven’t come back in quite as much of a complete circle, but they were previously most of the way round. 

[openspaceman]

Fairy ring - Wikipedia

EN.WIKIPEDIA.ORG

 

[spudulike]

Looks like mycelium to me. Those dark green bits of grass will have a lot of organic matter in the soil, this goes white with the mycelium fungus, the soil stops taking in moisture and the grass dies.

The only way of getting rid of it is to dig it out and replace the soil/grass.

Try cutting in to the soil and see if it is white 1-3" down.

[Stubby]

4 minutes ago, spudulike said:

Looks like mycelium to me. Those dark green bits of grass will have a lot of organic matter in the soil, this goes white with the mycelium fungus, the soil stops taking in moisture and the grass dies.

The only way of getting rid of it is to dig it out and replace the soil/grass.

Try cutting in to the soil and see if it is white 1-3" down.

Steve , everyone knows its to do with the fairys  🙂

[Rich Rule]

Is it not just fungi living on the dead matter of a previously removed tree?

[daltontrees]

I'd leave it alone as it may be mycorrhizal, living in mutually beneficial association with tree roots, providing essential atmospheric nitrogen fixing supplied to the tree in return for sugars. I'd take my cue from the condition of the tree crown. If it's doing well, it's probably becasue of instead of despite the fungus. One of the worst things for a tree is grass all around it. Grass is allelopathic.

[Michael h]

looks like Fairy Ring Champignon, 

Marasmius oreades, Fairy Ring Champignon mushroom

WWW.FIRST-NATURE.COM

Marasmius oreades (MushroomExpert.Com)

WWW.MUSHROOMEXPERT.COM

Saprobic in grass, not having anything to do with the tree

[daltontrees]

I mikght have to back-pedal a bit on my comments. Gleditisia is a member of the genus FAbaceae which usually (but not always) has root nodules housing bacteria that can fix atmospheric nitrogen. So there could be something more complex going on. Anyway, if the tree's well the tree's well. The pattern looks like it's following shallow  roots and lusher grass.

[Dan Maynard]

Is it not just fungi living on the dead matter of a previously removed tree?

I'd agree with this, the tree looks quite young so roots of one felled before that was planted will be nicely decaying now.

[Khriss]

I find them fascinating phenomenon(a)  possibly initiated from the leaf drop / composting, but wouldnt spoil their fun - i know gardeners hate them. K