“thing” growing in my lawn!

(Question)

         Hello, something popped up in my lawn overnight and I would like to know how to deal with it.  Last night I noticed a spot in my lawn (about 10 x 5 cm) that looked like a deposit of bright yellow pollen.  This morning a portion of the spot (about 5 x 3 cm) puffed out (1-2 cm above grass) and the surface reminded me of a yellow cauliflower. By the afternoon, the colour was more brownish but the “thing” was the same size (close up picture attached).  I spoke to a number of nurseries and got little help and phoned your hotline as well.  I presume this is some sort of fungus as it is near a root from a rotting stump.  Although this is the first time I saw something yellow, I had previously found a recurring patch of brownish-orangish material I thought was from a raccoon with an upset stomach!  Now I think this may have been the same thing but at a later stage.  This other spot was nearby and right next to the stump.  Do I simply cut this “thing” out?  I assume I should use gloves and hose down the spot after.  Are there any health concerns with this stuff?   Thank you for your assistance.

(Answer)

You are absolutely correct – it is a fungus.  More specifically, it is the fruiting body (commonly known as a mushroom) of a fungus.  You can remove it before the spores (how the fungus propagates) disperse.  There will be thousands of tiny spores inside the fruiting body.

I am not certain about the exact species or even group, as the photo is from the top.  It doesn’t appear to have a stalk and the shape probably means no gills.  When you saw the brownish patches, you are likely correct in that they have matured and dispersed their spores.  Fungus often change colour as they mature.

However, I did find a reference to a species that grow on decayed wood and spring up quickly on lawns.  It is a slime mold (Fuligo septica), a type of fungus that feeds on other fungi, bacteria and microscopic critters that feed on decaying material.  The following article further notes that the mold is harmless, but cannot be killed, so it recommends using a shovel and lifting it away, being careful not to break it and disperse the spores.  It is often found in mulch, as that is dead wood.

As noted, you can remove the fruiting body, however, that won’t remove the fungus in its entirely.  It exists already in the soil, threading throughout the area, probably eminating from the rotting stump and its rotting roots.  The fungal threads are called mycelia and act much like roots, in that they take up water and source nutrients.  Mycelia break down dead plant material for the nutrients and will eventually turn the stump and its dead roots into compost.