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Good Growing

Fungus Files: What to do about toadstools in your lawn

In that past two weeks, West Central Illinois has seen a much-needed return of rain after a summer of low precipitation. With the rain has come a handful of calls into the Extension office about mushrooms/toadstools popping up in lawns.

Most callers are curious as to why toadstools are showing up now, while a few are on the warpath to eliminate these fungal intruders. The lawn warriors often ask, "What can I spray to kill this fungus?" My answer: nothing, but there are remedies we'll discuss after a primer on dirt a.k.a. Soil.

You may have heard that in a teaspoon of healthy soil exists more microorganisms than there are people on Earth. Soil harbors a multitude of life – bacteria, algae, microscopic insects, earthworms, beetles, ants, mites, nematodes, fungi, and more. Soil represents the highest concentration of biomass anywhere on Earth according to the Natural Resource Conservation Service (NRCS). It is incredible to think that none of what exists today on our planet would be possible without that thin layer of dirt and the complex biology within that forms the soil.

When it comes to fungi, our soil is teeming with all different types and species, from single-celled yeasts to multi-celled macrofungi. Often humans experience the negative side of fungus – mold on the shower tiles, athletes foot, blue cheese (seriously its gross), but there are far more beneficial fungal species in the world. Many bugs fall victim to fungal infections, which entomologists credit for keeping insect populations in check. Plant roots have developed a symbiotic relationship with a soil-dwelling fungus called mycorrhiza. The plant gives the mycorrhiza some energy in exchange for increasing the reach of the root system to gather nutrients from the soil. Some scientists theorize it was the relationship between plant roots and fungi that allowed certain plants to survive the effects of the meteor impact that wiped out the dinosaurs.

When it comes to mushrooms/toadstools, these are merely the reproductive parts of the fungus. The body of the fungus, consisting of a network of fine white filaments (hyphae) is found within the soil. To spray a chemical to kill the toadstools would mean to saturate your soil with fungicide to eliminate the body of the fungus and indirectly all other fungi in your soil. Destroying all soil fungi is something you do not want to do (and likely cannot do) as it may also lead to the decline or death of anything else that relies on soil biology for survival, i.e., plants.

So what is a homeowner to do when facing toadstools in the lawn? With gloved hands, cut them down and toss them in the trash. That way you are removing spores, which may perpetuate that particular species. (Remember, toadstools are reproductive organs.) Otherwise, mow them off, rake them out, or take a pitching wedge to them as my father does. Fight fire with fire, by core aerating your lawn and topdressing with compost to increase the soil biodiversity.

But please, DO NOT eat mushrooms growing in your yard! There are old mushroom hunters. There are bold mushroom hunters. However, there are no old, bold mushroom hunters.

Have you been seeing rings of mushrooms popping up in your yard? These are called fairy rings. Check out my blog Green Speak to learn more about these amazing fungal structures.