Expert: Jim Gibbs - 5/20/2004

Question
I live outside Chicago Illinois and we have had quite a bit of rain lately.  All of a sudden I have mushrooms growing all throughout my lawn.  I don't understand why.  My neighbors don't have them.  What do I do to get rid of them?

Answer
Hi Andrea,

About Mushrooms and Toadstool Fungi in Lawns:

 As with weeds, mushrooms and toad-stools can be a continuous intermittent presence in the landscape.
 The appearance of mushrooms and toads-tools in the lawn is a good indication of soil fertility.  These and other fungi serve an important role in Nature's re-cycling of organic carbon containing molecules.

In contrast to some species of fungi which are nearly microscopic in size like the rusts, smuts, molds and mildew fungi, the much larger mushroom and toad-stool fungi species are not a threat to lawn grasses.

 In the residential lawn, they are at worst temporary eye-sores and nuisances.  Very rarely in the sub-urban scene a mushroom can be poisonous if eaten.  In fact, to find a poisonous fungus can require a great deal of hunting effort.

 Mushrooms and Toadstools are no threat to other plants; some Toadstools and "Shelf-Fungi" will pop up annually where there is a source of rotting wood or on the old bark of living trees.  These are generally harmless to growing trees and the plants they are saprophytically using as a substrate-food source.

Occasionally any fungal spores can be an allergen for humans and pets.

 FUNGUS SPORES (sub-visible or microscopic seed-like structures) are everywhere in the air and soil. They are freely transported or dispersed with  moisture droplets and dust particles. Almost any square meter of yard or liter of air will have a certain percentage of fungal spores, and often some of these will grow varieties of "Toad-stools" or "Mushrooms" under proper growth conditions.

 They generally need cool-moist/humid conditions and a highly fertile top-soil.

Mushrooms and Toadstools and other Fungi which pop-up sometimes it seems over-night, all have two basic parts:
a subterranean root-like growth called a "mycelium," and the upper-aerial reproductive structures we see on the landscape.

 If you harvest (mow/collect) these upper reproductive structures rapidly before they can produce the many thousands of sub-visible spores,  you can do much to prevent future populations.

 The mycelium will die-out once dry conditions prevail.
 If your lawn-mower collects grass clippings as you mow, usually you can just continue to mow the mushrooms down;  after a few rounds of this, the mushrooms will be history for a while.

Do not add fungus-spore containing debris to your compost system, this will only help the fungus to prosper in the area.

 You can suppress the growth of Fungi by watering affected areas with a solution of one ounce of IRON SULFATE in three gallons of water applied at the rate of about one gallon per square yard. ( I have never used this fix, but they say it is useful.)  Solutions of iron salts also affect soil and root zone chemistry.

 Iron Sulfate and commercial Broad-spectrum FUNGICIDE chemicals can be used to control/prevent FUNGI and MUSHROOM outbreaks. Iron Sulfate and fungicides can be found at garden/Farm supply stores.  Commercial FUNGICIDES are widely available, check hardware and department stores.

 In summary:
(As with weeds)
There is no enduring treatment or practice you can do to totally be free of these fungus growths;.... only the preventive and horticultural practices I have described will help to keep their populations down or non-problematic and rare.

 Other horticultural practices for all fungi in general include keeping lawn debris and thatch to minimum, aeration of the top soil strata, use less amounts of NITROGEN in fertilizing, stop fertilizing application in mid-late summer for the year, and avoid over-watering while encouraging greater sunlight penetration to lawns by tree-pruning/shaping.  Essentially: encourage dry and airy conditions and less humus for fungi to feed upon to get started.  Otherwise, try some of the chemical remedies I have mentioned.
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Again,...
Be sure you are not over watering the lawn.  Too much moisture in the top-soil and root-zone can cause fungus diseases and mushroom out-breaks.


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 Be sure to properly dispose of all un-identified fungi;... and keep all potent ally poisonous materials out of the reach and way of pets and children. Never believe the mushrooms on your lawn can be edible treats: RARELY some fungi are so toxic they should not even be handled without using disposable plastic gloves. Even a well informed Mycologist sometimes can't easily know a "safe" mushroom from an edible one without using a microscope.

Be sure to keep rakes and lawn tools clean and/or periodically sterilized with a bleach solution to prevent the spreading of fungal spores.

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I Hope this has answered your question(s)!

Visit my Lawn & Gardens webpage for more facts and links:
http://hometown.aol.com/eilatlog/lawnol.html

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