Mushrooms are truly unique organisms, and their ability to recycle agricultural wastes, tree stumps, and other decomposing matter is usually not fully appreciated because they tend to do it right in the middle of our well cared for lawns!
Now the mushroom-producing fungi that we are going to talk about today are lawn management or nuisance problems but do not necessarily cause lawn diseases.
Mushrooms, sometimes called toadstools, are the reproductive (fruiting) structures of some kinds of fungi. Other reproductive structures sometimes found in lawns include inky caps, puffballs, stinkhorns, and bird’s nests.
Many fungi do not produce visible fruiting structures, including those that cause many lawn diseases. Most fungi in lawns however, are beneficial because they decompose organic matter, thereby releasing nutrients that are then available for plant growth.
In order to understand what is involved in the permanent removal of lawn mushrooms, it is important to know where they come from, and what causes them.
Lawn mushrooms are simply the product of fungi infested in your yard soil in one or more areas of your yard. They are actually the fruit of this fungus, and feed off different sources that could be present.
Lawn mushrooms feed off decaying matter such as:
Rotting tree stumps
Abundance of food sources for the fungi in your yard soil will pretty much ensure the presence of lawn mushrooms in your yard. The more food sources for the fungi, the bigger the lawn mushrooms will grow.
That’s the reason sometimes the lawn mushrooms will be very large, and sometimes they will be very small. It all depends on the amount of food sources the fungi has available. Permanently ridding your yard of lawn mushrooms means totally eliminating the food sources for the fungi, but we’ll get into that in a minute.
Mushrooms in Lawns
Because mushrooms are merely the fruiting bodies of fungi, removing them does not kill the underground mycelia from which they are growing. Picking mushrooms, puffballs, stinkhorns, or other reproductive structures soon after they appear may prevent their spores from spreading to new sites.
Because most spores are wind-blown long distances however, they can easily come into a lawn from neighboring areas. The primary reasons for removing mushrooms from lawns are to keep them away from children and pets (because you don’t want them eating them by accident) and to improve the lawn’s appearance.
Mushrooms in Newly Laid Sod
Mushrooms often appear in a new sod lawn during the period of sod establishment because new sod lawns require frequent irrigation to become established, creating an ideal environment for the growth of mushrooms. The mushrooms do not harm the lawn and will disappear when irrigation is reduced.
Why Mushrooms Form
Mushrooms found in lawns often develop from buried scraps of construction lumber, dead tree roots, or other organic matter. The fungi that produce these mushrooms are beneficial because they decompose organic matter in the soil, making nutrients available to other plants.
These mushrooms usually are harmless to grasses, but some people consider them unsightly or want to get rid of them because young children play in the area.
LIFE CYCLE OF A FUNGUS
The mushrooms that you see are not the whole fungus. You are in fact seeing the fruiting body, which has a prime function of spreading spores to create new colonies. It is what’s going on under the ground, that keeps the fungus alive.
Most mushrooms reproduce asexually by releasing thousands of spores through their gills into the open air for dispersion into the environment.
Here is the mushroom life cycle simplified:
It all starts when the spores are released from the gills, (or whichever surface the mushroom happens to carry spores on). Millions of spores are released into the elements, (air, water, animals..) these spores are dispersed by various methods, (depending on the kind of mushroom).
When the conditions are right, the spores germinate sending out tiny threads called hyphae (single: hypha). In order for the hyphae to develop and eventually produce a mushroom it has to find other hyphae that are compatible.
When two compatible hyphae meet, they fuse together to form a network or threads called a mycelium. This mycelium eventually forms what is known as a hyphal knot which grows and develops into a pinhead which in turn grows and develops into a mushroom and then it all starts again.
Though the fruiting body of the fungus only stays around for a matter of days in most cases, the main body of the fungus, under the ground, can last for years, and only produce fruiting structures when conditions are favorable, such as after periods of prolonged wet weather, or when there is a sudden change in weather e.g. warm and sunny one day, cold and rain the next.
This is what usually triggers them to grow. Each fruitbody contains thousands of spores and if one lands in a suitable site, it will germinate and grow to form a new mycellium.
MEANS OF CONTROL
Many mushrooms are associated with over-irrigation or poor drainage, and mushrooms tend to go away as the soil dries out. So water your yard less.
Better Air Movement:
Removing excess thatch and aerating the soil to improve water penetration may help in some cases, so you may want to think about having it dethatched and aerated to allow better air movement.
You can sometimes eliminate mushrooms growing from organic matter by applying nitrogen fertilizer. This helps, because fertilization speeds up decomposition of organic matter.
Apply fertilizer at a rate of 1 pound (.45 kg) of actual nitrogen per 1,000 square feet (93 square meters) of lawn. The nitrogen should be readily available and not slow-release or water-insoluble formulations.
Examples include 5 pounds (2.27 kg) of ammonium sulfate (21-0-0) or special lawn fertilizers such as 6 pounds (2.72 kg) of 16-6-8, or 4 pounds (1.8 kg) of 27-3-4 per 1,000 square feet (93 square meters) of lawn.
Another method to control mushrooms is to remove them as you see them throughout the year. Continual removal will keep the appearance of your yard up to par, but the source of the lawn mushrooms will still be present. Thus, the lawn mushrooms are likely to return in the future.
There is only one way to permanently rid your yard of lawn mushrooms, and that is to exhaust all of the food sources in your yard and soil. Performing the following tasks could aid in permanently ridding your yard of lawn mushrooms:
Clean up pet waste
Dispose of rotting mulch
Have old tree stumps ground
Having old tree stumps ground down and removed may aid in the permanent ridding of lawn mushrooms, but it could also cause a type of mushroom called fairy rings to appear. Most lawn mushrooms do not harm your lawn, but fairy rings are known to commonly kill grass in certain areas of your lawn.
Some people want to spray mushrooms with a fungicide, but you can’t really spray them because fungicides sprayed onto the mushroom itself do little good because the mushroom is simply the fruiting structure of the organism. Most of the fungus is below ground and inaccessible to the chemical.
What We Suggest:
What most professional and commercial landscapers do with mushrooms, is they pick them as soon as they see them appear because it helps prevent their spores from spreading to new sites.
And while it is true that many spores are wind-blown long distances, and they can easily come into your lawn and yard again from neighboring areas, if the conditions are not right, they won’t grow and form mushrooms.
The Good News:
Most lawn mushrooms do not harm your lawn nor cause any damage. They are simply, and quietly, decomposing organic matter and releasing nutrients that are then available for plant growth back into the soil, and that’s good to know.