IN THE YARD: What's up with the fungus among us

The conditions for producing mushrooms in our lawns must be about perfect right now.

There have been numerous calls to the Danville extension office concerning this “problem.”

One question that I often asked is if these are safe to eat. We don’t really know if they are safe to eat so our advice is to not eat them. Mushrooms are difficult to identify without a lot of education and experience. Those that are safe to eat will often have a similar appearance to poisonous mushrooms.

It is always best to play it safe and assume a mushroom is poisonous unless it is known for a certain fact to be safe. There is nobody in the Danville extension office that is qualified to make this determination so we will always advise against eating them.

The next question we get is regarding the origin of these mushrooms. Where do they come from? Mushrooms are the fruiting body of various fungi that live in our lawn and garden soils. They are not the actual fungi but simply the reproductive part of the organism. The purpose of the mushrooms is to rise up into the air and release spores that can be spread.

If the spores land in a spot where suitable conditions exist, a new colony of fungi will begin to establish. For the mushrooms to develop, conditions must be right. The conditions will depend upon which species of fungus is present. Therefore these structures may appear in warm and humid weather or cool and dry weather. Sometimes a change in weather can trigger this fungal growth, such as a change from hot and dry to cool and wet or just the opposite. Therefore it is difficult to predict when mushrooms will grow in a lawn.

For the most part mushrooms are not evidence of a “sick” lawn. In many cases just the opposite is true. Most soil fungi have a job to do. They consume and break down dead organic material such as plant roots, grass clippings, buried wood debris that was left after construction, dead animals and insects and pretty much anything else in the soil that used to be alive but is not alive any longer. The result of work of the fungi is a healthier soil that is rich in nutrients. This helps plants to be healthy.

There are some fungi that can damage lawns. The only one that consistently produces visible mushrooms is the fairy ring fungus. A fairy ring starts from dead wood such as a stump or wood mulch — seldom from bark mulch. It is usually expressed as a well defined ring of dark green or blue-green grass. The grass inside the ring looks normal. Sometimes the dark colored grass will die. Under the right conditions, the ring will produce a circle of toadstool like mushrooms. Fairy rings are very seldom fatal in a lawn. If the owner wants to get rid of them the best thing to do is to till up the ring and plant new grass in the fall. The second best thing is to aerate with a hollow-core aerator, some people call this aerator a plugger.

In general mushrooms do not damage the lawn. Some property owners, however feel they detract from the appearance of the lawn and therefore do not want them. There is no chemical control to combat mushrooms. The fungi are usually too deep in the soil for any fungicides to be effective. Picking and removing the mushrooms is a good method but they will often return when the conditions are right.

Aeration is about the best method to control a lawn mushroom condition. Spike aerators may have some affect but the hollow-core aerators, or pluggers, will work the best. These aerators will jerk out plugs of soil about the size of a little finger. This allows for a significant increase in the amount of fresh air penetrating into the soil which will allow the soil to dry faster, which will help to avoid the conditions necessary for the fungi to produce mushrooms. The fungi will still be in the soil doing the work they do so well, they just won’t be reproducing quite so much.

Many people will just wait and do nothing because they know the mushrooms will eventually go away.

Sutphin is a horticulture extension agent with the Virginia Cooperative Extension, Danville unit office. Contac him at (434) 799-6558.