Thanks to a synergistic timing of rain from Tropical Storm Imelda followed by temperatures ratcheting back up, you may be seeing a bumper crop of mushrooms in your lawn or flower beds. Such an occurrence always leads to a myriad of questions about how to control them.
As I’ve said many times, however, there is truly no need for controls.
Thanks for your time, drive safely and have a great weekend.
Okay, you deserve more information than that, so let's start with the ones in the turf. They’re commonly referred to as "fairy rings," and any plant pathologist will tell you that they don't damage the turf. In fact, in most cases, you should pat yourself on the back for providing the high level of organic matter in your soil that the saprophytic fungus is feeding on.
These mushrooms appear when wet weather is followed by warmer temperatures, and they’ll continue to thrive as long as there is organic wood or thatch available to feed on. Once it is all consumed, the mushrooms will disappear. Sometimes, though, that can take several months or even years.
So, you can just ignore them. But if they really bother you, rake them out or pluck them up when they appear. There is no "silver bullet" spray that will make them go away - not without killing all the good fungal spores and beneficial bacteria around them. There are, however, a couple of topical fungicides that can reduce their numbers. Consan 20 (you may remember it as Consan Triple Action 20) will work, as will dusting with agricultural sulfur, if you want an organic method.
I’m also asked if these mushrooms are poisonous. Well, what makes a mushroom poisonous is the organic matter they’re growing in. So, depending on environment, time of year, weather conditions and other factors, some mushrooms popping up in your yard may not be safe to eat.
I think it’s best to assume that any mushroom growing in your yard is poisonous, unless you know for certain otherwise. And even if they aren't poisonous, some may be a bit toxic, meaning they can produce stomach discomfort.
Other mushrooms pop up under living trees. Many of those are from another beneficial fungus known as mycorrhizal fungi. Basically, they're living in association with the roots of the tree, and sometimes they help the tree take up nutrients. Again, there is very little need to control them since they are more a curiosity than a problem.
When mushrooms appear in mulched landscape beds, you may also see what is referred to as “slime mold.” These are primitive microorganisms that can produce white, yellow, orange or brown blobs of fungus-like material called sporangia (spores). Slime mold patches, when mature, are powdery and break apart easily during rain or when knocked around by your shoes. The spores survive in soil or organic debris and germinate during wet weather to form motile swarm spores. Some of them fuse to become amorphous amoeba-like structures that engulf other organisms or organic matter. Some even move or flow across soil or plant surfaces. Although unsightly, they are not pathogenic to living plant material. Check out my tip sheet on fungus in mulch for more info.
So, in conclusion, remember that most mushrooms are a sign of good things in the soil - there’s no need to attack them with an arsenal of sprays or dusts. To control their spread, though, just harvest them out before they open up. Once they open like an umbrella, they will throw out more spores. I've given you a couple of treatment methods, but if you've employed others with success, let me know in an email to randy@ktrh.com