June 17, 2010

Here's Randy's Weekly KTRH GardenLine Tip:

Issue #166

Thanks to a synergistic timing of rains, warm temperatures and summer fertilization, you may be seeing a bumper crop of mushrooms in your lawn and flower beds. Such appearances always prompt many calls to the radio show or e-mails with questions about how to control them. Well, there really is no need to control them! Thanks for your time, drive safely, and have a great weekend!!!

Okay, I'll give you more than that — but it is really not necessary to control mushrooms.

With that said, let's start with the ones in the turf. They're commonly referred to as "fairy rings." Any plant pathologist will tell you that fairy rings don't damage the turf. In fact, in most cases you can pat yourself on the back for having a high level of organic matter in your yard — it feeds this type of "saprophytic" fungus. They will continue to appear in warm weather, following wet weather, as long as there is enough organic wood or thatch to feed on. Once it has all been consumed, the mushrooms will disappear. However, that can often take several years.

The best solution is to ignore the mushrooms, rake them out, or pluck them up when they appear. There is no spray that will make them go away without killing everything else in the soil, too. There are, however, two topical fungicide treatments that can reduce their numbers. I've recommended Consan Triple Action 20 for years for that purpose. And for a true organic method, dust them with agricultural sulfur.

Listeners also want to know if such mushrooms are poisonous. While it is unwise to eat mushrooms from your yard, they are probably not poisonous. It's the organic matter that mushrooms grow in that makes them poisonous. However, the types found in yards can vary due to environment, time of year, and weather conditions, so it is best to assume that any mushroom in your yard is poisonous. Even those that aren't poisonous by definition, are still somewhat toxic and can bring on stomach discomfort. It's never worth taking a chance.

Other mushrooms pop up under living trees. Many of those are beneficial mycorrhizal fungi. Basically, they live in association with the roots of trees, and sometimes they help the tree take up nutrients. Again, there is very little need for control measures since they are more a curiosity than a problem.

Mushrooms that appear in mulched landscape beds are affectionately referred to as "slime molds." These are primitive microorganisms that can produce white, yellow, orange or brown blobs or patches of fungus-like material known as sporangia (spores). Slime mold spore masses, when mature, are powdery and break apart easily during rain or when knocked around by your shoes. The spores of the slime mold survive in soil or organic debris and germinate during wet weather to form motile swarm spores. Some of these spores fuse to become amorphous amoeba-like structures that engulf other organisms or organic matter. Slime molds can actually move or flow across soil or plant surfaces. Although unsightly, these organisms are not pathogenic to living plant material. Check out my tip sheet "Fungus in Mulch" for more info.

In conclusion, remember that most mushrooms are a sign of good things in the soil. So, you don't need to attack them with an arsenal of sprays or dusts. To control their spread, however, just remove them before they open up. I would also like to hear of any idea you've employed to successfully eliminate them. Just send me an e-mail or call the radio show this weekend.

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