Question
I have a fescue lawn in central NC. I have a large infestation of what beleive to be mushrooms? These are hard white growths in the lawn from marble size to baseball size. If the mature they release a black powdery substance. Any ideas on what these are and how to prevent them? Thanks a lot.

Answer
Rake up those mushrooms every morning, Gary, and do something about the drainage under that fescue.

Yes, it's Mushrooms Week at Allexperts.

Could be wood chips were added to your soil in some misguided soil-fortification program?  I see that suggestion now and then - you should never add wood chips unless you want to give yourself a case of Mushrooms.

Any idea if there was a tree down under that grass in another lifetime?  I ask because, 100 years later, a tree stump can still be decomposing.  All that Carbon-rich Lignin - Mushrooms LOVE that.

If there is a tree down there, it's simple.  Microbes decomposing the tree stump suck all Nitrogen out of the soil during decomposition.  The wood lignin makes work this extra tough, and it takes extra long.  Grass in the area becomes weak from being Nitrogen starved, and eventually can't hold up.  Mushrooms see a window of opportunity.  They love it.  This is just what the doctor ordered.

Grass would struggle in that same spot, all Carbon and no Nitrogen; if you have no problem with your grass there, other than the invading Mushrooms, a rotting tree stump is NOT going to be at the root of the matter.  Keep looking.

But even over trees, mushrooms can't grow without lots of moisture.  Since they don't have roots, they have to soak up nutrients like a sponge.  That's where the moisture comes in.  Ditto, shade.  Turn off the automatic lawn sprinkler and let your grass dry out.  There's probably plenty of dew on the grass in the morning contributing to the problem.  If drainage is the problem, add more organic matter to fix it.

At least part of your problem is probably the pH.  To raise the pH, you can apply Lime or, in a pinch, Baking Soda, which has a pH around 8.1.   If dogs are making daily visits to your house, perhaps leaving a calling card, they may be acidifying the lawn enough that any thatch underfoot becomes the ultimate mushrooms breeding ground.

The key is to make the area as inhospitable for mushrooms as possible.  

Dry it out.  

Raise the pH.  

And pour on the ORGANIC Nitrogen fertilizer -- grass clippings, compost, bloodmeal, etc. -- to make the grass nearby as strong as possible.

Rake every morning.  Count them as you rake.  In a week, you should notice the numbers slipping.

Will you ever have to stop raking in the morning?  Hard to say.  It depends on how much, if any, wood (or other lignin source) is down there, how much moisture there is, how much of a correction you need to make to your soil, and whether or not you have microbes in your soil to hasten decomposition of organic matter.  All these factors contribute.  But the quickest fix is still the best:  Rake.