Question
Hi,

Two weeks before Christmas I laid down some classic St Augustine. http://edis.ifas.ufl.edu/LH010 I watered it every day for an hour for about three weeks. It started to rain here lately and I'm starting to notice a little yellowing coming out. I'm sure over watering caused it. Without using chemicals should I use cornmeal? I know your big on soil testing first, but I laid it on new construction fill sand. My zip is 32608.

Thanks for your time
Paul

Answer
Watering new Grass is a balancing act that is frankly an imperfect science.  Too little, and your new Grass grows weak, or fails completely.  Too much, and you end up cultivating Fungus on top of the Turfgrass.

As you probably already know by now, Fungus is Amongus ALL THE TIME.  Like I've said before, if you throw a wet towel on the floor and leave it there, it WILL grow Mildew.  Do you get out the Fungicides to kill the Mildew?  NO!  You get the towel off the floor, you hang it up, and the Mildew is history.  Unfortunately, all most people know about Lawn Care is what the Lawn Products companies tell them.  Common sense goes out the window; toxic waste goes in.  Let me be the first to congratulate you on using your common sense to solve this simple problem.

First, of course, you have to fix your watering schedule.  You can't do nothin' 'bout Mother Nature; if it's going to rain, your Grass will get wet, period.  But try to be more diligent about watching the weather forecast.  Your Grass is now established.  Let it dry out.  Water DEEP and ONLY when you need to.

Now, will Cornmeal help here?  There are two kinds of Fungus that St Augustine Lawns are most susceptible to.  One is Gray Leafspot Disease.  It shows up as little splotches on the blades.  Gray Leafspot fortunately is not a serious disease and it is rarely fatal.  Real Green Lawns, a progressive landscape and Lawn care company based in Texas, posts photos of St Augustine Grass that's caught Gray Leafspot:

http://www.realgreenlawns.com/austin_tx_texas/greyleafspot.htm

The other common St Augustine Fungus is Brown Patch Disease.  One Southern Sod seller, Carolina Fresh Farms, describes this ailment thusly: 'Brown Patch will look as if someone poured hot oil on the lawn the night before.  Within a few days, these areas will die and they infected area will continue to grow in size.'  Real Green Lawns has a picture of this, too:

http://www.realgreenlawns.com/austin_tx_texas/brownpatch.htm

I like the way Real Green describes Brown Patch:  'Patches up to several yards in diameter commonly develop in the Fall, Winter and Spring when these grasses are approaching or emerging from dormancy, evening temperatures are below 68 degrees F, and rainfall usually increases.  Active infections are noticeable by yellow leaves at the edges of patches.  Leaf sheaths become rotted, and a gentle tug on the leaf blade easily separates the leaf from the runner.  Brown Patch usually does not discolor roots.  Disease develops most rapidly when air temperatures are between 75 and 85 degrees F and wet conditions are present and generally subsides when air temperatures rise above 90 degrees F.'

Cornmeal is an option that won't cause any unwanted side effects.  But I personally think you should save the Cornmeal and make muffins instead for the time being.  Go easy on the H2O and the problem will solve itself.  And yes, get yourself a Soil Test -- your Grass is going to need it.  Followups welcome.  Thanks for writing.