Question
Very hot and dry this year in South Carolina, further south than your area but your answer will help me I am sure. I border a swampy forest, you name it, it can get to my yard. We run an automatic spinkler 20 min. each morning. It is fairly close to 100% coverage. From the messages here, it seems I should change the cycle to 2 hours 2 times a week maybe? The front has centipede and is doing well. I think yellow tones after a rain are from low nitrogen (from what I read and guessing), some centipede yards here have a very yellow look. I spread lime front and back and it seemed to help the centipede immediately. OUR PROBLEM: Two winters ago we laid an average size backyard of St. Augustine.  The ground had been tilled about 2 months  earlier and is a hard thick clay under the thin top soil. Last year St. Augustine came out fairly well. This year there were a few dead looking spots, that I thought would grow eventually. It is as if winter damaged the yard, and it was a normal winter. I did not fertilize. I have seen brown and greyish looking (almost white) spots and watered those deeply.
I won't tell you what I just did, and the bag (or cost) of "summer fertilizer and critter killer" I just put down because I am going to learn more about organic and sugar. I found these message posts about an hour after I did the treatment. I would hate to have to get another truckload of St. Augustine pallets.
If it matters, there are only a few lawns that are doing well on my street, and they have to work at it hard.

Got any ideas?

Answer
Hello Mark in SC, By the way I love your license plates, I see them around New York every once in a while on the Long Island Expressway and they are the prettiest things on the road.  Just had to take the opportunity to finally get that out of my system!

I should not be answering this question, Mark - I know a lot about cool season grasses but I pay very little attention to warm season grasses.  I would not be the best person to solve your problem.

That said, I do a lot of industry reading and I listen to as many lectures as I can just because I think this whole subject area is so interesting.

And from everything I have ever heard, fungus needs moisture to launch an attack on a lawn anywhere on earth.  Scariest part is, most of these pathogens are already in your soil, all the time, waiting for just the right time to invade.  Most of them need some serious moisture or they can't lift a finger.  So you have to be really accommodating to the fungi kingdom or they simply won't give you any business.  The way things are, after you read about them, you wonder how people manage to get fungus growing in their lawns.  It really is something.

And it does sound to me like you are pulling out all the stops for the neighborhood fungi.  The invitations are engraved and you've put the notice in the paper.  If you want to stop them you had better do a 360 degree turnaround and keep that grass nice and dry.

But maybe your grass needs that water -- has it been very dry and hot in SC this month?

About your clay/topsoil, I don't see why the ground was tilled and you were observing hard thick clay under thin top soil -- weren't these tilled together?  With tilling, didn't someone put amendments in besides clay?  I guess you guys don't get a lot of deciduous leaves in the autumn - but manure and compost are ideal things to add to less-than-perfect-topsoil-tilled-with-clay.  Plus don't you guys have Starbucks down there?  Throw down some used Starbucks coffee grounds.  They're slightly acidic but do more good than harm - attract earthworms (which you are wiping out with your critter killer so you really do need this stuff), condition the soil, repel slugs.

Here is a link to Lawns (www.lawncareprofessionals.com/staugustine.htm)

For future reference, healthy grass does not get fungus.  So you never need fungicide.  Healthy grass does not get bugs.  So you never need critter killers (but you still have enough to feed the local birds in the morning).  Healthy grass does not take a lot of work.  Not the work needed to pamper a "high maintenance" lawn with powder to kill this, powder to kill that, more powder to get rid of this new problem, added powder to avoid those things etc etc etc.  Healthy grass works like a smooth, well oiled, humming machine.  

Personally I don't care if your neighbors have great lawns or not because if your lawn is the best, they will want to know what your secret is.  And that would be a very beautiful thing.

You will however have to go to bed without supper for the critter killer you poured on the lawn.