Question
I live in Northest Ohio. The lawn is about 4 years old (thin blade, bright green when healthy). Nicest lawn on in the neighborhood, until recently! We had some real high tempatures (90's)for the past 2 to 3 weeks.  I keep up with irrigating the lawn at 6 am for 25-30 min per zone X 8 zones.  The only thing I added was 2 weeks ago I applied Verago Weed & Feed 28-2-2. I also tend to let the lawn grow higher (4 on my John Deer rider) in hot weather because it seems to prevent/choke weeds.  Two weeks later I now have brown patches spreading throughout my front lawn (nowhere else significantly).  I read somewhere someone recommended "Corn Gluten".  So I have applied that.  Is there anything else I can do, and when do I start repairing it i.e. seed? fertilize? etc.

Answer
First, let's clarify about the Cornmeal Gluten.

Cornmeal Gluten is NOT Horticultural Cornmeal.  Yes, they both come from Corn.  Without going into the Chemistry right now, Cornmeal Gluten (and people mix these up all the time, you can see why) interferes with seed germination.  ANY seed in the vicinity of a grain of Cornmeal Gluten gets a fatal punch in nose, goes down for the count, and kicks the bucket.  That's CORNMEAL GLUTEN.  They discovered it by accident, the way most things are discovered.

Horticultural Cornmeal is a favorite food of a certain very friendly Good Fungus, called Trichoderma.  This Fungus also attacks several common Bad Fungi that attack Lawngrasses, specifically Sclerotinia ('Dollar Spot'), Sclerotium ('Southern Blight' and other diseases), and Rhizoctonia ('Brown Patch').  Scientists at Texas A&M Agricultural Dept did the research:

http://stephenville.tamu.edu/pp/pdncr/index.html

A section there, 'Biological Control of Soilborne Fungi', spells out the details:

'...certain Fungal species in the genus Trichoderma feed on mycelium and sclerotia of Sclerotinia minor.  Sclerotium rolfsii and Rhizoctonia sp.  All peanut fields in Texas tested to date have a natural population of Trichoderma. For several years, tests have been conducted in Texas using Cornmeal to stimulate Trichoderma development as a way to control the major soilborne disease fungi. When Yellow Cornmeal is applied to fields in the presence of moist surface soil, Trichoderma builds up very rapidly over a 5 to 10 day period.  The resulting high Trichoderma population can destroy vast amounts of Sclerotinia, Sclerotium and Rhizoctonia.  This enhanced, natural biological control process is almost identical to the processes that occur when crop rotation is practiced.  The level of control with Cornmeal is influenced by: (1) organic matter source, (2) soil moisture, (3) temperature, and (4) pesticides used.  Seasonal applications of certain fungicides may inhibit Trichoderma.'

Now this last part is VERY important.

See that language in Item 4?  See what it says there about 'pesticides'?  'Pesticides' as in 'Weed & Feed'?

Ding-Dong anybody home?

You know, Pete, I am not that old, and I have not really been doing a whole lot of Lawn-keeping in my lifetime.  But I have read a lot of books and studied a lot of Chemistry, which is one of my favorite subjects, and I love Botany, and I love all the research going on about Lawns.  My favorite passtime is to Watch Grass Grow.

So when I tell people over and over that these different Chemicals that the Scotts Companies sell them are BAD for their Grass, and no one listens -- well, maybe some people do, but most people don't pay any attention to this stuff -- it just disappointments me like you would not believe.

And I am never going to get anywhere as long as someone out there with a few billion dollars is going to spend it on Hollywood style commercials broadcast at Halftime telling everyone to Weed and Feed their Grass.

When someone does that, and then they put down something pushed as 'organic' and it doesn't work, they say, Organic doesn't work.

But you have to know what you're doing.  You can't just fertilize 'organically'.  You have to be smart about it.  And with all due respect, there is no such thing as a 'hybrid' approach to organic gardening.  Either you are pregnant, or you are not pregnant.

Let's get back to your Grass.  The 'Weed' part of the W&F was a Weedkiller that I won't even go into right now because it's way past my bedtime, but there is a lot of collateral damage with Weedkiller.  The 'Feed' part is also bad.  It's Salt.  Chemical Fact.  Wipe out the Microbes, and you tilt the balance in favor of Disease.  Vigoro Ultra Turf Weed & Feed contains 2,4D.  If you take a Lifesaver sized vial of 2,4D and pour it on 3 Kindergarten children, sir, you'll kill 2 of them.  They don't even have to drink the stuff.  The 2,4D does not break down in your soil, it stays there waiting for you to Mow, BBQ, play Frisbee, where you track it into your house and there without sunlight to break it down it stays forever.  Do you think this is good for the Birds?  The Butterflies?  The Earthworms that live inside that Soil and make it so healthy for the Grass?  No way Jose.  Now that you've doused it with 2,4D, it's going to stay there and work for months and years to come.  But it sounds nice.  Vigoro 'Weed and Feed' has a nice ring to it.

Here's what I would do if I bought your house and inherited your Lawn.

I would continue to Mow the way you are Mowing.  Smart system you have, but a little too high unless you are growing Grass in the Shade.

Cut back on the Watering.  Turn off the autosprinkler.  Wait a week.  Let the soil dry out.

Go out and buy Horticultural Cornmeal.  I would pour it all over the place.  Water it in.  If you have Brown Patch, you will be culturing beneficial, Bad Fungus hating Good Fungi IF -- this is a Big IF -- you have any Good Fungi populations left.  Gradually, it will disintegrate and turn into high Nitrogen Fertilizer.  (You sure can't say that about 2,4D.)

It is nearly September, time to sow Grass.  Cornmeal Gluten would prevent germination of Weed Seeds but it would also prevent germination of any other Seeds too, so you don't want to put Cornmeal Gluten down within 3 months of seeding.

Now, if you really love your neighborhood Birds and Bees, you will stop using those products pushed at Half Time and you will make the big switch to Organic.

That doesn't mean you will run out and spend oodles of discretionary income on everything labelled 'Organic'.  It means you will Weed and Feed and Seed intelligently, like the educated man you clearly are.  You will think about these things.  You will learn from your mistakes.  You will take what's left of the Vigoro and deliver it to the local Toxic Waste Disposal site, where all pesticides are supposed to end up.  And in the Spring, you will put down a couple of bags of Cornmeal Gluten and keep your Grass Weed Free.  Now and then, you can get down on the Grass with the neighborhood kids and teach them how to yank Dandelions out of the ground.

Sorry this is way too long, it is a passionate subject for me and I do seem to be swimming upstream.  If you are unsure about the Brown Patch diagnosis, please let me know.  There are lots of Fungi out there.  To fight them, you need different weapons.

Thanks for writing, and good luck with your Lawn this Blessed Weekend.