Have you also been getting a lot of rain? Or when did you start deep and infrequent watering? The grass looks like it's diseased. but what you're doing would not make me think it was.

Agreed it does look a lot like brown patch but with your watering schedule it doesn't make a lot of sense. Heritage G will knock it out.

Could be different in VA, but here in NC it has been raining quite frequently lately. I have not watered for 4 weeks but I'm starting to see signs of fungal disease again, so I added fungicide with my last round of T-Nex.

I would just suggest Headway G instead of Heritage G. It's the same active ingredient (azoxystrobin) but also contains propiconazole which protects you against the fungus developing immunity and also acts to kill the fungus through a different mode of action. Price is the same I believe . Kind of like taking two antibiotics.

We just bought the place in late 2014, and it was very weedy. So I'm gradually bringing it into shape. I killed the weeds and seeded with 100% TTTF last fall. Only been following the deep and infrequent watering schedule since this year really. I wouldn't say it's been raining frequently. In fact, I think I've only watered 3 times so far - nature has been pretty good. So I don't think it's a case of overwatering. And even though it's been hot lately, it hasn't been scorching, but I thought maybe it needed more water. It's a mystery. Like I said, it wasn't perfect, but it was looking pretty decent, and this seems to have come on kinda suddenly, just the past couple weeks.

The only thing I might be guilty of with my practices are that my mower blade could probably be sharper, and I might be cutting a bit more than 1/3 off at a time, even though I'm mowing pretty religiously every 6-7 days.

I'm split between waiting a bit more to see if there is any improvement, and putting something down asap. If I do, I'll go with Headway (thanks for the recommendation j4c11). I guess putting it down wouldn't hurt, even if it wasn't a case of fungus, right?

Fungicide is best applied preventively anyway, so no it will not hurt anything if you put it down. I know some folks are concerned about nuking fungi in the soil etc., but if it killed everything you wouldn't need to keep applying every 2-4 weeks, obviously there's plenty of fungi left over for subsequent rounds of lawn destruction.

I haven't applied anything yet, but did read about using plain cornmeal for fungus. Is this something y'all might recommend trying? I just called a feed store and was told they have "distiller's corn" which she said is "kinda like a meal", and "cracked corn" which is "some powder with chunks mixed in". I guess I'll need to go check it out in person, but do either of those sound like what I need? One better than the other?

Looks like "distillers corn" is a by-product of the production of ethanol (alcoholic beverages or biofuel), which is used as livestock feed. Would I want to spread this on my lawn?

My lawn has a fungus and looks similar to some of your pics. I took pics to Lowe's and they recommended a fungal treatment that I applied a few days ago. I am praying that it starts to work.

I'm going to try to be more diplomatic about this subject :-)

Cornmeal for fungus control is akin to homeopathy for treating illness. Some people swear by it, the claims sound good, but there's no scientific backing and results vary wildly. For those that do get some sort of results, it's unclear whether it was the corn, the nitrogen in the corn, change in environmental conditions, placebo etc. The track record of corn meal for brown patch control is poor to dismal. The choice is obviously yours, if you feel it's worth risking your lawn over $50 go for it and let us know how it turns out. Otherwise, Headway G is a sure shot.

Yup it's fungus. Buy generic propaconozol it works great. 3 weeks my lawn looked great after a nasty fungus patch.

OK. I've done a little more reading on the cornmeal, and while I didn't find that much out there, I do see that there's nothing sure about it combating fungus. I'm stopping by this feed and lawn store tomorrow. l'll see what they have in the way of Headway G or generic propiconazole. My local Southern States only has Heritage G. Thanks for the advice both of you.

Headway G application rate is 2 lbs/1000 every 14 days or 4 lbs/1000 every 28 days. Is there any advantage of one rate over the other? I'm thinking the lower rate every 14 days would be if using strictly as a preventative? Since I'm already showing symptoms, should I use the higher rate to hit it hard and stop the progress asap?

I would go with the higher rate since the turf is already being affected.