OK, here's the story.
We mowed this client on June 12, fertilized on June 13. It was hot and dry that week and has been since. Only about a 1/10" of rain if even that. Fert used in 99% of the pictures was the Nature Safe 15-2-8, here's the spec sheet for it:
http://www.naturesafe.com/content/pr...15-2-8spec.pdf Virtually impossible to burn turf with it. Nature Safe's reply was to take a handful and throw it on the turf to show that it won't burn--no, I didn't do that. I did take my vendor's sales rep with me for that 'objective' opinion. This client needs to be hand-held through these processes as he knows enough to be dangerous. (long, long story; same guy that wanted to know what kind of sand to use as traction control in the winter) My rep knows this as he has dealt with him directly on some things as well.
No evidence of any insect problems was seen. There is some evidence of dollar spot beginning and possibly some necrotic ring spot. Not even red thread. THere is a whole bunch of

soil conditions over this entire place.
You can see in some of the areas that it is worse than others, but all areas are already starting to regrow-new blades coming out of the crown. There's one proof for no fert burn. Another is no particles of fert sitting on the ground in brown areas. Another is the diurnal banding--horizontal yellow streaks in the grass blades that show the blade of grass was cracked while under stress--drought stress in this case. No doubt that it was under stress when the mowing occurred, but as seen in the pics, how do you mow only the green parts when they're scattered all over? Or I get complaints about long grass\areas not mowed, pretty much a Catch 22 for me. I would have mowed it under the assumption irrigation is occurring.
SO there you have it, I would have assumed that regular irrigation is occurring. You know what happens when someone assumes, right?
Well, it does come out that there was an irrigation problem over a weekend and that irrigation may not have occurred for a period of 3 days. We get all done with our walkaround looking at many other areas (there was some obvious fert burn in a couple other locations, absolutely no denying and we will fix that ASAP) and the rep and I are leaving when the guy in charge of irrigation happens by. (I have some issues with this guy as he is a former employee that was a month away from getting 'laid off' by me when he handed in his 2 week notice, for which I am eternally thankful.) So we talk to him for awhile. He thinks it's fert burn, I tell him it was impossible. He then goes into "Well, we did have some controller issues for a 2-3 day period." IN the process of talking with him--I let the rep do it, he's smarter than me--we find out that it was at least a 4-6 day period with no irrigation and\or if it was working the pump was not putting out the volume it was supposed to. When it comes down to it, he has no idea how long the irrigation was not operating properly because the system they are using (Toro Sentinel) only tells the operator that the valve opened and closed, but does not tell him that it actually happened or if there is a leak, head out, etc. He tells us that he was receiving phantom times--the program was showing it operating but it wasn't. Throw that in with the pump only producing 150 GPM vs. 180 GPM minimum and we're off the hook for fert burn, as I suspected all along. But I did have to rule that out and everything else.
Congratulations to Stonehenge, Nebraska, Forge, TrickyDick, PSUscaper, NCSULandscaper, and partials to Dale and agla.
I've seen the same thing with Casoron, agla. Not a good thing.
Solution: We're going to paint it because it is very high visibility and we will be removing the sod\soil and resodding where actual burn occurred and I will be giving an employee a swift kick in the ass for burning the other areas.
Thanks for everyone's help and opinions. I hope and pray to not have to do this again anytime soon. Didn't make for a very nice weekend even though I was 90% sure of what the problem was.