Note, that on the back yard in the middle of it there's a slope that usually accumulates standing water after heavy rain or watering. Yellow grass is mostly along that slope so I wonder if the soil in that area is over watered and it is causing whatever disease that is?

 

I have the exact same issue. I think it's too much moisture or my alkaline soil. I've spread peat moss and am trying to dry it out by not irrigating to see if there's any improvement.

 

K deficiency or iron chlorosis? I might spray that section with 0.3 lbs K/1000 and throw in a liquid iron supplement and see what happens.

 

Probably the small amount of quinclorac from the image yellowing it up ..not enough to kill it but it will yellow/stunt it for a few weeks

 

Those spots look like fungus disease and the yellowing is a iron deficiency

 

Think you had a chemical reaction between the application of disease ex and image

Try some Iron Chelated

When applying Iron, here are a few things to consider:

Don't apply in the middle of the day: wait until the temps drop off. As we say, moist soil and good pH will contribute towards the best results.

No need to water after: we are wanting the Iron to sit on the foliage, so it can be absorbed by the plant. Best to allow it to sit for 3 to 6 hours before any rainfall or irrigation.

Even application is one of the biggest things to consider. Iron can show you where you applied too heavy and where you didn't.

If using granular with Iron, it always pays to blow the granules off your paths and driveways before watering in.
Regular applications are better than a single heavy dose.

 

Just to give an update: we had really good storms on Wednesday morning leaving some 1.2" of good waters. Had been shiny ever since with temps at 82F during the day. Yellowishness is pretty much gone on the back yard and completely gone in the front. Here are some pics of the front yard. I also have some bare spots from last year's abuse and I wonder if the will fill in and close up. It looks like there are runners coming across but I'm just looking for SA experts opinion.
Overall, it seems to be greening up nicely. Had Milo applied around 10days ago and waiting for it to kick in.

Also did a soil test today and PH on the front appears to be in check as well as phos and potash. Low on nitrogen though, so I'll probably feed it with some 32-0-10 for sothern lawns at half rate in a week or so.

Feel free to comment and suggest folks, it is greatly appreciated

 

btw, last picture top half is my neighbor's lawn lol