On thing that I learned is that if there are any rocks just under the soil even if the are 4-5 inches under that area will heat up more than the rest, hold less water and dry up much faster and get hotter than the rest of the lawn. I found this out the hard way. Also areas close to paved or concrete floors/sidewalks will get hotter and drier faster. A lot of times just a little extra water does the trick. Generally even during "wet" periods the higher altitude areas in the inter-mountain west, even Denver, have no issues with fungus. I have never used fungicide. Just dont water every day and you are good. If you do overwater during wetter periods you might get some poa triv growing which is lime green and hated by lawn enthusiasts but in our climate its easy to control if you dont water every day. Easy.
That is what I was thinking.
I also read an article with a caution about evening watering because lawns are more prone to fungus, and I did have a few mushrooms growing in my yard earlier in the spring. Not something we usually see in Reno.
During that rainy time I did not have my irrigation on.
This area has been problematic every since we moved here, and it does get direct sunlight during a really hot part of the day and recently I was looking at older photos from when this house was listed. It appears that the area I'm talking about used to be a place for planting flowers or something, not lawn so I also wonder if the sprinklers, don't saturate there the same as the rest of the lawn.(see picture below.) So...I increased my two AM watering times by 2 minutes each but left the one evening watering at a original 6 minute time.
Sooooo, I took an old window screen and used it for cover, reseeded, watered with a fertilizer.
We shall see what happens.
If this doesn't work, I may order this for that patch area.