Is this heat stress or a fungus?
Why is some of my grass turning yellow and dying off? It looks healthy. I had a couple spots I thought were “ Dollar Spots” I have treated the lawn with propiconazale and Scotts disease x. I have had a couple large dead grass yellow spots show about six inches across In the yard.
Sherburne County Minnesota
A microscope is needed to identify fungal infection unless it is very advanced. I can’t see any detail in the grass blades in the photos. Wet and damp weather does promote fungus. Dry off from heat would be more wide spread unless you watering misses a spot or a little too much fertilizer in one place.