We assumed it was a sprinkler problem, so every spring I've dug up and adjusted the sprinkler. It still dies. I don't think it's a fungus or bug because it's edges are not as well defined as those cause.

Yesterday I mowed the lawn and discovered the patch is already dry, which is odd because we haven't even turned on our sprinklers yet. I noticed that the dry spot is long and skinny, and aligns with the path between the sun and some bedroom windows on that side of the house. So my theory is that in the afternoon, that patch of grass is getting twice baked by the sun and the reflection.

The reason this became an issue a few years ago was because I pruned a tree back from those windows.

Have any of you dealt with this? Are there any solutions that don't include obstructing the window with bushes or something?