Hi Jami,

Here is a link to look at, check out rust;

https://apps.extension.umn.edu/garden/diagnose/plant/turf/

Have you dug under any of the dead turf ? You could also be seeing damage from Japanese beetles. Excavate a few inches under some areas and look for white fat grubs that curl into a c shape. I see a LOT of damage out there from these grubs that love green, well watered lawns.

https://extension.umn.edu/news/white-grub-control-lawns

Hope this helps but you can always send a grass sample into the diseas clinic,

Sally Granath

St. Louis County MG