Wow, that is an interesting symptom. The way the symptom appears on the low mown and surrounds higher cut is unusual. It means that height of cut did not change the plant response to the cause. Definitely send in a sample for diagnosis.
What is the turf type and what fungicides have been applied in the past six weeks? With that information, we would have a pretty good idea of what disease is NOT causing the problem and then guess at a treatment without having a disease ID - but you should get a diagnosis. Here is a list of labs (top link):
http://www.paceturf.org/index.php/public/free_stuff/