The following is a post from Luke Dant of Syngenta products about a disease called Waitea patch, caused by Waitea circinata var. circinata. The picture above is from Ron Calhoun at Michigan State. It shows the disease attacking Poa annua, but stopping when it gets to the bent.
Luke, thanks for the post.
Recently in industry magazines, or via conferences you may have heard of a new disease referred to as Brown Ring Patch or Waitea patch. In my travels, I have only seen the disease twice, both times in MN, once on bentgrass putting greens, once on Poa annua greens.
In both cases that I have seen, it appeared after 3-4 days of highs reaching 75-85 degrees with high humidity (65+ degree dew points).
In the particular case pictured here, it occurred on Poa annua and the rings were identified on Tuesday, June 23. An application of Headway at 3oz/1000 sq. ft was applied on Wednesday, June 24 and by Friday, June 26 (the date the I took the picture) most of the rings had dissipated and would go unnoticed by the average golfer. In this instance, there was no turf loss and the rings have not reappeared.
I have included two links as references:
Syngenta Professional Products