Well, if you have those bright yellow rings on annual or rough bluegrass and its between 65 and 90 degrees F, there's a good chance you have some brown ring patch (aka Waitea patch) brewing this spring.
Like John mentioned earlier this week, symptoms can look a lot like yellow patch or even the early stages of southern blight or fairy ring. A definitive diagnosis should be made - but bright yellow rings with a slightly green ring inside of that are good symptoms of brown ring patch on Poa greens. Here's a classic photo of the disease taken a while ago by Pat Gradoville at Palos Verdes Golf Club.
There's a downloadable PDF on my website that covers the symptoms, biology and control
In a nutshell - at least two fungicide applications are often needed for complete control. Some fungicides like Headway or Endorse appear to give quick knock down of the disease, while others like Trinity or ProStar apear to take longer to act but can give very good residual control.
Other than that - rapid blight continues to hit salt affected Poa greens in the west (more on that next week) and spring dead spot symptoms are popping up on bermudagrass as we are in full transition to warm season turf growing conditions here and some guys are ony now seeing how thin (or dead) their bermuda bases are. Check out Lane's timely post on SDS for tips and tricks for dealing with SDS recovery.