As mentioned in a tweet Dr. Kerns sent out a couple a weeks ago, the current weather conditions are ideal for Pythium root rot on creeping bentgrass putting greens. This will likely occur in areas with poor drainage first or follow drainage patterns, however, don’t rule this disease out in well-drained areas because we have observed it there many times also. Remember, there are dozens and dozens of Pythium species that attack turf and they all have different temperature ranges … don’t believe the old wives tale that Pythium only attacks during hot weather. We currently recommend that everyone start their Pythium root rot prevention program off with Segway due to it being very good in our trials over the past couple of years, even at the 0.45 oz/M rate. At the 0.45 oz/M rate, you can apply Segway 6 times instead of 3 according to the label, so you will want to rotate that in with other products like Subdue, Banol, Stellar, Appear, or Signature (in no particular order).
More information about Pythium root rot.
Finally, we have already diagnosed multiple samples with Pythium blight on bermudagrass putting greens. Any decent Pythium fungicide such as Subdue, Segway, Banol, Stellar, Appear, or Signature (in no particular order) should do a nice job of preventing this disease. You will likely have to make repeat applications every couple of weeks until the weather changes. Rotate through the different chemistries to help with resistance management.
For more information about Pythium blight, click here.