About once a decade, we get just the right weather conditions to cause a serious loss of Poa annua during the winter. This was not the year in central Iowa. Our bentgrass and Poa appear to be recovering very will this spring. However, I am getting some contacts from the Chicago area and Wisconsin indicating that they are seeing some Poa loss. This apparently happened this spring after snow cover melted. The following pictures are from Marc Davison of Green Bay country club in Wisconsin. The first one shows ball sized spots of Poa on the green that are dead, while the surrounding bentgrass is healthy.
The second picture shows a green with healthier grass in swales where snow cover persisted longer than on other parts of the green. Evidently, the snow protected the turf, while exposed areas lost Poa. This would require just the right spring weather conditions. My guess is that the Poa began to green up earlier than the bent. Then there was some wet weather, followed by a quick freeze that selectively killed the Poa. That is just a speculation at this point, but it seems to make sense from discussions that I have had with other superintendents in that region who lost Poa.
I am wondering if any Iowa superintendents are seeing this problem. I have not observed it here, but I know that the Northeast and Northwestern parts of the state have had some very unusual weather conditions. In fact it is still snowing in late April in Northwest Iowa. If you lost some Poa, send me some pictures by e-mail and I will get them on the blog