Winter kill scenarios like crown hydration are problematic at this time of year particularly when you have Poa plants that break dormancy, start growing and start taking in water. Any situation where you have Poa plants breaking dormancy, wet weather, followed by cold weather you have a recipe for crown hydration. Crown hydration in plants is similar to taking a sledge hammer to a glass window, cell membranes in Poa plants burst similar to breaking glass and cause death of that plant. The next couple nights are expected to be very cold. Tonight in particular lows are supposed to reach the upper teens. After receiving 5"+ of rain the ground is way past field capacity and the Poa plants are full of water. This could lead to some crown hydration which means death of some Poa plants.
What can we do about protecting Poa plants at this point?
Nothing. Our only saving grace is if the snow stays and acts as a blanket to protect it from the cold air. Or it does not get as cold as the forecast is predicting.
Low areas and poorly draining areas with Poa are at risk for crown hydration. And greens with large amounts of Poa are at risk. For example #14 green is 95+% bentgrass and has virtually no risk of damage while #4 green has ~50% Poa with some poor drainage characteristics is at high risk.
What can we do in the future to protect against this type of injury?
PROMOTE BENTGRASS!! If we have damage occur it will be on weak Poa, not on bentgrass. We have made great strides in promoting bent over Poa, that being said we still have some greens and some areas with significant amount of Poa. Also improving drainage especially surface drainage will go a long way in keeping turf drier which will ultimately help curb winter kill and summer stress.
Remember that Poa annua is a golf courses greatest liability in this climate. It is by nature weak and succumbs to winter and summer stress. 99% of winter injury occurs on Poa and a large majority of summer injury occurs on Poa. Poa requires more water, fertilizer and pesticides to stay alive. It becomes bumpy and uneven which can impede smooth consistent ball roll on greens.
I know that I talk a lot about Poa on this blog and that is because of all of the liability issues it presents as a turf manager. But keep this in mind during the summer months, when the golf course is a little firm or you see some brown areas from lack of water, or you see some trees that have been removed, remember this blog post about how Poa as a golf courses greatest liability. Remember that a soft, overly green golf course is an unhealthy golf course full of liability. With all of the winter kill issues, summer stress issues, playability issues, and large cost involved in maintaining Poa, would you invest in it long term?
Here are some great articles about winterkill and crown hydration: