Winter Weather

The 2012-2013 winter had perfect conditions for the health of the grass courts.  A moderating blanket of snow with no ice layer and consistent temperatures was optimum for the plants.  The winter of 2013-2014 has been a different story.  Wet conditions and above normal temperatures followed by extreme cold is a worst case scenario for winter injury to our Poa annua courts.  And that is exactly what we have had.  More than once, conditions of heavy rain, temperatures in the high 40's to low 50's and then single digit temperatures within hours have occurred!

The Poa annua plants can handle cold and ice (though not as well as other northern climate species) - they do every year.  So why might there be a problem this year?    The timing of the wet conditions along with the temperature swings can cause an injury called crown hydration.  What happens is the plant wakes up a bit in the warm temperatures and begins taking in water.  The water dilutes the "antifreeze" (carbohydrates) in the plant, temperatures fall and the water in the plant freezes creating crystals that puncture cells.   During winter dormancy the plant is alive and respirating slowly, using carbohydrates. As the winter progresses, the plant has less and less of these carbohydrates that prevent freezing and the plant becomes more susceptible to freezing.  So one positive of the weather we have had is that all of this has occurred fairly early in the winter season.  If this weather pattern continues into late February and March, we could have some problems with winter injury.

As a turf manager, what can I do to prevent this?  Most important was autumn preparation.  Various cultural practices were used to promote carbohydrate reserves and healthy dormancy.  After that, preventing the plants from being in wet conditions is most important and we addressed that by continuing to improve drainage on the courts.  But we can only do so much in the low site of Longwood.  Protecting the courts with an impermeable cover might help the situation by keeping out water, but covers can also hurt the situation by restricting oxygen and causing temperatures to rise too high underneath the protective layer.  Many golf courses do this on some of their greens with great success, but these sometimes elaborate systems are not practical for our site.

As soon as we get a substantial thaw, we will bring some samples of the turfgrass into the clubhouse and see how the grass is doing.  For now, no worries, but let's hope for moderate conditions for the remainder of the winter.

January 23, 2014.  3 degrees F.