Preventing winter injury to poa annua greens??

The dominant grass on the putting surface at Meadowbrook Country Club is poa annua or annual blue grass.  This type of grass makes an excellent putting surface but can be prone to winter injury vs. bent grass.

The Top 3 Winter Concerns.

1. Turf Pathogens, pink and gray snow mold.  Applying fungicides usually gets good control.
2. Ice Damage, little science and some theories why the poa annua plant dies.
3. Crown Hydration, plant breaks dormancy and takes in water and then freezes rupturing the cells in the plant resulting in death.

Ice damage and crown hydration both require water for turf damage.  So in theory reducing surface water during freeze thaw cycles will help reduce turf loss on poa annua putting greens.  Greens most susceptible to ice damage and crown hydration have poor surface drainage, surrounded by trees or north facing, these areas tend to keep snow and ice for longer periods.

Maintenance practices in place to help prevent against winter turf injury to poa annua greens.  Remember water is the villain, water that collects in low areas or having free water on the surface during freeze thaw cycles can be deadly to the poa annua plant.

Impermeable Covers.  The bubble wrap cover system is what we use at MCC on greens that are most susceptible to winter injury.  This system has two covers, first cover to go down is the bubble wrap, strong enough to support your weight, bubbles placed down, and this cover is used for air movement and insulation.  The impermeable cove is to repel water keeping water off the putting surface and is placed on top of the bubble wrap, the impermeable cover reflects light reducing excessive heat.  We cover 8 greens 2,3,5,6,10,11,13 and the turf nursery, we have been using this type of cover for the past 5 years with good results,  negatives expensive and storage can be an issue.

Snow Removal.  On non-covered greens excess snow is removed (reduce water) but leaving some snow for insulation.  Snow removal is done through out the winter.

Sand Topdressing.   Heavy application of sand is applied to the putting surface just prior to winter.  The theory, that when ice is formed it crushes the cells in the plant causing death.  The layer of sand may act as shock absorber limiting the crushing damage.  The sand may also assist for easier ice removal.

Moving Water.  During big thaws we try to keep the water moving off the green especially if nighttime temperatures are going to be frigid.  Keeping the water moving can be done by removing strips of sod from the green for better surface drainage.  Standing water puddles in low areas can be removed with a pump or shop vac.  Removing water helps but when a solid layer of frost is in the ground it is impossible to remove all excess water.

      14 Green with sod strips removed to improve surface drainage. 

                                                                                                        

Summary
Ice and crown hydration injury  is very difficult to prevent vs turf pathogens.  Turf pathogens you spray a fungicide and have good results but Ice and crown hydration  mother nature has the final say keeping  free water off the putting surface especially when frost is in ground is a very difficult if not impossible task to prevent injury.