Preparing for Winter

Last year's winter proved to be one of the longest coldest winters that we have experience in this area in quite some time.  As a result we lost some turf, primarily on greens 4, 5, and 6.  I wanted to share with you some changes that we have made heading into this winter that will hopefully reduce the likelihood of this type of damage from occurring again.

First you need to understand what leads to turf loss in the winter.  The main causes of turf loss in the winter include; crown hydration, low temperature kill, desiccation, fungal diseases and ice sheets.  Let's examine each of these and find out what we have done to help prevent them from causing damage this winter.


Crown Hydration.

In the fall grass plants prepare themselves for winter by moving water out of their cells (de-hydrate).  This process commonly referred to as hardening off.  If plants did not go through this process, the water in their cells would freeze, expand and rupture the cell walls causing the plant to die.  Some grasses, particularly Poa annua, when exposed to warm temperatures are quick to re-hydrate their cells.  If the warm temperatures that caused the plant to re-hydrate are then followed by a period of cold temperatures the cells could rupture.  This typically occurs in the late winter or early spring.

If you allow grass plants to set in above freezing water during the day as the snow melts and then expose the plants to cold night time temperatures you greatly increase your chances of turf loss through crown hydration.  Anything that can be done to prevent water from running onto the green and then getting it off the green as quickly as possible will help reduce the chance of this type of damage from occurring.

First we looked at how we might help the water get off the greens quickly.  When inspecting #4 and #5 greens we could see that the collar in front of the green was at a slightly higher height than the green surface.  Caused by years of applying sand topdressing to the greens, this sand build up in the collar was essentially creating a dam.To fix this we stripped the sod in front of the greens, re-graded the soil and then replaced the sod.

Lowering the front of #4 green

We also performed a deep tine aeration on greens 4, 5 and 6.  We used a special aerifier that used solid 1/2" diameter tines that went down 10" deep into the green.  Our plan is to leave these holes open so that as the snow melts the water will run down into these holes and keep the crowns of the plants from sitting in a pool of water.

Deep tine aerifying #4 green

Next we looked at preventing water from flowing onto the greens.  The 5th green and the 6th green both had areas that could be improved so that less water would run onto the greens.

On the 5th hole we installed a drain line and catch basin to the left of the green.  Our hope is that this new drainage will catch water coming off the hillside and direct it away from the green

Installing drainage on the hillside above #5 green

Likewise on the 6th green we identified an area where water from the cart path was moving down onto the green.  To correct this we added some mounding along the cart path which will divert water away from the green.

Preparing to add mounding along #6 cart path

Low Temperature Kill and Desiccation

Just as the name suggest low temperature kill is caused by exposing the turf to extremely low temperatures particularly when the weather changes rapidly and you get a drastic drop in the temperature.  Bentgrass can tolerate temperatures down to -30 degrees while poa annua can only tolerate temperatures down to -10 degrees.

Desiccation can also lead to turf loss and is caused by cold winter winds blowing across exposed turf leading to the plants to drying out.  The best insurance against both these types of damage is a good layer of snow.  Snow is a great insulator and the temperature at the surface under the snow will typically be right around 32 degrees even on the coldest days.

Unfortunately snow is not always present in the winter so to help protect the turf from these two forms of damage, late in the year, we apply a heavy layer of sand to the greens.  This layer of sand covers the crowns of the grass plants and acts to insulate the plants.

Topdressing greens with sand

Fungal Diseases

Fungal diseases that occur in the winter are generally called snow mold.  There are two types of snow mold, gray snow mold and pink snow mold.  Gray snow mold requires extended periods of snow cover while pink snow mold can occur with or without snow cover.  Both types of snow mold can cause extensive damage over the winter.  To prevent this we apply a protective fungicide late in the year to the greens, tees and fairways.

Spraying for snow mold

Ice Sheets

While snow is beneficial to the turf in the winter, ice is bad.  One of the hardest decisions to make in the winter is when and if to remove ice from the greens.  The rule of thumb is that Poa annua can survive 60 days under continuous ice cover, while bentgrass can tolerate 120 days.  We will closely monitor the formation of ice on the greens this winter so that we know how long the ice layer has been on the greens.  Even after knowing how long the ice has been on the green, the decision to remove the ice or not remove the ice is not an easy one.  Sometimes the process of removing the ice can do more harm than good.  Also once the ice is off the greens you then expose the turf to low temperatures which could also lead to turf loss.  Never the less, we will keep a close eye on things and cross that bridge when we need to.

One way to help prevent ice from remaining on the greens for long periods of time in the first place is to allow more sunlight to reach the greens.  If you look at the greens that were damaged last year you will notice that they all share the same characteristic of being surrounded by dense trees.  Without sunlight reaching these greens during the day the ice tends to last much longer on these greens than it does on other greens.  To help correct this we have removed several trees around these greens but more will likely need to be removed in the future.

Tree removal to allow more sunlight to reach #6 green

As you can see we have taken several steps to help prevent loosing turf again this winter.  However there are no guarantees. Ultimately we are still at the mercy of Mother Nature.  Hopefully with some good preparation, some close monitoring and a little luck we will make it though the winter unscathed and be ready to go next spring.