WINTER DESSICATION

Continuing with the topic of winter injury, todays post highlights winter dessication.  Dessication occurs when the turf dries to the point of death.  Dessication can be very detrimental to large areas of turf if the conditions are favorable.  The best defense for dessication is a cover on the turf to prevent exposure to the sun and wind.  During the winter months, this is best accomplished with snow.  If there is no snow cover, it may be necessary for irrigation to be applied.

Through the winter, the turf still needs available water, albeit, much less than when it is actively growing in the summer.  After the soil becomes frozen, moisture in the soil becomes unavailable to the plants.  If the leaves above ground are exposed to the sun and wind the turf can dry out to the point of death.

Winter dessication can occur here, but is less common that other areas of the country.  Courses in the plains states are regularly taking actions to prevent dessication.  Other areas prone to low humidities, high winds, and lots of sun regularly deal with this issue.  If conditions are favorable for dessication, the best thing to do is apply water.  In northern states, most golf courses winterize their irrigation systems to prevent water from freezing in the pipes.  It is common for courses that regularly deal with dessication to install supplemental water lines below the frost line that allow for water applications through the winter.

Sean McCue, Superintendent at The Country Club at Castle Pines in Colorado maintains a blog and has recently posted about how they deal with winter dessication: Dead or Alive

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FREEZE INJURY

If you watched the video on Freeze Smothering I linked to yesterday, you may have heard Dr. Karl Danneberger mention that ice formation, although able to sufficate turfgrass, is most often associated with freeze injury.  Freeze injury occurs when water in the plant freezes and results in death.  Freeze injury most often occurs in the early winter time or early spring when temperatures can be very warm during the day, then drop below freezing at night.

The turf's natural defense against freeze injury is its ability to harden off for the colder months.  The plant does this by moving water from inside cells to the outside.  This increases the concentration of solutes inside the cell to help prevent its vulnerability to freezing.  When the plant begins to loose the green color in the late fall, this process is underway.  When the plant does not have the time to complete this process, it is exposed to possible freeze injury.  As an example, this could happen when rain falls during the day and the plant takes up the water from the rain, but, after the rain pushes through, the temperature drops rapidly to below freezing and freezes the water the plant just took up.  As you know, when water freezes it expands, this leads to ruptured cell membranes which results in the death of the plant.

Freeze injury is nearly impossible to prevent due to its reliance on weather conditions.  Things that can help avoid the possibility of freeze injury are adequate sunlight and good surface and subsurface drainage; but those things should be done already to provide good turf.

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Even though the winter involves much less work on the course, as evidenced by my lack of turf related posts, our concerns of the turf's well being is not lessened.  There are several maledies that can compromise the turf's health through the winter and into the spring transition.  Some of those include winter dessication, ice cover, freezing damage and disease.  I have touched on the diseases that can damage turf in the winter (November 20), but will go into some more detail here.

ICE COVER

I will start with ice cover because that is what promted this post.  There are several areas on the course that have had sustained ice cover for about the last 30 days, and the ice is still fairly thick.  Some of those areas are 14 fairway just over the hill, the start of 11 fairway and 5 green.  These areas have not become a concern yet, and likely will not, but we will keep our eye on them.

ice cover on 5 green

Ice cover becomes a problem after extended periods of time by preventing the turf's ability to properly exchange air.  Even in the winter, turf is still relying on air exchange to continue necessary processes while dormant.  If a cover of ice is in place, it prevents that necessary exchange of air.  As a result the air under the ice cover developes excessive supplies of carbon dioxide and the turf begins to sufficate.  It's the same reason you were told as a kid not to put a plastic bag over your head!  If turf is covered in ice long enough, it will die from suffication.

Ice cover would become a concern if annual bluegrass or kentucky bluegrass are covered for 60 days, and if creeping bentgrass is covered for 120 days.  We may consider removing the ice if it is still in place after 60 days, but even then just breaking the ice to allow sufficient air exchange will prevent damage.  Some ideas for removing ice include topdressing with sand, or a dark material to aid in the melting process; or mechanically removing the ice with through aerification.

Here are some links with additional information:

Winter Injury: Freeze Smothering - Karl Danneberger, Ph.D, The Ohio State Univeristy (Video)
Ice Cover and the Role in Freezing Injury - Karl Danneberger

I will continue in the successive days with information on winter dessication, freezing damage and disease.

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