Wednesday, April 18, 2018

Winter Injury, Earth Science and Tomatoes!

Hello and welcome to The Greenkeeper!  Today is Wednesday, April 18th and Winter Kill is defined in Merriam-Webster as "to kill a plant (or part of a plant) by exposure to winter conditions."  Now, that is a vague definition, but winter kill is a vague phenomenon as exposure to low temperatures alone are not the sole cause of plant injury or death.  To be clear, I am speaking solely about warm-season grasses and specifically about Bermudagrass.

We have over 100 acres of Bermudagrass growing on our tees, fairways, rough, and practice areas, and there are reports of winter injury and winter kill surfacing throughout North and South Carolina again this spring.  This article by the Carolinas Golf Association (CLICK HERE) was released less than two weeks ago as an alert to golfers and owners to help everyone better understand what conditions they are currently experiencing on their golf courses.  Granted the article focuses more on recent ultra-dwarf Bermudagrass putting green conversions, but Bermudagrass grown at any height of cut can be subject to the whims of Mother Nature.  
No. 1 Fairway
I stated above low temperature alone is not a sole cause and factors such as low light (shade), elevated moisture (too wet), and heavy traffic significantly contribute to Bermudagrass injury during cold winters.  Sometimes just a fraction of an inch more in height of cut, or one or two degrees more of temperature can be a difference maker.
This past Monday we assessed the overall health and condition of our 100 acres and determined about 1 acre, or one percent suffers from significant winter injury requiring replacement.  There are some additional areas although injured with enough healthy plant material present they will heal with a little extra management (fertilizer and water) as soon as Mother Nature agrees to provide appropriate growing conditions (but that's a different topic).  Today I want to talk a little about the areas needing replacement, and how we plan to repair them.  But before we get deep into those details let's take a closer look at the golf course from above to gain a better understanding of the types of winter injury we've encountered and why.
Google Earth Image of Carolina GC
Remember back in elementary school when they taught us in Earth Science the sun always rises in the east and sets in the west, and the sun makes its way across the southern sky on its daily trek across the earth.  In the summer the sun travels at a very high arc, nearly overhead and the days are long and quite warm.  In the winter however, the sun is much lower in the sky and the days are shorter.  Also, because the sun is lower in the sky, that angle creates long shadows formed by objects (trees, buildings, etc.) located on the south side.  
Hole No. 1
Holes No. 11 & 12




















When I was growing up in VA my grandparents lived in a ranch house that faced due north.  In the winter months there was either frost or snow lingering in the shadow of the house long after it was gone in other portions of the yard.  In the two photos above you notice the trees located to the south and west (in the case of 11 & 12) of the respective golf holes and thus it's easier to understand why the turf in this area of the property may be subjected to more winter related injury than others.
Hole No. 9
Hole No. 16




















Holes 9 and 16 are also not immune as they both possess large trees growing on their southern sides that create cooler micro-climates throughout the dormant season.  Even the practice tee located at the back of the range is at risk, as those same trees that provide comfortable shade in the summer provides too much shade during the coldest of winters.
Back Range Tee
Does this mean we need to cut down all the trees?  No, especially since not all the trees I've highlighted are growing on club property.  But what it does mean is there is a reason the majority of winter turf injury during extreme cold years occurs mostly on the southern border of the property.  In fact, of the entire one acre of turf loss estimated approximately 95 percent of it is located in those areas I highlighted above.
Tale of Two Halves
Interestingly, it is not just a factor of trees and shade either.  Do you also remember in Earth Science that cold air sinks and hot air rises?  Well, the area above the blue line is the portion of highest elevation on the property compared to below.  The highest place on the golf course is the tee box on Hole No. 6 at roughly 765 feet above sea level and most of Hole No. 1, along with No.'s 11, 12, and 13 all sit below 700 feet (now you know why most putts break towards No. 1 green).  Sixty-five feet in elevation may not sound like much but when you are talking about prolonged exposure to extreme winter conditions that may cause plant injury, even a few feet can be the difference in a degree or two.

So now you understand why the injured turf on the golf course is located where it is on property, and you want to know what we are going to do about repairing it.  I have reserved two truck-loads of new sod to be delivered in the next two weeks (one truck each week).  This will remedy the injured turf on the golf course.  We will give a little more patience to the practice range areas before committing to new sod.  The plan next week is to replace all the injured turf on the collars and tees before proceeding to other areas in need.  What doesn't get completed next week will be repaired the week after.  

SIDEBAR - I know some of you read "injured turf on the collars" and your heart sinks as that is an issue we battled quite extensively for several years.  I can tell you the amount of turf damage this year is far less than experienced in 2015 and I'm certain the impact to your golf activities will be as minimal as can be.

One other important piece of the ever mystifying winter injury puzzle is varietal differences.  If you're confused by what I'm referring to, I mean the different types of Bermudagrass present on the golf course can have different tolerances to winter extremes.  Wait, you mean you didn't know there are more than one type of Bermudagrass on the golf course.  Well, let me ask you a question, do you like tomatoes?  If yes, what's your favorite type?
Tomato/Tomatoe
You see, there are many different types of tomatoes and similarly there are many different types of Bermudagrass.  Our 100 plus acres is mostly comprised of Tifway Bermudagrass (A.K.A. 419) but there also areas of Tifgreen (A.K.A. 328), Celebration, and Common growing on the golf course along with genetic off-types mutated from the 419 planted ten years ago (Grandma's Quilt).  You may or may not have noticed certain irregular shaped patches greening up quicker than its neighbors earlier this spring.  Similarly, there is a newer Bermudagrass variety now on the market known as Latitude 36 CLICK HERE.  It was bred to possess a higher cold tolerance threshold than 419 or others and is available from our grass supplier.  We will be incorporating some in these injured areas to see how well it passes the test.  Fingers crossed the Latitude 36 could well be the key to reducing winter injury in our susceptible areas in the future.

That's all for now, time to get back on the course and continue to give our Bermudagrass the TLC it needs to get the course where we all want it.  If you have any questions, comments, or concerns please don't hesitate to email me directly.  I am always happy to help.

See you on the course,

Matthew Wharton, CGCS, MG

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