COURSE CARE
It’s Not Dead…It’s Brown November 12, 2013 By Chris Hartwiger

Puzzled by brown bermudagrass in winter? The answer involves chlorophyll, light intensity, and temperature.

Sometimes we are so accustomed to things around us that we forget people may see things differently. Many years ago, I recall a conversation I had with a golfer visiting the Southeast during the winter. He enjoyed the golf course, but was convinced all the bermudagrass was dead because it was brown. I shared with him the reality that when temperatures get cold enough, warm-season grasses like bermudagrass lose their green color and turn brown. Unfortunately, I did not have a good answer for why the bermudagrass turned brown. A quick trip to my turfgrass library and the answer was provided in Dr. Beard’s book Turfgrass: Science and Culture. A brief description of winter discoloration of bermudagrass is described below. 

An explanation of why bermudagrass turns brown in the winter involves an interaction of three items: chlorophyll, light intensity, and temperature. Chlorophyll is a green pigment that gives turfgrass leaves their color. It absorbs light in the energy-producing process called photosynthesis. Chlorophyll production in a turfgrass plant is highest when light intensity is lowest. This can be seen by observing green turfgrass plants in shaded environments. As light intensity increases, the rate of breakdown of chlorophyll increases and the total content of chlorophyll in the leaf decreases. As temperatures decrease, the growth rate of the plant decreases and which includes the production of chlorophyll. When light intensity is high and temperatures are low enough, the rate of chlorophyll breakdown exceeds the rate of chlorophyll synthesis and the turfgrass plant leaves turn brown (Beard, 1973). In other words, chlorophyll is breaking down faster than it can be produced. 

We are now entering a season where golfers will see plenty of brown grass on southern golf courses. Fortunately, golf is played on grass, not on color. Enjoy the nice fall days ahead and we hope to see you on the links or at an upcoming turfgrass conference. 

References: 

Beard, James B., 1973. Turfgrass Science and Culture. Prentice-Hall, Inc., Englewood Cliffs, NJ. 658 p.

Source: Chris Hartwiger (chartwiger@usga.org)

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