Lack of Air Movement Thins-Out #6 Green

Hot humid days and nights, 23" of rain in 9 weeks and a lack of air movement over the surface of this small green weakened the grass to such a degree that it no longer can tolerant normal golfing traffic or mowing without thinning out.

An article in the Wall Street Journal, The Ugly Summer of 2010, by John Paul Newport explains why this occurs. "Grass does have a mechanism to cool itself. It's called evapotranspiration and is analogous to perspiration. The roots draw up water from the soil and it evaporates through the plant's leaves, dissipating heat. But when greens are scalped to a quarter-inch, an eighth of an inch and even shorter, the leaf surface available for transpiration declines."
"Prolonged heat causes other problems. One is that root systems shrink, sometimes to within a half-inch of the surface, reducing the amount of water drawn up to the top. Humidity and heavy rain make things even worse. Humidity retards evaporation, while soggy soil stays hot longer than dry soil does. Puddles and saturated soil also create barriers that prevent needed oxygen from getting to the roots. Even when the combination of these factors doesn't kill bentgrass and poa annua outright, it weakens the turf significantly and renders greens more susceptible to fungus and disease."
"When hot weather hits bentgrass courses, course superintendents raise mowing heights. That yields more leaf surface and improves evapotranspiration but can slow down putts by a foot or more on the Stimpmeter, which measures green speed. "Better slow grass than no grass" is a mantra among greenkeepers, but the pressure from golfers to keep the greens rolling fast is relentless.
We have raised the mowing height on #6 to aid in its recovery and have roped off the front of the green to divert traffic away from its bottleneck approach.