Oak Tree’s Greens Are Ready for a Tussle

Oak Tree National superintendent Josh Cook (pictured) uses a prism gauge to better monitor the condition of the putting greens during the U.S. Senior Open. (USGA/Brian Whitlark)
By Ron Driscoll, USGA
July 11, 2014

EDMOND, Okla. – Despite temperatures topping 100 degrees earlier this week, and similar figures expected this weekend, Josh Cook, the golf course superintendent at Oak Tree National, is pleased with the course’s condition for the championship.

“If you had asked me a year ago, we would have taken this,” said Cook, who became the superintendent here in January 2012. “It’s a challenge, but it’s a manageable challenge. We could be a lot hotter and more severe in July.”

Cook’s maintenance regimen leading into this week has helped Oak Tree National’s greens retain the firmness that the USGA prefers for its championships.

“We topdressed our greens last week, which might be considered unusually close to the championship,” said Cook. “But it was part of a very aggressive program we established to achieve firmness with good moisture. The topdressing allows the greens to play a bit firmer and roll a little bit truer. I think if we hadn’t done it, we might have wished before the week was over that we had more [topdressing] sand down there.”

Cook believes that the approach he and Brian Whitlark, USGA agronomist for the Southwest Region, are taking is not only beneficial for this week’s U.S. Senior Open, but for the long-term health of the putting surfaces, which are made up of dominant creeping bentgrass.

“If we could keep the greens sopping wet and still challenge these guys, well, sign me up,” said Cook with a laugh. “We know that’s not realistic, just as saying I’m gonna go ahead and dry them out tons is not a good approach, either. You can only use water to manipulate firmness to a degree. It’s a balancing act, where you’re walking the line of maximization of performance and maximization of health.”

Cook, who apprenticed with David Stone at The Honors Course in Ooltewah, Tenn., for six years before coming to Oak Tree National, has stepped up his expertise in green mower setup, which he thinks will help his putting surfaces in the long term.

“When you are able to mow more efficiently and not stress the plant, your greens are going to develop deeper roots,” said Cook. “When you’re deeper-rooted, the greens have more access to water, so you can reduce the amount of water you have to put down. Less water means that you’re less susceptible to disease, with the result that you will require fewer [chemical] inputs. So you can protect the plant while still challenging the players. It’s completely holistic – at the end of the day, we’re lessening our environmental impact.”

Cook’s quest for improved mower setup includes the use of a prism gauge, an innovative tool that allows him to study the putting surface magnified at ground level and make adjustments not discernible to the naked eye.

“The gauge’s value is twofold: it’s really useful for evaluating the quality of the mower cut, and it also allows you to measure the effective height of cut,” said Cook, who earned his graduate degree in turfgrass management at Penn State.

“There’s this assumption that if we set the mower at one-10th of an inch, that it’s mowing at a 10th of an inch,” said Cook. “Right now, we are mowing at .150 of an inch – which is a pretty conservative height of cut, particularly for a championship. If we were cutting at that height and that was the effective height of cut, we would have some pretty disgruntled players. But in effect, the height of our greens is between .08 and .09 of an inch. People are tempted to look at that difference and wonder how it is even possible.”

Cook and Whitlark note that a number of variables can affect the measurement, principally the “angle of attack” of the mower blade. The mower reel cuts the grass on what is called the bedknife, and the more that it stands up the grass blade, the lower it cuts the blade. This angle of attack can vary the effective cut by 0.60 to 0.70 of an inch.

“If we actually mowed at .80 of an inch, we would probably kill our greens,” said Cook. “We would literally cut the sod off the top. It’s important for us to understand what the plant is experiencing, and when something doesn’t look right, the prism gauge is the first thing I’m going to look at.”

Whitlark works with hundreds of courses throughout the Southwest, and he is a strong advocate for using the prism gauge.

“It’s pretty eye-opening, isn’t it?,” he said of the 30 to 40 percent difference between mower height and effective green height seen at Oak Tree National. “We really encourage using them regularly to evaluate the green’s charateristics.”

In the meantime, Oak Tree National’s greens are primed for a grueling July weekend.

“These greens are tough and resilient and ready to get punched in the face, if you will,” said Cook. “They’ve got a good jaw right now."

Ron Driscoll is the manager of editorial services for the USGA. Email him at rdriscoll@usga.org.

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