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
“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
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
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
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
Driscoll is the manager of editorial services for the USGA. Email him at