I mentioned in an earlier post that I would describe how I maintain greens
and why I do it the way I do. If you look at how a green performs there are a
number of items that have to be taken into consideration. Firstly there’s the
playability, which the golfer is most concerned about. Speed plays a
factor but more importantly is how smooth and true the surface puts. There’s no
point in having a fast green if the ball deviates from the line due to a poor
surface. To a point these three items are connected to each other and if one if
out if can affect the others. The second part is how the green performs
agronomically, again if it’s improperly maintained the playability is affected
and the potential for turf loss increases.
The greens at LedgeRock are built to USGA specifications, which means
they are sand based and designed to drain water quickly while still holding
some to sustain growth. It is based on a perched water table which essentially works
like a toilet, ie it retains water to a point until it reaches a point where it
flushes. For this reason it is important to manage water correctly as to ensure
the system isn’t overloaded and remains too wet. I described in the irrigation post how we monitor the moisture and keep them as dry as possible only loading
the system when necessary and then drying it down. By doing this it ensures
that we don’t run into issues with waterlogging which can ‘drown’ the turf. The
more air that is available to the plant the better, both on the surface and to
the root system. By keeping the greens
dry, they are firmer which is the first part of maintaining speed and trueness.
The greens here are creeping bentgrass which is an ideal turf as it
produces a great consistent surface all year. The other main greens type turf
in the northern US is Poa annua which is essentially a weed grass that is very competitive
and can get established quickly if it is not taken care of. Poa is a winter
annual so prefers cooler wet conditions (and a reason why keeping the turf dry
helps keep it out) so it doesn’t do well during the summer. Since it adapts to
its environment quickly, it can be very different plant from one place to
another – even on a green – hence why bentgrass is the better option for year
round consistency. Poa is also capable of producing seed without a large seed
stalk so in the spring it is a major concern as when it goes to seed as it creates
a bumpy surface. Bentgrass does not go to seed at low heights of cut so this is
another reason why it is a better putting surface.
There are a number of ways to try and eliminate poa annua but it is very
difficult to keep out. There are chemicals available but they can be risky on
greens height turf (although there is one coming out soon that looks really promising).
Plant Growth Regulators (PGRs) can be used also to manage poa in bentgrass turf,
but, I believe they are a cheater way to manage greens and they can make the
plant fat and lazy. I liken them to humans using steroids…… By regulating
growth they are also used to manage green speed, however, if done correctly,
this can be done using nitrogen – ie reverse growth regulation, if you don’t
feed it, it won’t grow!! My other issue with growth regulators is that they
make topdressing more difficult. If the plant isn’t growing, then it can’t grow
through the topdressing so therefore you can’t put as much sand out. One could
use the argument that if the plant is regulated then it’s not growing so you
don’t need as much sand but under regulation it is still producing thatch and ‘fattening’
the plant so topdressing is still important. I keep poa out by managing the
bentgrass in a way it likes, but poa annua does not (ie minimal water with low and
slightly acidic fertility). It is not 100% fool proof but it is very effective
and our poa content is minimal (<1%) which is fantastic for a course of our
age.
This leads me to thatch management.
Thatch is the buildup of organic matter in turf. Mat is the name given to
thatch that has been broken up with sand. The organic build up comes from the
plant itself. Creeping bentgrass is a stoloniferous grass which means it
produces runners – like a strawberry plant. These runners grow along the
surface and as the plant grows it produces more which in turn causes thatch to
build up. It can be physically removed by verticutting (literally ripping them
out in a vertical motion), by core aeration, topdressing to dilute it and managing
how much it grows. I’m not a big fan of verticutting (although it can have it’s
place). A stolon will produce a new shoot if cut, so if you cut a runner you
are essentially creating a new plant so creating a vicious cycle. It should be
noted that a little mat is essential
to make the greens receptive and he surface more resilient.
Here are two cores pulled from LRGCs greens mid last July. These roots are excellent for that time of the year when due to the heat etc roots are in decline. Have roots this long means the plant is capable of handling more stress. In the second picture you can notice the slightly darker soil near the grass end which is the mat layer and shows how well managed LRGCs greens are as it is largely consistent with the sand in the remaining profile.
Grooming is a version of verticutting but it is not aggressive and usually
is not deep enough to cut the stolons. They are fitted the front of a mower and
help stand the turf up for a better cut. Since it adds more stress to the plant
I usually stop it during the summer months (and after we topdress as it pulls
up the sand!!!) but use them a lot in spring and fall to ensure a perfect cut.
A Toro fairway Grooming Reel (the groomer is the black piece in front of the blade)
The limiting factor to any
drainage system is the slowest draining part and thatch is very slow to drain –
hence why keeping it under control is essential to keeping a green performing
correctly. Due to using PGRs and the inconvenience topdressing a lot of
superintendents are topdressing with very small amounts of topdressing on a
frequent basis. While this makes some sense to me the volumes are still not as
much as just going out every 2-3 weeks and putting out a proper amount of sand that
can be brushed in. The brushing process is very important as it moves the sand
around (while also knocking it in) and it fills in any imperfections which
helps smoothness and trueness. By going with the small frequent amounts you
miss out on this important factor. Below is a picture of a green being brushed after (hollow core aeration) and topdressing.
The sand used is also very important as it is essential that it matches
what is in the rootzone to ensure the drainage works properly and that the sand
doesn’t move or shift underfoot. When we topdress I also aerate using needletines
(tiny solid spikes that are barely noticeable) which helps dry out the green
and also provides air to the roots which keeps them strong. Sometimes I will
spike instead which is a small triangular tine which doesn’t go deep but due to
the larger surface area provides more air the surface. We hollow core aerate
twice a year. This physically removes thatch and also proves a nice channel
that can be filled with fresh sand to provide air to the roots for a longer
period. It is neat to see during periods of high stress the greener circles
where the last aeration holes were. I have our topdressing program tweaked to
the point where it is not a major inconvenience. I use a product that
eliminates the dew on the mornings after I topdress, in doing so, the mowers do
not pull up sand and balls are not affected by it. Remember topdressing is key
to keeping thatch under control and by doing so keeps the greens firmer and it
also is a major factor in smoothness and trueness which in turn increase
greenspeed. Here are some pictures of the needletine aerator in operation. The roller on the back of the machine ensures disruption is kept to a minimum.
And this is a video of the same machine core aerating.
Most young golf courses have a ‘grow-in thatch’ layer which is caused by
pushing the turf with fertilizer during construction to get the course open. I
was aware of this before the grow-in here and ensured I grew it in a way to prevent it. Luckily we had the benefit of having some extra time for the grow-in so the greens reaped the long term benefits. This has
proven to be a great decision as we did not have the dreaded layer and our
thatch/mat levels are exactly where they should be and fully in check. I have
tests performed every two years to ensure that the thatch is remaining under
control and that the programs in place are working effectively and if not I can
make changes before it becomes an issue.
By not using PGRs I do need to mow low which causes more stress on the
plant, however by maintaining the greens the way I do (and the fact they are
bentgrass) means they handle the stress with ease. But by doing this
they sometimes look a little thin especially when the (black) algae appears but
this is nothing to worry about once they remain to putt extremely true and
smooth, their playability is my biggest concern. The thin turf means you can
see the algae whereas normally it would be hidden under the leaves…. Air
movement is essential to keeping it under control but, unfortunately, due to
rain I don’t always have that luxury so we have to deal with it. Since it is on
the surface it does not affect ball roll so does not affect the greens
performance other than not being aesthetically perfect. These are pictures of algae on greens.
The last thing to talk about is rolling. I check green speeds daily and roll accordingly. Due to the way I maintain the turf, rolling is not always necessary as it would make the greens too quick!!! So if the speed is in the optimum range I will skip it that morning, so just because the roller isn’t out it doesn’t mean the speeds are any slower!!
The last two items I will discuss further in
another post are why we need the fans and why frost causes issues.
So to sum up, I don’t use (like) PGRs but
manage growth with fertility, I like heavy topdressing every 2-3 weeks to keep
thatch under control and keep them smooth and firm, keep water to a minimum and
manage poa annua by making the bentgrass more competitive.
If you managed to make it to here, sorry
for the long post, but I like having it all as one rather than spread out throughout
the blog….
