Friday, October 19, 2012

2012 Fall Cultivation

Autumn is a favorite time of the year for most golf course turf programs in our area particularly if they are managing predominantly cool season turf. The vast majority of the turf varieties here at Granite Bay are of these cool season varieties and these types of grasses will always perform much better when it is cooler hence the classification. Cool season varieties actually start to vigorously grow again after a slowdown during hot weather along with a natural rejuvenation which makes this time of the year one of the best times to cultivate and help this rejuvenation process along. 

We have many different ways to cultivate turf on golf courses and have addressed many of these cultivation processes in past course updates. The two most frequently used cultivation techniques utilized by turf managers include Aeration  and  Vertical Mowing. There are many different ways to aerate or vertical mow utilizing many different pieces of equipment that are specialized for different areas of the course like putting surfaces or fairways. We tried a new cultivation technique on our fairways this fall that I think will be very beneficial moving forward.

Removing thatch #11.
The unique fairway situation we have here at Granite Bay has been addressed in the update "Why We Get Wet in the Summer". In short we have different grasses in our fairways with a large percentage of  the turf being bentgrass. Bentgrass by nature produces a very dense and soft thatch layer below the turf leaf surface that literally acts like a sponge. This thatch layer is what makes Granite Bay soft in the summer and incredibly difficult to irrigate. We spend allot of time and effort in Irrigation Management yet overall firmness in the summer continues to allude us. The culprit of this softness is this bentgrass thatch and the solutions are not without some sacrifice. 

The new cultivation tecnique that we just concluded has promise in the removal and dilution of this thatch and I am optimistic can be very beneficial to our fairways. Core aeration has always been our traditional method of removing thatch in the fairways. That process removes a core of  turf and thatch along with  soil and roots which is allowed to dry and are then picked up after chopping and dragging and vacuuming up whats left. We remove some thatch in the process but but the holes produced  become clogged up during the above mentioned cleanup and difficult to get our new founded allotment of topdressing sand into. This new allotment of sand should technically firm these surfaces up in time but we need to get the sand into the thatch layer to dilute, firm and facilitate further biological breakdown. 

Deep slicing to a depth of 3/4". We feel this process removes
more thatch while facillitationg sand and seed  along with
being less disruptive then core aeration.

Harper verticle mower in action removing spongy thatch
only, no soil.

Therefore we tried a different process this fall which is a form of vertical mowing. Vertical mowing remember is the cultivation procedure where verticle blades actually slice into the turf canopy removing thatch in the process. Getting down deep enough to actually thin out this spongy thatch required a new piece of equipment that worked very well. The process removed over twice as much organic matter then core aeration and no native soil so the cleanup process was  much quicker allowing us to get sand and seed down directly after cleanup and into the narrow slits effectively diluting the bentgrass sponge layer. After going through the entire process, I believe it is a superior way of thatch removal for our fairways as opposed to core aeration. Punching holes to provide air in the root zone is necessary and beneficial for our fairways however can be achieved with solid tine aeration in conjunction with this new deep vertical mowing. Again I really think this procedure can make a diffrence with what I would considor less disruption and quicker recovery.

Cleaning up the mess

Applying topdressing sand immediatly after cleanup of
the deep verticle mowing.

Weed Control
Directly ahead of our fall fairway cultivation we sprayed out a weed called Knotgrass (paspallum distichum) which has been encroaching in certain areas of the course for awhile. Currently there are no good selective control products available for Knotgrass, (herbicides that remove the weed and don't effect the desirable grass) and we should know as we have tried a number of them over the years. The Knotgrass encroachment reached unacceptable levels this summer so just prior to fall cultivation we treated the areas of encroachment with a non selective product (herbicide that kills vegetation indiscriminately). The treated areas are  currently very noticeable but have been seeded and will in a short time fill in with desirable          turf. It is currently the best season for germinating seed hence our timing of treating the Knotgrass just prior to cultivation. 

Closeup of Knot Grass (paspallum distichum). This is a perrenial
weed that will come back every year from dormant roots and
cintinue to spread.

Spot treated fairway in an attempt to selectively control
Knot grass with an experimental product. The combonitation
experimental product worked better in the desireable  turf
so we treated with a non selitive product and followed up

Putting Surface Aeration
Two weeks ago we completed the 5th aggressive aeration to the putting surfaces. Since employing this aggressive procedure in the fall of 2010 the surfaces have improved however have not been with out issues. On the improvement side they have gotten firmer and recent physical soil analysis has shown that air pore spaces vs. water pore spaces in the top 3" have moved from 4 to 1 respectively to 2 to 1. Ideally we would like to get to 1 part air to 1 part water holding as far as soil pore sizes are concerned in the top 3".  These changes are due to the aggressive core aeration we have adopted which removes excessive organic matter and dilutes the profile with mineral sand. The goal of a 1 to 1 ratio is achievable considering the movement that has been made in two years . Setbacks this past year were  root disease issues that still have a link to organic matter and its moisture holding capicity so continued diligence in core aeration is a must. Additionally the bad batch of sod and the rush job in which we replaced the perimeter of #14 green awhile ago is not acceptable so we are replacing it with thick cut homegrown nursery sod this week. At some point we just have to  literally "cut" our losses. 
Continued agressive core aeration will be the key to getting
the putting surfaes at Granite Bay performing the way we
all want.

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