on the greens
Date : 11/17/2015
Growing Grass, It
In a previous post I described our algae problems from this last summer using the “Pest / Disease Equation”***, which is a THEORETICAL model by which we gauge pest / disease pressure, which in a golf course setting is almost always fungal disease.
A pest / disease needs three components or situations to exist for it to effectively be considered a pest:
- Host: Something for the pest / disease to grow on or attack, in our case the host is grass
- Pest / Disease Presence: A pest / disease cannot exist if there is no living presence of the fungi, virus, grub, etc.
- Suitable Environment: Like any other living organism, pests and diseases can often only grow and survive under certain environmental conditions
The pest/disease equation works like this:
Pest or Disease Pressure = Host x Pest Presence x Environment
Now this is in large part, THEORETICAL. We really can’t thoroughly quantify these variables. For instance, we can’t be very specific about the suitability of an environment, but we are able to gauge if it’s very suitable, kind of suitable, or not at all suitable. So lets apply this to a real-life situation. Michrodochium Patch (pictured right) is the bane of PNW golf course management. Here is how we use the pest / disease equation to gauge disease pressure and how to best combat the occurrence of it:
- (Host): Our greens have a type of grass that is very susceptible to M. Patch, so this variable is HIGH
- (Presence): We’ve had a history of substantial M. Patch pressure in the past so our disease presence most likely is HIGH
- (Environment): M. Patch thrives in wet, cold, cloudy climates, so our environment variable is SET TO POWER RANGER (VERY HIGH)
Our M. Patch equation looks like this:
(Host) High x (Presence )High x (Environment) Very High
Thus (Disease Pressure) = High to very high
One of the first things we were taught about multiplication is that anything multiplied by 0, equals 0, so our goal in the management of M. Patch is to set any of the variables in the equation to 0. THEORETICALLY , depending on what fungicide we use, we either eliminate the growth of M. Patch (equation 1), or protect the turf so the disease can’t attack it (equation 2). So ………
1: (Host) High x (Presence) Zero x (Environment) Very High
2: (Host) Zero x (Presence) High x (Environement) Very high
Either way, (Disease Pressure) = 0 (THEORETICALLY)
IT’S NEVER THAT SIMPLE, but this does represent how we think about disease management.
In the same way that the disease equation helps conceptualize how disease develops, the Grass Growth Equation can help us think about the impact that Dodd-Frank has had on our 401K contributions over the past calendar year.
……. Wait, what?
Just kidding, it helps us think about how grass grows. ( I had other names like ‘Al-Grow-rithm’ and ‘Paycheck = Grass x Fertilization’ …… it just wasn’t my day for making up names)
Let me first say that this equation is a GROSS OVERSIMPLIFICATION that doesn’t take into account soil type, the presence of soil or a growing medium, grass type, temperature, disease pressure etc., but for all intents and purposes, gives us an important starting point for gauging the potential health of our turf. All other details aside, the components of this formula need to be available in some capacity for grass to grow at all.
Grass grows by photosynthesis, in which it harnesses light energy from the sun and uses water and nutrients to produce new plant material:
Growth = Direct Sun Light x Water x Nutrients or Fertilizer
Just like the disease equation, if any of these variables are set to 0 then you don’t have grass. For instance, this last summer, we were severely lacking in Water and thus, despite an abundance of Light, we didn’t have a lot of grass growth in some places on the golf course.
Like the disease equation, we don’t have a great way to quantify these variables, BUT we are able to recognize when these variables are very low or essentially set to 0.
Smart phones are incredible tools. Available on the Iphone is an app called Sun Seeker, which shows the path of the sun throughout various times in the year from where you are standing at that moment. By standing in one spot and slowly rotating 360 degrees while holding the camera at a steady height, you can get an on-screen representation of the path of the sun throughout different times of the year. This allows you to see where the sun rises and sets, in addition to showing where buildings, trees, or geographical features may block out sunlight on that given area for a given time of the year.
Recently I used Sun Seeker to map the path of the sun from the back of the third tee box on the Green course. It’s an area turf that always struggles, and it is no secret that sunlight is lacking. However, I wanted to know exactly how little it was getting:
The various sun paths are represented by these lines:
Aqua Line: Path of sun on Decemeber 21st (approximate winter solstice, appears in pictures 3-7)
Yellow Line: Path of sun on that day’s date (November 5th, appears in pictures 3-7)
Light Green Line: Path of Sun on March 19th (approximate spring eqinox appears in all pictures)
Red Line: Path of sun on June 21st (approximate summer solstice, appears in all pictures except 5)
Facing the Northeast, the sun is only in that part of the sky for the very middle of the summer. In addition, during that time of the year the pictured Pin Oak is full of leaves and the branches hang down even further, so the tee box receives effectively no direct sunlight from that part of the sky all year long
Facing East by Northeast you can see that in the middle of the summer we start to see a little bit of sunlight from this part of the sky, maybe 15 minutes around the time of the summer solstice.
Facing effectively due East, you can see that the tee box receives anywhere from 1 to 4 hours of direct sunlight from the March 19th to the September 20th (which would effectively be the same sun path as March 19th). The reason that this tee box survives at all is probably due to the fact that this is mostly early morning sunlight, which for photosynthetic efficiency reasons, is often the most effective for grass growth.
Almost zero sunlight for the entire year. These pictures effectively cover the remaining cardinal directions. The red line is partially or entirely outside of the frame in these pictures, but even so, it never gets high enough to get over the trees surrounding the tee box.
So lets use this information to test our Grass Growth equation for this point in the year:
Direct Sun Light = nearly zero
Water = High
Nutrients or fertilizer = Moderate
Plugging that into the equation we get:
(Direct Sunlight) Nearly Zero x (Water) High x (Nutrients) Moderate = (Growth) zero or nearly zero
So THEORETICALLY there shouldn’t be much grass growing in this location…..
…… and there certainly isn’t much!
Like I said before, this equation is an over simplification. It doesn’t take into account disease pressure, species of grass, soil type, etc. The important message is when we diagnose problems with our turf quality we have to start with the most important components. If all of the above are adequate, and we still have problems, then we have to get a little more scientific, but sometimes we have to be sure not to make the troubleshooting process more difficult than it has to be.
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