Tips From The Pros

HOW TO LOOK AT TURFGRASS – PART 1: THE BASICS

April is the time when many turfgrass managers in the middle and northern parts of the US see their cool-season grasses begin to green up. It’s a great time of year, you feel like a turfgrass manager again.

Regardless of where to practice your craft, the very successful turfgrass manager has developed her or his observational skills to an advanced level, even if they don’t know it. Let’s face it, we can test the soil, water and even the grass tissue. We can collect data on all sorts of things, and these data are crucial information for the turfgrass manager. But many, if not most, of our most important field management decisions are based on our routine observation of the turfgrasses and playing surfaces. It’s really a learned skill, how to see turfgrass and use what we notice in the read-and-react world of elite turfgrass managers. Sure, you can often get by on a pre-planned, recipe-style of turfgrass management. In fact it’s essential. But I believe that to get to that next level as a turf manager; what separates the “grass-whisperer” from the average is a well-developed set of turfgrass observational skills. Perhaps it is best described as a subjective art, based in science. If you can already spot and identify signs and symptoms of turfgrass stresses and other maladies before anyone else, you already know what I mean and hopefully you can find a few tips here that can further advance your hard-earned skill as a sight turfer.

Turfgrass, in the ideal sense, is a uniform, mowed mat of healthy grass or grasses cultivated to meet our particular need. Uniformity, or consistency of the green color is perhaps the first thing we humans notice as an indicator of a quality stand of turfgrass. If it is uniformly green, mowed and dense in canopy, that is what we like. Doesn’t it then stand to reason that if we like and look or uniformity and green color that anything we notice that is not green and uniform is not what we like and are looking for in a quality turfgrass?

The basis of sight turfing is using our eyes as our most important and effective turfgrass health and happiness diagnostic tool. A little background on how our eyes is helpful.

We know that the human eye is sensitive to electromagnetic radiation in wavelengths ranging from about 400-700 nm. This is called the visible spectrum that ranges from blue light at the lower end of the visible spectrum and up to red light at the high end of the wavelength spectrum of visible light.

The important thing to know

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In daylight, we humans have a much greater sensitivity to green light, right at the edge of yellow, than at anywhere else in the spectrum. It’s interesting that in dark conditions, our highest sensitivity to light drops down to around 507 nm, the lower end of the green light wavelengths, almost blue. Perhaps this is an inherited evolutionary trait, the result of eons of natural selection in humans. Perhaps it was an advantage at one time to have anything green in our world stand out to us and be noticed. In a world of brown rocks and soil contrasted by green plants, a random mutation resulted in a higher sensitivity to green light wavelengths and this held as an advantage over those that did not inherit this mutation where the cones that sense green light react most easily and over a larger part of the visible spectrum. Green meant the location of foliage, of sustenance. Just a wild guess on my part. All the sight turfer needs to really understand is that we are far more sensitive to green light than the other colors, even close to 100 times more sensitive to green light than light in the extreme red or violet ranges of the visible light spectrum.

This “green-wash” effect is no good for sight-turfers. It effectively gives us a biased look at how green our grass is. We have difficulty teasing out the other wavelengths that are also reflected by green grass leaves. Remembering basic botany and how healthy plant leaves generally absorb and use light in the red and blue wavelengths, while reflecting light in the green color of the visible spectrum. So when we look at turfgrass, we see the green light reflected off the leaves of the grass plant. With our green sensitivity, we are awash in green.

One good sign of stress in the grass plant is the breakdown or damage to the chlorophyll in the leaves.

When this happens, for whatever reason, the leaves will start reflecting less green and start reflecting more of the other colors. So when your turfgrass plants begin going into stress, they begin looking less green. For example, when turfgrasses go into drought stress, one of the signs is slight blue to purple coloring of the turf. But because of our spectral sensitivity to green, we don’t notice the changing colors until it becomes more pronounced.

Turf Tips 101: Quality Sunglasses as a Turfgrass Observational Tool

This high sensitivity to green light in humans is why I always have a high quality pair of sunglasses to observe turfgrasses. Maybe we should call sunglasses “light conditioners”, this would make more sense. They are not made for looking at the sun. On a basic level, they filter and condition the light that is reflected off things (our turfgrasses) or emitted by things before it reaches our eyes and is sent to the brain for interpretation. With the right filters, we can essentially tone-down our high sensitivity to green light when we observe our turfgrasses. We can tone down the blue light, which tends to easily scatter and reduce contrast and clarity. Knowing that when we are observing turfgrasses we are looking at reflected light, we can filter out glare, our difficulty in seeing in the presence of bright light.

Good sunglasses will tone down to intensity of outdoor light so our eyes can work more efficiently. Light intensity can be measured in lumens (lm). Typical indoor artificial lighting is 400-600 lm. A bright, sunny day is typically about 1,000-6,000 lm, and above 4,000 lm our eyes can begin to have difficulty in absorbing light. At 10,000 lumens (think high-altitude snow field on a sunny day), damage can begin to occur to the eyes. Different tints and thickness, along with the material used in making the lenses will affect how much light is transmitted through the lens to the eye. The percentage of the suns light that passes through is often called Visible Light Transmission or transmission rates. The better sunglass companies show this rate for their different lenses. For brighter outdoor lifestyles, I like about 12% for a transmission rate, but your preference may be different.

A quality pair of sunglasses will filter out UV and other rays harmful to the eyes. Some of these rays are linked to degenerative eye maladies over time. Cheaper sunglasses may not afford these protections and may even make things worse.

It’s hard to pin down one tint or type of sunglasses as best for observing your turfgrasses. Light angles and intensities from the sun change during the day as the sun moves through the sky and changes occur in the atmosphere, like water vapor and clouds. In lower light conditions like dawn, dusk and heavy cloud cover, yellow tinted glasses are my preference because they tend to “gather” light and increase contrast. As the sun rises higher in the sky, say mid-morning, a copper or rose tint is what I like. They tone down the growing light intensity as the day progresses and cut down some of the easily scattered blue light, helping with clarity and contrast. In the high, bright sun of mid-day, I would prefer a grey tint to best reduce intensity and improve visual clarity. Then, as the afternoon progressed, back to copper tint, then back to yellow tint at dusk. Obviously few of us can afford 3 sets of sunglasses for the day and it isn’t practical. Some companies offer sunglasses with interchangeable tints to play out the day and changing conditions. I have not had very good success with these, but maybe you will. So I go with the more middle-road copper tint. They work in all conditions of the day. I put a green mirror on them to decrease the transmission a little more and reduce more green wash.

Again, you may prefer different tints and transmission percentages. There is no wrong way to go here. Just make sure you get a quality pair that you like and are comfortable. As a turfgrass manager, you will likely be wearing them a lot.

NOTE: Don’t confuse sunglasses with required safety glasses you need for certain tasks. Some sunglass lenses may be made of the right materials to qualify, many do not. So do your homework before you assume your favorite sunglasses also qualify for your safety glasses.

You have got to get the right frame, and frame sizes for your head. The arms of the frames should also hinge outward a little to accommodate winter caps you want to wear over your ears. This way, you can widen-out and go outside the hat, a warmer and more comfortable way to go.

If you wear prescription eye glasses, you want to find a company that can make you lenses that accommodate your prescription.

In selecting your daily sunglasses, keep in mind that you want to strike a balance between the filtering of green light (and others) with a comfortable look all day. In other words, you don’t want to filter and whack-out your view all day, just condition the light comfortably to give you a better view of what is happening with your turfgrass. If your turfgrass looks a little worse than with the naked eye (green-washed), you have found the balance. Bottom line, is get a tint you like in a comfortable frame. In some climates, you might wear these every day, all day.

Any good pair of sunglasses will be polarized. Make sure yours are.

Where I buy my sunglasses.

There are other fine sunglass companies where you can a pair that is just right for you, but I recommend you design your own frame and lenses at Costa Sunglasses. I believe their technology and quality are superior, and they have a great repair service that is fast and inexpensive, should you break yours. My preference is the copper lens with a green mirror. Send them your eyeglass prescription and they will make them for you.

If you want to really filter out all of the green light reaching your eyes, you might try some plant stress detection glasses. These are the purple-lens glasses that block out almost all of the green light.

Coming May 2017: Part 2 – Take it to the Field. Using this knowledge to improve your turfgrass observational skills.

Resources of the Month:

Physicsclassroom.com has a good primer on light waves and color here.

Lightmeasurement.com has all sorts of information on light, including this description of spectral sensitivity or “Green Wash”.

Drill down deep on sunglass technology listening to this 30-minute fly-fishing podcast with the VP of Product Development for Costa Sunglasses. Great advice on choosing the best pair for you.

End Quote:

“You can observe a lot by watching” – Yogi Berra