Relieving Turfgrass Stress: Part 1

Banyan-huahinWhenever I see unhealthy turfgrass, my first advice is to relieve plant stress. Relieving plant stress may involve adjusting the amount of water or air in the soil, optimizing the availability of essential plant nutrients, increasing the mowing height to allow more light absorption by the leaves, and very important but sometimes overlooked is this: cutting the grass cleanly.

My front lawn near Bangkok has three sections. Near the driveway is St. Augustine grass (Stenotaphrum secundatum), in the center section is centipedegrass (Eremochloa ophiuroides), and in the corner in broadleaf carpetgrass (Axonopus compressus). I took a selection of photos from the St. Augustine grass section last week, showing the damage that can occur when mower blades are not sharp or are not adjusted properly. Because St. Augustine grass has a wide leaf blade, the damage from dull mowers is especially evident in these photos.

Leaf-blade-mow 1 The tip of an unmown St. Augustine grass leaf has a boat-shaped tip. This is how a normal leaf tip looks, at right, with no damage at all from mowing. Once we mow the grass, what kind of damage can we expect? Remember, by relieving stress on the grass, we can make it healthier. If we have healthier turfgrass, we can manage it to create the desired playing surface. Obviously grass must be mowed to create the desired playing surface, so we need a good plan for mowing to avoid putting undue stress on the grass.

Leaf-blade-mow 3 Here is another leaf of St. Augustine grass from my lawn, but it has been mowed. You can still see the V-shaped leaf, but the boat-shaped tip of the leaf is now gone. A small amount of yellow scarring is visible at the mown tip, but this is a basically clean cut with no shredding. This is the type of clean cut you want because it minimizes the stress on the turfgrass plant.

Leaf-blade-mow 2 At bottom right is what you don't want to see when you mow. This is another St. Augustine grass leaf from my front lawn. The damage and shredding at the leaf tip from cutting with a dull mower puts stress on the grass and causes a problem with plant health, with visual appearance of the turf, and eventually that causes a problem with playability as well.

So to relieve stress on your turf, make sure that you are mowing with sharp, well-adjusted mowers, and that you are getting a clean cut and not one that is shredding the turf. Sometimes from a distance you can see a whitish or yellowish tinge to the grass; upon closer inspection (get down and have a look at the leaf tips) you may see that the leaves themselves are green and healthy but the leaf tips are shredded and damaged by the mower.

Also, think about what mowing height is appropriate to give the desired playing conditions and appearance. And if you mow the grass with a thoughtful and creative mowing pattern, you can improve the appearance of the grass while reducing some other inputs.

Five Ways to Improve Turfgrass Conditions

Golf_business_asia_cover_aug2009 I can actually think of ten simple ways to improve turfgrass conditions -- these are only the first five ways, and I will write more later about another five ways to improve grass. The article I wrote on this topic has been published in Golf Business Asia and can be downloaded here. So what do I think are the first five ways to improve turfgrass conditions?

1. Set course maintenance standards. If we have a certain level of grass quality, and want to reach an improved level of playability or appearance, we need to define what that standard is and what work must be implemented in order to achieve the desired quality level. For more details, an article I wrote on this topic can be downloaded here in English and downloaded here in Chinese (中文). A simple example is grass quality and tolerance of weeds in the fairways. If there is no standard for this, than at what weed threshold are the fairways acceptable, or unacceptable? When I was a golf course superintendent I was not a big fan of these types of standards, thinking them extraneous, but I now think that written standards, no matter how simple, are the starting point for any turfgrass management (or turfgrass improvement) program.

Warm_season_grass 2. Choose the right grass. I cannot overemphasize this enough. There are certain grasses that are well-adapted to certain growing conditions and that can be managed to provide the desired playing surface. There are other grasses that are less well-adapted to your growing conditions and that require a tremendous amount of maintenance in order to produce the desired playing surface. Or perhaps you struggle to achieve the type of playing surface that you want. Would a different species of grass or an improved variety of the one you are currently growing help to improve turfgrass conditions? It seems like a lot of wasted resources to manage grass that is not well-adapted to your site. For more information about this, you can search for the information you are looking for. There are some excellent turfgrass specific information resources available online, and I wrote about the best of them (in English) and you can also download the article about information resources in Chinese (中文). Also, you may wish to read an article I wrote for Golf Business Asia about managing and choosing warm-season grasses. And you can see a selection of photos of different warm-season grasses, along with some advantages and disadvantages of each, at this photo gallery.

3. Fertilize the right amount. This is critical for improving the grass. If I want to be healthier, one of the first things the doctor will tell me to do is to evaluate my diet, right? And I should eat a balanced diet with the right amount of fruits and vegetables and vitamins and minerals and so on. Well, grass is the same way, except it is a lot simpler. With grasses, we can conduct a routine soil nutrient analysis (a laboratory test of the soil's chemical properties) to determine how much of the essential plant nutrients are present in the soil, and how much should be added as fertilizer. In many soils, there is already enough phosphorus to meet the needs of the grass, and in some cases there is enough potassium as well. If there is not enough, then we simply add more. The key element to get right in the fertilization program is nitrogen. This is like me, if I am on a diet, being concerned about how many calories I eat every day. Eating more calories than I burn each day will make me gain weight, while burning more calories than I eat results in me losing weight. If the grass gets too much nitrogen it will grow too quickly, and if the grass doesn't have enough nitrogen it will become yellow and grow too slowly. The goal is to control the growth rate of the grass to create the desired improvement to turfgrass conditions by applying exactly the right amount of nitrogen. For many grasses, a good starting point for the amount of nitrogen to apply is about 3 g N m-2 month-1, during the seasons when the weather is conducive to vigorous grass growth. The exact amount of nitrogen to apply can be adjusted based on the turfgrass performance. For more information about this, see this article I wrote for Golf Course Seminar (in Japanese, 日本語) or this article from the Hawaii GCSA newsletter.

Sicc_zoysia_mow_pattern 4. Mow with a plan. After choosing the right grass and applying the right fertilizer, there is no way to get the desired quality without mowing properly. That means using mowers with sharpened blades, set at the proper mowing height, and operated at the optimum mowing frequency for a particular area. And as long as the mowers are going to be sent out to mow the grass, why not mow an attractive pattern into the grass? This may be a type of stripe or checkerboard or even no stripes at all, but it takes a plan to achieve the desired appearance after mowing. Get the mowing right and the grass conditions will almost certainly improve.

5. Keep the grass as dry as possible. Or perhaps more accurately, keep the soil as dry as possible. How is that going to improve turfgrass conditions? If the soil is kept dry, there will be more air space in the soil. When the water content of the soil is high, there is not much space for air. Roots_dry_soil Grass roots grow better when there is plenty of air space in the soil, and if you can establish a healthy root system, the playing surfaces will be more stress tolerant and the grass plants will be more healthy. To really manage the soil moisture, I find it is extremely useful to use a soil moisture meter such as the Hydrosense from Campbell Scientific, the Theta-Probe from Delta-T Devices, or the TDR Meters from Spectrum Technologies. For most turfgrass sites, I like to maintain the soil moisture at more than 10% (by volume) and less than 25%. You can find the optimum range for your site, and by using one of these meters, you can monitor the soils as they dry, only applying water when the soil reaches the critical point when the grass will begin to wilt. I wrote about soil water management extensively in this article for Golf Course Seminar (in Japanese, 日本語) and in Irrigation for Bentgrass Greens: Theory and Practice (for the Kanto Golf Association and also in Japanese, 日本語). If you are interested to know more about this, please send me an e-mail inquiry or leave a comment here.

The Five (plus one) Basics of Turfgrass Maintenance

Stanley Zontek is the director of the USGA Green Section's Mid-Atlantic region and is one of the most experienced and respected turfgrass specialists in the world. Zontek is also the longest-tenured employee of the USGA, working for this organization for the past 38 years. So when Stanley Zontek has something to say about turfgrass maintenance, I listen, and he has just written a superb article for the Green Section Record, which I think it is worthwhile to discuss here. The article is entitled When the Going Gets Tough, Go Back to Basics, and is summarized in a five word declarative: Basic turfgrass management costs less.

Zontek writes that "basics cost less and probably will, in the end, help you grow better grass for the golfers to enjoy." I agree completely, and am baffled at times by the complicated and costly maintenance practices that are sometimes employed on golf courses with questionable effect on the playing conditions of the turfgrass. Zontek goes on to outline the five most important basics, as he sees them.

Grass and sunlight Sunlight: Grass requires light for photosynthesis. Anything that blocks the light, whether it be cloud cover or trees or other sources of shade, will cause a reduction in photosynthesis and reduced plant vigor. Zontek says that "Huge amounts of money can be spent and all sorts of different products, programs, and techniques can be tried, but there is no substitute for sunlight. If sunlight is limited, you have a problem." So remove the source of shade, if you can. If it is clouds that are blocking the sun, then I suggest pre-conditioning the grass for low light conditions by increasing the mowing height, applying trinexapac-ethyl, and reducing the nitrogen application rate.

Water: Of course grass needs water, but Zontek says that "too much water kills grass faster than too little water, and playing conditions suffer." And he also notes that "water and the electricity needed to pump it are expensive." Water management of golf courses can always be improved, and minimizing the amount of water that is applied to a golf course should be the goal. I have seen too many irrigation systems being operated when the soils are already wet and when the sky is cloudy and even when rain is falling. Application of water in those situations is nothing more than a waste of money -- don't apply too much water, ever!

Urea on zoysia Nitrogen: Don't be confused by complicated expositions of plant nutrition and biostimulants. Most golf courses could save a LOT of money by more careful attention to their fertilizer applications. Zontek asks "What fertilizer nutrient really is the most important? Where should you spend your fertilizer dollars? The answer is very simple . . .  absolutely the most important is nitrogen . . . Nitrogen is the nutrient the grass plant needs the most." I can assure you that if other required nutrients (such as phosphorus or potassium) are at sufficient levels in the soil, then application of nitrogen only will be sufficient to produce the desired playing surfaces. Grass leaves contain (on a dry weight basis) about 4% nitrogen, 0.5% phosphorus, and 2% potassium. When there is already enough phosphorus and potassium in the soil, don't add more -- it will not give any benefit beyond application of a nitrogen-only product. If phosphorus and potassium are at low levels in the soil, then do add more, keeping in mind that the nutrients are in the grass leaves in a 8:1:4 ratio, and an annual fertilization plan with approximately that ratio of nutrients will produce healthy turfgrass plants. Fertilization really is that simple.

pH: If fertilization is really that simple, there is another simple soil chemical property to be aware of, and that is pH. Zontek says that "grass grows best in soils with the proper pH. It's just that simple . . . get your pH right. It allows the soil to take care of itself." What pH should the soil be at for optimum turfgrass growth? The pH should ideally be at more than 5.5. (at a pH of 5.5 or below, soluble aluminum increases and can be toxic to turfgrass roots). And if the pH is much above 7, the availability of some micronutrients can be decreased. For the most vigorous growth, maintain the soil pH in a range between 5.5 to about 7.5. Do you know the pH of your greens? Of your fairways? You should.

Set Priorities: Zontek asks "What is necessary for your golf course to survive? Remember, the beauty of the game is that every golf course is different. It is imperative to determine what is important for your facility and the golfers who play there." So think about what the priorities should be at your facility, and how to create the best-conditioned golf course that you can possibly have.

Those are Zontek's five most important basics: sunlight, water, nitrogen, soil pH, and setting priorities. Note that three of those basics (water, nitrogen, and soil pH) all have something to do with the soil conditions. The reason grass quality declines when too much water is applied is because the soils become soft and air in the soil decreases, causing a shortening of the root system. Nitrogen is ultimately taken up primarily by roots in the soil. And the pH is obviously a soil property. So the soil conditions are very important, but I want to add one more "basic" that I think all turfgrass managers should remember, one that is related to the turfgrass surface.

Kentos golf club panda mow Mowing: That basic is mowing, which is something that is done almost every day. Care must be taken to always mow with sharp mower blades at the appropriate mowing height. And I would encourage every golf club to consider the mowing patterns used at their facility. Mowing the grass in a pattern can enhance the appearance of the course and additionally a simpler mowing pattern may save 20% or even 30% in time and operating costs compared to a more complicated pattern. Mowing is perhaps the most important maintenance activity we do to the grass, and doing the mowing right will enhance the appearance and health of the turfgrass stand.

What are the most important basics of turfgrass management for you? Do you have other tips? I would love to hear them.

Mowing Patterns & Sharp Mower Blades


Turfgrass appearance is enhanced by the mowing pattern. Careful attention should be given to the mowing pattern that will be used at any turfgrass area, because just as a good mowing pattern improves the appearance of the turf area, a poorly-chosen mowing pattern can detract from the appearance of the grass and may also waste time and money. Some mowing patterns are more efficient and can save time to mow a given area. But it is not just the mowing pattern that should be considered; having sharp mower blades is also critical in creating mowing patterns that last (and not inconsequentially, sharp mower blades are essential in maintaining healthy turfgrass plants).

In a recent study at the Sports Turf Research Institute (STRI), the striping effect produced when cutting the grass was found to be more pronounced when using a sharpened mower using no contact between the reel blade and the bedknife. The study was commissioned by Bernhard & Company, who manufacture sharpening equipment for mowers. Mowing is perhaps the most important maintenance activity for any turfgrass area, and mowing is essentially what separates turfgrass from forage grass.


The photo above (click the photo or here for a larger image) shows the damage that can occur when turfgrass is mowed with a maladjusted mower. This otherwise healthy sward of Zoysia matrella now has a white appearance because the leaf blades are all shredded. In addition to changing the color of the grass, making it less green, damaging the grass with a mower also puts a tremendous amount of stress onto the turfgrass plant, and may cause increased disease incidence and lack of vigor and a general decline in turfgrass performance. So, if we are to have beautiful stripes on the grass, or are to create any type of mowing pattern, whether it be complex or simple, the starting point is to cut with sharp mower blades.

Mowing Patterns & Grass Color

Did you watch the Masters Tournament in April? Did you notice the immaculate appearance of the wide fairways? Please have a look at the photo below, taken from behind the 9th green. Do you notice a color difference between the 1st and 9th fairways?

Angc mowing pattern

The reason for the color difference is the mowing pattern; for the Masters Tournament, mowers drive in the direction from green to tee, and this causes a slight leaning of the grass blades, and then there is a noticeable color difference in the grass.

Why do I mention this? To emphasize the importance of having a well-considered mowing program. The way the grass is mowed has a huge impact on the appearance of the golf course. Grass may not be perfect, but if the mowing program is planned to accentuate the appearance of the grass, then the course will look better. It is possible to make the grass look greener without using more fertilizer, appear weed-free even when there are some weeds, and to emphasize the fairway or the rough or other areas of the course, all by implementing an effective mowing program.


This is the 2nd hole of Kentos Golf Club in Tochigi-ken, Japan. This mowing pattern emphasizes the center of the fairway as an aiming target, saves mowing time (perhaps 20% time reduction at the average facility), and in this case the left side of the fairway is mowed from tee to green, while the right side of the fairway is mowed from green to tee.


Here we see the 9th hole at Pebble Beach Golf Links in California, where a diagonal or "diamond" mowing pattern is used. This pattern takes skilled operators to implement, and it takes more time to mow the fairways in a diamond pattern, but it can create a visually stunning fairway appearance.


Above we see the 18th hole at Hanoi Golf Club in Vietnam. This is what I call a "zebra" mowing pattern, and is one that is often used on courses in Asia.

The important thing to remember is that the way grass is mowed has a tremendous impact on the visual appearance of a golf course and the golfers' perception of the course. Below we see a beautiful golf hole with an unclear mowing pattern in the fairway. The grass is mowed, and the playability is excellent, but there is not a striking mowing pattern. Any small imperfections in the grass could be overshadowed by a clear mowing pattern. I hope you will think about the way the grass is mowed at your facility, to make the most efficient use of your mowers and at the same time optimizing the visual appearance of your grass.

Unclear pattern