More Art Than Science
Over the centuries the art of greens maintenance was passed from one generation to the next by greenskeepers of chiefly Scottish descent. Many of the early greenskeepers in the U.S. were Scottish. In fact, there was a time in this country when one was not considered a skilled greenskeeper unless he came form Scotland. The Scots seemed to have had a monopoly on the art of greenskeeping since Scotland was the origin of golf and the country where most golf courses were found prior to the 20th century.
Today, the golf course superintendent has replaced the greenskeeper, and science is rapidly replacing art in the profession of greens maintenance. Yet, there still may be more art than science involved in greens maintenance. For example, science tells us when to fertilize greens, which nutrients to apply and what ratio of nutrients are needed to maintain a healthy turf on greens. But, science tells us little about the effect of fertilizer on the playability of the greensthe speed, uniformity, texture, graininess and trueness. Playability of greens depends more on the skill of the superintendent to judge when to apply fertilizer, how much to apply and what material to use. Too often textbook fertilization practices produce thatchy greens, excessive grain and disease problems all of which lead to poor playing surfaces. On the other hand, the superintendent who relies more on experience and observation to develop a fertilizer program usually has very good playing greens.
Similarly, greens irrigated by automatic systems programmed to apply water at specific times and amounts are often too spongy for good playing surfaces. Whereas, greens watered by a superintendent based on experience and frequent observation are usually firmer, less weedy and better playing surfaces.
Topdressing is another practice that requires more art than science. The scientific approach to topdressing using particle size distribution, percolation and moisture retention can provide helpful information, but tells the superintendent little about putting quality, ball holding or compatibility with existing greens mixtures. The superintendent must develop a topdressing material with all of these criteria in mind. Even after developing a topdressing material, he must also decide when to topdress, how much to apply and how to work the topdressing into the turf so as to provide the least interference with play. These decisions on topdressing, watering and fertilization are a part of the `art of greens maintenance'.
My point in this discussion is not to play down the contributions science has made to greens maintenance, but to emphasize the importance of experience and observation to the maintenance of fine playing surfaces. Without the skills acquired by experience and observation, even the best educated individuals fail in the development of fine playing greens. Their greens may look great, but the speed, uniformity, trueness and holding ability of the greens may not be acceptable for golf.
The superintendent must also keep in mind that practices which work for one golf course may not work for another. Greens construction, grass species, location and maintenance programs all affect the response to specific practices. Also, superintendents must recognize that the difference between success and failure is often in the timing of maintenance practices. Cultural practices, equipment and people required for greens maintenance cannot be put together in a haphazard order. Timing of each operation can be as important as performing the operation. Even though you may have a list of good excuses for delays in carrying out operations, delays only result from poor planning. Maintenance programs must be flexible to allow for unusual conditions and unscheduled activities.
Mowing Practices Determine Putting Quality
Regardless of other practices, proper mowing, is required for good putting greens. Proper mowing includes daily mowing, daily changing of mowing patterns, mowing at the correct height, precise adjustment of mowers, daily cleaning and sharpening of mowers, training of mower operators and visual inspection of results. Mowing is the single most important practice in greens maintenance.
Mowing height is the only variable in proper mowing practices. Mowing height is dependent on grass species, the amount of traffic, environmental conditions and the desired speed of greens. Tifdwarf bermudagrass and bentgrass greens can be mowed as short as 1/8-inch, but Tifgreen bermudagrass should not be mowed below 5/32-inch. During mid-summer heat stress bentgrass greens should be raised to 3/16- or 1/4-inch mowing heights. Overseeded bermudagrass greens may be mowed as high as 1/4-inch during establishment, but should be lowered to 3/16-inch within 4 weeks after planting and 5/32-inch or less by early spring.
If fast greens are desired for tournament play, mowing heights can be lowered below the recommended minimums for a short period. However, other practices such as brushing, verticutting and rolling may also be used to increase the speed of greens. Where heavy play is a factor, extremely short mowing heights can only be tolerated for a short time.
Daily mowing at recommended heights produces dense, fine textured putting greens without shocking the turf. Less frequent mowing results in the removal of an excessive amount of leaf tissue at each mowing and puts the grass under stress. Removal of half of the leaf tissue at a single mowing can result in severely reduced root growth for several days.
Changing mowing patterns at each mowing helps to eliminate graininess, to reduce wheel or mower wear and compaction and to establish a target by setting the green apart form the apron or collar. Where triplex greens mowers are used, the final cut around the perimeter of the green should be moved in and out at least the width of a wheel each day, or should only be mowed on alternate days. Some superintendents make this perimeter cut with a walking greens mower to reduce wear and compaction.
Even with daily mowing at the proper height, poor mower adjustment produces unslightly greens and poor putting conditions. Precise mower adjustment and sharpening is essential to produce a clean, uniform cut on putting greens. Immediately after use, each mower should be thoroughly cleaned, height and cut adjustments checked, reels lapped-in and other maintenance performed as needed to have the mower ready for use the next day. If this routine is followed, equipment failures can be prevented or corrected before the next use. However, standby mowers should always be available in case a mower is taken out of service for several days.
Not everyone can mow a golf green. Even with training some people do not have the physical or mental dexterity to mow greens. Greens mowing is a skill acquired only by experience and observation. Training people to mow greens requires instilling an appreciation for a uniform, smoothly cut green in addition to teaching techniques. Just going through the physical exercise of mowing a green is not enough...the operator must appreciate the finished product.
Lastly, the golf course superintendent must inspect greens frequently to be sure they are properly mowed. Perhaps, this is best accomplished by occasionally playing the course.
Greens Often Overwatered
Watering practices have nearly as much effect on playability of greens as mowing practices. Wet greens provide poor playing conditions and lead to infestations of weeds and algae. Ball marks and footprinting are also problems on wet greens. On the other hand, dry greens are usually very hard and do not hold a well-played golf shot.
Watering practices must be based on soil properties (greens construction), grass species, environmental conditions and other maintenance practices. Watering schedules are critical on greens with poor drainage or on greens with excessively high infiltration rates. Properly constructed greens allow a much wider margin for error in watering schedules.
Greens with poor drainage must be watered slowly, or at frequent intervals, to wet the soil 4 to 6 inches deep. On poorly drained greens, if water is applied at rates above 0.5 inch per hour, water runs off the green faster than it moves into the soil. Thus, the collar and apron get wet before the putting surface is adequately watered. Automatic systems should be cycled so that water is applied intermittently to such greens. Intermittent watering allows water to penetrate several inches into the soil before excessive runoff occurs. Then, with the exception of spot watering, greens should hold up several days without watering.
Sand greens with very high infiltration rates require light and frequent applications of water. Again, the collar and apron of these greens are often wet while the putting surface appears dry. Careful design of the irrigation system may be required to maintain the putting surface without keeping the surrounding area wet.
Environmental conditions have more influence on watering than any other factor. Water use rates may vary from 0.05 to 0.3 inches of water per day depending on temperature, wind, humidity and sunlight. In drier climates during summer months water use rates will approach 0.3 inches of water per day. Under these conditions, frequent watering is almost a necessity. During cooler months, water use rates are less than 0.1 inch of water per day and weekly watering may be adequate. Watering schedules must be adjusted according to fluctuations in water use rates. For lack of a more accurate measure of water use rate, daily evaporation readings available from meteorological stations may be used to estimate water use rates. In most southern climates daily water use rates are about three-quarters of the daily evaporation rate reported by the weather bureau.
Management practices such as dethatching and aeration also influence watering practices. Thatch restricts water penetration and leads to shallow rooted turf. Thus, light and frequent applications of water are required on thatchy greens. Vertical mowing, aeration and topdressing aids thatch removal and decomposition and improves water penetration. Spiking and coring also help to alleviate crusts and surface compaction. Thus, these cultivation practices improve moisture conditions on greens and allow for longer intervals between irrigations.
Avoid Excess Nitrogen
Fertilization practices affect growth rate, density, color, drought tolerance, disease activity and putting quality of golf greens. Ideally, nutrients should be available to the grass in amounts needed to maintain growth and color without increasing susceptibility to drought and disease and without increasing grain and thatch. Realistically, the superintendent should maintain adequate levels of phosphorous, potassium and minor nutrients in the soils and provide nitrogen and iron as the grass requires.
Soil test and plant tissue analyses help the superintendent monitor the amount and availability of phosphorus, potassium and minor nutrients. However, visual observations of color and density and clipping removal are essential for estimating nitrogen needs. Soil tests and tissue analyses alone are not enough to determine nitrogen needs on putting greens.
Considerable expertise is required of the superintendent to maintain healthy, dense turf and good color without developing "lush" growth. While grass species, environmental conditions, greens construction and cultural practices influence the nitrogen requirements of putting green turf, the superintendent must evaluate all of these factors to maintain the required level of nitrogen.
Bermudagrass greens require approximately 0.05 pound of nitrogen per 1,000 square feet per day during the growing season; bentgrass greens require much less. The only means the superintendent has of meeting that requirement is to apply nitrogen daily through fertigation. If a superintendent applies only 0.5 pound of soluble nitrogen per 1,000 square foot in a single application, he exceeds the daily requirement of bermudagrass 10-fold for the next several days. Thus, there would be a short period of luxury consumption of nitrogen resulting in "lush" growth.
Organic and slow-release nitrogen sources should be used to provide small amounts of soluble nitrogen over a longer time period. For maintenance, soluble nitrogen should be applied at rates less than 0.5 pound per 1,000 sq. ft. on bermudagrass and 0.3 pound on bentgrass. Slow-release products such as sulfur-coated urea, IBDU and ureaformaldehyde can be applied in combination with soluble nitrogen sources to extend the period of nitrogen availability.
Potassium's importance as a major fertilizer nutrient is often overlooked on putting greens. Researchers consistently show grass responses to potassium to include root growth, drought tolerance, disease resistance, wear tolerance and color on putting green turf. These responses to applications of potassium are observed even where soil levels of potassium are adequate. Research at Ohio State University suggests that potassium applications may reduce the requirements of bentgrass for nitrogen. Thus, some of the desired responses to fertilization such as root growth, color and disease tolerance can be produced without the excess growth associated with nitrogen applications.
Since potassium losses on greens are similar to those of nitrogen, light and frequent applications of potassium are required to maintain its availability to the grass. On golf greens, potassium should be applied at about the same rate and frequency as nitrogen.
Relative to nitrogen and potassium, lower levels of phosphorus are required for greens maintenance. Also, phosphorus accumulates in the soil, whereas nitrogen and potassium are readily leached below the rootzone of grasses. Under most conditions, two or three applications of phosphorus per year are adequate for either bermudagrass or bentgrass greens.
Since iron is readily tied-up in alkaline soils, and not available to the grass, light and frequent applications of iron are required to maintain its availability on most greens. Monthly applications of iron sulfate or iron chelate required under conditions where iron is not readily available to the grass.
Cultivation Improves Putting Greens
Cultivation practices including spiking, coring, brushing, verticutting and topdressing affect putting quality more than they affect turf quality. Most of these practices are unique to putting green maintenance since they affect ball roll and ball holding. Spiking, coring and topdressing help soften the green and improve ball holding. Brushing, verticutting and topdressing reduce graininess and thatch accumulation and improve the uniformity, trueness and speed of greens.
Again, there is more art than science involved in determining how often to perform these operations, how severely to verticut, how much topdressing to apply and what materials to use for topdressing. Ideally, all of these operations are performed often enough to avoid disrupting the putting quality of greens.
Brushing can be done in conjunction with mowing to reduce graininess. During spring and fall on bentgrass and summer on bermudagrass, greens can be brushed lightly everyday. Frequent brushing can reduce the need for vertical mowing, but vertical mowing is required to help control grain and thatch, to increase the speed of greens and to prepare bermudagrass for overseeding. As with brushing, light and frequent vertical mowing is required during the growing season. Bermudagrass greens should be verticut weekly during summer months. And, with the new grooming mowers, greens can be lightly vertical mowed on a more frequent basis.
Spiking and coring are important to aeration (root growth), water penetration, thatch and ball holding. Spiking improves conditions caused by surface crusts and surface compaction. Greens can be spiked frequently with little disruption to play. Coring provides more effective aeration and thatch control, but causes greater disruption of play than spiking. Coring also improves the ball holding ability of greens more effectively than spiking. Depending on the severity of problems, greens should be cored 2 to 3 times each year and spiked often as needed to maintain water infiltration rate, break surface crusts and hold properly played golf shots.
Topdressing is one of the most important, yet most neglected practices in greens maintenance. There was a time when topdressing was the "greenskeeper's" most effective tool. Topdressing was used for fertilization, disease control, thatch control and improving putting quality. The "art" of topdressing seems to have been lost since the widespread use of commercial fertilizers, pesticides and mechanical aerifiers. The high cost of labor, equipment and materials has also contributed to the reduced emphasis on topdressing as a cultural practice.
For best results, topdressing materials should be screened, sterilized and composted prior to use on greens. Materials used for topdressing should be evaluated by a laboratory to avoid the addition of excess silt or clay which could seal drainage on a green or the addition of fine gravel which interferes with play and mowing equipment. Topdressing materials should be prepared during the "off season", if such a time exists, so that they can be composted and available when needed.
Like all cultivation practices, light and frequent topdressing is more effective and more desirable than occasional applications of a heavy topdressing. Heavy topdressings are disruptive to play and tend to produce layers that interfere with water movement and root development. For most management programs, 4 or 5 applications of topdressing, properly timed, are adequate for bermudagrass or bentgrass greens. Topdressing should follow aeration in late spring and fall and at least twice between those applications to maintain putting quality and ball holding ability of greens throughout the summer.
Pest Management - Insects, Diseases and Weeds
The cultural practices discussed above are intended to develop fine putting greens as well as to reduce pest-related problems. Practices that promote healthy, dense turf also help prevent many pest problems. Proper mowing, fertilization and watering practices help resist invasions of weeds and reduce outbreaks of some diseases. However, even where recommended cultural practices are routinely followed, problems occur when environmental conditions are favorable for insect, disease or weed development.
Preventive applications of pesticides are recommended on golf greens when environmental conditions favor pest development. For example, fungicides should be applied under humid conditions in the spring and fall for brownpatch. Similarly, preemergence herbicides may be applied in the fall to prevent annual bluegrass infestations. Pest problems such as brownpatch, annual bluegrass and others that have history of developing each year should be controlled on a preventive schedule.
Other pest problems that are less predictable should be controlled on a curative, or as needed basis. Repeated use of some pesticides can lead to problems such as pest resistance thatch accumulation or injury to turfgrass. Therefore, only those applications that are needed to prevent damage to greens should be made.