A Publication on Turfgrass Management by the United States Golf Association May/June 1981 USGA Green Section Bunkers Require Constant Care USGA Green Section RECORD EDITOR: Alexander M. Radko MANAGING EDITOR: Robert Sommers ART EDITOR: Miss Janet Seagle Vol. 19, No. 3 MAY/JUNE 1981 GREEN SECTION COMMITTEE CHAIRMAN: Stephen J. Horrell 3007 Dehesa Road, El Cajon, Calif. 92021 NATIONAL DIRECTOR: Alexander M. Radko ASST. NATIONAL DIRECTOR: Carl H. Schwartzkopf United States Golf Association, Golf House, Far Hills, N.J. 07931 • (201) 766-7770 GREEN SECTION AGRONOMISTS AND OFFICES: Northeastern Region: United States Golf Association, Golf House, Far Hills, N.J. 07931 • (201) 766-7770 Carl H. Schwartzkopf, Manager William S. Brewer, Jr., Senior Agronomist James T. Snow, Senior Agronomist Mid-Atlantic Region: Suite B4, 9017 Forest Hill Avenue, Richmond, Va. 23235 • (804) 272-5553 William G. Buchanan, Manager Patrick M. O’Brien, Agronomist Southeastern Region: P.O. Box 4213, Campus Station, Athens, Ga. 30602 • (404) 548-2741 James B. Moncrief, Manager Charles B. White, Agronomist North-Central Region: P.O. Box 592, Crystal Lake, Ill. 60014 • (815) 459-3731 Stanley J. Zontek, Manager Mid-Continent Region: 17360 Coit Road, Dallas, Tx. 75252 • (214) 783-7125 Dr. Douglas T. Hawes, Manager Western Region: Suite 107, 222 Fashion Lane, Tustin, Calif. 92680 • (714) 544-4411 Donald D. Hoos, Manager 2001 Main Street, Vancouver, Wash. 98660 • (206) 695-2181 Timothy G. Ansett, Agronomist Maintenance by Priority by Charles B. White Golf Path Curbing by Stanley J. Zontek Drip Irrigation for Establishing and Maintaining Trees by Don Clemans Putting Green Responses to Sand and Sand/Soil Topdressing by R. J. Cooper and C. R. Skogley Back Cover Turf Twisters Cover Photo: The 16th hole at National Golf Links of America, New York. ©1981 by United States Golf Association. Permission to reproduce articles or material in the USGA GREEN SECTION RECORD is granted to publishers of newspapers and periodicals (unless specifically noted otherwise), provided credit is given the USGA and copyright protection is afforded. To reprint material in other media, written permission must be obtained from the USGA. In any case, neither articles nor other material may be copied or used for any advertising, promotion or commercial purposes. GREEN SECTION RECORD (ISSN 0041-5502) is published six times a year in January, March, May, July, September and November by the UNITED STATES GOLF ASSOCIATION, Golf House, Far Hills, N.J. 07931. Subscriptions and address changes should be sent to the above address. Articles, photographs, and correspondence relevant to published material should be addressed to: United States Golf Association Green Section, Golf House, Far Hills, N.J. 07931. Second class postage paid at Far Hills, N.J., and other locations. Office of Publication, Golf House, Far Hills, N.J. 07931. Subscriptions S3 a year. Frequent aeration of peripheral areas around greens ... an important cultural program. Kiawah Golf Links, South Carolina. Maintenance by Priority by CHARLES B. WHITE Agronomist, Southeastern Region, USGA Green Section KT■ HAD TERRIBLE LIES in the JL roughs today!” “Why aren’t the woods cleaned out — I can never find my ball.” “Why aren’t the roughs mowed and maintained like the fairways?” “Yeah, I even had to play out of a divot hole in the fairway!” If you are a golf course super­ intendent, golf professional, or green committee chairman, I’m sure these are familiar complaints. Today, too much emphasis is placed on out-of-play areas on golf courses. Golfers for the most part have been spoiled by quality turf conditions not only from tee to green, but also into the woods. The rough is not supposed to be as uniform as fair­ ways, nor are fairways supposed to be as uniform as the tees and greens. Think back to the days when golf originated. The greens received major emphasis while fairways, roughs, and for the most part tees, received little attention. Granted, weed control is necessary, but all turf need not be maintained as carpet. After all, if a ball lands out of the playing area, isn’t the golfer supposed to be penalized some­ what? Let’s take a strong look at course maintenance priorities and try to deter­ mine where the emphasis should be placed. As the costs of labor, materials and fuel continue to increase, all golf courses, especially those with modest budgets, must adjust priorities, because in the future it may no longer be feasible to pursue high management programs over the entire golf course. The first place to cut back mainte­ nance is in the roughs. The rough should be maintained at a fair pace, but this does not mean frequent mowing of two or less inches and constant weed control. Reduced fertilization and water will, in turn, make for reduced mowing. Some slight increase in weed infestation may be expected, but a significant savings in course budget will be realized. The next possible cutback could be in reduced maintenance on fairways. MAY/JUNE 1981 1 mowings followed by light topdressings of about l/s cubic yard per 1,000 square feet are very effective in establishing smooth, fast and uniform putting sur­ faces. The topdressing is lightly matted or brushed into the turf. Light, frequent vertical mowings and topdressings may also help increase the green speed. Remember that root development is directly related to cutting height, nitrogen level, cutting frequency, soil mixture and water management; there­ fore, all programs must be well-coordi­ nated for true excellence in putting surfaces. Vertical mowing and topdressing programs are especially important in encouraging upright turfgrass growth and minimizing grain and other surface inconsistencies. This does not mean that greens on all courses should putt the same; putting green design and differences in turf stands prevent that. However, each superintendent should strive to ensure that all greens on his course putt uniformly. The grooming practices mentioned will help course managers achieve the degree of uniformity and consistency that current golfing stan­ dards demand. Reduced fertilizations and waterings will be a first step, but also a reduced mowing schedule may be forced upon us because of increasing energy costs. This is not to say that fairways should be maintained poorly, but the frequency of mowing will have to be cut back to two or three times a week. Less weed control work will also be experienced, but specific problems, such as nematode and mole cricket controls on Florida and coastal courses, will have to be sustained to ensure a quality turfgrass stand. Turf maintained at this lesser pace does not greatly reduce playing quality, but it will certainly reduce maintenance costs. Whether or not playing quality is reduced, and how much, is the key question in deciding the extent to which maintenance prac­ tices should be cut back. AS PRIORITIES are considered, greens must appear at the top of the list. Greens undoubtedly are the most important areas on the golf course because, theoretically, the scratch golfer takes half his strokes on the green. In many cases, putting surfaces are not maintained to the quality they should be today, because too much emphasis is placed on the requirements of large acreage areas. It is not enough to maintain greens with routine aerifi­ cation, mowing, fertilization, and spraying. Expert grooming is required to produce the best quality putting surfaces. The most basic requisite of quality grooming is an excellent mowing pro­ gram. Greens should always be mowed with mowers that are sharp and well- adjusted. Mowing patterns, however, are equally important. Greens should be cut at least five times each week, preferably six times, during active growth periods. Changing direction helps reduce grain and provides a cleaner, more uniform cut. Other implements important to management can be attached to mowers. These include rollers, combs or brushes. Wiehle rollers help cutting units main­ tain a truer height of cut. Brushing in spring and fall helps the grass to stand up, allowing for better cut. When planning routine maintenance, prac­ tices such as light, frequent vertical mowing and topdressing must also be considered. During active growth, weekly to biweekly light vertical 2 USGA GREEN SECTION RECORD These practices are important in overseeded bermudagrass greens during the winter to keep the overseeding somewhat thinned out, but more importantly, to keep it growing upright. This program is also beneficial in the spring to dissipate the overseeding earlier so the bermudagrass can begin its active growth early for the new season. JUDICIOUS FERTILIZATION is also a key factor to putting surface uniformity. For the most part, putting greens tend to be overfertilized. A lower total nitrogen program of light, frequent applications is better for turf and provides fewer peaks and valleys in the season’s growth curve. Supplemental applications of micro­ nutrients mixed in with routine main­ tenance sprays can help provide the healthful growth and color desired without having to apply as much nitro­ gen. Micronutrients are important to turfgrass growth, and it is up to turf managers to keep a close check not only on major factors such as soil pH, nitrogen, phosphorus and potassium levels, but also on the minor trace elements as well. All nutrients must be carefully considered when designing the best program for optimum growth. Since greens are the most important areas on the golf course, it follows that care of green surroundings should be almost equally as important. The perimeter area includes bunkers and extends out to a radius of 20-50 feet beyond the collar. Green surround­ ings must be kept weed-free to prevent the putting surfaces from becoming weed infested, and perimeters should be maintained uniformly to provide for delicate approach play to the putting surface. Green surroundings should be aerated two to three times per season. The plugs can be dragged in to serve as a topdressing. This program helps ensure uniformity and promotes deeper rooting and stronger turfgrass growth. The second area of priority in golf course care is the tees. As mentioned above, greens receive one-half the strokes of a theoretical scratch round of Naturalizing out-of-play areas on the golf course saves time and money. Jupiter Hills Club, Florida. golf and tees receive another one-fourth. When these two small acreage areas are considered, the playing areas for three- fourths of the strokes of a scratch round of golf have been consumed. This being the case, it is evident that these two areas must be quality maintained. TEES RECEIVE the most concen­ trated wear. To maintain tees at the level desired, wear must be offset through aerification, topdressings and vertical mowings. Tees should be aerated two or three times per season, followed by topdressing. Topdressings should be frequent enough to maintain a smooth and level surface for firm footing. Vigorous growth promoted by these cultural programs is needed to fill in divots and other worn areas due to traffic and play. It is unfortunate that many golf courses suffer from the lack of adequate teeing space today, so any time a new tee is considered, it should be large enough to accommodate the amount of play expected on that par­ ticular golf course. Constant rotation of the tee markers is also essential for distributing wear over the entire teeing surface. On bermudagrass tees, the best program, except for nitrogen, is to maintain them like greens. Bermuda­ grass tees should receive less total nitrogen than putting greens because of the danger of excessive thatch buildup. Cool-season grass tees require slightly more nitrogen, more aeration and less irrigation than greens. Tees, too, benefit from a well-balanced nutritional program that includes minor elements. Tee surrounds also must be maintained as weed free as possible in order not to infest teeing surfaces. The third area requiring intensive maintenance is the bunkers. They receive a tremendous amount of play, are expen­ sive to maintain, but must be well cared for because unsightly bunkers detract greatly from pleasurable play. Well­ managed bunkers also add to the aesthetic quality of the course. Golf courses definitely have areas of high priority maintenance. As golf course managers find themselves backed into a corner with budget limitations, they will be forced to be more selective between higher and lower maintenance areas, and they will have to adjust programs accordingly. It is advisable to begin selective types of maintenance programs soon. A gradual compliance will make for an easier transition to reduced mainte­ nance in roughs and higher maintenance of greens, tees and bunkers. Education is the key to success for introducing new programs to the golfing public. It is up to the superintendent to inform the membership in any way possible of the necessity of priority maintenance as it relates to managing the golf course within the budget. Golfers who truly love the game will agree for the sake of economy that the priority areas need to be maintained first, and other areas can be maintained to the degree dictated by the budget. MAY/JUNE 1981 3 Golf Poth Curbing by STANLEY J. ZONTEK North-Central Manager, USGA Green Section AS AGRONOMISTS for the USGA Green Section, we see hundreds of golf courses each year. Nearly all of them are on some sort of cart path installation or maintenance program. These paths are generally installed in areas of wear and tear where traffic makes the management of quality turfgrass practically impossible. Because of the nature of the game, these wear areas are first seen near greens and tees where traffic congregates. The path is then installed, and that’s it! Figure 1. A common occurrence — worn area adjacent to paved cart path. Unfortunately, what occurs next is a deterioration of the turf along the edge of these paths in areas where the carts drive off the man-made surface. Even though a path is provided, the people often stray from the path and wear out the adjacent turf, thereby defeating the original purpose of the path. Herein lies the purpose of this article ... to suggest the proper installation of curbing in order to better control cart traffic and save the adjacent turf, to improve the overall appearance and playability of the golf course. Figure 1 illustrates an all too common occurrence. A quality cart path has been installed, but the area immediately adjacent to the path is worn bare. Why? Is it that the path is improperly located? Is it in an area several feet from where carts routinely travel? Or could it be that when it is time to stop the vehicle, the driver pulls the golf cart off the path, thus inadvertently starting the gradual deterioration of the turf adjacent to the path. I believe all of these situations contribute to this prob- 4 USGA GREEN SECTION RECORD lem, but the latter illustration is more often than not the case, especially near greens and tees. Perhaps the golfer unconsciously feels he is exercising accepted rules of the road by pulling off the path. AS A MOBILE society, we have been educated en masse to respect the written or understood rules of the road. One such rule when you stop your vehicle is never leave it on the pave­ ment; pull it to the side, off the paved surface in order to allow other traffic to go by. This rule works well on high­ ways with shoulders designed expressly for this purpose. On golf courses, how­ ever, this results in worn areas near greens and tees that quickly become bare, muddy, dusty and generally an eroding eyesore. Besides just looking bad, these worn areas adjacent to exist­ ing paths are a headache to maintain and to play from. FIGURE 2 illustrates an important final step in a good cart path development and maintenance program: the installation of a curb in potential wear areas. The curb essentially makes the cart path, which is an expensive project anyway, function as intended and support the vehicle while leaving the adjoining turf intact. The secret of success in this installation program, whether done initially or long after installation, is to make the curb blend into the area and not stand out as an eyesore and maintenance problem. Figure 2 illustrates this point. The curb has an attractive built-in look. Also, and most importantly, note that the soil behind the curb is raised so the grass is at the same level as the top of the curb. This greatly eases mowing. Compare this feature and savings to the extra hand work and bother involved with free-standing fences, stakes and ropes, all of which must be removed and replaced every time the area is mowed. When constructing these four- to six- inch curbs, there is a good choice of materials to use. The most common are asphalt and treated wood beams or ties, even though stone, brick, or block also could be effectively used. Things to consider are the character of the course, the price of each material, the ease of installation and material availability. One point should be stressed again. No matter what material you use, build the curb into an existing bank, or create your own bank by backfilling with soil behind the curb. It will not only look better, but this new curb will also be easier to maintain. IN SUMMARY, even though we may not like it, golf carts will continue to be an enigma. More paths will inevitably be installed on many courses. Old paths will have to be widened or repaired. When doing such work, remember the importance of traffic control and good golf cart usage by designing and install­ ing effective curbs. They can be success­ ful in keeping these vehicles ON THE PAVED SURFACE WHERE THEY ARE SUPPOSED TO BE, especially near greens and tees. They also can serve to direct water away from potential washout areas. If properly designed and installed, cart paths with curbs can function practically unnoticed without being another maintenance headache to the golf course superintendent. They can even help him do a better job of main­ taining a neater and more playable golf course by controlling traffic, saving turf, diverting water, easing maintenance and eliminating an eyesore. Support Notional Golf Week The Green Section of the United States Golf Association salutes the Professional Golfers Association for its annual contributions to turfgrass research. Through its National Golf Week Fund, the PGA has contributed over $288,000 to the USGA Green Section Re­ search Program since 1952. These funds not only make it possible for the USGA to support a number of worthwhile turfgrass research projects, but also help train leaders in the field of turfgrass management. Research findings from funds channeled through the USGA Green Section Research Program benefit golf. All Green Section recommendations benefit the player, the course and the game. National Golf Week will be played June 22-29, 1981. Figure 2. Well-installed curbing, wood on left, Ozaukee Country Club, Milwaukee, Wisconsin; asphalt on right, Firestone Country Club, Akron, Ohio. Polyethylene tubing, emitter and “spaghetti” tubing in trench before burying. Drip Irrigation for Establishing and Maintaining Trees by DON CLEMANS, CGCS, Golf Course Superintendent, Olive Glenn Country Club, Cody, Wyoming IN JUNE of 1974, I attended an irrigation meeting at the University of California where one of the topics of discussion was drip irrigation in vine­ yards and avocado and citrus groves. Our course is in the sagebrush belt, so I felt the talk would be of little value to me, but as I listened, I began to realize more and more that the prin­ ciples of drip irrigation could be very useful to our club. Olive Glenn is located on the eastern slope of the Rocky Mountains in the Big Horn basin in northwestern Wyoming. We grow combination Kentucky bluegrass-fescue fairways and Penncross bentgrass greens under nearly continuous irrigation. The golf course is 5,100 feet in elevation; we annually receive six to nine inches of rainfall and lots of wind. Over 1,000 trees were planted in 1970, when the course was new. Basically 6 USGA GREEN SECTION RECORD the irrigation pattern of sprinklers, but because of the water cutoff, the trees began to wilt. To resolve the problem, we installed drip irrigation to these trees as well. WE HAVE NOW operated our drip irrigation system for six seasons. During that time fewer than 1 percent of the emitters have required service. Each spring we activate the system, and after two or three days we check each plant to make certain the emitter is functioning. The system is then shut down for two or three weeks, until the trees require more water, after which they are watered according to need throughout the season. As fall approaches we again check each emitter to be certain that every tree goes into the winter well watered. During 1980, we planted more than 500 landscape plants around a new clubhouse-tennis court complex. Every plant is individually drip irrigated. Drip irrigation lends itself particularly well to foundation plantings around build­ ings and in parking lot islands. It is also practically invisible and to my knowl­ edge is less prone to damage by vandals than other types of irrigation systems. I am confident that the drip irrigation system works; the plants benefit from deep watering, salt accumulation is no longer a problem, and the cost of labor involved in watering all our plants is far less than with any other option available under these conditions. End of “spaghetti" tubing at base of tree. The only part of drip system above ground. they are of three species: Russian olive (Eleagnus angustifolia), green ash (Fraxinuspennsylvanica ‘lanceolata’) and Colorado spruce (Picea pungens). About 700 of the trees were planted outside the reach of our fairway sprinkler irrigation pattern. During the establishment phase the trees were hand watered by hose from quick-coupling valves in the summer, and water was hauled by tank wagon during the early winter and early spring to attempt to keep them alive. With wind (40 mph is not uncommon) and low humidity, tree survival was difficult to ensure. Hand watering produced a shallow root system and also contributed to salt accumu­ lation on the soil surface. Another problem was the unreliability of the workers who watered the trees. After several days of hand watering, it seemed very easy for them to simply skip a tree here and there to hurry up the job. The problem was that I didn’t know that trees were being skipped until the following spring when I found that some had died. In the spring of 1975, with little information available, we embarked on a project to provide drip irrigation to 700 trees. Our initial purchase included 30,000 feet of %" polyethylene (80 psi) pipe which came in 400-foot coils and 700 emitters. The poly was buried three or four inches deep using three techniques — vibratory plow, irrigation ditch plow, and a narrow trench. The emitters were buried along with the pipe. The trickle tube from the emitters to the trees was buried by slitting the ground with a spade; thus the entire system was buried except the very end of the trickle tube. This minimized possible vandalism damage and allowed motorized equipment to drive over the system without doing any damage. By 1976 it was obvious that our system was working well. Tree loss was nearly eliminated. The growth rate of some trees doubled, and in some cases it was tripled. The labor required to water all the trees on the course was reduced from days per watering to just the few minutes required to open the valves controlling the water flow to the %" polyethylene pipe. During the summer of 1976, we had a shortage of water due to a lack of snow­ fall in the mountains the previous winter. It was necessary for us to water our roughs only enough to keep them alive — but not green. We had recently planted 300 more trees that were located within Putting Green and Sand/Soil by R. J. COOPER and C. R. SKOGLEY1 Responses to Sand Topdressing Fall color retention was noted in November of each year. The dark green turf plots seen here are those which received monthly sand I soil topdressing. They retained good color later into the season than turf receiving other programs. Topdressing is the application of a thin layer of selected or pre­ pared soil to a turfgrass area. Turf managers have been aware of the importance of topdressing since the early days of green keeping at the Old Course, in St. Andrews, Scotland. The benefits of an effective topdressing program include smoother putting surfaces, less thatch and grain, and tighter and finer-textured turf. Research has shown that topdressing is more effective than either vertical mowing or core cultivation in reducing thatch on fine turf areas. Topdressing also improves turfgrass establishment, cold tolerance, water and fertilizer infil­ tration, and annual weed control. While the value of topdressing putting green turf is well known, opinions often vary as to what constitutes a good top­ dressing program. The USGA Green Section recommends using a mixture containing sand in the range of 0.11 to 1.0 mm with at least 75 percent medium to coarse sand (0.25 to 1.0 mm). They emphasize that the mixture must be laboratory tested to determine the exact percentages of sand, soil and organic matter since sources vary so widely throughout the United States. The Green Section also recommends 10-20 percent of a well-decomposed organic matter, but only if the prepared mixture is’composted months in advance of use. Topdressing with mixtures conform­ ing to these standards has been success­ ful and is practiced by many turf managers. In recent years, however, interest has increased greatly in a pure ’Research Assistant, Ohio State University, and Professor, University of Rhode Island, respectively. MAY/JUNE 1981 9 sand topdressing program developed by Dr. John Madison and his associates at the University of California. They recommend light, frequent topdressing using sand in the 0.05 to 1.0 mm range, with at least 75 percent being fine and medium sand. The sand is applied without soil or organic matter being added. Anticipated benefits from this program include: elimination of alter­ nate layers of soil and thatch which often arise from infrequent topdressing, no thatch formation since stolons are continually buried, and a reduction in weeds and disease due to continual burying of seed and inoculum. Although pure sand topdressing has become very popular, some turf researchers hesitate to recommend this practice due to possible problems with excessive drainage and leaching, low microbial activity, insufficient water retention, and low organic matter con­ tent. Also, once a sand program is initiated, changing to a finer-textured topdressing can cause problems with water movement through the soil profile. It is generally accepted that sand can be applied over a fine-textured soil without restricting water movement. Once a surface sand layer is developed, however, changing to a finer-textured topdressing material can result in a perched water table and problems with surface wetness, compaction, and increased disease susceptibility. IN ORDER TO compare sand top- dressing to more traditional sand/soil topdressing programs, a study was conducted at the University of Rhode Island from 1976 through 1979. Penn- cross and emerald creeping bentgrasses and Kingstown velvet bentgrass were maintained under putting green con­ ditions and subjected to the following topdressing programs: MS — Three cubic feet of sand per 1,000 square feet applied monthly from April through November. M S/S — Three cubic feet of sand/ soil topdressing per 1,000 square feet applied monthly from April through November. 2 S/S — May and September appli­ cation of 7.5 cubic feet of sand/ soil topdressing per 1,000 square feet without cultivation. 2 S/S C — May and September application of 7.5 cubic feet of sand/soil topdressing per 1,000 square feet following cultivation. The sand topdressing contained 55 percent fine and medium sand, and 31 percent coarse sand. Although this is slightly more coarse than desired, the sand was typical of the type available to golf courses in the area. The sand/ soil material was a coarse sand and silt loam mixture containing 82 percent sand. With the 2 S/S C program, cultivation in May and September consisted of coring and grooving, respectively. The bentgrass plots were maintained as putting green turf and mowed regularly at % inch. Irrigation was practiced when necessary to avoid drought stress, except during 1979 when soil moisture data were collected. An average of four pounds of nitrogen per 1,000 square feet was applied each year. Both complete fertilizers (12-2-8 or 25-5-10) and activated sewage sludge (6-2-0) were used, with sludge being applied during periods of high tem­ perature. One of the most important aspects of any management practice is how it affects turfgrass quality. Visual ratings of turf quality were taken monthly and were based on color, texture, density, uniformity, and disease incidence (Table 1). Monthly sand/soil topdressing (M S/S) resulted in higher turf quality than any other program from 1977 through 1979. This was due to the periodic addition of nutrients contained in the soil component of the topdressing. Monthly sand topdressing (MS) resulted in poorer quality turf than both M S/S topdressing and semiannual topdressing with sand/soil (2 S/S) during 1978 and 1979. Semiannual sand/soil topdressing following cultivation (2 S/S C) con­ sistently resulted in the poorest quality turf. This was probably due to infrequent application combined with injury from the cultivation process. The spring and fall color response of the turf also varied considerably among programs. Monthly sand/soil top­ dressing resulted in better spring and fall color than all other topdressing programs during 1978 and 1979. This was due to the monthly addition of nutrients contained in the material, as well as to the increased absorption of solar radiation by the dark sand/soil mixture. Also, monthly sand/soil top­ dressing in September, October, and TABLE 1 Average monthly turf quality scores for all bentgrass varieties during 1977, 1978, and 1979 Topdressing Program MS M S/S 2 S/S 2 S/S C Turf Quality1 1978 6.0 c 6.9 a 6.5 b 5.6 d 1977 6.9 b* 7.2 a 6.8 b 6.5 c 1979 6.8 c 7.4 a 7.1 b 6.6 d 1Scale: 1 to 9; 9 = ideal turf. ‘Scores within years followed by the same letter are not significantly different at the 5% level. 10 USGA GREEN SECTION RECORD View of gypsum block placed approximately I inch deep in the soil to monitor available water during the 1979 growing season. The wire lead is attached to a soil moisture meter. November may have helped the turf survive the winter in better condition than turf receiving other topdressing programs. BOTH MONTHLY topdressing pro­ grams (MS and M S/S) resulted in more dollar spot on creeping bentgrass than the semiannual programs (2 S/S and 2 S/S C). This difference in dollar spot severity was especially great during 1977 and 1978. An increase in dollar spot incidence with monthly topdressing has also been noted in past research. Dollar spot was not a problem on Kingstown velvet bentgrass throughout the experimental period, but a slight infection of copper spot did occur occasionally. One of the primary criticisms of sand topdressing is that it results in droughty putting greens which lack good moisture retention. Soil moisture content under the various topdressing programs was measured during 1979 using gypsum blocks in order to evaluate moisture retention. Plots receiving monthly sand topdressing retained less water than plots subjected to sand/soil topdressing programs throughout the growing season. Although sand topdressed plots were most droughty, their available water content never fell below 55 per­ cent at any time during the summer. Also, while sand topdressed plots dried out more rapidly than plots receiving other programs, they did not wilt any faster than other plots. This was due to a much denser root system under sand topdressed turf than under sand/soil topdressed turf. Thus, the superior root density of sand topdressed turf allowed it to absorb soil water more efficiently than sand/soil topdressed turf. A major difference between sand topdressing and sand/soil topdressing is the organic matter content of the topdressing mixture. Advocates of sand topdressing feel that it makes little sense to add organic matter to topdressing MAY/JUNE 1981 11 These soil profiles show the amount of topdressing accumulation after three years. The white lines indicate the original green surface. A — Monthly sand — 2 inches; B — Monthly sand/ soil — l/i inches; C — May and September topdressing without cultivation — 1 inch; D — May and September topdressing following cultivation — I inch. when we are trying to reduce the thatch (an organic matter layer) on a putting green. This is a logical assumption; however, some minimum organic matter content is needed for optimum turf growth. It has been reported that as little as 5 percent soil or 10 percent organic matter added to pure sand can provide adequate nutrient storage for putting green turf. In this study, monthly sand topdressing resulted in less organic matter in the upper inch of soil than any other program. Sand topdressed plots contained about 2 percent organic matter while the sand/ soil topdressing programs averaged 10 percent organic matter in the upper inch of soil. Sand topdressed putting greens having such a low organic matter content may become difficult to manage because of their inability to store and supply nutrients to the turf, especially as the depth of the sand layer increases. One of the most important reasons for topdressing is to help control thatch 12 USGA GREEN SECTION RECORD accumulation. In order to measure thatch buildup, cores were taken from all plots during September of 1979. The cores were compressed with a 1-kilogram weight before thatch depth measure­ ment in order to eliminate any air pockets present in the thatch layer. Monthly sand topdressing resulted in only 2 millimeters of thatch during the three-year test period, while sand/soil topdressing programs averaged 12 milli­ meters of thatch. The firm, virtually thatch-free putting surface that results from light, frequent sand topdressing is one of the main reasons the program is so popular. It should be noted that frequent sand topdressing does not decompose exist­ ing thatch as much as it prevents thatch development from occurring. The prin­ ciple behind frequent sand topdressing is to topdress often enough to allow continual dilution of the organic matter being produced so that no thatch layer is allowed to form. Ideally, topdressing frequency should be adjusted to the turf growth rate, topdressing more frequently during periods of maximum growth and less often during periods of slow growth. In general, three- to four-week application intervals have worked best in most areas. Clippings were collected and weighed weekly from June through October during 1979 in order to evaluate the relative growth and vigor of the turf. Monthly sand/soil topdressing produced the highest average clipping yields during the growing season. Monthly sand/soil applications supplied nutri­ ents, which resulted in more vigorous turf growth than the other programs. Monthly sand topdressing produced less growth than monthly sand/soil topdressing during all months. The slower growth rate of sand topdressed turf resulted in less recovery from injury and less stolon growth than turf receiving sand/soil programs. Also, pecking injury from birds searching for cutworms was much more severe on sand topdressed plots. Semiannual sand/soil topdressing following culti­ vation (2 S/S C) resulted in less growth than the other sand/soil programs during September and October due to the injury associated with cultivation. LIGHT MONTHLY sand/soil top­ dressing resulted in higher quality turf and better spring and fall color than light monthly sand topdressing or semiannual sand/soil topdressing. Light sand topdressing provided a smooth, firm, thatch-free putting sur­ face; however, the low organic matter content and infertility of pure sand can result in less vigorous turf and slower recovery from injury than sand/soil topdressing. While sand topdressing resulted in the most droughty root zone and less available water for the turf, wilting did not seem to be a problem. Both monthly topdressing programs resulted in much more dollar spot incidence than semiannual topdressing. However, this problem can be solved by using a preventive fungicide program. The overall results of this study show that light, frequent sand/soil top­ dressing is superior to heavy, infrequent application for maintaining high quality putting turf. In addition to the agro­ nomic benefits, frequent light top­ dressing causes less inconvenience to golfers than infrequent heavy appli­ cations. While monthly sand/soil topdressing provided superior turf in this study, the decision whether to use pure sand or topdressing containing some soil and organic matter is not clear cut. Sand topdressed greens do not store or supply nutrients as well as sand/soil top- dressed greens. The infertile nature of sand can be overcome by fertilizing more heavily or using more slowly available nitrogen sources. The excellent putting surface provided by sand top­ dressing must be weighed against the increased fertility and management level necessary to maintain sand top- dressed greens. This decision will become even more crucial in the future as fertilizer becomes more expensive and water availability for golf courses becomes less certain. Topdressing is an important, expensive management practice. It is a good idea to review the advantages and disadvantages of any topdressing program before you begin using it. REFERENCES 1. Cooper, R. J., 1980. An evaluation of several topdressing programs for Agrostis palustris Huds. and Agrostis canina L. putting green turf. MS thesis. University of Rhode Island. 2. Hall, J. R., 1978. Avoid the temptation of sand topdressing. Tech Turf Topics. Virginia Polytechnic Institute and State Univ., Blacksburg, Va. 3. Madison, J. H., and W. B. Davis, 1977. Problems or progress. Tee 2 Green Corporation, 1212 W. 8th St., Kansas City, Mo. 16 p. 4. USGA Green Section Staff. 1977. Top­ dressing mixtures: the Green Section’s position. USGA Green Section Record, 15(6):5-8. Maintenance Aids A TIP FROM ALBERT (LES) ALLEN, Retired Golf Course Superintendent, Kernwood Country Club, Salem, Massachusetts DURING HIS long tenure as super­ intendent at Kernwood Country Club, Les Allen, who is now retired, was known as an excellent mechanical innovator. One of his ideas, pictured here, shows a Del Monte rake attached to a mechanical sand rake. The one- piece rake easily is interchangeable with the sand raking apparatus normally attached. The Del Monte rake is used to comb greens occasionally prior to mowing, thereby reducing grain. A hydraulic lever controls precise down­ ward pressure needed. USGA GREEN SECTION RECORD MAY/JUNE 1981 TURF TWISTERS TO SET STANDARDS Question: Recently, a salesman told me his company sold a sand that was “USGA approved.” Is there a USGA approved sand? (Kentucky) Answer: The USG A does not approve or endorse any product. The USG A sets standards of specification for those who wish to conform. The USGA offers no objection to any sand company stating that its sand conforms to USGA specifications, if indeed it does. The burden of proof, however, rests with the advertising company, not the USGA. Also understood is that the USGA will not allow statement or implication in ads to the effect that we endorse any product. KEEP NUTRIENT BALANCE Question: I have been using iron sulfate to maintain good color on my putting green turfgrass. I’ve noticed that although I still get a response, it is not as good as it used to be. Could you offer any explanation? (Ohio) Answer: Try adding magnesium sulfate (Epsom salts) to the spray mixture. Iron sulfate stimulates the production of chlorophyll, and since magnesium makes up the center molecule of chlorophyll, you truly need both in balance. Therefore, add magnesium sulfate at the same rate you use the iron sulfate and see if the turf response improves. AND DON’T FORCE GROWTH Question: The dry weather of last year has us worried about our greens. What can we do? (Eastern Pennsylvania) Answer: Be sure to aerate your greens this spring to take full advantage of precipitation and to minimize surface runoff. Several applications of wetting agents will also help to improve water infiltration. Also, try to reduce the growth rate of the grasses. A plant that is growing slowly will require less water. A very good first step is to reduce the amount of nitrogen applied in early spring months. Let nature provide the early growth, and do not force growth earlier than necessary.