Contents January-February 2008 Volume 46, Number 1 1 Green Side Up! Sodding putting greens can be a viable method of establishment with proper care, good product, and reasonable expectations. BY MATT NELSON 6 Bermudagrass Freeze Tolerance Oklahoma State University researchers use laboratory and field evaluations to compare bermudagrass freeze tolerance. BY JEFF ANDERSON, CHARLES TALIAFERRO, DENNIS MARTIN, YANQI WU, AND MICHAEL ANDERSON 12 Going for the Gold with the Ultradwarf Bermudagrasses This is part three of an occasional series on bermuda­ grass putting greens and focuses on surface management and minimizing grain. BY JOHN H. FOY 1 6 Cultivating to Manage Organic Matter in Sand-Based Putting Greens University of Arkansas researchers provide important insight for managing organic buildup on putting greens. BY JOSH LANDRETH, 10 Don’t Wait Until the Well Runs Dry Changing water sources: from good to good. BY TOM WERNER, CGCS DOUG KARCHER, AND MIKE RICHARDSON 20 Ski Season Golf courses provide recreational opportunities throughout the year, even when it snows. BY MATT NELSON Green Section Committee Chair Patrick W. McKinney 37 Legare Street Charleston, SC 29401 Turfgrass Environmental Research Chair Steve Smyers 2622 W. Memorial Blvd. Lakeland, FL 33815 USGA President Walter W. Driver, Jr. Executive Director David B. Fay Dr. Paul Raymer is utilizing the extensive seashore paspalum germplasm collection assembled by Dr. R. R. Duncan to generate new genetic variation through recombination. The University of Georgia holds the largest collection of seashore paspalum ecotypes in the world. 22 Seashore Paspalum: 22 Washing Breeding a Turfgrass for the Future Work continues at the University of Georgia on the development of this salt-tolerant species. BY P. L. RAYMER, S. K. BRAMAN, L. L. BURPEE, R. N. CARROW, Z. CHEN, AND T. R. MURPHY 27 Welcomed Mats for Small Practice Tees Which is better for a small practice tee — artificial turf or bare ground? BY TODD LOWE 20 Define the Line A simple mowing strategy to maintain the dimensions of greens and the width of collars. BY KEITH HAPP Your Cares Away Gaining an equipment wash rack upgrade as part of the turf management center master plan. BY JOSHUA CONWAY 2 4 News Notes 25 2008 USGA Green Section Education Conference and 2008 USGA National & Regional Conferences 2 6 A Question of Credibility Don’t believe everything the “experts” tell you. BY CHRIS HARTWIGER 2 8 Turf Twisters Editor James T. Snow Associate Editor Kimberly S. Erusha, Ph.D. Cover Photo Managing the sod layer with aeration and topdressing is critical to the long-term performance of a putting green. Green Side Up! Sodding putting greens can be a viable method of establishment with proper care, good product, and reasonable expectations. BY MATT NELSON Quality bentgrass sod will establish quickly when placed on a well-chosen and prepared sand rootzone. Given the option, most cool-season turf managers would prefer to establish putting green turfgrass directly from seed. Seeding enables turfgrass plants to germi­ physiological stress for best establishment. When grow-in goes well, greens seeded in mid to late August are ready for play by late May or early June of the next year across most of the northern United States. nate, establish, and mature in the rootzone selected for the greens. Strong roots will develop in a well-oxygenated sand rootzone, and the developing thatch/mat layer can be integrated with sand during grow-in to avoid layering and maintain optimal soil structure. Surfaces can be prepared during construction and maintained during grow-in with topdressing, grooming, and rolling to provide superior smoothness and playability. Typically, creeping bentgrass estab­ lishment from seed requires at least 12-16 weeks of good growing weather for sufficient matura­ tion to tolerate play. Seeding in late summer is preferred, taking advantage of warm soils, cool­ ing nights, reduced disease pressure, and limited At many northerly and higher-elevation sites, however, a limited growing season extends the amount of time required to open seeded putting greens. A longer grow-in may not fit the time­ line at higher-end projects dependent upon real estate sales and/or revenue generation. Sod has become increasingly utilized at these types of locations to compress the window between con­ struction and opening. Winterkill and renovation projects also con­ tribute to the demand for high-quality putting green sod. Replacing putting green turf domi­ nated by annual bluegrass (Poa annua) with creeping bentgrass sod significantly improves JANUARY-FEBRUARY 2008 turfgrass reliability over the winter. Installing bentgrass sod will not overcome limitations with respect to shade or poor design, but improved resistance to freeze injury can be expected. Regrassing with improved creeping bentgrass cultivars also may be a viable means of meeting golfer expectations with respect to putting quality and turfgrass performance.1 Many of the newer cultivars of creeping bentgrass exhibit good tolerance of close mowing, disease resist­ ance, outstanding morphological characteristics, and enhanced overall stress tolerance. In some climates it is a real challenge to meet current golfer expectations for ball roll and consistency with a mix of annual bluegrass and older geno­ types of creeping bentgrass due to anthracnose, nematodes, and/or physiological stress. A long grow-in time does not always fit into a project timeline. Sod provides an opportunity for rapid putting green establishment. Sod quality and production has evolved considerably in recent years, meeting industry demands for agronomic excellence and superior playability in a short time. This article will address some of the major issues regarding putt­ ing green sod selection and establishment for the best opportunity for success. Although the infor­ mation in this article pertains directly to creep­ ing bentgrass putting green turf, the principles of agronomy should be pertinent to the culture of bermudagrass sod in warm-season climates. SELECTING THE BEST SOD Of paramount importance when selecting putting green sod is rootzone compatibility. Sod grown in soil that is finer textured than 2 GREEN SECTION RECORD the underlying rootzone will likely pose estab­ lishment difficulty, as excess moisture held in the sod layer will limit root growth and gas exchange. Creeping bentgrass sod grown in a clay, silt, or loam soil placed on a sand rootzone is practically doomed from the start and should never be considered. Superintendents or project managers should visit potential sod farms and ask for particle size distribution analyses from the top one or two inches (depending upon cutting depth) of the sod rootzone. These tests results can be compared with rootzone mix parameters of the putting greens to estimate physical com­ patibility. If in doubt, seek input from an agrono­ mist, university extension specialist, or a USGA- accredited physical soil testing laboratory. In recent years, soilless sod has become avail­ able in the western United States. This patented technology involves producing creeping bent­ grass sod on thin plastic with only enough sand to germinate seed and establish the turf. The risk of rootzone incompatibility may be reduced with this type of sod, although organic matter accumulation must be managed appropriately, a concern with practically all types of bentgrass sod. Sod grown on plastic does not require bottom cutting for harvest; thus, turfgrass roots remain intact although bound in the thatch/mat layer. Producers market the lack of root cutting as a benefit to establishment. Sod produced on plastic can usually be harvested at various widths, since undercutting is not required. Selecting young sod (less than one year or so) is usually desirable, since thatch will be more manageable. Excess thatch can restrict gas exchange into the rootzone, hold too much moisture near the surface, decrease tolerance of environmental extremes, increase the likelihood of mechanical injury as cutting heights are lowered, and compromise recuperative potential of the turf. About 0.75 inch of thatch or less would be considered desirable when selecting putting green sod. Cultivar selection can be based upon regional NTEP (National Turfgrass Evaluation Program) trials, regional performance, compatibility with existing turf (if only sodding one or a few greens), player expectations, and maintenance capability. If a major renovation involving sod is to be carried out, most producers will contract to grow the cultivar of choice and, within reason, manage accordingly. Perhaps growth regulator applications and/or topdressing will be desired, and these practices are feasible provided equipment and costs are identified. Long­ distance transport for the sod may require refrigeration to avoid desiccation and damage to the sod. ESTABLISHMENT TIPS— GREEN SIDE UP! Anybody who has had the good fortune to have hands- on involvement with major sod projects has heard all the installment jokes, none of which will be repeated here. Jokes and puns aside, however, there are some tried and true tips worth considering when working with putting green sod. Sod grown on plastic may reduce soil compatibility issues and does not require cutting turfgrass roots during harvest. Using big rolls of sod is not necessary for a successful project, but they provide some advantages. Big rolls speed the installation process, which can be advantageous under many circumstances. Fewer pieces of sod also mean fewer seams for potentially smoother surfaces earlier, slightly easier management, and reduced risk of edge desiccation. The prepared finished grade should be smooth and firm. Ideally, the surface should be firm enough that footprints are less than 0.25 inch deep. Check grades with a digital level and survey equipment to ensure that putting greens have positive surface drainage for water dis­ charge. This point is especially critical where winterkill is an issue; water from melting snow and ice needs to flow off of putting green turf. When renovating existing greens, cut the existing sod deep enough to remove organic matter from the upper soil profile. Leaving behind excess organic matter compromises soil structure and potentially skews the balance between capillary and non-capillary porosity. Roots from the new turfgrass sod will have a difficult time penetrating thatch or mat layers present in the rootzone. Aggressively cultivating the rootzone of older greens prior to installing sod presents a good opportunity to modify soils with sand for improved physical properties and performance. Conventional or deep-tine aeration both are viable options, depending upon root- zone properties, and aggressive cultivation prior to sod establishment can enhance success with potentially reduced surface disruption during establishment. Physical testing of existing root­ zone parameters prior to renovation and regrass­ ing will provide valuable insight into necessary rootzone modifications. Install sod as uniformly as possible and, with renovations, pay special attention to grade tie- ins. Offset seams for reduced displacement, mechanical damage, and desiccation. Avoid damaging the prepared finished grade or impart­ ing excess wear on newly installed sod by using plywood to walk on or drive installation machinery. Once sod is installed, aggressive rolling will firm and smooth the surface. Walk-behind vibratory asphalt rollers or riding one-ton asphalt rollers typically provide best results. Rolling can begin immediately after the sod has been laid and can be repeated every few days during the establishment process. Smoothing the surface limits mechanical damage (scalping) from mowers as height of cut is reduced in preparation for play, and it also helps provide optimal playing quality. Begin mowing at a reasonable height of cut as soon as possible to avoid scalping and mechanical damage. It is important to begin mowing soon after installation to avoid letting the turf become J A N U A R Y-F E B RU A R Y 2008 3 with respect to vigorous establishment. Aeration can often be conducted within the first week of installation with the proper technique. Small­ diameter solid or hollow tines (0.25-0.375 inch) provide good results since the primary objective of early cultivation is to maintain good gas exchange through the sod layer and encourage roots to penetrate into the underlying rootzone. Repeating this procedure once or twice prior to opening the greens is advised since cultivation is typically more difficult to employ once the greens are opened for play. Periodic aeration with small-diameter solid tines or slicing units during the first season will safeguard turf health by promoting gas exchange into the rootzone and preventing sealing that is often a concern on newly sodded greens. Watch for signs of reduced turf vigor, poor recuperative potential, or development of black algae on the surface. These conditions usually indicate insufficient oxygen in the rootzone. Fertility recommendations vary considerably between new construction and renovation of existing greens. Soil testing is a good place to start. With new construction, pre-plant fertility usually includes a homogenous starter fertilizer application at a rate of around 1 lb. nitrogen and P2O5 per 1,000 sq. ft. Good results have been observed where starter fertilizer is augmented with additional controlled-release fertilizer in a balanced formulation of nitrogen, phosphorus, and potassium at 1-2 lbs. each per 1,000 sq. ft. Pre-plant fertilization rates for existing root­ zones will be lower than new construction. Consult with your regional USGA agronomist, soil testing laboratories, and/or university turf­ grass extension personnel for best advice at your particular location. Once installed, relatively modest and frequent applications of complete fertilizer usually provide good results. IN-HOUSE CUSTOM SOD Occasionally there is a need to renovate one or more greens at an older golf course not experi­ encing agronomic problems. The design may be outdated, with excessive slopes for modern green speed or insufficient area to adequately support the volume of play.2 Property sales or trades may necessitate relocating a green. In these instances, matching the turfgrass composition and play­ ability with the existing greens is a primary objective. At most cool-season golf courses, this Using plywood helps to limit wear injury to sod and is a good tip during successful installation. puffy and to start the process of lowering the height of cut in preparation for the planned opening date. Floating-head, walk-behind mowers equipped with a smooth, out-front roller minimize the potential for mechanical damage. Be diligent with cutting height reduc­ tions to prepare the surface for play, but don’t hesitate to raise the height of cut in the event of excessive scalping, as mechanical damage can take a long time to recover and may jeopardize the opening date, playing quality, and short- and long-term performance of the turf. Taking the time to hand topdress the sod seams will limit the potential for mechanical injury, lessen the potential for desiccation of sod edges, and hasten the development of the desired surface smoothness. Green colored sand has worked well for seam topdressing during cool spring weather, as colored sand will absorb more heat and some superintendents report quicker stitching of individual sod pieces. Heavy sand topdressing of the entire sodded green at rates of 250-350 lbs. of sand per 1,000 sq. ft. for the first three to four weeks also will be very important for surface smoothing and preparing the green for play. Integrating sand into the organic matter layer as quickly as possible also will establish sand as the dominant component of the thatch/mat matrix and provide balanced soil structure for good agronomic performance and playability. Physically incorporate sand into the turfgrass canopy by brushing or dragging. Aerating new sod as quickly as possible has repeatedly demonstrated great results in the field 4 GREEN SECTION RECORD constitutes a mix of various genotypes of annual bluegrass and creeping bentgrass. respect to agronomic realities and golfer expectations is advised. With proper planning, a nursery green can be created utilizing aeration plugs from the existing greens and perhaps a little bentgrass seed? Usable sod normally can be obtained in about a year, depending on the growing season, management capability, and nursery location. Similar manage­ ment protocol will apply as suggested above, and using the best available means to harvest uniform sod will yield the best results.4 DETERMINING AN OPENING DATE Creeping bentgrass putting green sod usually requires at least 4-6 weeks of decent growing weather for adequate establishment to tolerate play. Root growth should be at least a few inches into the rootzone for anchoring and stability, and to take up sufficient nutrients and water for vigorous growth and recovery. Surface prepara­ tion needs to be advanced enough to provide good ball roll characteristics and tolerate reason­ able mowing without scalping. Ultimately, reasonable expectations need to be established early on in the construction and renovation process. Opening newly sodded greens too early can jeopardize performance, result in turfgrass failure, and threaten a signifi­ cant investment. Green speed expectations should be properly balanced with long-term performance during the first few months of playing the sodded greens. Scheduling some time for cultivation and topdressing will safe­ guard success. Closing one day or half a day per week and providing the turf a chance to recover from wear and stress can make an enormous difference in putting green performance. Among the best recommendations for managing newly sodded greens is to give the golf course superintendent and green committee sole discretion to close the greens should turf­ grass decline or failure become evident. New sod generally does not have the recuperative potential of established turf, and a modest to heavy volume of play can result in rapid and significant decline. A “soft opening” during the first few weeks of play, whereby the greens are played for 3 or 4 days and then rested for 2 or 3 days is often a good way to allow golfers on the greens fairly quickly (4-6 weeks after installation) while still enabling the new sod to establish and mature. Every situation is slightly different, but adopting a fairly conservative approach with GREEN SIDE UP! Sod production methods have evolved consider­ ably in the past decade or so and present viable options with respect to turfgrass establishment on putting greens. Production on construction specification sand, washed sod, and sod grown on plastic have facilitated smoother and more successful projects and can provide champion­ ship-level putting surfaces in a previously unattainable time frame. Proper planning, product selection, installation, and construction techniques, and good management make sod a realistic option for putting green turfgrass establishment at new or existing golf courses. Green side up! An instant putting green. LITERATURE CITED 1. White, C. 2006. Rebuild or resurface. USGA Green Section Record. 44(l):l-6. 2. Kinder, B., M. Condon, D. Weiss, R. Phelps, G. Bartold, J. Gamble, and M. Nelson. 2005. Renovation at Rolling Hills. USGA Green Section Record. 43(5):30-33. 3. Gross, P. J. 1999. Poa/Bent nurseries — a perfect match. USGA Green Section Record. 37(2):9-ll. 4. Nelson, M. 1997. Sew it seams. USGA Green Section Record. 35(3):7. Author’s Note: The author would like to recognize James Beebe, CGCS, Priddis Greens Golf and Country Club, for his contributions to this article. Matthew “Sod” Nelson is senior agronomist in the USGA Green Section’s Northwest Region, visiting golf courses in the Rocky Mountains of the United States and Canada. JANUARY-FEBRUARY 2008 5 ^Sponsored Research You Can Use Bermudagrass Freeze Tolerance Oklahoma State University researchers use laboratory and field evaluations to compare bermudagrass freeze tolerance. BY JEFF ANDERSON, CHARLES TALIAFERRO, DENNIS MARTIN, YANQI WU, AND MICHAEL ANDERSON urfgrass managers spend a considerable amount of time and energy to establish and maintain turfgrasses for aesthetic, environmental, and recreational purposes. Both genetic and environ­ mental components interact to determine how well a chosen cultivar performs in a particular location. An increasing number of fine- textured bermudagrasses are being developed and evaluated for resistance to environmental stresses. Freeze damage is a primary concern in the northern boundaries of the bermudagrass adaptation zone. Some years are relatively mild and cause little or no damage, while other winters are sufficiently severe to cause extensive winterkill. The costs, in terms of loss of use and dollars to re­ establish turf following winterkill, can be substantial. Therefore, our long­ term goal is to develop seed- and vegetatively propagated bermudagrasses with high turf quality and improved freeze tolerance. A common way to compare relative freeze tolerance of a group of cultivars is to establish them in the field and wait for cold temperatures to sort them out. However, during a mild winter, temperatures may not be cold enough to kill any cultivars of interest, and no progress would be achieved. If evalu­ ations were conducted at a northern or high-elevation location, low tempera­ 6 GREEN SECTION RECORD documented susceptibility of newly seeded bermuda­ grasses may involve physio­ logical and/or morpho­ logical factors such as stolon density.6 YEAR-ROUND WINTER INDOORS Laboratory-based methods to measure freeze tolerance have been developed. One approach has been to acclimate plants naturally in the field, followed by laboratory-based exposure to sub-freezing tempera­ Regrowth of CIS-CD7 seeded bermudagrass varied after exposure to a range of sub-freezing temperatures. tures may kill most or all of the ber­ mudagrasses. Therefore, several years of observation may be required to experience temperature conditions that distinguish different levels of freeze tolerance within a group of bermuda­ grass cultivars. Relying on test winters makes it difficult to repeat studies over time and across climatic locations. Another factor that comes into play during natural freezes is the nature of the freeze itself. Differences in freezing rate or duration, even with the same minimum exposure temperature, can result in different plant responses.4 Whether or not a snow cover is present can have marked influences on plant survival due to insulation effects. Developmental and morphological features also can be factors in winter survival. The presence of rhizomes can contribute to freeze avoidance by being sufficiently deep in the soil profile to avoid temperature extremes. The well- tures. Studies also have been conducted entirely indoors, with plant materials established and acclimated in growth chambers, followed by exposure to a range of temperatures in a freeze chamber. Laboratory-based freeze­ tolerance evaluations generally corre­ spond well with field observations and have provided useful information on relative freeze tolerance of turfgrasses.2 Our objective was to quantify freeze tolerance of advanced lines, recently released cultivars, and standard varieties entered in the 2002 National Turfgrass Evaluation Program (NTEP) bermuda­ grass trial using laboratory-based methods. Standardized, quantitative information on bermudagrass freeze tolerance is vital to scientists to track progress in developing new cultivars. Freeze tolerance data also are beneficial to turfgrass managers selecting turf­ grasses for the transition zone. Bermudagrass plants were established and maintained in growth chambers. For studies with seed-propagated culti­ vars, seed from the lots used in the 2002 NTEP bermudagrass trial was obtained from the sponsors. Twenty­ seven of the 29 seed-propagated entries were included in this study. Experi­ ments with seed-propagated bermuda- grasses were divided into five groups. Entries were randomly selected and assigned to groups with Arizona Common included as a standard in each, allowing the potential for com­ parisons across groups. Vegetative cultivars were propagated from indi­ vidual phytomers using Tifway as the standard cultivar in each of the three groups. Experiments were conducted on three dates for each group, consti­ tuting replications in time, with staggered plantings allowing uniform establishment periods and plant age. After plants had acclimated to fall- like temperatures, they were trimmed of top-growth and placed in a freeze chamber with a temperature sensor in each pot. The chamber was pro­ grammed to slowly cool the plants, allowing them to be removed over a range of temperatures. Ideally, no damage would occur at the warmest temperatures, and all plants would be killed by exposure to the coldest temperatures. After being removed from the freeze chamber, plants were thawed and returned to the growth chamber to observe regrowth. Non-frozen controls were treated the same, except without the freeze chamber exposure. Evaluating the temperature-survival curve allowed estimation of a Tmid value, similar to the LD50 (lethal dose for 50% of the subjects) in a toxicity screen. Data were combined into seeded and vegetative types. Perfor­ mance relative to the standard cultivar (Arizona Common or Tifway) was determined by subtracting the Tmid for each cultivar from the Tmid value for the standard in that group. Figure I Deviation temperature (°F) from AZ Common ◄------------------- Less Freeze Tolerance More ------------------- ► Freeze tolerance of seed-propagated bermudagrasses relative to Arizona Common. Deviation temperatures represent the Tmid value (midpoint of the survival-temperature response curve) of the cultivar minus the Tmi(f value for Arizona Common. Cultivars significantly different from Arizona Common are indicated by an asterisk. Adapted from Anderson et al.5 CONSIDERABLE VARIATION IN FREEZE TOLERANCE Seed-propagated bermudagrasses ranged in freeze tolerance from 22.5°F (-5.3°C) (SWI-1003) to 16.3°F (-8.7°C) (CIS-CD6). Even though three cultivars were numerically less freeze tolerant than Arizona Common, none of the three was significantly different. FMC 6, Mohawk, Princess 77, and SWI-1046 were identical in freeze tolerance to Arizona Common. Fifteen cultivars had numerically greater, yet non-significant differences, in freeze tolerance relative to the stan­ dard. Transcontinental, SWI-1014, Riviera, and CIS-CD6 were signifi­ cantly more cold hardy than Arizona Common. Although Yukon and Trans­ continental differed from Arizona Common by the same amount, the difference was not significant for Yukon at the 5% level due to greater variability in data from Yukon. A previous study that included these two cultivars found Yukon to be signifi­ cantly more freeze tolerant than Arizona Common.1 JANUARY-FEBRUARY 2008 7 Laboratory-based methods have been developed to measure turfgrass freeze tolerance. Thermo­ couple temperature sensors are used to measure soil temperatures. Bermudagrass plants are acclimated to fall-like temperatures, trimmed of top growth, and placed in a programmable freeze chamber to be exposed to sub-freezing temperatures. Freeze tolerance of vegetatively propagated bermudagrasses relative to Tifway. Deviation temperatures represent the Tmid value (midpoint of the survival-temperature response curve) of the cultivar minus the Tmid value for Tifway. Cultivars significantly different from Tifway are indicated by an asterisk. Adapted from Anderson et al.s Vegetatively propagated bermuda­ grasses ranged in freeze tolerance from 20.8°F (~6.2°C) (GN-1) to 11.3°F (-11.5°C) (OKC 70-18). Three culti­ vars, GN-1, Celebration, and MS- Choice, were significantly less freeze tolerant than Tifway. Tift #4, Tifsport, Premier, Tift #3, and Aussie Green had cold hardiness levels similar to Tifway. Midlawn, Ashmore, Patriot, and OKC 70-18 were significantly more freeze tolerant than Tifway. Freeze tolerance estimates generally corresponded well with previous experience.3 Both Midlawn and Patriot exhibited greater freeze tolerance than Tifway as previously reported.4 Greater freeze tolerance of Riviera than Princess 77 is consistent with earlier findings.5 In a previous report, we also 8 GREEN SECTION RECORD found GN-1 to be significantly less freeze tolerant than Midlawn.3 It is important to distinguish between Tmid temperatures determined in the laboratory and air temperatures experienced during a natural freeze. In the laboratory, conditions are set to ensure that plants reach the target temperatures. Critical tissues, such as crowns, of plants in the field will usually be considerably warmer than air temperature due to the thermal buffering capacity of the soil. Substantial progress is being made by turfgrass breeders to develop seed- propagated and vegetatively propagated bermudagrasses with improved freeze tolerance. Although many factors in addition to freeze tolerance will be assessed in making cultivar selections, choices are now available with freeze tolerance suitable for areas of the transition zone requiring superior winter hardiness. LITERATURE CITED 1. Anderson, J., C. Taliaferro, M. Anderson, D. Martin, and A. Guenzi. 2005. Freeze tolerance and low temperature-induced genes in bermudagrass plants. USGA Turfgrass and Environmental Research Online. 4(l):l-7. 2. Anderson, J. A., C. M. Taliaferro, and D. L. Martin. 1993. Evaluating freeze tolerance of bermudagrass in a controlled environment. HortScience. 28:955. 3. Anderson, J. A., C. M. Taliaferro, and D. L. Martin. 2002. Freeze tolerance of bermuda­ grasses: vegetatively propagated cultivars intended for fairway and putting green use, and seed-propagated cultivars. Crop Sci. 42:975-977. 4. Anderson, J. A., C. M. Taliaferro, and D. L. Martin. 2003. Longer exposure durations A Q&A with Dr. Jeff Anderson regarding the use of artificial freeze testing to evaluate turf for cold hardiness. Q: Artificial freeze testing seems like a good method to screen turf­ grass selections for freeze tolerance, but how often do laboratory freeze-testing methods disagree with field testing? What other factors besides temperature affect field-grown plants that may lead to these differences? A: Research conducted at several universities has shown that field and laboratory results on turfgrass freeze tolerance are usually in agreement. While there are instances when rankings from field studies do not completely match laboratory studies, there also have been cases when results from one field study do not match another. Different locations could have different environmental conditions before a freezing episode, leading to different patterns of acclimation. It also is possible for a cultivar exposed to one environmental stress to be more susceptible to other stresses. Q: How long have laboratory freeze-testing methods been used on turfgrasses? Are the methods the same as they were in earlier tests? A: Laboratory-based methods of freeze tolerance evaluation have been available for many decades. Ongoing research has led to refinements in testing methods, resulting in greater precision and reproducibility. Important refinements include ice nucleation to negate supercooling and monitoring the temperatures of each experimental unit. Use of microprocessor-controlled chambers and precision monitoring equipment has further improved the precision and reproducibility of the testing procedures. Q: In other articles, the bermudagrass germplasm that Dr. Yanqi Wu collected in China has been mentioned. Have you freeze-tested this Chinese collection and/or evaluated its cold tolerance? From your experience, is it likely that the Chinese bermudagrass germplasm will help improve freeze tolerance of yet-to-be-released bermudagrass cultivars? A: The addition of Chinese bermudagrass germplasm to the Oklahoma State University collection provides additional variability that can be used to develop new stress-tolerant, high- quality bermudagrass cultivars. Characterization of this collection and subsequent progeny for freeze tolerance is a priority and will proceed as funding permits. Based on geographic locations of where these plant materials were collected, there is a high probability that a portion of the collected material contains genes that will make plants suitable for locations that experience cold winters. Q: How does the “rate of freeze” affect freeze-tolerance measurements? A: Plant survival during freezing stress is favored by slow rates of cooling. Most studies use cooling rates of about 2°F per hour, similar to natural conditions. The rate of tissue cooling is not always the same as the rate of air temperature decline, especially for below-ground plant tissues. In addition to the buffering effect of the soil, plant temperatures will be moderated by the heat released when soil moisture freezes. Therefore, the rate of temperature change, the temperature minimum, and the duration of the low temperature exposure will all contribute to the intensity of freezing stress. Q: Growing plants in the greenhouse to evaluate survival after subjecting those plants to low temperature seems time-consuming. What additional tests are available that scientists can use to measure tissue viability after freezing that don’t take as much time? Q: From your experience, does the maturity of the turfgrass stand impact its cold tolerance? Can superintendents expect seeded bermudagrasses to be less cold tolerant the first winter following seeding, and more cold tolerant in subsequent winters? A: Viability testing has been a major focus of plant stress studies for many years. Approaches range from whole plant responses to biochemical assays, with each procedure having its strengths and weaknesses. Assays such as electrolyte leakage can be performed much more rapidly than regrowth analysis and have been applied to turfgrasses. When compared, the two procedures are in general agreement. However, there have been instances when electrolyte leakage has either overestimated or underestimated freeze tolerance when compared to regrowth results. One reason may be that freezing stress yields a more gradual electrolyte leakage versus temperature response compared with heat stress, which is very well suited to electrolyte leakage assays. One of the challenges of using electrolyte leakage for freeze tolerance of below-ground structures like crowns and rhizomes is the requirement that tissues be separated from soil/media without introducing artifacts. A: Although the mechanisms are not fully understood, the long-held belief that seeded bermudagrasses are more freeze susceptible shortly after planting has been reinforced by compelling evidence from research at the University of Arkansas and other locations. Q: What should superintendents learn as a “take home” message from your work, Dr. Anderson? A: Plant breeding programs around the country are doing an excellent job in developing new bermudagrass cultivars. It is no longer necessary to sacrifice turf quality to achieve stress resistance. Increased freeze tolerance in fine-textured bermuda­ grass lowers the probability of winter injury in traditional planting locations. While use can be extended to colder locations, even the most freeze-tolerant varieties currently available will be susceptible to winterkill under extreme conditions. increase freeze damage to turf bermudagrasses. Crop Set. 43:973-977. 5. Munshaw, G. C., E. H. Ervin, D. Parish, C. Shang, S. D. Askew, X. Zhang, and R. W. Lemus. 2006. Influence of late-season iron, nitrogen, and seaweed extract on fall color retention and cold tolerance of four bermuda­ grass cultivars. Crop Sci. 46:273-283. 6. Richardson, M. D., D. E. Karcher, and J. W. Boyd. 2004. Seeding date and cultivar affect winter survival of seeded bermudagrasses. USGA Turfgrass and Environmental Research Online. 3(13):l-8. Editor’s Note: An expanded version of this paper can be found at USGA Turfgrass and Environmental Research Online (http://usgatero.msu.edu/v06/ nl8.pdf). Jeff Anderson, Ph.D., Professor, Dept. Horticulture & LA, Oklahoma State University, Stillwater, Okla.; Charles Taliaferro, Ph.D., Emeritus Regents Professor, Dept. Plant & Soil Sciences, Oklahoma State University, Stillwater, Okla.; Dennis Martin, Ph.D., Professor, Dept. Horticulture & LA, Oklahoma State University, Stillwater, Okla.; Yanqi Wu, Ph.D., Assistant Professor, and Michael Anderson, Ph.D., Associate Professor, Dept. Plant & Soil Sciences, Oklahoma State University, Stillwater, Okla. JANUARY-FEBRUARY 20 0 8 9 Don’t Wait Until the Well Runs Dry Changing water sources: from good to good. BY TOM WERNER, CGCS Water will be diverted into the pond in the foreground. Multiple ponds can be interconnected for increased storage. Water transfer can be creative and add aesthetic features to the course. Even though the old adage goes, “If it ain’t broke, don’t fix it,” sometimes we do not have a choice or must look for other options. with the opportunity to incorporate a waterfall, which is not naturally occur­ ring in the Houston area, but it looks attractive on a golf course. This was the case at Shadow Hawk Golf Club and The Houstonian Golf and Country Club in Richmond, Texas, as it pertains to changing water sources. HISTORY OF THE FACILITY Both golf facilities are located on the same 470 acres of suburban Houston. They also share one pump station currently fed by well water. Close to 20% of the property consists of lakes, ponds, and wetland areas. The largest lake covers 60 acres and was part of the original property, which was dredged and enlarged during construction. Only the 15-acre lake is fed by well water; all the others rely on surface runoff and can be filled with the irri­ gation system when levels drop below an acceptable point. The two wells can supply about half of the maximum flow of 3,800 gallons per minute to the irrigation lake. This lake has a great holding capacity and could supply about one week’s worth of water during peak season before needing to be resupplied. Another advantage is the fact that this lake is higher than the others and is situated next to the largest lake. The height advantage also afforded the architect 10 GREEN SECTION RECORD Up until a few years ago, the thought of changing water supplies was far from anyone’s mind. The facilities were relatively new (opened in 1999) and well water was the logical irrigation source at the time. It was as simple as acquiring a permit and start­ ing the irrigation system. Except for an annual permit fee for both wells, there was no charge for the amount used, unless the clubs exceeded their original allotment. At the time the courses were under construction, the surrounding area was largely rural, but civilization was creeping in at a rapid pace. Growth in Fort Bend County is largely residential, with the usual amount of retail growth. Residents enjoy the good life in the country and choose to commute to work in the more industrialized nearby Houston area. Within five years, the two courses will be surrounded by subdivisions (there are no houses on the property). These residents will need potable water supplied by underground wells. A GRADUAL REDUCTION OF GROUNDWATER USAGE The Fort Bend County Subsidence District oversees the permitting and monitoring of all underground water in the county. The newly imposed rules state that every entity using more than 10 million gallons of groundwater per year shall use a different water source or face administrative penalties. It is not uncommon for the two courses to use 10 million gallons of water in a week during the growing season. Conversion requirements in our district state that: • By January 2008, a Groundwater Reduction Plan (GRP) must be filed with the subsidence district. • By the year 2013, groundwater usage must be reduced to a maximum of 70%. • By the year 2025, groundwater usage must be reduced to a maximum of 40%. Developing a GRP is made easy when you have help from the outside. A newly formed organization known as the North Fort Bend County Water Authority (NFBCWA) has since been created, and its mission is to reduce groundwater use in our area. We no longer get our well water for free, even with a permit ($5,000 annual charge). What got our attention rather quickly was the proposed 20% price increase every year starting in 2008. Annual water costs for our facilities would go from $40,000 to close to $300,000 by 2025. That number was a shock to everyone. As mentioned earlier, not too long ago the surrounding area was largely rural, and the planned subdivisions were only the dream of future land developers. Effluent water just eight years ago was not an option due to lack of supply. This is not the case any longer, and fortunately the nearest treatment plant is within one mile of the property. In our area, water usage and disposal is managed by a Municipal Utility District, or MUD. MUD district officials approached us and other end users with the proposal to supply non-potable water of the highest property line and will be metered from there. The distance to the irriga­ tion lake from this point is approxi­ mately 700 yards, and the distance will help disperse any solids in the effluent water. It is simply a matter of diverting this water from one lake to the other. Diversion is even easier, as the two lakes are 20 yards from each other. The distance from the diversion spigot to the irrigation intakes is another 150 yards, further aiding in solid dispersal. The cost of the diversion device (we chose a submersible system) came in at $25,000 and has since been installed. of water over time, even with the capital expenditures necessary. Thirdly, we can lock down pricing and avail­ ability for 50 years. Lastly, the life of the underground wells will be increased through lower usage. There are some negatives associated with the use of effluent water. The greatest concern is the quality as com­ pared to well water. Our current management practices will have to be altered in the future and may put a slight burden on the memberships at both golf courses. This burden may come in the form of increased aeration This photo shows the installation of a submersible diversion pump so another structure is not seen on the golf course. The maintenance of submersible pumps is not difficult. quality type (TYPE 1). The MUD also needs our water credits as part of the process and must assess a reasonable fee structure to recoup the expense of the pipeline to the property. Once the water gets to the property, the expense of getting it to the irrigation lake be­ comes the responsibility of the owner. Irrigation heads and valve covers will need to be converted to the non- potable, light purple color at an esti­ mated cost of $40,000. Some of the fairway heads have already been con­ verted. Permeability testing of the clay lining in all lakes also was performed at a cost of $10,500. HOW DOES THE WATER GET TO US? The process of signing off on this proposal looked good on paper, but other costs needed to be factored in. Fortunately, one of the fingers of the largest lake is situated 30 feet from the property line, so there would be no damage to the property from the pipeline construction. The proposed effluent supply line will come to this WHAT HAPPENS NOW? Actually, nothing has changed yet, and construction of the effluent pipeline has not yet begun, but we are ready when it does proceed. After careful consideration, we decided it best to use at least 70% effluent water (or as much as the supplier can send us) and make up the balance with well water. First and foremost, it is the right thing to do. Secondly, we can reduce the cost and use of products such as lime and gypsum to maintain soil pH. My impression is that only the most dis­ cerning golfers will notice. It will be our task to keep them educated. We have already informed our member­ ship advisory committees of the con­ version process. After all, they are the ones who will benefit in the long run. Author’s Note: I would like to thank James Edgmon, golf course superintendent at The Houstonian Golf and Country Club, and Bill English, formerly with Redstone Golf Manage­ ment for their help in writing this article. Tom Werner, CGCS, is golf course superintendent at Shadowhawk Golf Club. J A N U A R Y-F E B RU A R Y 2008 II Going for the Gold with the Ultradwarf Bermudagrasses This is part three of an occasional series on bermudagrass putting greens and focuses on surface management and minimizing grain. BY JOHN H. FOY To compensate for a shallower depth, double verticutting and going over the same area in opposite directions is a common grain and surface management strategy with the ultradwarfs. T"he first full set of ultradwarf (Champion) bermudagrass putting greens were planted in Florida in the summer of 1997. The following year, Floradwarf and TifEagle became available and were used on a few courses in Florida and the Southeast. Also in 1998, an On-Site Evaluation of Bermudagrass for Putting Greens project was initiated and sponsored by the National Turfgrass Evaluation Program, USGA, and Golf Course Superintendents Association of America. Subsequently, there has been a steady increase in the use of the ultra­ dwarfs, and today Champion, Mini-Verde, and TifEagle have replaced Tifdwarf as the standard for warm-season turfgrass putting greens. Although the ultradwarfs are bermudagrasses and there was some preliminary work done as far as their management requirements, as we all know, fine tuning of best management practices occurs in the field over a period of several years. With the ultradwarfs having been in use for ten years, a sound information base now exists for producing consistently top-quality putting green conditioning. It should be reiterated that every golf course is unique and “there are a lot of ways to skin a cat.” Having visited numerous facilities through­ out Florida and having discussed ultradwarf putting green management programs with superintendents from the Carolinas across the Southeast to Texas, there are a number of common denominators. The following is a review of the key surface management practices being used to produce top-quality ultradwarf putting greens. HEIGHT OF CUT IS NOT THE TOTAL ANSWER Along with a finer leaf blade and increased shoot density, the ability to tolerate a height of cut of 0.125 inch was one of the primary criteria used in selection of the ultradwarf cultivars. As to be expected, however, heights of cut have been taken lower and lower in an effort to produce very fast putting green speeds. However, just because it can be done does not mean that maintaining the lowest height of cut possible is necessary or even best for providing top-quality 12 GREEN SECTION RECORD putting green conditioning. Time and again, university research and field experiences have shown that there is a point of diminishing return where no additional increase in speeds is achieved with further reductions in height of cut. It should also be reiterated that the continual practice of maintaining excessively low heights of cut nega­ tively impacts general turf health and increases its susceptibility to disease and nematode pest problems. Thus, today, an effective height of cut in the range of 0.105 to 0.125 inch is being routinely practiced at the vast majority of facilities where top-quality ultradwarf putting greens are being maintained. Along with being able to provide medium fast to fast putting speeds, the turf has improved disease and environmental stress tolerance. However, during extended periods of inclement weather and in the fall when prepar­ ing for the winter, slightly elevated heights of cut need to be maintained. The higher shoot density of the ultradwarfs compared to Tifdwarf is a positive characteristic as far as smoothness of ball roll is concerned. Yet, this also is something of a negative when it comes to speed because of the additional resistance or friction created. To compensate and maintain fast to very fast putting speeds, light­ weight rolling or double cutting are considered necessary and routine practices. These practices typically are employed three or four times per week, but at some facilities they are done on a more frequent basis. Generally, when sustained turf growth is occurring, this is not a problem, but additional care needs to be exercised to prevent excessive wear and damage to the perimeters and collars of greens. Having sand particles integrated into the turf canopy also aids in reducing ball-to-leaf-blade contact, which in turn helps maintain faster speeds and a smoother, truer ball roll. Thus, fre­ quent but very light sand topdressing is another necessary and routine ultradwarf surface man­ agement practice. Throughout the growing season, lightly topdressing on a 7- to 14-day interval is the standard regime. It should further be pointed out that regular sand topdressing plays a dual rule and is needed for dilution of thatch and organic matter accumulation in the upper rootzone. While more frequent topdress­ ing than ever before is being practiced, it is also very important to make sure that a sufficient quantity of sand is being applied annually to achieve true dilution. Several factors, such as length of the growing season and nitrogen fertilization rates, need to be considered, but applying between 30 to 50 cu. ft. of sand per 1,000 sq. ft. annually would be suggested as a target. The turfgrass growth regulator Primo (trinexapac-ethyl) is a very beneficial putting surface management tool with Tifdwarf bermudagrass greens. It was initially questioned, however, if there would be any real benefit to treating ultradwarf greens, given the fact that a very dense turf canopy already existed. Yet, it was quickly found that with suppressing vertical shoot growth, more consistent putting speeds throughout the day and from one day to the next, along with slightly faster speeds, are achieved with adherence to a regular treatment program. This has become a standard, and it should be pointed out that at a lot of courses in Central and South Florida, weekly treatments on The tools of the trade must be available to the golf course superintendent to maintain ultradwarf bermudagrasses. From left: a triplex unit with carbide- tipped blades for verticutting, rotary spreader for applying dried bagged sand, putting green mower with groomer attachment, and another triplex with brushes. JANUARY-FEBRUARY 2 0 0 8 13 Close-center core aeration followed by removal of the debris and incor­ porating topdressing sand to backfill the holes is very unpopular with golfers and the maintenance staff. Yet this regime is absolutely necessary and must be con­ ducted at least two to three times per year for controlling organic matter accumulation and compaction so that top-quality surface conditions can be provided the majority of the time. virtually a year-round basis are being performed. The only time they are stopped is just prior to the arrival of a cold front and when nighttime temperatures of 50 degrees or colder are expected. GRAIN CONTROL AND SURFACE GROOMING Due to its stoloniferous growth habit, controlling grain is a major management concern with ber­ mudagrass greens. There is a strong argument today that with intensively managed, closely cut ultradwarf greens, the influence of grain on ball roll has been minimized to the point that this is not a concern for the vast majority of average to high-handicap golfers. Yet, very distinctive grain patterns do occur and are accentuated by more frequent rolling and mowing regimes. Since golf, and especially putting, is highly perceptual based, it is imperative to always try to keep grain to a minimum. Along with promoting a dense, upright shoot growth character to minimize grain, aggressive 14 GREEN SECTION RECORD Topdressing with dry sand helps incorporate the material into the dense turf canopy of the ultradwarf bermudagrasses. Sand storage silos are becoming a more common sight at Florida golf courses with ultradwarf greens. verticutting of Tifdwarf putting surfaces has been a standard practice. This also aids in con­ trolling thatch and organic matter accumulation. Verticutting in this manner every two or three weeks is effective, yet it also results in significant mechanical stress and damage. It has been a standard recommendation to severely verticut Tifdwarf greens with walk-behind units in the early summer and in conjunction with core aeration replications. It was determined fairly quickly, however, that the ultradwarf cultivars do not tolerate severe verticutting and recover very slowly from this abusive cultural regime. Regular verticutting of ultradwarf putting surfaces, at least every couple of weeks during the growing season, is being conducted at most facilities. However, along with using the new type of blade options that cut rather than rip through the turf canopy, they are adjusted to operate at no more than 0.0625 to 0.125 of an inch below the effective height of cut. The basic philosophy of routine verticutting of ultradwarf putting surfaces has changed from aggressively removing leaf surface area, thatch, and surface organic matter accumulation, to only thinning the turf canopy and grooming an upright shoot growth habit for grain control. With a shallower depth of penetration with regular verticutting, it has been found that a pronounced difference in the effectiveness of the process occurs when working into the grain compared to going down grain. To compensate for this grain effect, double verticutting and going across the putting surface in one direction and then turning around and coming back down the same pass in the opposite direction is needed. As with routine mowing, the direction of attack with verticutting should be changed with each replication. Circle verticutting is another variation being employed at a few courses in South Florida because it also varies the direction of attack into the grain pattern. While adherence to a regular verticutting schedule throughout the growing season is needed, this also needs to be closely monitored and adjustments made to make sure that excessive thinning, mechanical damage, and stress are not exerted on the turf. Furthermore, if more aggressive verticutting is required to alleviate a severe grain problem, this should be restricted to the late spring to early summer when maximum sustained growth is occurring. In addition to regular verticutting, putting green mower-mounted brushes or groomer To date, the develop­ ment of off-type bermudagrass areas in ultradwarf greens has not been a problem, but encroachment of fairway and rough bermudagrass does still occur and must be addressed at some point. attachments are important management tools. Constantly promoting an upright shoot growth character helps keep grain in check, and with minimizing ball-to-leaf contact, a smoother, truer ball roll and faster putting speeds are achieved. Use of brush or groomer attachments in conjunction with routine mowing is typically performed three to six times per week and in between the routine verticutting replications. SUMMARY Although not discussed in this review, very careful and judicious nitrogen fertilization and irrigation are common denominators at the courses where top-quality ultradwarf putting greens are being maintained. Thus, in many respects, ultradwarf and bentgrass putting greens are managed very similarly today. There is no argument that the ultradwarfs require more intensive and careful management compared to what works successfully with Tifdwarf bermuda­ grass greens. This has been raised as a concern by some because of the additional commitment of time and resources required. However, on the other hand, if top-quality putting green condi­ tioning is desired or expected, this certainly can be achieved with the ultradwarfs, and the results justify the efforts. John H. Foy is the director of the USGA Green Section Florida Region and has spent more than 20 years helping courses provide the best possible conditions with their bermudagrass greens. J A N U A RY-FE B RUA R Y 200 8 15 ^^^Sponsored Research Yoh Can I ’sc Cultivating to Manage Organic Matter in Sand-Based Putting Greens University of Arkansas researchers provide important insight for managing organic buildup on putting greens. BY jOSH LANDRETH, DOUG KARCHER, AND MIKE RICHARDSON It is not uncommon for newly constructed creeping bentgrass greens to perform very well during the first few years fol­ lowing establishment, but then decline in subsequent years. This is likely the result of the rootzone physical properties changing over time, especially near the surface where organic matter accumulates. It has been demonstrated that organic mat­ ter concentrations greater than 4 to 5% in a USGA rootzone will decrease water percolation through, and air movement into, the rootzone.2’3 Recent cultivation techniques that are effective in reducing organic matter and maintaining desirable rootzone physical properties include aggressive verticutting and core aeration with closely spaced tines. Verticutting equip­ ment such as the Graden GS04 has been demonstrated to aggressively cut channels through surface organic layers in putting greens, removing more organic matter than traditional core aeration treatments. Another recent trend in putting green core aeration is the use of more closely spaced tines, either by retrofitting older aeration units with adapters or through the introduction of new aeration units with closer tine spacing. A moderately aged USGA putting green typically has desirable physical 16 GREEN SECTION RECORD of Arkansas Research and Extension Center (Fayetteville, Ark.) on a one-year-old Penn G-2 creeping bentgrass putting green built according to the USGA method of putting green construction.1,4 Cultivation treatments were applied using either a Graden verticutter or a Toro greens aerator in the spring and fall of each study year. Verticutting treatments were made to a 1-inch depth to ensure complete penetration through Although verticutting treatments (left) removed more surface organic matter, plots that were core aerated (right) recovered significantly faster. properties throughout the profile, except near the surface where organic matter has accumulated. Under such conditions, an aeration tine needs only to be long enough to completely pene­ trate and remove cores from the organic matter layer. Longer tines would only result in excess sand debris being pulled to the surface, increasing the labor required to remove the debris and the amount of sand needed to backfill aeration channels. The objective of this research was to determine the effects of various aggres­ sive verticutting and core aeration treat­ ments on surface organic matter removal from a sand-based putting green. CULTIVATION EXPERIMENTAL METHODS A two-year experiment was initiated in the spring of 2003 at the University the thatch/mat layers and included varying blade widths (1,2, and 3 mm). Core aeration treatments included various combinations of tine spacing (1.25 x 1.50 or 2 x 2.5 inches), tine diameter (.25 or .50 inch), and tine penetration depth (1.5 or 2 inches). Cultivation treatments were made to individual plots measuring 5 x 20 feet, and each treatment was replicated four times. ORGANIC MATTER REMOVAL All of the verticutting treatments removed more surface organic matter than any of the core aeration treat­ ments (Figure 1). The 3 mm verti­ cutting treatment removed more than four times the amount of organic mat­ ter than each core aeration treatment. There was not much difference in The Graden GS04 verti- cutter is capable of cutting channels through the surface organic layer of putting green rootzones. organic matter removal between the 1 and 2 mm verticutting treatments; however, they only removed about half the organic matter compared to the 3 mm treatment. Turf managers with sand-based rootzones very high in organic matter content should con­ sider aggressive verticutting to remove excessive organic matter near the root­ zone surface. Among the core aeration treatments, the larger-diameter, closely spaced, deeper-penetrating treatment removed the most organic matter. Although core aeration was not as effective as verticutting in removing large amounts of organic matter from the rootzone, it was more efficient in completely penetrating through the organic matter layer without bringing excess sand to the surface, especially those treatments with shorter tines. TURFGRASS RECOVERY AND QUALITY Turfgrass recovery evaluations follow­ ing cultivation are summarized in Figure 2. Cultivation channels healed over more quickly for core aeration treatments compared to the verticutting treatments. The time required for the verticutting treatments to heal follow­ ing cultivation was nearly 60 days, approximately twice that necessary for turf that was core aerated. Many of the verticutting channels had partially closed, making it difficult to fill the channels with sand and smooth the surface. Aeration holes created by coring treatments were less prone to collapsing and were more completely filled with topdressing sand, creating a smoother surface that hastened recovery. In all plots that were core aerated, the amount of topdressing sand that was incorporated back into the turf canopy was greater than 100% of the volume of the debris that was removed during cultivation. In contrast, only 70% of the volume of cultivation debris could be incorporated back into the canopy as topdressing sand for turf that was verticut. Once the cultivation treatment debris was collected, sand topdressing was applied and brushed into the turf until the cultivation channels were filled. This greens aerator has been retrofitted with tine adapters allowing for a tine spacing of 1.25 x 1.5 inches. JANUARY-FEBRUARY 2008 17 Figure I Comparisons of the amount of organic matter removed by various aeration methods Surface organic matter removed and percent organic matter in the cultivation debris as affected by cultivation treatment. Data collected May 21, 2003, in Fayetteville, Ark. Within evaluations, treatments with bars sharing a letter are not significantly different. Aeration Method Figure 2 Turfgrass recovery ratings following various aeration treatments Turfgrass recovery from cultivation as affected by cultivation treatment. Data collected September through November 2003 in Fayetteville, Ark. Error bar represents least significant difference value between treatments within a single evaluation date. 18 GREEN SECTION RECORD Among core aeration treatments, recovery time was affected predomi­ nantly by tine diameter. Turf cored with .25-inch-diameter tines recovered in 14 days, about half the time of turf treated with ,50-inch tines. Neither tine depth nor tine spacing affected turf recovery in this study. Consequently, a turf manager can use a closer tine spacing to affect a larger percentage of the putting surface without affecting recovery time. A shallow tine is prefer­ able to a deeper tine, since less debris is brought to the surface, and the amount of organic matter removed and recovery time are equivalent. After three sets of cultivation treat­ ments and 14 months after the study was initiated, aggressive verticutting was most effective at minimizing organic matter content in the surface inch of the rootzone (Figure 3). Although all of the closely spaced core aeration treatments resulted in lower surface organic matter content than the control, differences were slight and not statistically different after three sets of treatments. Verticutting treatments were more aggressive and effective at removing organic matter from the surface inch of the putting green rootzone than core aeration treatments. However, the verticutting treatments removed a dis­ proportionately large amount of debris and recovered more slowly. Therefore, aggressive verticutting may be most useful when a large amount of organic matter must be removed at once and recovery time is not a primary con­ sideration. Core aeration with closely spaced tines may provide more general surface organic matter maintenance for putting greens that must return to a high level of quality shortly following cultivation. LITERATURE CITED 1. Landreth, J. W. 2005. Cultivation techniques to maximize the efficiency of organic matter removal from sand-based putting greens. M.S. thesis. Univ, of Arkansas, Fayetteville. 2. Murphy, J. W„ T.R.O. Field, and M. J. Hickey. 1993. Age development in sand-based turf. Int. Turf. Soc.J. 7:464-468. 3. Neylan, J. 1994. Sand profiles and their long-term performance. Golf & Sports Turf Aus. Aug:22-27. 4. USGA. 1993. USGA recommendations for putting green construction. USGA Green Section Record. 31 (2): 1-3. Editor’s Note: An expanded version of this paper can be found at USGA Turjgrass and Environmental Research Online (http://usgatero.msu.edu/v06/ nl9.pdf). Josh Landreth, Research Technician; Doug Karcher, Ph.D., Associate Professor; and Mike Richardson, Ph.D., Professor; Department of Horticulture, University of Arkansas, Fayetteville, Ark. Figure 3 Comparisons of organic matter in the upper one inch of rootzone after three sets of cultivation treatments in the 14-month study Organic matter content in the surface one inch of the rootzone as affected by cultivation treatment. Data collected June 21, 2004, two months after the third set of treatments was applied. Treatments with bars sharing a letter are not significantly different. JANUARY-FEBRUARY 2008 19 Ski Season Golf courses provide recreational opportunities throughout the year, even when it snows. BY MATT NELSON Golf courses are valuable com­ munity assets in many ways, providing open space within urban communities and an important component to landscape conservation. In addition, they can provide valuable sources of wildlife habitat and fdter storm water. Turfgrass has been shown to mitigate air pollution, reduce noise and glare, provide a cooling effect, and sequester carbon from the atmosphere. Golf courses also contribute to the social and economic fabric of com­ munities. Sales revenue, real estate enhancement, employment oppor­ tunities, and support of the local ser­ vice industry all can be linked to golf. Numerous golf facilities host weddings, meetings, or retreats, provide a venue for high school cross-country meets, or provide educational opportunities for youth. Across much of the northern U.S. and Canada, golf courses also are a perfect venue for Nordic skiing. With a few considerations, premiere Nordic skiing conditions can be offered with minimal risk to the turf and playability of the golf course the next spring. The key to good Nordic skiing on the golf course without compromising turf or playing quality is a reasonable plan. Among the most important con­ siderations for skiing on the golf course is to select appropriate routes for trails, and keep skiers on them. Grooming designated Nordic ski trails with dedi­ cated implements that establish a track is best. This trail helps prevent skiers from going just anywhere across the golf course and allows the turf manager to designate the most appropriate skiing locations. Snow machines with tow- behind grooming attachments are widely used at reasonable cost. These 20 GREEN SECTION RECORD Winter activities can showcase the golf course as a year-around community asset. units typically are easy to operate and establish a good surface for both classic and skate skiers. Some facilities have invested in more elaborate grooming equipment, which is considerably more expensive, if they are a destination Nordic skiing site with prolonged snow cover. Ski trails should not traverse greens, tees, landing areas, or other sensitive areas of the course. Spring green-up is usually a few weeks late beneath groomed trails, and using roughs wherever possible is advised. Solid-tine aeration of turf under the trail system in early spring can help increase soil temperature and stimulate earlier growth. Groomed ski trails of com­ pacted snow can create a physical barrier to rodent movement beneath the snow pack and help prevent meadow voles and other undesirable animals from migrating from native habitat onto the maintained turf and causing damage. A well-placed trail system may therefore be beneficial by reducing turf damage from feeding animals. Also, snow mold rarely forms under the groomed trails. Groomed trails also may create a barrier to surface drainage, so be aware of the possibility of impounding water and subjecting underlying turf to freeze injury. Again, careful route selection can minimize the potential for this type of injury. Once snow begins to melt, trenches may need to be cut across the trails to allow for drainage. Grooming can start when an appro­ priate amount of snow has accumulated, usually a minimum of 6 to 12 inches. Before grooming, packing the trails with a rubber-tired skid steer or similar unit can be beneficial. Slush is not recommended for grooming, and if Snow machines with tow-behind grooming attachments are an affordable and efficient method of grooming Nordic ski trails on golf courses. Sophisticated trail grooming units are employed on golf courses at destination Nordic skiing sites like Sun Valley, Idaho. insufficient snow cover exists, direct injury to the turf could result. Most facilities that are serious about skiing and striving to provide the best condi­ tions will groom several days per week, if not daily. Cart paths may not be the best location for ski trails if the paths need to be cleared in the spring for access to the greens and tees for snow removal. Asphalt and concrete also will not hold the snow as well, and melting or breakup of the snow pack is more likely. Golfers need to be aware that grooming ski trails will likely result in reduced visual quality for a few weeks in the spring, as the turf under the trails will take extra time to recover. If the trails are properly located (out of play), the impact will be minimal and short lived. If skiing is allowed at your golf course, formulate a good plan for traffic management and safeguard the most sensitive playing surfaces. Invest­ ing in some type of grooming equip­ ment is advised to provide the best skiing and to control traffic. Nordic skiing is a popular sport that provides some revenue in the form of trail passes to golf facilities that provide public access and offer concessions. This winter alternative could prove to be a viable use of a golf facility, enabling both golfers and staff to get a little winter exercise. And unlike most golfers, just about anyone can get around 18 holes in less than four hours on skis. As senior agronomist in the USGA Green Section’s Northwest Region, Matt Nelson enjoys the spectacular turf uniformity observed when two feet of snow is present. Groomed ski trails may delay spring green-up of turf by a few weeks, thus proper location to minimize interference with play and presentation is critical. JANUARY-FEBRUARY 2008 21 Sponsored Research You Can Use Seashore Paspalum: Breeding a Turfgrass for the Future Work continues at the University of Georgia on the development of this salt-tolerant species. BY P. L. RAYMER, S. K. BRAMAN, L. L. BURPEE, R. N. CARROW, Z. CHEN, AND T. R. MURPHY Seashore paspalum, the grass originally billed as “only a niche grass” for use on salt-affected sites, is now gaining popularity and becoming the turfgrass of choice on many new golf course installations where salt and irrigation water quality are not primary issues. The University of Georgia Breeding Program is now recognized as a major contributor to the recent success of seashore paspalum as a turfgrass species. Challenges associated with salinity have become increas­ ingly more prevalent in managed turfgrass over the past 10 years. Water conservation strategies that include non-potable, alternative irrigation sources such as recycled water, storm water, saline ground­ water, and seawater blends have been a primary contributor. Many of these alternative water sources contain higher salt levels than traditional irrigation waters. The trend for use of more salt-laden irrigation waters on turfgrass sites is expected to continue and to further increase interest in developing more salt-tolerant grasses. These trends have created the need for a high-quality turfgrass that can tolerate stresses associated with salt-affected sites and even irigation with brackish water. WHY SEASHORE PASPALUM? Seashore paspalum (Paspalum vaginatum) is a warm-season perennial grass that is particularly well adapted to moist and salt-affected areas common in coastal regions. It tolerates sandy and infertile soils, high salt concentrations, and occasional inundation by seawater, as well as waterlogged conditions. It also has many morphological characteristics that make it desirable as a turfgrass. It 22 GREEN SECTION RECORD the recent success of seashore paspalum as a turfgrass species. Thus far, this program has focused on development of cultivars suitable for use by the golf course industry and has released three cultivars. Dr. Duncan released two cultivars, Seaisle 1 for use on fairways and tees and Sealsle 2000 for use on greens prior to 2003. The most recent UGA release, Sealsle Supreme, was licensed to sod producers in 2005 and is touted as a cultivar suitable for course-wide use (Table 1). Sealsle Supreme has better salt tolerance than the previous releases and should be well suited for use as a fine turf in environments where salt is a problem for other turfgrasses. Sealsle Supreme is a low-growing and rapidly spreading semi-dwarf type that tolerates a wide range of mowing heights and still maintains good turf density and quality. This property makes Sealsle Supreme attractive as a grass that can be used on all parts of the golf course, from roughs to fairways to tees and greens. Sealsle Supreme also has an extremely vigorous spread­ ing growth habit that aids in rapid establishment, grow-in, and recovery from maintenance challenges. Thus far, Sealsle Supreme licenses have been granted to five domestic growers, and it is being marketed aggressively internationally. CURRENT BREEDING EFFORTS The current breeding program is an interdisciplinary effort with strong col­ laboration from a host of turf scientists, including Drs. Kris Braman, entomolo­ gist; Lee Burpee, plant pathologist; Bob Carrow, stress physiologist; Promising experimental lines are grown in small replicated field plots where they are mowed and managed similarly to golf course fairways. In this preliminary trial, 37 seashore paspalum experimental lines are compared to commercial varieties for turf quality, density, texture, color, seed head production, and other important traits. Dr. Duncan led the paspalum breed­ ing program until his retirement in 2003, when Dr. Paul Raymer assumed leadership of the program. During his 10-year tenure with this program, Dr. Duncan assembled a collection of ecotypes from around the world and began an intensive program to assess the turf traits and genetic potential of this species as a turfgrass. Working closely with Dr. Bob Carrow and other turf scientists, a series of manage­ ment studies also were undertaken to determine proper management protocols for this new turf species. The University of Georgia seashore paspalum breeding program is now recognized as a major contributor to produces both stolons and rhizomes, has an intermediate to fine leaf texture, an attractive dark green color, good density, and good tolerance to low mowing. Seashore paspalum is con­ sidered to be the most salt-tolerant warm-season turfgrass species and also holds great promise for reclamation and soil stabilization of unmanaged salt-affected sites. UNIVERSITY OF GEORGIA BREEDING PROGRAM The first seashore paspalum breeding program was initiated by Dr. R. R. Duncan in 1993 at the University of Georgia Griffin Campus. The potential of seashore paspalum as a species that could potentially meet the future needs of the golf course industry as a high-quality salt-tolerant turfgrass was quickly recognized. During the mid- 1990s, the USGA and the University of Georgia (UGA) entered into a joint project to develop seashore paspalum as a turfgrass species suitable for use on golf courses with salt-related problems. Table 1 UGA-Developed Seashore Paspalum Cultivars Propagation Method Year Released Marketer Applications Cultivar Sealsle 1 Vegetative Sealsle 2000 Vegetative Sealsle Supreme Vegetative 2000 2000 2005 Sealsle Growers Tee to green and sports turf Sealsle Growers Tee to green SI Supreme Growers Tee to green and sports turf JANUARY-FEBRUARY 20 08 23 (Above left) Each year thousands of unique individual plants are grown in the University of Georgia greenhouse. Plants are hand-trimmed, and undesirable plants are eliminated prior to screening for salt tolerance. (Above right) Seashore paspalum individuals can vary greatly in salt tolerance. Each year thousands of individual plants are screened for salt tolerance in the greenhouse. Individuals in the plant tray in the foreground appear less salt tolerant than those in the tray in the background. Note the salt accumulation on the edges of the tray. Zhenbang Chen, molecular biologist; and Tim Murphy, weed scientist. Our primary objectives are to further improve salt tolerance, insect resistance, and disease resistance, as well as to improve weed management strategies and develop molecular tools to support breeding. SALT-TOLERANCE SCREENING Previous research has demonstrated that seashore paspalum ecotypes vary greatly in their salt tolerance, ranging from no better than the best bermuda­ grass hybrids to highly salt tolerant. Therefore, it is necessary to screen potential seashore paspalum cultivars prior to their release to document and ensure that they have high levels of salt tolerance. The existence of salt- tolerant plants (halophytes) and differ­ ences in salt tolerance among geno­ types within plant species indicates that there is a genetic basis to salt response. Furthermore, genetically controlled variability for salt tolerance among genotypes infers that it may be possible to further improve salt tolerance of this species through breeding and selection. 24 GREEN SECTION RECORD A prerequisite for the development of new cultivars with improved salt tolerance is an efficient and effective salt tolerance screening method suitable for evaluation of large numbers of breeding lines. Such a screening method has been developed at the University of Georgia. This screening technique is now being used as part of the breeding program to attain even higher levels of salt tolerance in future releases. The germplasm base for the Univer­ sity of Georgia paspalum breeding program is the largest and most diverse collection of seashore paspalum eco­ types in the world. A traditional breed­ ing approach based on hybridization is now being used to generate new genetic variation through recombination. Each year more than 6,000 individuals also are screened for salt tolerance in the greenhouse. Salt-tolerant individuals are transplanted to field plots for further evaluation of turf quality and dollar spot resistance. This approach allows efficient evaluation of large numbers of individuals for important traits and should insure continued improvement in turf quality, disease resistance, and salt tolerance in future cultivar releases. CULTIVAR IDENTIFICATION Differentiating seashore paspalum cultivars has been a challenge since most cultivars used commercially are morphologically very similar. The ability to accurately identify cultivars is useful in protecting intellectual property and provides an extremely useful tool for verifying the identity of cultivars and confirming off-types dur­ ing the certification process. Amplified fragment length polymorphism (AFLP) is currently the most commonly used method for DNA fingerprinting. Simple sequence repeats (SSR) are growing in popularity and can be used in conjunction with AFLP for genotype identifications. We have used AFLP and SSRs to fingerprint the most commercially available seashore paspalum cultivars as well as all accessions in the USDA germplasm collection. The use of AFLP banding patterns has already proven to be useful as a new tool in resolving a number of industry issues related to cultivar identity and to quality control (identification of off- types) within our commercially released cultivars. Thirty-seven experimental seashore paspalum lines and five commercial cultivars were compared for disease progress when artificially inoculated with the dollar-spot fungus. Disease severity ratings were taken weekly for seven weeks after inoculation and used to compute the area under the disease progress curve (AUDPC). Higher values indicate higher disease levels. Of the 37 experimental lines tested, 17 lines had dollar-spot ratings below the best commercial cultivar, indicating good potential to improve the disease resistance levels of future releases. DISEASE RESISTANCE Currently, the disease susceptibility of seashore paspalum cultivars is largely unknown. Although this new turfgrass is best adapted to coastal areas of the tropics and sub-tropics, it is now being commonly used in more inland areas where fungal diseases may be a signifi­ cant problem. Dollar spot caused by Sclerotinia homoeocarpa and large patch (brown patch) caused by Rhizoctonia solani are likely to be major fungal diseases impacting seashore paspalum turf quality. A preliminary disease screening conducted at Griffin during the fall of 2004 indicated considerable genotypic variability for dollar spot resistance among eight standard cultivars evaluated. Screening for dollar spot resistance has become part of the routine evalua­ tion protocol for our breeding program. Each year, approximately 2,000 indi­ viduals in the single-plant evalution nursery are artificially inoculated in mid-September with the dollar spot fungus by Dr. Lee Burpee, UGA turf­ grass research plant pathologist. At approximately one month after inocu­ lation, all plots are rated for dollar spot symptoms. Disease resistance of all selected individuals is also later con­ firmed in replicated field plots. All UGA breeding lines entered in advanced, regional, and NTEP turf field trials are compared to standard commercially available cultivars in replicated field disease evaluations. SUMMARY UGA-patented cultivars have been well accepted by the turf industry both domestically and internationally. The grass that was originally billed as a “niche grass” for use on salt-affected sites or where irrigation with brackish water was necessary has suddenly be­ come the turfgrass of choice on many new course installations where salt and irrigation water quality are not issues. Marketers of paspalum cultivars boast a host of superior traits, including multiple stress resistance and reduced requirements for water, fertilizers, and pesticides. The paspalum traits that seem to be the most critical to course owners and superintendents are the JANUARY-FEBRUARY 2 0 0 8 25 A Q&A with DR. PAUL RAYMER regarding seashore paspalum program. breeding the University of Georgia's Q: Do you know of many instances using seashore renovated water? reclaimed paspalum where golf courses following have been to the use of conversion reduce root growth and slow establishment. Both be used during establishment because water should be tested prior to establish­ water possible cleanest salts can greatly the soil and irrigation ment. Saline amendment establishment are working to better define limits currently recommend more than 2,000 ppm are not well defined, during programs but several We during establishment. water should contain no research that irrigation TDS for optimum establishment. or sodic soils may require tillage prior to planting. Irrigation water thresholds aggressive and a more common situation, water has led to renovation using seashore A: Yes, I am sure there are several instances where conversio11 reclaimed Perhaps paspalum either to be used or it is projected sources is prescribed reclaimed Sealsle of the University Do you have additional for use on a new course development, water source is water I, Sealsle 2000, of Georgia's or some other salt-laden may occur in the future. to alternative is where seashore that conversion Q: Your paper describes as cultivar breeding cultivars paspalum. releases however, because to and Sealsle Supreme seashore paspalum program. that golf course superintendents about-to-be-released can expect? lines entered A: We have three experimental during 2007. We have an established paspalum additional evaluations in advanced that at least one of these six lines will be released three years. NTEP trials three lines in Georgia. I expect within the next into the seashore Q: Where did seashore collection diversity trips ta those areas in an effort to increase of your breeding come from? Are you planning the genetic paspalum stock? A: Paspalum and Europe, Africa. regions germplasm period and contains program's breeding germplasm existing contains collection Pacific from the vaginatum and it is believed is considered indigenous to have originated to Africa, Asia, in southern and sub-tropical of collection by Dr. Duncan over a ten-year tropical Our current It is now distributed throughout of six of the seven continents. was largely assembled ecotypes from many areas of the world. My focus thus far has been to recombine to generate very little new diversity. material Rim would be my top collection Since the UGA priority. our from Asia, adding ecotypes Q: Our Green Section when referring term as it describes to seashore agronomists paspalum. seashore paspalum? o�en mention the "wow factor" What is your response to this factor" is related that the terminology to the paspalum beauty of a well-maintained does accurately A: As I understand it, the "wow overwhelming I do believe emotion you feel the first time you step onto a well-maintained seashore "wow factor" to some extent the pure novelty doubt, some course owners are using paspalum create the "wow factor" their competitors'. of paspalum turf. Without to and its ability from their courses WOW. Major contributors and texture, desirable soft a golf course. the as a way to distinguish are brilliant green color, describe paspalum course. to the Q: Although spedal precautions establishment? mature seashore paspalum that superintendents is very salt tolerant, are there need to be aware of during A: This is an excellent paspalum turf is very salt tolerant, we recommend that the point. Even though mature seashore Q: All three of the University propagated. Do you hove plans to develop of Georgia seeded types? cultivars are vegetatively A: I would estimate that is now directed We still cultivars factors that control flowering I expect that several production. released have a lot to learn related and have research towards the development about 20 percent of our breeding of new seeded cultivars. of seeded effort to the production underway to learn more about the and the best environments for seed by the seed industry within will be new seeded cultivars the next year or two. Q: How much of an impact do you think improved will have on the golf course niche grass description? industry, and will they expand beyond the seashore paspalums has already had a significant The availability of this grass has made on some of the most striking around the world where it was not possible before Somewhat surprisingly, expanded beyond the use of that of a niche use on many new courses paspalum golf courses that seashore to build new A: I believe impact on the golf industry. it possible coastal venues issues. of salt-related because seashore paspalum has already grass as evidenced by its frequent where salt and irrigation use seashore its uniqueness expect the use of seashore not expect it to displace season turfgrass and exceptional paspalum paspalum water quality species bermudagrass soon. anytime on these venues quality are not issues. Decisions to driven by are most likely I Although to increase, warm­ and beauty. to continue as the dominant I do to retain better ability months, overwhelming cained color during the wimer ball support, and the beauty of a we!J-rnain­ paspalum species. This seashore program is well positioned to of challenges turfgrass breeding meet many the golf course industry. of the future paspalum golf course. The rapid growth in global popu­ of sea­ far exceeds of the latest generation larity shore paspalum early expectations. state that seashore earned a spot on the list of recognized cultivars It is now safe to paspalum has NOTE: An expanded EDITOR'S of this paper can be found at USGA Tr.,,fgrass Online n21.pdf). finally alld Environmental Research (http://usgatero.msu.edu/v06/ version f Crop S. K. BRAMAN, PH.D., of Ento111olagy; L. L. BvRPEE, e P. L. RAYMER, PH.D., Prefessor and Soil Sciences; Prqfessor PH.D., Prefessor ef Plant Pathology; R. N. CARR.OW, PH.D., Prqfessor ef Crop a11d Soil Sciences; Research of and T. R. MURPHY, PH.O., Prefessor Crop and Soil Sciences; University ef Georgia, Griffin Ca111pHs, Scientist Z. CHEN, PH.D., Griffin, Ga. of Crop and Soil Sciences; 26 GREEN SECTION RbCOl