Regrassing Cool-Season Putting Greens with Sod an Old Concept with a New Twist Sparks Renewed Interest in Regrassing Greens for Northern Golf Facilities in the U.S

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Regrassing Cool-Season Putting Greens With Sod An old concept with a new twist sparks renewed interest in regrassing greens for northern golf facilities in the U.S. and Canada. BY JIM SKORULSKI

egrassing putting greens was once looked upon as an inter- R esting concept that was suited primarily for high-budget golf facilities with members willing to tolerate the process. Convincing northern golfers of the merits of shutting down their golf course in early to mid-August and then opening the following spring to provide a monostand of creeping bentgrass was never an easy sell. Recently, however, there has been renewed interest in regrassing and rebuilding cool-season putting greens — and for good reason! New bentgrass cultivars are durable and provide excellent playing conditions over a wide range of weather and moisture conditions. Annual bluegrass (Poa annua), on the other hand, is far less reliable in that it is highly vulnerable to annual bluegrass weevil and disease pathogens, com- bined with poor heat and cold tolerance. The quality of the sod, whether grown on sand that meets USGA recommen This equates to high management dations or that is washed, is critical to the establishment of the sod and ultimate costs and many sleepless nights for success of the project. those who manage it. The growing availability of quality commercial bent- first. Poorly designed greens with to sun and air movement. Those not grass sod and renewed confidence serious drainage issues are always willing to remove the trees necessary in its use have also made regrassing better candidates for reconstruction. to properly manage bentgrass should programs a more practical option in Reconstruction is more costly, but it not pursue this option! Annual blue- cooler climates where a disruption in offers an opportunity to address major grass, for all its weaknesses, does play for any reason is not popular. design and agronomic flaws. It involves tolerate shade and wet environments Golf facilities that have successfully altering the architectural design (if and is a better choice in those situa- regrassed or rebuilt greens are necessary), installing new rootzones, tions. The USGA Turf Advisory Service rewarded with much improved and adding internal drainage, and, finally, can be a highly valuable tool in helping more reliable playing surfaces that can resurfacing the greens with new turf. to evaluate your green complexes and be managed to be consistently firmer Conversely, simply regrassing is much provide an objective opinion on and faster. This article will take a closer less invasive and will usually include regrassing or rebuilding options. look at the regrassing concept and some aggressive soil modification how it might be more applicable to techniques, the installation of sand SOD SELECTION your golf facility than you think. channel drainage (where necessary), Regrassing greens with sod is the fumigation, and replacing the turf. primary focus of this article. Most turf REGRASS OR REBUILD? Either option is only suitable when the managers would prefer establishing Regrassing is not recommended for green complexes and sites themselves putting green turf from seed, and many every golf facility, and it may not even can support bentgrass growth. More have done so successfully. But, in be an option unless greens are rebuilt specifically, this includes full exposure reality, sod has become a more prac-

©2012 by United States Golf Association. All rights reserved. Green Section Record Vol. 50 (24) Please see Policies for the Reuse of USGA Green Section November 16, 2012 Publications. Subscribe to the USGA Green Section Record. TGIF Record Number 212912 Page 1 Considerations before regrassing: ● Is regrassing or rebuilding the best option? ● Will the existing rootzone support creeping bentgrass? ● Are major grade changes required to provide surface drainage or enlarge hole location areas? ● Have the growing environments for each green been thoroughly assessed to make sure there is adequate sunlight and air circulation? ● Will the membership support the project and the related work to prepare the green sites for regrassing and proper management of bentgrass? tical choice in northern climates where washed sod, but it will also be more ducer. Meet with sod producers and a shorter growing season makes late expensive. The option to contract with tour their facilities. The fields should be summer course closures required for a sod producer to grow sod on sand clean and free of annual bluegrass and seeding very unpopular. The use of that you specify may be an option in other weeds. Check the soil texture in sod will significantly increase project regions where washing equipment is the fields where the sod is produced. cost but should shorten the time not available. Determine whether the grower is will- greens will be out of play. That said, There are certain things to look for ing to produce sod on specific sand for the project’s ultimate success relies when selecting a commercial grower to you or if they have washing capabilities. heavily on the quality of sod used to produce sod for a project. Obviously, Ask the grower about their mainte- regrass the greens. It is critical for golf the grower should be reputable for nance practices. Do they have the facilities planning to use sod to begin reliability and the quality of sod pro- equipment and capability to manage the selection process far in advance of duced. It is a good idea to tour other the bentgrass to putting green stan- the project to ensure that high-quality golf courses where sod has been used dards? Are bentgrass fields topdressed sod will be available. Regrassing and inquire about the quality of the with sand? Will they topdress your sod projects that are done on short notice sod at the time of delivery and overall if requested? Ask the grower what have much less flexibility and are often experience of working with the pro- cultivars are being produced and if forced to accept whatever sod is they are willing to contract-grow specific available at the time. cultivars. Will the grower establish the There are several types of commer- fields based on the date it is to be cial bentgrass sod used to regrass harvested for your project? Ask about greens, the two most common being fertility practices. Check thatch levels sod that is harvested from sand-based in fields that are marked for harvest. rootzones or sod that has been washed What is the height of cut at which the to remove soil. Sod produced on native sod is maintained and will be har- soils that will be installed over high- vested? Are plant growth regulators sand rootzones should always be used, and what programs are in place washed to remove the soil that would to eradicate annual bluegrass? How otherwise create an unwanted soil will the sod be harvested and shipped layer condition that will impact water to your golf facility? movement through the soil profile and adversely affect establishment. Sod REGRASSING PROCESS that is grown on sands that meet Every regrassing process differs USGA Recommendations for a depending on many site-specific vari- Method of Putting Green Construction ables, including the condition of the can be placed over other high-sand rootzone, whether surface modifica rootzones so long as the sands are tions are necessary to improve drain- compatible. A physical soil analysis Sod grown on a native soil was placed age or soften contours, if green perim- should always be completed to make over a sand-based rootzone, creating eters have been lost and are to be sure the sands are compatible. Both a layer condition that will have long- restored, if slit drainage will be added, types of commercial sod are used term impacts on establishment and the and whether the green complexes will successfully for green establishment greens’ performance. Aggressive be fumigated. The regrassing process projects. Sod grown on sand will cultivation will be needed to remove offers a unique opportunity to com- probably establish more quickly than the soil layer and its impacts. plete practices that would otherwise

©2012 by United States Golf Association. All rights reserved. Green Section Record Vol. 50 (24) Please see Policies for the Reuse of USGA Green Section November 16, 2012 Publications. Subscribe to the USGA Green Section Record. Page 2 be too disruptive. Use the opportunity to address contouring and drainage issues as well as thatch or other soil- related problems. Speak with superintendents, sod growers, and contractors who have completed regrassing projects to help formulate a specific plan at your facility. Work closely with your USGA agronomist to evaluate the putting green rootzone and determine the best cultivation methods to prepare the surfaces for sodding. The process will include multiple core aerations. Sometimes deeper soil modification is necessary where thatch levels are excessive or more extensive soil modification is recommended. If only organic accumulation near the surface requires attention, then core aeration and deep vertical mowing may be all that is needed after the old sod has been removed from the surface. Fertilizer amendments should be added at this Annual bluegrass control programs begin with soil fumigation and continue as time, and the surfaces raked and rolled soon as the sod is installed. Hand picking or dabbing plants and the use of growth to create a smooth, firm surface that regulators and preemergent herbicides offer the best control options. Several new ties in smoothly to the green surrounds. selective herbicides are also showing promise against annual bluegrass in trials. Most who have regrassed greens also fumigated the rootzones to rid the soil of annual bluegrass seed, disease pathogens, and parasitic nematodes. The most popular fumigant, methyl bromide, will be phased out by 2013, so those wishing to fumigate after that time will be required to use alternative products like Basamid®. There are other alternatives as well, but their cost and use protocols differ from methyl bromide. Several references regarding the fumigation process are listed at the end of the article.

ESTABLISHMENT PROGRAMS The methods for establishing bent grass putting green sod vary depend ing upon the type of sod, i.e., washed versus unwashed, and its condition. Sod that has been managed to putting green standards in the field will establish and transition more quickly and easily into putting green turf at your site. Sod that has excessive thatch will always be more difficult and slower to establish, while also requiring more intensive cultivation to reduce thatch. Sod delivered to the golf course should be fresh with no obvious signs of Sod is being removed from a green which can then be cultivated and fumigated desiccation, heat damage, or disease prior to installing new sod. activity. Check washed sod to make

©2012 by United States Golf Association. All rights reserved. Green Section Record Vol. 50 (24) Please see Policies for the Reuse of USGA Green Section November 16, 2012 Publications. Subscribe to the USGA Green Section Record. Page 3 sure that most of the soil has in fact been removed. Washed sod will often be fragile. Do not be alarmed, as this is a good indication that the sod was harvested at a good stage of development. It may look weak, but its establishment and performance long term will be better than that of older sod with too much thatch. Do not accept sod that is contaminated with annual bluegrass or is showing obvious signs of damage from harvest or transport. Coordinate the delivery of the sod to minimize the time between harvest and installation. Order enough sod to establish a putting green nursery that is built with the same sand rootzone mix that is used to topdress greens. That sod will be used to replace any sod that does not establish well or where annual bluegrass becomes established. Overly mature washed sod can be too thatchy. A thick thatch mat will make it more The basic establishment processes challenging to establish the sod and will require more cultivation. focus on promoting rapid root development while gradually lowering mowing the grade. The sod may shift slightly, rollers can then be used once the heights and preparing the surface for but seams can be topdressed. Washed washed sod is better established and play. Rolling is an important aspect sod can be rolled with lighter rollers, stable. Regular, light sand topdressing during establishment. Sod produced such as those commonly used on should be initiated soon after sod on sand can be rolled with heavier putting greens, tennis courts, or for installation to begin to stabilize and rollers, such as a one-ton roller, almost landscape purposes, after it has level the surface in preparation for immediately after installation to smooth knitted to the underlying soil. Heavier lower mowing heights and to protect plant crowns. Mowing is initiated as soon as the sod is stable enough to do so. The sod will be vulnerable to scalping, so be patient and lower the cutting units in increments of 0.01 to 0.02 inches as the surfaces become smoother and more stable from topdressing and rolling. Maintain collars at the same mowing heights as the greens through- out the establishment of the sod. Equip mowers with smooth front rollers at least in the initial establishment phase. Mowing and other forms of mechanical injury can go unnoticed but seriously impede the establishment process. Take a conservative approach to mowing new sod. The presence of off-color or chlorotic patches of turf across the surface is a subtle sign that mowers are probably set too low and that more topdressing and/or rolling are required before the height of cut is lowered further. Ball roll will be very good over Rolling is an important process in establishing new sod. Rolling with a heavier the new surfaces, but it should not one-ton roller was initiated after the washed sod was well knitted and stable or dictate management decisions. Do not about four weeks after installation. push new sod too aggressively in its

©2012 by United States Golf Association. All rights reserved. Green Section Record Vol. 50 (24) Please see Policies for the Reuse of USGA Green Section November 16, 2012 Publications. Subscribe to the USGA Green Section Record. Page 4 first season of growth. Remember, the good gas exchange through the upper there. Utilize mats, boards, or lattice objective is to establish and enjoy the rootzone and interface, and it is critical where mowers are forced to turn on new stand of bentgrass for years to for turf establishment. Work closely sodded collars. come, so exercise extra caution in the with your USGA agronomist to help There is a wide array of ideas first year or two. formulate a cultivation program to regarding fertility management plans One primary challenge with using ensure a successful sodding project, for new greens. A balanced pre-plant sod has been overcoming the effects of and especially so if there is a soil fertilizer should be made. A natural the interface between sod and under- layering problem or excess organic organic fertilizer can be used as long lying soils. The interface is caused by matter associated with the sod. as soil temperatures remain warm a physical incompatibility between the enough to ensure nitrogen availability parent material on which the sod was to the turf. Triple 10-10-10 (N-P-K) or a grown and the rootzone soils in the starter fertilizer can also be raked into greens. The interface, or layer, is most the surface soils to provide 0.5 pound problematic when the parent soils con- of nitrogen per 1,000 square feet. tained within the sod are finer textured Post-plant fertilizer programs during than the underlying rootzone soils of establishment focus on providing the greens. A soil layer of this sort will enough nutrients to keep the sod retain excessive water in the sod that growing vigorously and to produce a leads to saturated surfaces. This pre- dense root system. The specifics of vents gas exchange and inhibits root the fertilizer program for your site and development. The wet surfaces will conditions can be discussed with your remain soft, making the turf more USGA Green Section agronomist susceptible to mechanical injury. This is why it is critical to make sure that ANNUAL BLUEGRASS purchased sod is grown on sand com- CONTROL patible with that in your greens or that The most effective strategy for manag- soil is washed and removed from the ing annual bluegrass in regrassed sod. A soil interface or layering effect greens is to begin with clean sod and can also be the result of a dense thatch soil. Fumigation remains the only and/or mat resulting from overly mature means to eliminate the annual blue or poorly managed sod. grass seed bank from the soils. Collars, Managing or eliminating soil layering approaches, and rough in the green involves a structured cultivation pro- surrounds containing annual bluegrass gram. The aggressiveness of that should be fumigated or at least re- program depends on the extent of the New washed sod is being rolled grassed to keep annual bluegrass as interface between the sod and under- carefully not long after installation to far from the greens as possible. The lying soils. Cultivation with ¼-inch- begin to stabilize and smooth the first line of defense against annual diameter solid or hollow tines is usually surface. bluegrass is to hand pick plants as completed as soon as the sod is they become visible. This strategy has securely rooted to the underlying soil. Collars can prove to be more chal- delayed the onset of annual bluegrass That program will be repeated the lenging to establish than greens. New encroachment into new greens at following spring or continued regularly bentgrass is prone to traffic damage, many golf courses. Dabbers containing through the season if sod is installed especially once it has thinned or if it is herbicide can also be used to control in the spring. Cultivating with larger allowed to grow longer or become individual colonies of annual bluegrass ½-inch-diameter hollow tines may be leggy. Maintaining the collar at the as they become noticeable. Larger- required where thatch levels are very same height of cut as the putting green scale chemical control programs using high or a distinct soil interface exists. will help develop a dense turf canopy plant growth regulators paclobutrazol Expect to cultivate the new surfaces that has better wear tolerance. The or flurprimidol, as well as the preemer every three to four weeks through the collar height of cut can be finalized gent herbicide Bensulide, are also first few years of establishment. Most after the sod is fully established and options to control annual bluegrass of that will involve venting the greens at some point after the greens are populations. The growth regulator with smaller needle tines, but ¼-inch- opened to play. Bench setting heights programs rely on regular applications diameter hollow and solid tines should of 0.325 to 0.350 inch are not uncom of the products through the growing be used as well to maintain adequate mon for establishing new collars. season. Bensulide is usually applied in gas exchange in the rootzone. Frequent Brush and cut the collars to keep the a split in late summer to prevent annual cultivation of the new surfaces may surfaces upright and dense. Do not bluegrass establishment in the fall. seem contradictory to some, but it is allow mowers to turn directly on collars Controlling annual bluegrass will be an important strategy that will maintain or greens rollers to stop and start a major challenge in managing the

©2012 by United States Golf Association. All rights reserved. Green Section Record Vol. 50 (24) Please see Policies for the Reuse of USGA Green Section November 16, 2012 Publications. Subscribe to the USGA Green Section Record. Page 5 More northern golf courses are turning to commercial sod to establish greens that have been rebuilt or regrassed. A good-quality sod can speed the establishment process and reduce the time greens are taken out of play.

new surfaces. Superintendents and systems, disease and insect manage establishment program, and realistic turf managers need to remain vigilant ment programs, seed suppression play expectations, it can produce and be almost fanatical in keeping the programs, and the labor to manage superior putting surfaces that should greens clean. One or two individual annual bluegrass greens are not only require fewer management inputs. plants can quickly become 10 to 20, high but not always successful. Golf and in no time the problem explodes. courses that have suffered extensive FURTHER READING There is hope that a safe and selective damage to annual bluegrass greens to Booth, J., 2011. Regrassing Greens at herbicide for controlling annual blue- winterkill, heat stress, or pest damage New Haven Country Club. USGA grass on bentgrass greens will one day are fully aware of revenue losses Green Section Record, 49(7) 1-3. be available. There are several herbi- incurred when temporary greens are Landschoot, P. J., Park, B. J., 2004. cides that show promise and one, required. The monetary benefits of a Renovating Putting Greens Without Methiozolin, is particularly promising regrassing project, other than potential Methyl Bromide. Golf Course in research trials. We all hope that the cost savings alluded to above, are Management, 72(2) 127-131. silver bullet for managing annual blue- harder to define but might be equally grass will soon be found. Until then, important to a golf course operation in McClellan, T., 2009. Will the Real we will be left to use a combination of a competitive market. The ability to Alternative to Methyl Bromide Please cultural practices and chemical controls provide uniform, smooth, and fast Stand Up? USGA Green Section to suppress annual bluegrass. playing surfaces on a more consistent Record, 47(2) 14-18. basis will keep the golf course appeal Nelson, M., 2008. Green Side Up! COST BENEFIT ing to golfers and competitive with USGA Green Section Record, 46(1) Is the investment to regrass greens other operations. A successful regrass- 1-5. worth it? After all, a project like this can ing operation is not only a strong Niven, S., 2011. Taking the Guesswork cost $250,000 to $500,000, depending marketing tool but also is a means to Out of Regrassing Your Greens. Tee to on the depth of work included. There create a more sustainable operation in Green M/J Newsletter are costs associated with tree removal, the modern era of golf. Walker, T., 1989. Gassing and installation of sand slit drainage, green The increased availability of Regrassing. USGA Green Section contour changes, green extensions, bentrass sod and the allure of new Record, 27(4) 10-12. and regrassing approaches and green bentgrass cultivars have created an surrounds. This estimate does not unprecedented opportunity for northern White, C. B., 2006. Rebuild or include lost revenues from closing the golf courses to raise the quality and Resurface. USGA Green Section course to complete the project. The dependability of their putting surfaces Record, 44(1) 1-6. sticker price of upgrading to pure bent- as never before. Regrassing is not for grass greens may seem high, but so every golf course, but with thorough JIM SKORULSKI is a senior agrono are costs of doing nothing. The annual planning, the right growing conditions, mist working with golf facilities in New costs associated with winter cover the use of quality sod, a good England and Eastern Canada.