Convert Fwys to CB to Rdc Inputs

Converting Fairways to Creeping Bentgrass to Reduce Inputs

March 2022

Turfgrass species and variety are important drivers of nutrient, pesticide and water inputs required to provide adequate playing conditions. Fairways represent the largest finely mowed surface on a golf course where the greatest benefits of reducing inputs can be realized, especially in Northern climates when transitioning from a poor performing mixed stand with significant populations of annual bluegrass. For example, reductions in irrigation and fertilizer requirements of creeping bentgrass (Jacobs & Gross, 2019; Dobie, 2020) as well as fairway fungicide use (Bekken et al., 2021) suggest that ROI of installing creeping bentgrass (CB) can be as little as 1.3 years (Jacobs & Gross, 2019). Despite the benefits, golf facilities often reject the investment in converting surfaces to new grasses due to cost and disruption to play. In general, due to the pervasiveness of annual bluegrass and its’ persistence in the seedbank, there is often no assurances for Superintendents that a conversion will successfully lead to a thorough shift in species populations. Therefore, a decision-making strategy must address the time frame, planting strategy and follow-up care to ensure new species success. It is important to determine if CB is a suitable replacement prior to any turfgrass conversion program.

For example, any site modification that improves light penetration (tree removal) or drainage will provide long-term insurance on the conversion. Additionally, large scale installation of CB must recognize the potential for organic matter accumulation among the creeping bentgrasses. This will require significant shifts in nutrient management to minimize the need for large scale cultivation and/or sand topdressing. Options for conversion fall into two categories. The first is a methodical approach focusing on exclusion of weaker grasses to allow gradual transition to CB, while the second could be classified as a “total reset”, aimed at eliminating the old sward and rapidly replacing it with CB. The methodical approach slowly weakens the less desirable species with plant growth regulators and herbicides, overseeds desirable species, and alters cultural practices to favor the desirable species. This method is often visible to golfers as the annual bluegrass steadily declines and occasional “over regulation” of CB can reduce visual quality. However, many have successfully navigated this method through effective communication. Aggressive “reset” conversion programs require complete eradication of existing stand and sometimes

Aerification is an essential step in the seedbed preparation process.

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bensulide will suppress true winter annual recruits. Post-emergent herbicides are available, and many have been shown to be safe on CB however, they have not received widespread interest due to potential risk of CB injury and cost. Products such as Velocity, Prograss EC and Xonerate have all demonstrated effective annual bluegrass control. Recently, a new selective herbicide was developed for annual bluegrass control, Methiolzolin (PoaCure). This selective herbicide has both pre- and post-emergence activity that is remarkably slow and often allows for seamless Methodical reduction of annual bluegrass in fairways will routinely leave voids that allow seeding of CB to be effective. The Summer presents an ideal time to seed CB as day lengths are at their maximum to promote establishment without competition from annual bluegrass (Brede, 2006; Bauer et al., 2012; Klein, 2021). Creeping bentgrass can be slit-seeded into void areas at rates of 2-3 lbs/1000 square feet for most effective establishment, followed by applications of nitrogen fertilizer up to 0.5 lbs/1000 square feet. Irrigation can be applied routinely in small amounts to keep seeded areas moist until establishment. The benefits of this approach are that course closure and drastic disruption practices are not required. However, there are several obstacles that make this approach less than ideal. Communication Established turf, even managed into a stressed state, will always have an advantage over seedlings (Cattani & Nowak, 2001). Stressed playing surfaces with large voids can disrupt play and be undesirable for golfers. The golfer must cope with several years of this sub optimal playability, and one must assess if golfers will accept these conditions to support long-term payoff. Therefore, an alternative option that intentionally disrupts play for less time to reset the desirable CB population might be a preferrable long-term solution. Eradication “Reset” Approach An eradication strategy uses a non-selective vegetation control strategy that eliminates the existing stand of turfgrass and re-establishes the fairways by seeding new desirable CB varieties. Recently, this method was used and well-documented by John Hoyle of Corning Country Club. This method is a more aggressive derivative of processes studied previously (Bauer et al., 2012), and has a formula as described in several USGA Greens Section articles (USGA Green Section, 2018; Jacobs & Gross, 2019; Klein, 2021). transition from mostly AB to mostly CB. Introducing Creeping Bentgrass

the seedbank if a fumigant is available. Aggressive conversion programs are the most disruptive to golf play but allow for the most rapid conversion. Either conversion program must have persistent exclusion strategies to prevent recolonization of annual bluegrass or other less desirable species. Methodical Approach Ecology The methodical approach centers on shifting to new varieties without large-scale disruptive practices over a long period of time (5-7 years). As described in a variety of scenarios (Gaussoin & Branham, 1989; Reicher & Hardebeck, 2002; Dobie, 2020: Diehl et al., 2021) this process requires management alterations to purposely impose stress on the undesirable species providing a competitive advantage for CB. As annual bluegrass populations decline and leave voids, it is imperative to have seed at the ready for seeding of CB into the voids leftover. This is a long-term approach, requiring many years before the transition to CB fairways can be Alteration of routine cultural practices to favor CB requires a wholesale shift in ideology. Essentially, discipline is required to withhold inputs (water, nutrients and pesticides) that are required for optimum performance of annual bluegrass. Creeping bentgrass performs better under lower soil moisture, lower Nitrogen levels, and fewer pesticides than annual bluegrass (Laskowski, 2017). In addition, damage thresholds can be raised to allow certain pests (dollar spot, anthracnose, annual bluegrass weevil) to selectively kill annual undesirable species, thereby promoting population shifts to CB (Diehl et al., 2020). Plant Growth Regulators The scientific literature is awash with research conducted on the use of plant growth regulators for suppressing annual bluegrass. Specifically, the use of class B growth regulators (paclobutrazol, flurprimidol) can reduce annual bluegrass populations (Dobie, 2020; Diehl et al., 2021; Klein, 2021; Petelewicz & Orlinski, 2021) that will significantly aid in this methodical approach. Herbicides Herbicides are simply plant growth regulators applied at lethal rates. There are several selective pre- and post emergent herbicides available for annual bluegrass control in fairways, but be aware of restrictions when shifting to CB, as not all selective materials are labelled or safe for use on CB. Herbicides are essential tools in the early phase of the exclusionary strategy. Once a good stand of CB is established, late summer applications of preemergence herbicides such as considered a success. Change Culture

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1.) Eradication: Two applications of a nonselective herbicide were applied, spaced one week apart, to ensure complete elimination of current fairway turfgrass species. 2.) Seedbed preparation: Slicing conducted in two directions, followed by debris removal and aeration. 3.) Seeding: Seeding of CB broadcast spread at a rate of 1-1.25 lbs/1000 square feet. Ideal timing for seeding is late July when light levels are at their peak. 4.) Fertility: Nitrogen fertilizer application of 0.5 lbs/1000 square feet applied to promote establishment. Nitrogen rates can be adjusted to account for seedling establishment and, if necessary, split into multiple applications. A starter fertilizer including Phosphorous may be necessary if soil testing indicates deficiencies but is likely not required if adequate soil Phosphorous is present (Liu & Landschoot, 2018). 5.) Irrigation: Irrigation applied frequently and in small amounts to encourage a moist, but not

saturated surface until full establishment. 6.) Mowing: First mowing date conducted approximately 2 weeks after seeding. 7.) Resumption of play: Corning Country Club reported that play resumed between four and six weeks after seeding. 8.) Continued exclusion: Continue an exclusion strategy by spot treating areas with herbicides, altering cultural practices to favor new improved species, and growth regulators to maintain proper growth rate and long-term annual bluegrass control. Course closure during prime golfing weather in NY may not be a valid option for some facilities. At Corning CC, the decision was made to complete this process on several fairways per year, completing all fairways in 6 years. This allowed much of the course to remain open, with minor modifications made to allow golfers to play renovated holes either as par 3s, or as normal with a local rule to move balls hit in the fairway to adjacent rough areas. The benefits are numerous. Facilities will immediately realize cost savings of managing new varieties.

Methodical Approach Eradication Approach

Eradication (staggered)

Pros

• No course closures • No drastic disruptive practices

• Immediate realization of reduced input savings from management of new varieties • Immediate improved playability • All materials can be purchased at once • Can allow for additional projects to occur during course closure

• Golf course can stay open with minor rule changes for holes in process of conversion • Allows for ability to improve on conversion method year-over-year • Golfers can observe benefits of improved varieties comparing pre- and post-renovated fairways • After the first year, the superintendent must separately manage two types of fairways: pre- and post-renovation • Cost savings from reduced inputs are deferred in part due to several years of maintaining several pre renovation fairways • Materials for conversion must be purchased each year, which may vary in cost or availability over time

Cons

• Complete conversion is unlikely • Golfers may find annual voids and seeding practices disruptive • Requires long-term commitment to low-input management principles even when turf quality is not ideal

• Requires complete course closure • Quality of grow-in and length of closure can be affected by poor weather

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Complete eradication of undesirable species creates an immediate competitive advantage for CB, allowing for easier control of undesirable species. Additionally, the period of course closure may also provide an ideal time to conduct other necessary course projects. Finally, and perhaps most importantly, golfers will have immediate access to the improved playability of new varieties. While this staggered approach is less than ideal for several reasons, such as; managing Pre- and Post renovation fairways for several years, annual materials purchasing; it does have its benefits. Stretching the renovation over several years offers slightly deferred cost savings and allows perfection of the renovation technique year-over-year, thus, improving establishment success over time (USGA Green Section, 2018). This option also allows golfers to compare Pre- and Post-renovation fairways to highlight the value of the conversion. The fairway is dragged and cleaned after being sliced and aerified.

Which Approach to Take? One must consider facility-specific factors when choosing one of these three conversion approaches. The methodical approach may be appropriate for facilities who value undisrupted play and can tolerate annual disruptions to turf quality however, it should be noted that full CB conversion will be difficult to achieve (Cattani & Nowak, 2001). The Eradication approach has a higher probability of success, but also requires appropriate resources to carry out work and a tolerance for disruption of play. To aid in the decision-making process, a pro/con list was created so that these value judgements can be weighed and applied to your facility.

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This fairway will be ready for play in 4-6 weeks.

Resources Bauer, S., Horgan, B. P., Watkins, E., Hathaway, A., Calhoun, R., Frank, K. (2012). Establishment of Creeping Bentgrass in Annual Bluegrass Fairways Using Glyphosate and Interseeding. Applied Turfgrass Science, 9 (1), 1-10. https://doi.org/10.1094/ATS-2012-0127-01-RS Bekken, M. A. H., Schimenti, C. S., Soldat, D. J., Rossi, F. S. (2021). A novel framework for estimating and analyzing pesticide risk on golf courses. Science of the Total Environment, 783 (1), 146840. https://doi.org/10.1016/j. scitotenv.2021.146840 Brede, D. (2006). Four Tips to Interseed Bentgrass into Poa annua. Turfgrass Trends, November 2006(1), 41-42.

Cattani, D. J., Nowak, J. N. (2001, August). Interseeding in creeping bentgrass: A viable option or wishful thinking?. Golf Course Management, 69 (8), 49-54. Diehl, K. H., Elmore, M. T., Koppenhofer, A. M., Murphy, J. A., Kostromytska, O. S. (2021). Annual bluegrass weevil, paclobutrazol, and overseeding for annual bluegrass control in cool-season turfgrass. Crop Science, 61 (2), 1458-1467. https://doi.org/10.1002/csc2.20430 Dobie, F. (2020, April). Goodbye Poa annua, hello bentgrass. Golf Course Management, 88 (4), 50-56. Gaussoin, R. E., Branham, B. E. (1989). Influence of Cultural Factors on Species Dominance in a Mixed Stand of Annual Bluegrass/Creeping Bentgrass. Crop Science, 29 (2), 480-484. https://doi.org/10.2135/cropsci1 989.0011183X002900020048x

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Jacobs, P., Gross, P. (2019, September 6). Fairway Regrassing – Can You Afford Not To?. USGA Green Section Record, 57 (17). https://www.usga.org/content/ usga/home-page/course-care/green-section record/57/17/fairway-regrassing--can-you-afford-not to-.html Klein, B. (2021, July 2). Fairways for the Future. USGA Green Section Record, 59 (12). https://www.usga.org/ content/usga/home-page/course-care/green-section record/59/12/fairways-for-the-future.html Laskowski, K. (2017). Effects of irrigation and traffic stresses on physiological responses and water use characteristics of creeping bentgrass and annual bluegrass (xxi) [M.S. Thesis, Michigan State University]. Michigan State University Digital Repository. Liu, B., Landschoot, P. (2018). Influence of Phosphorus in Starter Fertilizer on the Establishment of Tall Fescue. HortScience, 53 (12), 1897-1906. https://doi. org/10.21273/HORTSCI13416-18

Petelewicz, P., Orlinksi, P. M., Baird, J. H. (2021). Suppression of annual bluegrass in creeping bentgrass putting greens using plant growth regulators. HortTechnology, 31 (2), 155-165. https://doi.org/10.21273/ HORTTECH04737-20 Reicher, Z. J., Hardebeck, G. A. (2002). Overseeding Strategies for Converting Golf Course Fairways to Creeping Bentgrass. HortScience, 37 (3), 508-510. https:// doi.org/10.21273/HORTSCI.37.3.508 Russell, T. R., Karcher, D. E., Richardson, M. D. (2019). Daily Light Integral Requirement of a Creeping Bentgrass Putting Green as Affected by Shade, Trinexapac-ethyl, and a Plant Colorant. Crop Science, 59 (4), 1768-1778. https://doi.org/10.2135/ cropsci2018.08.0501 USGA Green Section. (2018). Bentgrass Fairway Conversion Improves Playability And Reduces Inputs . https://www.usga.org/content/usga/home-page/ course-care/water-resource-center/bmp-case studies/2018/bentgrass-fairway-conversion-improves playability-and-reduces-in.html

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