Fairway Turf Research Articles

Using local weather stations to generate growing degree‐day data to predict the flowering pattern of an annual bluegrass fairway in Michigan

AbstractSix 1‐yr observational studies were conducted from 2001 to 2006 at the Hancock Turfgrass Research Center in East Lansing, MI to characterize the timing, duration, and amplitude of annual bluegrass (AB) (Poa annua L.) seedhead emergence in a 10‐ to 15‐yr‐old AB fairway. The objective of this research was to collect data that could be used in the development of a growing degree‐day (GDD) model to predict AB seedhead emergence at other locations by using readily available weather station data. New GDD models were compared with previously published models. Plots were established on two adjacent perennial stands of AB maintained at 1.5 cm, receiving 0.5 to 0.6 cm of automatic daily irrigation throughout the growing season and 120 kg N ha–1 yr–1 from 2001 to 2006. The soil type is a Marlette sandy loam (fine‐loamy, mixed, semiactive, mesic Oxyaquic Glossudalf). Line intersects and visual estimations of seedhead cover were evaluated multiple times throughout the spring seedhead emergence period. A base temperature of –5 °C most accurately predicted the onset, peak duration, and completion of the AB seedhead emergence period for all 5 yr. The final model flowering rate = (–3.331599 × 10–6 × gdd2) + (6.968782 × 10–3 × gdd) + –2.841894, accurately predicted (R2 = .64) flowering stages of an AB fairway turf over 6 yr in Michigan.

Novel action thresholds of a logistic regression model to forecast dollar spot on bentgrasses

AbstractDollar spot (Clarireedia jacksonii) susceptibility varies among bentgrasses (Agrostis spp.). This trial assessed the ability of five action thresholds of the risk index (RI) of a logistic regression model to forecast dollar spot incidence on bentgrass fairway turf grown on a sandy loam in North Brunswick, NJ. Dollar spot incidence was assessed over 128 observation periods (May to Nov. annually) over 3 yr and related to five action thresholds for prediction accuracy. Action thresholds included a RI threshold of 20% (RI 20%), interpreting the change in the RI over time (RI slope), adjusting the RI upwards to maximize accuracy (RImax), combining RI 20% with RI slope, and combining RImax with RI slope. The RI 20% accurately predicted disease on 63 to 66% of observation periods for highly susceptible creeping bentgrass (A. stolonifera L.) cultivars Shark, Penncross, and Independence; other action thresholds improved accuracy by only 10% or less for these cultivars. Prediction accuracy on lower susceptibility cultivars (007, Declaration, and colonial bentgrass Capri; A. capillaris L.) was substantially improved with four novel action thresholds by reducing over‐predictions compared to RI 20%. Accuracy was improved by as much as 32% when the RImax and RI slope were combined for Declaration compared to RI 20%. On low susceptibility cultivars, turf managers may be able to use action thresholds that incorporate a RI greater than 20% and/or RI slope to reduce fungicide inputs and maintain acceptable dollar spot control compared to RI 20%.

Carbon Sequestration in Zoysiagrass Turf under Different Irrigation and Fertilization Management Regimes

Core Ideas Further research is required to evaluate and develop management practices that may sequester C in turfgrass soils. Hidden C costs, which are energy‐based inputs from turf maintenance, should be factored into soil C sequestration calculations. A higher‐input management regime in turf will not increase net C sequestration compared with a low management input regime. Zoysiagrass golf course fairway turf had an average gross C sequestration rate of 1.01 Mg C ha–1 yr–1. Carbon dioxide (CO2) is an important greenhouse gas (GHG) implicated in climate change. Turfgrass covers an estimated 12.8 to 20 million ha in the United States and has the capacity to sequester or emit significant amounts of CO2 from/into the atmosphere. Our objective was to evaluate irrigation and N fertilization management practices that may increase sequestration of atmospheric CO2 in turf soils. The rate of change in soil organic carbon (SOC) at 0 to 30 cm was investigated under two management regimes in ‘Meyer’ zoysiagrass (Zoysia japonica Steud.). A high management input (HMI) (urea + medium irrigation) and low management input regime (LMI) (unfertilized [no N fertilizer] + low irrigation) were implemented. Hidden carbon costs (HCC) of maintenance practices and nitrous oxide emissions (another GHG) were estimated to account for energy expended in Mg of carbon equivalents (CE) ha–1 yr–1. Prior to subtracting HCC, average gross C sequestration rates were not statistically different at 1.046 and 0.976 Mg C ha–1 yr–1 in HMI and LMI, respectively. Once total estimated HCC was included, the average net sequestration rate was 0.412 and 0.616 Mg C ha–1 yr–1 in HMI and LMI, respectively, with no statistical differences. Results indicate that under the conditions of this study, a higher‐input management regime will not increase net C sequestration compared with a low management input regime. Further research is required over additional turfgrass species and management regimes to develop management practices that increase C sequestration.

High and Low Management Input Regimes Result in Similar Net Carbon Sequestration Rates in Zoysiagrass Golf Course Fairway Turf

High and Low Management Input Regimes Result in Similar Net Carbon Sequestration Rates in Zoysiagrass Golf Course Fairway Turf

Glyphosate Efficacy as Influenced by Cultivation Practices on a Creeping Bentgrass Fairway Turf

Glyphosate is routinely used to eradicate existing turf in golf course fairway renovations. However, current label recommendations suggest delaying cultivation of glyphosate treated areas for 7 days. A 2-year field study was conducted to assess how various seedbed preparation techniques (i.e., verticutting, core-cultivation, or verticutting + core-cultivation) influence glyphosate efficacy on creeping bentgrass fairway turf when completed at various intervals shortly after application [0–7 days before cultivation (DBC)]. Percent green cover declined from initial values of ≈90% to ≤0.2% at the end of the study after glyphosate application at all timings, regardless of cultivation during both years. All cultivated plots had 37.9% to 72.3%, or 5.9% to 62.1% less green cover compared with noncultivated plots when glyphosate was applied ≤3 days before cultivation in 2014 and 2015, respectively. Generally, the number of days until green cover reached 1% (GC1) ranged from 6.6 to 11.1 in 2014 and 5.2 to 6.9 in 2015. Within glyphosate application timings, no differences in GC1 were observed between cultivated and noncultivated treatments in 2014, except at 0 DBC. The GC1 for verticutting was 5.1 days longer than noncultivated plots; however, all other cultivation treatments were equivalent to noncultivated plots when glyphosate was applied 0 DBC. All cultivation treatments reduced GC1 1.7 to 2.5 days compared with the no cultivation treatment, regardless of glyphosate application timing in 2015. Results from this study indicate that cultivation of creeping bentgrass fairway turf within 7 days of glyphosate application is not detrimental to long-term herbicide efficacy, and in some cases may actually enhance the rate of decline of glyphosate treated creeping bentgrass.

Off-site transport of nitrogen fertilizer with runoff from golf course fairway turf: A comparison of creeping bentgrass with a fine fescue mixture.

Maintaining quality golf course turf often requires irrigation and application of fertilizer. The transport of excess nutrients with runoff water from highly managed and fertilized biological systems to surrounding surface waters has been shown to result in enhanced algal blooms and promotion of eutrophication. Environmental stewardship includes looking for new approaches to reduce adverse environmental impacts of current practices. One strategy is to replace traditional turfgrass with low-maintenance turfgrass species. Fescue grasses have been shown to provide characteristics desirable for golf course fairways. Thus side-by-side studies comparing runoff from plots planted in creeping bentgrass (CGB) or fine fescue mixture (FFM), similarly managed as a golf course fairway, were conducted to measure runoff volumes and the amount of ammonium nitrogen (NH4-N) and nitrate nitrogen (NO3-N) transported off-site with runoff. Greater runoff volumes and mass of applied nutrients were measured in the runoff from the FFM, representing a 38% and 56% median increase in the off-site mass transport of NH4-N and NO3-N with surface flow. Shoot density, thatch depth and soil moisture were the most important factors related to runoff volume. Results of this research will be useful to grounds superintendents and researchers for selecting and developing management strategies to improve environmental stewardship of managed turf while providing desired turf quality.

Evaluation of nitrogen and phosphorus transport with runoff from fairway turf managed with hollow tine core cultivation and verticutting

Enrichment of surface waters with excess nutrients is associated with increased algal blooms, euthrophication and hypoxic zones, as reported in the northern Gulf of Mexico. A source of nutrients to surface waters results from fertilizer runoff. Management strategies used to maintain turf on golf courses and recreational fields often include aerification and application of fertilizer. Although research exists on benefits of core cultivation and verticutting (VC) to reduce thatch and the transport of applied chemicals with runoff, there are no studies reporting the effect of coupling these management practices with the goal of further reduction of off-site transport of fertilizer with runoff. We hypothesized that the addition of VC to hollow tine core cultivation (HTCC) would enhance infiltration of precipitation, reduce runoff and nutrient transport with runoff and therefore influence concentrations of nutrients in surface waters receiving runoff from turf managed as a golf course fairway. Greater runoff and mass of soluble phosphorus and ammonium nitrogen transported with runoff were measured from plots managed with HTCC+VC than HTCC; however, the reverse was noted for nitrate nitrogen. Only a portion of the observed trends proved to be statistically significant. Our research showed no reduction or enhancement of risk associated with surface water concentrations of phosphorus or nitrogen, resulting from runoff from creeping bentgrass turf that was managed with HTCC+VC compared to HTCC. Data obtained in this research will be useful to grounds superintendents when selecting best management practices and to scientists seeking data relating runoff to land management for watershed-scale modeling.

Nutrient loss with runoff from fairway turf: An evaluation of core cultivation practices and their environmental impact

The presence of excess nutrients in surface waters can result in undesirable environmental and economic consequences, including nuisance algal blooms and eutrophication. Fertilizer use in highly managed turf systems has raised questions concerning the contribution of nutrients to surrounding surface waters. Experiments were designed to quantify phosphorus and nitrogen transport with runoff from turf plots maintained as a golf course fairway to identify which cultural practice, solid tine (ST) or hollow tine (HT) core cultivation, maximized phosphorus and nitrogen retention at the site of fertilizer application. Simulated precipitation and collection of resulting runoff were completed 26 ± 13 h following granular fertilizer application (18-3-18: N-P₂O₅-K₂O) and 63 d and 2 d following core cultivation. Runoff volumes were reduced in fairway turf plots aerated with HT relative to ST (63 d: 10%, 2 d: 55% reduction). Analysis of the runoff revealed a reduction in soluble phosphorus, ammonium nitrogen, and nitrate nitrogen losses with runoff from plots managed with HT; a 5 to 27% reduction after 63 d; and a 39 to 77% reduction at 2 d. Golf course runoff-to-surface water scenarios were used to calculate estimated environmental concentrations (EECs) of nitrogen and phosphorus in surface water receiving runoff from turf managed with ST or HT core cultivation. Surface water concentrations of phosphorus remained above the U.S. Environmental Protection Agency's water quality criteria to limit eutrophication, with the exception of concentrations associated with HT core cultivation at 2 d. Regardless of management practice (ST or HT) and time between core cultivation and runoff (63 d or 2 d), all EECs of nitrogen were below levels associated with increased algal growth. Understanding nutrient transport with runoff and identifying strategies that reduce off-site transport will increase their effectiveness at intended sites of application and minimize undesirable effects to surrounding surface water resources.

Evaluation of core cultivation practices to reduce ecological risk of pesticides in runoff from Agrostis palustris

Pesticides associated with the turfgrass industry have been detected in storm runoff and surface waters of urban watersheds, invoking concern of their potential environmental effects and a desire to reduce their transport to nontarget locations. Quantities of chlorpyrifos, dicamba, dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-D), flutolanil, and mecoprop-p (MCPP) transported in runoff from bentgrass (Agrostis palustris) fairway turf managed with solid tine (ST) or hollow tine (HT) core cultivation were compared to determine which cultivation practice is more efficient at mitigating environmental risk. Plots receiving HT core cultivation showed a 10 and 55% reduction in runoff volume and a 15 to 57% reduction in pesticide transport with runoff at 63 d and 2 d following core cultivation. Estimated environmental concentrations of the pesticides in a surface water receiving runoff from turf managed with ST core cultivation exceeded the median lethal concentration (LC50) or median effective concentration (EC50) of nine aquatic organisms evaluated. Replacing ST core cultivation with HT core cultivation reduced surface water concentrations of the pesticides to levels below the LC50 and EC50 for most these aquatic organisms, lessening risk associated with pesticides in runoff from the fairway turf. Results of the present research provide quantitative information that will allow for informed decisions on cultural practices that can maximize pesticide retention at the site of application, improving pest control in turf while minimizing environmental contamination and adverse effects associated with the off-site transport of pesticides.

Plant growth regulator and nitrogen fertilizer effects on soil organic carbon sequestration in creeping bentgrass fairway turf

The objective of this study was to determine the effects of plant growth regulator (PGR) (no PGR, trinexapac-ethyl, and paclobutrazol) and N fertilizer (zero N, an average of 37 kg N ha−1 month−1, 6 and 12 kg N ha−1 week−1) on soil organic C (SOC) and soil N in creeping bentgrass (Agrostis stolonifera L.) fairway turf. After 4 years of field experiments soil samples were obtained from soil depths of 0–2.5, 2.5–5, 5–7.5, 7.5–10, 10–15, 15–20, and 20–30 cm. Soil bulk density, SOC, total N, NO3−–N, and NH4+–N concentrations were determined. Paclobutrazol and trinexapac-ethyl application increased SOC. The 37 kg N ha−1 month−1 application increased SOC at the 0–2.5 cm depth with both PGRs. When paclobutrazol was used, N fertilizer always increased SOC; however, the greatest increase was observed with the 12 kg N ha−1 week−1 application when compared to other rates, inversely related to the NH4+–N concentration. Nitrogen application increased soil total N and NO3−–N in the upper three depths. The application of PGRs and N fertilizer to creeping bentgrass fairway turf is an effective strategy for promoting C sequestration.

Traffic Stress Effects on Bentgrass Putting Green and Fairway Turf

Creeping bentgrass (Agrostis stolonifera L.) has received more study and use as golf course turf than velvet bentgrass (A. canina L.). The objective of two field trials, managed as putting green and fairway turf, was to evaluate the performance of creeping and velvet bentgrass in mixed swards with annual bluegrass (Poa annua var. reptans Hausskn.) when subjected to traffic stresses. The trials were initiated on a sandy loam (fine‐loamy, mixed, mesic Typic Hapludult). Wear (no‐wear and wear) and compaction (no‐compaction and compaction) were applied in a factorial combination to 15 creeping or velvet bentgrasses. Turf quality, turf density, and bentgrass populations of cultivars were more susceptible to wear stress than compaction. Velvet bentgrass performed and resisted the spread of annual bluegrass better than most creeping bentgrasses. Cultivars that formed denser turf performed well in both trials; ‘Vesper’, ‘7001’, and ‘Penn A‐4’ had the best overall performance. Interactions indicated ‘SR 7200’, ‘Penn G‐2’, and ‘Providence’ were susceptible to compaction. ‘Pennlinks’ and ‘Penncross’ were ineffective at maintaining desirable bentgrass populations particularly in the putting green trial. Management strategies that minimize wear damage may have a greater impact on turf quality and bentgrass populations in mixed stands than practices intended to manage compaction, particularly on well‐drained soil.

Dynamics of Foliage and Thatch Populations of Introduced Pseudomonas fluorescens and Streptomyces sp. on a Fairway Turf

Populations of bacteria (Pseudomonas fluorescens A506 and Streptomyces sp. strain 93) applied to a creeping bentgrass/annual bluegrass fairway turf were followed over time on leaves and thatch. While introduced populations remained at detectable levels over a period of 11–25 days, they usually declined gradually and did not increase after their application to turf. Streptomyces rapidly disappeared from leaves while P. fluorescens was able to maintain similar population sizes on both thatch and leaves, after an initial decline of about 1-log unit, showing that it was actively colonizing the foliage despite loss of biomass from lawn mowing. Throughout these experiments, populations of indigenous microbes on foliage and thatch remained stable, about 106 and 108 cfu g−1 for fungi and bacteria, respectively, and were not affected by the application of bacterial antagonists. Niche-clearing with hydrogen peroxide, which temporarily reduced the population size of indigenous microorganisms two-fold, caused population size of P. fluorescens to increase approximately ten-fold within 24 h, while it declined by about one log unit on untreated turf. It is concluded that the indigenous microflora competes with introduced bacterial antagonists and interferes with their establishment and persistence on turf. Additional studies with P. fluorescens revealed that its population size was inoculum dose-dependent and that solid top dressing was slightly more efficient than spraying liquid suspension in establishing the antagonist. It was possible to maintain P. fluorescens populations above 105 cfu/g of thatch and leaves for 2 weeks or more with both top-dressing or spraying with about 1 to 3 × 1010 cfu m−2.

Segway and Golf Car Wear on Bermudagrass Fairway Turf

Segway and Golf Car Wear on Bermudagrass Fairway Turf

Use of the growth regulator paclobutrazol in the management of dollar spot of creeping bentgrass in Minnesota

The control of dollar spot by paclobutrazol applied as a growth regulator on a creeping bentgrass (Agrostis palustris) and annual bluegrass (Poa annua) fairway turf was compared with two standard fungicide treatments in Minnesota during two growing seasons. Paclobutrazol was applied every 3 weeks, staggered by about 10 days with fungicide treatments (chlorothalonil or propiconazole), also applied every 3 weeks. Paclobutrazol alone significantly reduced the number of dollar spot infection centers during both summers, often by as much as 80%. Chlorothalonil or propiconazole were usually more effective in controlling dollar spot than paclobutrazol. Paclobutrazol improved disease control by fungicides when tested in combination with various rates of chlorothalonil or propiconazole. Paclobutrazol applied as a growth regulator could thus be used to reduce the base line severity of dollar spot of turf.

Conversion of Fairway‐Height Perennial Ryegrass Turf to Kentucky Bluegrass without Nonselective Herbicides

Many golf course superintendents wish to convert perennial ryegrass (Lolium perenne L.) fairways to other cool‐season species such as Kentucky bluegrass (Poa pratensis L.) because of the former's high fungicide requirement. However, interseeding into a mature turfgrass stand often results in poor seedling survival because of competition from the existing stand. The objective of this research was to evaluate methods for enhancing Kentucky bluegrass (KB) establishment when interseeded into a mature perennial ryegrass fairway turf. Core aeration, scalping, plant growth regulators (PGRs), postseeding low mowing (PSLM), high seeding rates, and multiple seedings were used singly and in factorial combinations. Postseeding low mowing (0.6 cm twice weekly for 4 wk) and high seeding rates [196 kg pure live seed (PLS) ha−1] were most effective in enhancing KB establishment. Plots receiving PSLM averaged 31.9% KB 21 months after seeding (MAS) compared with 18.1% in non‐PSLM plots. Seeding KB at 196 kg PLS ha−1, both fall and spring, resulted in an average of 29.8% KB 21 MAS while seeding at 98 kg PLS ha−1, in the fall only, resulted in only 19.7% KB. A single preseeding core aeration or scalping treatment did not increase KB establishment, nor did preseeding applications of the PGR trinexapac‐ethyl [4‐(cyclopropyl‐α‐hydroxy‐methylene)‐3,5‐dioxo‐cyclohexane‐carboxylic acid ethyl ester]. Mefluidide {–[2,4‐dimethyl‐5‐[[(trifluoromethyl)‐sulfonyl]amino]phenyl] acetamide} increased KB establishment at 6 MAS, but the effect was gone by 21 MAS. Where nonselective herbicides are not used, fastest conversion to KB will occur with a combination of PSLM and high seeding rates.

Measuring Ball Lie on Golf Course Fairways

Ball lie on a golf course fairway can impact a golfer's ability to control a shot. At present, there is no quantitative method to accurately measure golf ball lie (the amount of the ball exposed above the turfgrass canopy) on short‐cut fairway turf. The objective of this work was to develop an instrument capable of accurately and quantitatively measuring golf ball lie on short‐cut (1.27 cm) fairway turf. In previous work, a device (Lie‐N‐Eye) that measured golf ball lie on high‐cut fairway turf (1.6–2.5 cm) was developed and tested on 25 Kentucky bluegrass (Poa pratensis L.) cultivars. That device lacked the sensitivity required to make measurements on short‐cut turf. An improved device (Lie‐N‐Eye II) was developed to measure golf ball lie on short‐cut (1.27 cm) bentgrass (Agrostis spp.) fairway turfgrasses. In October 2000, Lie‐N‐Eye II was tested on three creeping bentgrass [Agrostis stolonifera var. palustris (Huds.) Farw.] and three colonial bentgrass (A capillaris L.) cultivars and adequately measured ball lie differences among bentgrass cultivars and species. Ball lies ranged from 38.7 mm to 40.7 mm of the ball exposed above the canopy (90.7 to 95.4% of the golf ball). Power curves generated from 18 measurements on each of six bentgrass cultivars indicate Lie‐N‐Eye II was able to detect a 1.65‐mm difference between ball lies with a probability of approximately 90%.

Measuring Ball Lie on Golf Course Fairways

Ball lie on a golf course fairway can impact a golfer's ability to control a shot. At present, there is no quantitative method to accurately measure golf ball lie (the amount of the ball exposed above the turfgrass canopy) on short-cut fairway turf. The objective of this work was to develop an instrument capable of accurately and quantitatively measuring golf ball lie on short-cut (1.27 cm) fairway turf. In previous work, a device (Lie-N-Eye) that measured golf ball lie on high-cut fairway turf (1.6–2.5 cm) was developed and tested on 25 Kentucky bluegrass (Poa pratensis L.) cultivars. That device lacked the sensitivity required to make measurements on short-cut turf. An improved device (Lie-N-Eye II) was developed to measure golf ball lie on short-cut (1.27 cm) bentgrass (Agrostis spp.) fairway turfgrasses. In October 2000, Lie-N-Eye II was tested on three creeping bentgrass [Agrostis stolonifera var. palustris (Huds.) Farw.] and three colonial bentgrass (A capillaris L.) cultivars and adequately measured ball lie differences among bentgrass cultivars and species. Ball lies ranged from 38.7 mm to 40.7 mm of the ball exposed above the canopy (90.7 to 95.4% of the golf ball). Power curves generated from 18 measurements on each of six bentgrass cultivars indicate Lie-N-Eye II was able to detect a 1.65-mm difference between ball lies with a probability of approximately 90%.

Saskatchewan Regional Meeting, 2000, The Canadian Phytopathological Society

Pathogenic variability within a population of Mycosphaerella graminicola, a leaf-spotting pathogen of wheat. M. Razavi and G.R. Hughes. Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada. Genetic control of insensitivity to necrosis induced by the culture filtrate of Pyrenophora tritici-repentis race 2. P.K. Singh and G.R. Hughes. Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada. Chromosomal Location of Bt10 Common Bunt Resistance. R.E. Knox, J.G. Menzies, Z. Popovic, and J.D. Procunier. Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, Box 1030, Swift Current, SK S9H 3X2, Canada; and (J.G.M., Z.P., J.D.P.) Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada. Effect of lodging resistance and apetalous canola cultivars on sclerotinia stem rot incidence and seed yield. H.R. Kutcher, T.K. Turkington, and G. Clayton. Saskatoon Re-search Centre, Agriculture and Agri-Food Canada, Melfort, SK S0E 1A0, Canada; and (T.T., G.C.) Lacombe Research Centre, Lacombe, AB T4L 1W8, Canada. Dollar spot disease on golf fairway turf in Saskatchewan. J. Drew Smith. Nos. 309–318, 108th Street, Saskatoon, SK S7N 1P8, Canada. Fusarium head blight in common and durum wheat and barley in Saskatchewan in 2000. M.R. Fernandez, P. Pearse, G. Holzgang, and G. Hughes. Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, Swift Current, SK S9H 3X2, Canada; (P.P., G.H.) Saskatchewan Agriculture and Food, 3085 Albert St., Regina, SK S4S 0B1, Canada; and (G.H.) Department of Plant Science, University of Saskatchewan, Saskatoon, SK S7N 0W0, Canada.

Effect of the Growth Regulator Proxy on Creeping Bentgrass Fairway Turf

Effect of the Growth Regulator Proxy on Creeping Bentgrass Fairway Turf

Effect of the Growth Regulator Proxy on Creeping Bentgrass Fairway Turf

Abstract Proxy is a newly-labeled plant growth regulator (PGR) for use on golf course and commercial turfgrass areas. Four rates of Proxy (ethephon), 2.3, 3.6, 4.6, and 9.1 kg ai/ha (2.0, 3.2, 4.1, and 8.2 lb ai/A,) were compared to Primo (trinexapac-ethyl) at 1.0 kg ai/ha (0.9 lb ai/A) and an untreated control for clipping reduction and effects on aesthetics of creeping bentgrass maintained as fairway turf. Treatments were applied three times at 28-day intervals during 1998 at locations in Indiana and Wisconsin. Proxy was as effective at reducing clipping yields as Primo, although the magnitude of effects varied between the two locations. In general, Proxy was more likely to reduce turf quality and color than Primo. All rates of Proxy reduced clipping weights similarly, but low rates were less likely to reduce color or quality ratings. Turf density was not affected by Proxy or Primo. Effects of Proxy on creeping bentgrass occurred within two weeks after application and generally dissipated within four weeks, whereas Primo effects occurred within one week after application and generally dissipated within three weeks. Turf quality was occasionally reduced following application of Proxy.