Annual bluegrass (ABG, Poa annua L.) is often considered a weed on golf greens. Although numerous sustainable and low‐input management practices have gained popularity, no research‐based information is available on their ability to reduce ABG while promoting more desirable species, such as creeping bentgrass (CBG, Agrostis stolonifera L.). The objective of this 2‐yr field study was to elucidate the interaction of nitrogen (N) rates, plant growth regulators (PGRs), and iron sulfate (Fe) rates as they relate to reducing ABG populations in a golf green. Turf consisted of a mature stand of ‘L‐93’ CBG (∼75%) and ABG (∼25%). Factors included N from ammonium sulfate (21 N‐0 P‐0 K) (24 or 108–147 kg N ha−1 yr−1),the PGRs trinexapac‐ethyl (TE, 0.043 kg a.i. ha−1 application−1) and flurprimidol (FL, 0.28 kg a.i. ha−1 application−1), and Fe from iron sulfate (0, 12, or 49 kg Fe ha−1 application−1). Treatments were initiated in May and applied approximately every 3 wk in 2010 and 2011. Plots receiving 24 kg N ha−1 yr−1 received only four applications during the season. The effect of N and PGR was greatest on ABG populations. Few differences in ABG populations existed among plots treated with TE or no PGR. Turf within plots treated with FL had a seasonal average of 4 and 14% ABG in 2010 and 2011, respectively. Plots treated with 24 kg N ha−1 yr−1 generally had lower ABG populations. In 2011, ABG populations were negatively correlated with Fe rate in turf receiving 24 kg N ha−1 yr−1, but not in plots treated with 147 kg N ha−1 yr−1. Flurprimidol had the greatest effect on ABG populations in the N × PGR × Fe programs. Few differences in soil pH or organic matter levels, mostly agronomically insignificant, were observed among treatments. While ABG populations varied among select treatment combinations, the long‐term impact on species composition and overall turfgrass quality remains unknown.
Annual bluegrass (ABG, Poa annua L.) is often considered an undesirable species on golf courses in many regions of the United States. However, the long‐term effect of the cultural and chemical management practices of ABG control is not sufficiently investigated. The objective of this study was to determine the long‐term effect of N, Fe sulfate, and plant growth regulators (PGRs) on ABG populations in a creeping bentgrass (CBG, Agrostis stolonifera L.) golf green. The study was established on a mixed stand of ‘L‐93′ CBG (∼75%) and ABG (∼25%) and managed as a putting green in University Park, PA, from 2012 to 2018. Treatments included ammonium sulfate (24 and 147 kg ha−1 yr−1), Fe sulfate (0, 12, or 49 kg FeSO4 ha−1 application−1), and the PGRs trinexapac‐ethyl (TE, 0.043 kg a.i. ha−1 application−1), flurprimidol (FL, 0.28 kg a.i. ha−1 application−1) and a nontreated control. Treatments were initiated in late April or early May each year and reapplied where required every 3 wk for nine applications annually. In general, ABG populations were lowest under lower N rates and with applications of FL. The long‐term effect of FeSO4 was minimal. In the first year of this study (2012), turfgrass quality was reduced, but quality levels generally increased in subsequent years. Although low N and FL may reduce ABG and high N and TE may increase ABG, seasonal variations in environmental conditions may reduce the efficacy of these treatments.
Golf course managers manipulate cultural practices in preparation for golf tournaments to increase ball roll distance (BRD) for short periods of time. Brushing putting greens, thought to be a relatively minimally disruptive cultural practice using brush attachments mounted to mower units to vertically orient leaf blades prior to mowing, is growing in popularity despite little research validating purported benefits. The objectives of this study were to evaluate the impact of brush types (rotary, stiff push, and soft push brush) and brushing frequency (no brushing, once, or twice) combined with mowing on BRD and turfgrass quality on a creeping bentgrass (Agrostis stolonifera L.) putting green over a 2‐wk period. All brush types produced a >20‐cm BRD reduction compared with no brushing by the end of the 14‐d trial in 2016 and 2017. Additionally, all brush types significantly lowered turfgrass quality, with the stiff brush resulting in unacceptable quality. Brushing and mowing once reduced BRD and turf quality compared with not brushing with daily mowing. Double brushing and mowing increased BRD equivalent to a single mowing without brushing, but turfgrass quality declined below acceptable thresholds. The results of this study indicate that brushing incorporated into a daily mowing regimen over a short 14‐d period decreases creeping bentgrass putting green BRD and quality. Increasing mowing frequency may eliminate BRD reductions from brushing, but golf course managers should practice caution when implementing brushing, especially over shorter periods of time when BRD and turfgrass quality expectations are increased.
Cyanobacteria compete with putting green turf, resulting in algal surface crusts that can reduce turf density and quality. The objectives of this study were to assess preventive control of surface cyanobacteria colonization of putting green turf with various phosphite salt sources and formulations. An optimal rate of phosphorous acid to suppress cyanobacteria while minimizing phytotoxicity was also examined. Two field studies were conducted concurrently on an ‘L‐93’ creeping bentgrass (Agrostis stolonifera L.) putting green in Storrs, CT, during 2010 and 2011. Study 1 assessed various commercial formulations and sources of phosphite salts, potassium phosphate, and non‐phosphonate fungicides on percent plot area infested by algae. Study 2 identified rates of phosphorous or phosphoric acid applied as commercial formulations of potassium phosphite or technical preparations of potassium phosphite and phosphate, which reduce or enhance algae development and turf quality. Potassium phosphite reduced percent plot area infested by 90 to 100% and 52 to 86% compared with potassium phosphate in study 1 during 2010 and 2011, respectively. Few differences in plot area infested were observed among six commercial phosphite formulations and sources or non‐phosphonate fungicides throughout study 1. Area under the algae development curve decreased by 52 to 78% as phosphorous acid increased from 2.9 to 5.4 or 8.1 kg ha−1 throughout the 2‐yr study. Turf quality was reduced in phosphorous acid‐treated plots at rates greater than 10.8 kg ha−1. Phosphite products applied at 5.4 to 8.1 kg ha−1 every 14 d can be used to suppress cyanobacteria with reduced risk of phytotoxicity for putting green turf.
In preparation for golf course tournaments, turfgrass managers often seek increased ball roll distances on putting greens. The objective of this study was to determine the effect mowing height and frequency had on ball roll distance during simulated tournament conditions. Two 14-d field experiments were conducted in 2015 and 2016 at the Joseph Valentine Turfgrass Research Center located in University Park, PA. Each study was conducted on a 'Penn A-4' creeping bentgrass (Agrostis stolonifera L.; CBG) and annual bluegrass (Poa annua L.; ABG) putting green. Plots measured 1.5 m by 3.0 m and were arranged in a randomized complete block design with a 3 × 3 factorial treatment structure. For the main effect of height of cut (HOC), mowers were set to a bench height of 2.1 mm, 2.5 mm, and 2.9 mm. For mowing frequency (MF), plots were mowed once, twice, or four times per day. Single cut (SC) and double cut (DC) treatments were performed in the morning whereas double-double cut (DD) treatments consisted of a DC in the morning and again in the afternoon. Ball roll distance (BRD) and turfgrass quality were assessed. Although a few interactions were present in the ABG study, the main effects of HOC and MF were significant on 79% and 82% rating dates, respectively. On CBG, the main effect of HOC and MF were significant on 89% and 86% of rating dates. For both species, turfgrass quality was reduced during the trial as HOC was reduced and MF was increased. INTRODUCTIONPutting greens are the most intensely managed playing surfaces on golf courses. Ball roll distance (BRD), often referred to as "green speed" by golfers, and trueness of the ball's roll across a green have a major impact on the playability of putting surfaces. For golfers, green speed is directly associ-
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