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Because golf course fairways often border water features, the potential loss of fertilizer nutrients in surface runoff from fairways can be significant. The objective of this study was to determine if bermudagrass buffers mowed at increasingly higher heights could reduce nutrient runoff from golf course fairways better than bermudagrass buffers mowed at a single height by providing multiple physical barriers to runoff. Grass buffers, 5.5 m long by 12.2 m wide, were positioned perpendicular to 5% slopes at the bottom of six 12.2 by 18.9 m bermudagrass (Cynodon dactylon L.) fairway plots. The buffers on three plots were mowed at a consistent 51 mm height. The remaining buffers included three 1.8 m sections that were mowed at increasingly higher heights of 25, 38, and 51 mm as surface elevation decreased. Runoff from both irrigation and natural rainfall were collected at 5-min intervals for 1 hr following the initiation of runoff and tested for nutrient concentrations. Irrigation was applied 4 hr after granular urea and triple superphosphate were applied. Graduated buffers of increasing height delayed the initiation of runoff by 4 min during fairway irrigation and by 2 min during natural rainfall events. The graduated buffer resulted in 17% less N, 11% less P, and 19% less runoff volume during 60 min of natural rainfall runoff. The graduated buffer resulted in 18% less N and 14% less P during 60 min of irrigation runoff, and reduced runoff volume by 16%., OF THE MORE THAN 16 000 golf courses in the USA, fairways comprise about 12 to 16 ha per course and account for the majority of intensively maintained turf (National [...]

Common bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon], is increasingly used in the development of seed-propagated turf cultivars. Each seeded bermudagrass cultivar is a heterogeneous population composed of heterozygous genotypes. Therefore, the accurate identification of seeded bermudagrass cultivars is a challenge and has not yet been reported although this kind of information would be valuable for new cultivar development, seed certification, and intellectual property protection. Accordingly, the objectives of this study were (i) to characterize the genetic diversity within and relatedness between turf-type seeded cultivars; and (ii) to investigate the assignment of individuals to their source cultivars using simple sequence repeat (SSR) markers. Four seeded cultivars, NuMex Sahara, Princess-77, Riviera, and Yukon were used in the investigation. Thirty individual plants, two bulk samples, and two additional individual plants from each of the four cultivars were genotyped with 32 SSR markers that were sampled to span a major portion of the species genome. The number of alleles amplified per SSR locus ranged from 3 to 10, with a mean of 5. Six to nine signature alleles were identified for each of the four cultivars. Genetic distance estimates and clustering results were consistent with the respective breeding history. Individual plants formed four distinct groupings corresponding exactly to the four cultivars and all individuals were correctly assigned to their respective source cultivars. The total gene diversity of the four cultivars was 0.257, indicating high diversity. The posterior test also indicated that bulk samples and two additional individual plants were clearly assigned to their source cultivars. The approach developed in this study is useful for the accurate identification of seeded bermudagrass cultivars. [ABSTRACT FROM AUTHOR]

Common bermudagrass [Cynodon dactylon (L.) Pers.] has been widely used as a major warmseason turf and forage grass in the southern United States and in other regions with similar climates around the world. However, it will suffer severe winterkill when grown beyond its region of adaptation. Cold-hardy bermudagrass germplasm have been developed, but its genetic variation for important turfgrass traits remains unknown. The objective of this study was to quantify genetic variability and determine relationships among adaptive, morphological, and reproductive traits in selected cold-hardy common bermudagrass germplasm, including 48 clonal plants from 'Riviera' and 50 clonal plants from 'Yukon'. Large genetic variability existed for 12 of 13 adaptive, morphological, and reproductive traits within this germplasm. Spring greenup was found to be positively correlated with turf density and fall color retention. Leaf spot disease had negative correlations with spring greenup and inflorescence prolificacy, and percentage seed set was negatively associated with raceme length. Broad-sense heritability estimates were 0.03 to 0.25 for first internode length and fourth leaf blade width, 0.36 for first internode diameter, 0.64 for fourth leaf blade length, and 0.72 to 0.80 for inflorescence prolificacy, raceme length, and percentage seed set. The large genetic variability within the winterhardy germplasm will provide value in selecting superior parental plants, for producing improved interspecific hybrids, and in forming improved synthetic cultivars and breeding populations. [ABSTRACT FROM AUTHOR]

Bermudagrass (Cynodon sp.) is a highly productive, warm-season, perennial grass that has been grown in the United States for turfgrass, forage, pasture, rangeland, and roadside use. At the same time, many bermudagrass production and reclamation sites across the United States are affected by soil salinity issues. Therefore, identifying bermudagrass with improved salinity tolerance is important for successfully producing bermudagrass and for reclaiming salt-affected sites with saline irrigated water. In this project, the relative salinity tolerance of seven clonal-type bermudagrass was determined, including industry standards and an Oklahoma State University (OSU) experimental line. The experiment was conducted under a controlled environment with six replications of each treatment. Seven bermudagrass entries were exposed to four salinity levels (1.5, 15, 30, and 45 dS⋅m-1) consecutively via subirrigation systems. The relative salinity tolerance among entries was determined by normalized difference vegetation index (NDVI), digital image analysis (DIA), leaf firing (LF), turf quality (TQ), shoot dry weight (SW), visual rating (VR), and dark green color index (DGCI). Results indicated that there were variable responses to salinity stress among the entries studied. As salinity levels of the irrigation water increased, all evaluation criterion decreased, except LF. All entries had acceptable TQ when exposed to 15 dS⋅m-1. When exposed to 30 dS⋅m-1, experimental entry OKC1302 had less LF than all other entries except 'Tifway', while 'Midlawn' showed more LF than all the entries. Leaf firing ranged from 1.0 to 2.7 at 45 dS⋅m-1, where 'Tifway' outperformed all other entries. At 45 dS⋅m-1, the live green cover as measured using DIA ranged from 3.07% to 24.72%. The parameters LF, TQ, NDVI, DGCI, SW, and DIA were all highly correlated with one another, indicating their usefulness as relative salinity tolerance measurements. [ABSTRACT FROM AUTHOR]

Excessive concentrations of P can lead to the deterioration of surface waters through eutrophication. This study was conducted to test the effectiveness of a trench filter system for P removal from runoff and to determine the effect of P fertilizer on P losses in runoff from bermudagrass [Cynodon dactylon L. (Pers.)]. A total of 12 plots on a uniform 5% slope covered with 'Astro' bermudagrass mowed at 38 mm were used to collect pre- and postfiltered runoff from 14 natural or simulated precipitation events that occurred from March through September 2012. Runoff filtered by steel slag contained from 14.2 to 49.2% lower dissolved P concentrations than runoff filtered through an inert gravel control. The P concentrations in runoff from fertilized plots were always greater than unfertilized plots. The difference between P concentrations from the fertilized and unfertilized treatments tended to decline with each runoff event from 13.1 mg L-1 in an initial event after fertilization to 1.6 mg L-1, 133 d and nine runoff events later. Trench filter systems could be used to remove a portion of the P in runoff from turfgrass areas. [ABSTRACT FROM AUTHOR]

Annual bluegrass (Poa annua L.) is a problematic weed on creeping bentgrass (Agrostis stolonifera L.) putting greens. Annual bluegrass produces extensive seedheads in spring, and plant growth regulators (PGRs) are frequently used to suppress seedhead formation. This study investigated the effects of single and sequential applications of mefluidide, maleic hydrazide, and ethephon alone or in combination with trinexapac-ethyl (TE), on annual bluegrass seedhead formation. A secondary objective evaluated whether addition of TE enhanced the efficacy of ethephon while improving the safety on creeping bentgrass. Three independent studies were established on golf course greens during a 2-yr period, with initial PGRs application before annual bluegrass seedhead formation. Regardless of PGR treatment, single or sequential applications in all studies showed no differences in annual bluegrass seedhead suppression. Ethephon-containing treatments provided the best seedhead suppression with up to 95% reduction. No PGR treatments caused visible phytotoxicity to creeping bentgrass following single applications. Sequential applications of both mefluidide and maleic hydrazide caused significant phytotoxicity to creeping bentgrass for up to 3 wk after initial treatment (WAIT). With the exception of one evaluation date in the third study, tank mixture of TE with ethephon had little effect on annual bluegrass seedhead suppression. Tank-mixing TE with ethephon marginally enhanced turf quality of creeping bentgrass up to 6% compared to ethephon alone. [ABSTRACT FROM AUTHOR]

There is a growing trend of cultivating hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] on golf course putting greens in the transition zone because of its excellent quality in the summer months, coupled with less pesticide input than creeping bentgrass (Agrostis stolonifera L.). However, the long-term success of bermudagrass putting greens is hindered by low temperatures in winter months, particularly in the transition zone. To address this issue, in addition to genetic improvement for cold hardiness through the development of new cultivars, effective management approaches are necessary to enhance the winter survival of putting green–type bermudagrass. The objective of this study was to investigate the relative freeze tolerance of four bermudagrasses and the effects of raising mowing height on the freeze tolerance of putting green–type bermudagrasses. In this study, two experimental putting green–type bermudagrasses (11X2 and OKC0805) along with cultivars TifEagle and OKC3920 were tested at two mowing heights (3.2 vs. 6.4 mm) at freeze temperatures that ranged between –4 and –11 °C. The lethal temperature to kill 50% of the population (LT50) as well as regrowth vigor during recovery were evaluated. Variety ‘OKC3920’ demonstrated enhanced freeze tolerance compared with ‘TifEagle’ at both mowing heights. Increasing the mowing height from 3.2 mm to 6.4 mm improved freeze tolerance for most genotypes tested in this study. After exposing the grasses to –8 °C for 1 hour, genotypes such as 11X2 exhibited better regrowth vigor and demonstrated a faster recovery. This study suggests that golf course managers can enhance winter resilience of bermudagrass putting greens by selecting genotypes strategically with superior freeze tolerance and raising mowing heights in the fall acclimation process. [ABSTRACT FROM AUTHOR]