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Patricia Sweeney, Robert Golembiewski, and Karl Danneberger

Random amplified polymorphic DNA (RAPD) markers from leaf tissue extractions are effective for discrimination of turfgrass varieties. The usefulness of RAPD markers for turfgrass variety identification can be enhanced by use of seed rather than leaf tissue for DNA extraction. To determine whether DNA extracted from turfgrass seed was suitable for amplification, DNA was extracted from bulk samples and individual seeds of bermudagrass [Cynodon dactylon (L.) Pers.], chewings fescue (Festuca rubra var. commutata Gaud.), Poa annua L., Poa supina Schrad., creeping bentgrass [Agrostis stolonifera L. var. palustrus (Huds.) Farw.], Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca arundinacea Schreb.). All samples were successfully amplified using an arbitrary primer. Amplification intensity varied among species. With an almost infinite number of arbitrary primers available, it is likely that suitable primers can be found to amplify DNA from most turfgrass species. Amplification of turfgrass seed DNA, whether bulk or individual seed, is possible and should prove more useful than amplification of leaf tissue DNA for discrimination of turfgrass varieties.

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E.A. Guertal and J.N. Shaw

A 3-year study was conducted in Auburn, Ala., on an established hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy `Tifway'] stand maintained at a 2.54-cm mowing height. Treatments were level of soil traffic applied via a weighted golf cart to produce turf and soil that received varying amounts of traffic. Dormant bermudagrass was overseeded with perennial ryegrass (Lolium perenne L.) each October, which remained until May of each year. Spectral data were collected monthly using a multispectral radiometer. Percent reflectance data were acquired over 512 discrete wavelengths in visible (VIS) and near-infrared (NIR) ranges. Quarterly data collection included soil penetrometer and bulk density measurements to a depth of 15 cm. After 2 years of traffic, both soil penetrometer and bulk density data indicated statistically significant increases in soil compaction. In general, as traffic increased there were also increases in percent reflectance in the VIS range. Data were subject to temporal variation, however, as values changed with the date of sample collection. The NIR reflectance data provided little consistent correlation to measurements of soil compaction. Use of NIR and VIS radiometry to evaluate turf stress showed some potential, but temporal variation must be considered.

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Grady L. Miller

The effects of several soil amendments, following a single filling of core aerification holes, on growth and transpiration of `Tifdwarf' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] were examined during drought stress. Soil amendments had variable effects on turf quality. In general, turf grown in ZeoPro®- and Profile®-amended sand had the highest quality. Data indicated that the evaluated soil amendments have the potential to influence soil water content, ultimately influencing transpirational response to drought stress. Amended sand contained 1% to 16% more transpirable water compared with non-amended sand. Turfgrass grown in Axis®- and Isolite®-amended sand required 0.4 to 1.4 days longer to reach the endpoint (transpiration rate of drought stressed plants <12% of well-watered plants) during a period of rapid water depletion. Data from this study suggest that the total volume these amendments occupied in the root zone, following a single filling of core aerification holes in sand, may positively influence soil moisture status, resulting in an increase in drought avoidance.

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Marco Fontanelli, Michel Pirchio, Christian Frasconi, Luisa Martelloni, Michele Raffaelli, Andrea Peruzzi, Nicola Grossi, Lisa Caturegli, Simone Magni, Monica Gaetani, and Marco Volterrani

Turfgrass species can be classified into two main groups: cool-season and warm-season species. Warm-season species are more suited to a Mediterranean climate. Transplanting is a possible method to convert a cool-season to a warm-season turfgrass in untilled soil. It generally requires the chemical desiccation of the cool-season turfgrass. However, alternative physical methods, like flaming and steaming, are also available. This paper compares flaming, steaming, and herbicide application to desiccate cool-season turfgrass, for conversion to hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) in untilled soil, using transplanting. Two prototype machines were used, a self-propelled steaming machine and a tractor-mounted liquefied petroleum gas flaming machine. Treatments compared in this work were two flaming treatments and two steaming treatments performed at four different doses together with two chemical treatments with glufosinate-ammonium herbicide applications. The cool-season turfgrass species were tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne). The desiccation effect of the various treatments on cool-season turf was assessed by photographic survey 15 days after treatment. The percentage cover of hybrid bermudagrass was visually assessed at 43 weeks after planting. Steaming and flaming effects on both parameters were described by logistic curves. The highest doses of steaming and flaming almost completely desiccated cool-season turf, and similar hybrid bermudagrass cover was established by both the methods as the chemical application (50% to 60%). Thus both flaming and steaming may be considered as valid alternatives to herbicides aimed at turf conversion.

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Marco Schiavon, Brent D. Barnes, David A. Shaw, J. Michael Henry, and James H. Baird

Replacing cool-season turf with more drought and heat tolerant warm-season turfgrass species is a viable water conservation strategy in climates where water resources and precipitation are limited. Field studies were conducted in Riverside and Irvine, CA, to investigate three methods (scalping, eradication with a nonselective herbicide, planting into existing turf) of converting an existing tall fescue (Festuca arundinacea) sward to warm-season turf. Cultivars established vegetatively by plugging were ‘De Anza’ hybrid zoysiagrass [Zoysia matrella × (Z. japonica × Z. tenuifolia)], ‘Palmetto’ st. augustinegrass (Stenotaphrum secundatum), ‘Tifsport’ hybrid bermudagrass (Cynodon dactylon × C. transvaalensis), ‘Sea Spray’ seashore paspalum (Paspalum vaginatum), and ‘UC Verde’ buffalograss (Buchloe dactyloides). Cultivars established from seeds were ‘Princess-77’ bermudagrass (C. dactylon) and ‘Sea Spray’ seashore paspalum. Neither scalping nor planting into existing tall fescue were effective conversion strategies, as none of the warm-season turfgrasses reached 50% groundcover within 1 year of planting. All of the species except for st. augustinegrass reached a higher percentage of groundcover at the end of the study when glyphosate herbicide was applied to tall fescue before propagation compared with the other conversion strategies. Bermudagrass and seashore paspalum established from seeds and hybrid bermudagrass from plugs provided the best overall establishment with 97%, 93%, and 85% groundcover, respectively, when glyphosate was used before establishment. Quality of seeded cultivars matched or exceeded that of cultivars established vegetatively by plugging. These results suggest that eradication of tall fescue turf followed by establishment of warm-season turf from seeds is the best and easiest turf conversion strategy.

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Filippo Lulli, Claudia de Bertoldi, Roberto Armeni, Lorenzo Guglielminetti, and Marco Volterrani

Synthetic sports surfaces are increasingly subject to standardization of athlete-surface and ball-surface interactions (playability parameters). Such standardizations have led to an increase in the level of the engineering and predictability of these surfaces, and as such may be beneficial also for natural turf. In warm and temperate climates, many natural turf sports surfaces are established with warm-season (C4) turfgrass species due to their suitability to the environment in such areas. This study was aimed at evaluating the Féderation Internationale de Football Association (FIFA)-standard playing characteristics of different sports turf surfaces obtained from three commonly used C4 turfgrass species: 1) ‘Tifway 419’ hybrid bermudagrass (Cynodon dactylon var. dactylon × C. transvaalensis), 2) ‘Zeon’ manilagrass (Zoysia matrella), and 3) ‘Salam’ seashore paspalum (Paspalum vaginatum) for factors concerning leaf tissue (silica, lignin, water content) and canopy structure (shoot density, leaf architecture, stolon density, etc.). Results showed that surfaces of different C4 turfgrass species generate different playability parameters, with seashore paspalum being a harder faster surface, manilagrass being a softer slower surface, and hybrid bermudagrass showing intermediate characteristics. These playing quality results were associated with certain specific canopy biometrical/morphological parameters such as shoot density, horizontal stem density (HSD), leaf section, and, to a lesser extent, to certain plant tissue compounds (lignin, silica).

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Shawn Brewer and Michael Maurer

Transition of perennial ryegrass from bermudagrass athletic fields in the spring delays the establishment of bermudagrass when the establishment period is limited. The objective of this field study was to determine the effects of transition herbicides on the establishment of seeded bermudagrass. Treatments consisted of an untreated control, foramsulfuron, rimsulfuron, trifloxysulfuron sodium, metsulfuron methyl methyl, isoxaban, and oxadiazon at low- and high-labeled rates for transitioning perennial ryegrass. `Riviera' bermudagrass [Cynodon dactylon (L.) Pers.] seed was seeded immediately after treatment and 2 weeks after treatment. Turfgrass coverage was evaluated visually and by digital analysis. Although differences between methods of turfgrass coverage evaluation varied, the differences between treat-ments were similar. There was no significant differences in turfgrass establishment between foramsulfuron, rimsulfuron, trifloxysulfuron sodium, metsulfuron methyl methyl, and the control for either seeding date or rate. Turfgrass coverage was significantly less for isoxaban and no turfgrass was established in the oxadiazon treatments. Initial results of this research indicate that bermudagrass seed can be seeded immediately following the application of foramsulfuron, rimsulfuron, trifloxysulfuron sodium, and metsulfuron methyl methyl.

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Lambert B. McCarty, Raymond K. McCauley, Haibo Liu, F. Wesley Totten, and Joe E. Toler

Overseeded perennial ryegrass (Lolium perenne L.) aggressively competes with bermudagrass [Cynodon dactylon (L.) Pers.] for resources and may adversely affect spring transition by releasing allelochemicals into the environment. Growth chamber studies examined germination and growth of ‘Arizona Common’ bermudagrass in soil amended with 0%, 2%, 12%, or 23% perennial ryegrass root or shoot debris or in soil treated with irrigation water in which perennial ryegrass roots at 0, 5, 10, or 20 g·L−1 or shoots at 0, 10, or 20 g·L−1 had been soaked. Inhibitory effects on bermudagrass germination and growth were most extensive when soil was amended with ryegrass shoot debris, because germination, root ash weight, root length density, and root mass density were reduced 33%, 55%, 30%, and 52%, respectively. Soil amended with ryegrass root debris only inhibited bermudagrass-specific root length. Application of irrigation water containing either ryegrass root or shoot extracts only inhibited bermudagrass-specific root length. In conclusion, results obtained when soil was amended with shoot debris demonstrated perennial ryegrass can inhibit bermudagrass germination and growth in controlled environments.

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G.E. Bell, B.M. Howell, G.V. Johnson, W.R. Raun, J.B. Solie, and M.L. Stone

Differences in soil microenvironment affect the availability of N in small areas of large turfgrass stands. Optical sensing may provide a method for assessing plant N needs among these small areas and could help improve turfgrass uniformity. The purpose of this study was to determine if optical sensing was useful for measuring turfgrass responses stimulated by N fertilization. Areas of `U3' bermudagrass [Cynodon dactylon (L.) Pers.], `Midfield' bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt-Davy], and `SR1020' creeping bentgrass (Agrostis palustris Huds.) were divided into randomized complete blocks and fertilized with different N rates. A spectrometer was used to measure energy reflected from the turfgrass within the experimental units at 350 to1100 nm wavelengths. This spectral information was used to calculate normalized difference vegetation index (NDVI) and green normalized difference vegetation index (GNDVI). These spectral indices were regressed with tissue N and chlorophyll content determined from turfgrass clippings collected immediately following optical sensing. The coefficients of determination for NDVI and GNDVI regressed with tissue N averaged r 2 = 0.76 and r2 = 0.81, respectively. The coefficients of determination for NDVI and GNDVI regressed with chlorophyll averaged r 2 = 0.70 and r 2 = 0.75, respectively. Optical sensing was equally effective for estimating turfgrass responses to N fertilization as more commonly used evaluations such as shoot growth rate (SGR regressed with tissue N; r 2 = 0.81) and visual color evaluation (color regressed with chlorophyll; r 2 = 0.64).

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Monica L. Elliott, Robert B. Hickman, and Mark Hopkins

Type 1 (necrotic) fairy rings in turfgrass result in dead or badly damaged grass. This type of fairy ring is a severe problem on golf course greens as they interfere with the aesthetics and playability of the putting surface. In Florida, Lycoperdon spp., basidiomycetes that produce puffball mushrooms, have been implicated as a common cause of Type 1 fairy rings on hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) putting greens. The fungicide flutolanil has basidiomycetes as the sole fungal target. It is also the only carboxin-related fungicide registered for use on turfgrass. Two experiments were conducted to examine the effect of flutolanil as a curative and preventive treatment for fairy ring caused by Lycoperdon. One experiment, established after the rings were present, determined that flutolanil significantly reduced mushroom production. The second experiment was conducted on a golf course that had experienced Type 1 fairy rings previously. One-half of each of nine putting greens was treated with flutolanil on a preventive basis. The other half of each green served as an untreated control. Type 1 fairy rings, due to Lycoperdon, developed only on the untreated control half of each green. These experiments confirm that flutolanil does have curative and preventive activity against Lycoperdon spp. that cause Type 1 fairy rings.