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Y.L. Qian and M.C. Engelke

Determining the appropriate level of irrigation for turfgrasses is vital to the health of the turfgrass and the conservation of water. The linear gradient irrigation system (LGIS) allows long-term assessment of turf performance under continuous irrigation gradients from excess to no irrigation. The objectives of this study were to: 1) evaluate the minimum irrigation requirements and relative drought resistance of `Rebel II' tall fescue (Festuca arundinacea Schreb.), `Meyer' zoysiagrass (Zoysia japonica Steud.), `Tifway' bermudagrass [Cynodon dactylon (L.) Pers.], `Prairie' buffalograss [Buchloe dactyloides (Nutt.) Engelm], and `Nortam' St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze]; and 2) evaluate the long-term effects of irrigation levels on turf persistence, weed invasion, and disease incidence for the five selected turfgrasses under field conditions. Turf was sodded under LGIS with an irrigation gradient ranging from 120% Class A pan evaporation (Ep) to natural precipitation, along a 20-m turf area. Evaluation during the summers of 1993–96 indicated that grasses differed in drought resistance and persistence under variable irrigation regimes. Irrigation (Ep) required to maintain acceptable turf quality for respective grasses was `Rebel II' (67%), `Meyer' (68%), `Nortam' (44%), `Tifway' (35%), and `Prairie' (26%). Higher dollar spot (Sclerotinia homoeocarpa Bennett) infection was observed at 115% Ep irrigation regime in `Tifway' bermudagrass, whereas gray leaf spot [Pyricularia grisea (Hebert) Barr] was observed only at 10% Ep irrigation regime in St. Augustinegrass plots. An outbreak of brown patch (Rhizoctonia solani Kuehn.) occurred in Sept. 1996 in St. Augustinegrass plots receiving irrigation at >80% Ep.

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A.R. Mazur and J.S. Rice

Research was conducted to determine the influence of the rate of seeding perennial ryegrass (Lolium perenne L.) over bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt-Davy] on both the establishment of the ryegrass and the quality of bermudagrass golf greens. Increasing seeding rate from 90 to 180 g·m–2 resulted in more rapid establishment and a linear increase in turf quality. Turf density, as measured by leaf number, displayed linear and quadratic responses to seeding rates, with higher rates producing the greatest leaf numbers. Leaf width declined linearly with seeding rate, suggesting higher putting quality, as did tillers per plant. Spring transition to bermudagrass was slowed at high (150–180 g·m–2) seeding rates, with significantly more ryegrass present in late May. Emergence and growth of bermudagrass were suppressed longer at the higher overseeding rates. We conclude that the choice of seeding rate for ryegrass is a compromise between rapid development of, and maintenance of, quality turf vs. early smooth transition to bermudagrass in the spring.

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Michael T. Deaton and David W. Williams

The use of seeded bermudagrasses (Cynodon dactylon) is increasing as athletic field and golf course turf. Anecdotal evidence indicates probable and important differences in germination rates among cultivars when established in late spring or early summer. Germination studies were completed in May 2011 in the Turfgrass Science Laboratory at the University of Kentucky on 19 commercially available seeded bermudagrass cultivars. Evaluations for germination rate and total germination under varying temperature regimes representing 20-year average day/night temperatures for seeding times from 15 May to 1 Aug. were conducted to quantify any differences in germination characteristics among cultivars as affected by temperature. There were highly significant differences (P < 0.0001) among cultivars in germination rate and total germination when grown under 20-year average day/night temperatures. The cultivars Casino Royale and Riviera consistently represented the fastest/slowest to germinate and highest/lowest total seeds germinated across all temperature regimes, respectively. Significant differences (P < 0.0001) were also observed within cultivars for total germination across the temperature regimes tested. The average temperatures of 15 May and 1 Aug. represented slowest/fastest to germinate and lowest/highest total seeds germinated across all temperature regimes, respectively.

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K.L. Hensler, B.S. Baldwin, and J.M. Goatley Jr.

A bioorganic fiber seeding mat was compared to traditional seeding into a prepared soil to ascertain any advantages or disadvantages in turfgrass establishment between the planting methods. Bahiagrass (Paspalum notatum), bermudagrass (Cynodon dactylon), carpetgrass (Axonopus affinis), centipedegrass (Eremochloa ophiuroides), st. augustinegrass (Stenotaphrum secundatum), and zoysiagrass (Zoysia japonica) were seeded at recommended levels in May 1995 and July 1996. The seeding methods were evaluated under both irrigated and nonirrigated conditions. Plots were periodically rated for percent turf coverage; weed counts were taken about 4 weeks after study initiation. Percent coverage ratings for all grasses tended to be higher for direct-seeded plots under irrigated conditions in both years. Bermudagrass and bahiagrass established rapidly for both planting methods under either irrigated or nonirrigated conditions. Only carpetgrass and zoysiagrass tended to have greater coverage ratings in nonirrigated, mat-seeded plots in both years, although the percent plot coverage ratings never reached the minimum desired level of 80%. In both years, weed counts in mat-seeded plots were lower than in direct-seeded plots. A bioorganic fiber seeding mat is a viable method of establishing warm-season turfgrasses, with its biggest advantage being a reduction in weed population as compared to direct seeding into a prepared soil.

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John M. Kauffman, John C. Sorochan, and Dean A. Kopsell

Thatch-mat and organic matter (OM) accumulation near the putting green soil surface impacts soil physical properties and turf performance. Excessive thatch and OM can encumber infiltration of water and oxygen into the soil profile and slow drainage of excess water away from the putting surface. Proper sampling of thatch-mat depths and OM contents is vital for management of putting green turf; therefore, a study was performed in Knoxville, TN, to derive proper sampling procedures of these important parameters using ‘TifEagle’ and ‘Champion’ bermudagrass (Cynodon dactylon × C. transvaalensis), ‘SeaDwarf’ seashore paspalum (Paspalum vaginatum), and ‘Diamond’ zoysiagrass (Zoysia matrella). ‘TifEagle’ and ‘Champion’ accumulated thatch-mat to a greater depth than ‘SeaDwarf’ and ‘Diamond’. However, ‘SeaDwarf’ had a higher OM content than ‘Diamond’ and both had higher OM contents than ‘TifEagle’ and ‘Champion’. Data generated from sampling procedures indicate that previous studies often undersampled plots for thatch-mat depth; however, previous sampling procedures have not traditionally undersampled plots for OM. Data in this study provide a range of confidence and minimum detectable difference levels which may allow future researchers to more accurately sample ‘TifEagle’, ‘Champion’, ‘SeaDwarf’, and ‘Diamond’ putting green plots for thatch-mat depth and OM content.

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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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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.

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George E. Boyhan, Ray Hicks, and C. Randell Hill

This study was undertaken to evaluate natural mulches for weed control in organic onion (Allium cepa) production where current practices rely on hand-weeding or plastic mulch. Three experiments were conducted over 2 years, with two experiments conducted on-farm in different years and one experiment conducted on-station. Treatments consisted of hand-weeding or mulches of wheat (Triticum aestivum) or oat (Avena sativa) straw, bermudagrass hay (Cynodon dactylon), compost, and needles of slash pine (Pinus elliottii) and longleaf pine (P. palustris). All of the mulches with the exception of compost tended to lodge in the onion tops due to their close spacing. Wheat straw and bermudagrass hay reduced plant stand and yield. Compost settled well around the onion plants and initially smothered weeds, but over time the compost treatment became very weedy. Pine needle mulch (referred to as pine straw in the southeastern U.S.) showed the most promise with less stand loss or yield reduction, but did tend to lodge in the tops. None of these mulches were acceptable compared to hand-weeding.

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Gokhan Hacisalihoglu

Many warm-season turfgrass seeds have relatively poor germination percentages. Matriconditioning is a seed enhancement technique with a solid carrier and may be a practical solution to improve the germination characteristics of warm-season turfgrass. The objective of this study was to determine the effectiveness of matriconditioning on three nonaged and aged turfgrass cultivars: ‘Pensacola’ bahiagrass (Paspalum notatum), ‘Princess’ bermudagrass (Cynodon dactylon), and ‘Common’ centipedegrass (Eremochloa ophiuroides). Seeds were matriconditioned with a synthetic calcium silicate (MicroCel E) as a carrier and water at 30 °C for 5 days. Seed, carrier, and water ratio was 1 g, 0.5 g, and 1.5 mL, respectively. Matriconditioning increased final germination to 55% (bahiagrass), 90% (bermudagrass), and 70% (centipedegrass) compared with 92% in nontreated control seeds. Furthermore, matriconditioning decreased mean germination time 20% to 65% in all seeds compared with the nontreated control. Accelerated aging was induced by storing seeds for 0, 7, and 14 days at 42 °C and 95% relative humidity. Germination percentage decreased and mean germination time increased with the aging, especially after 14 days of aging treatment. These results suggest that matriconditioning is an effective technique to improve turfgrass seed performance.

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Warren Roberts, James Shrefler, James Duthie, Jonathan Edelson, Bob Cartwright, and Nancy Roe

We conducted several experiments to determine the best system for production of spring cabbage (Brassica oleracea L. Capitata group) with conservation tillage (CT) in the southern plains of the United States. Rye (Secale cereale L.) was selected as the best cover crop to cover the soil in a short time. Raised beds were formed in the fall and planted with rye. With most studies, the rye was allowed to remain on the soil surface rather than being tilled into the soil. Planting densities, rates of nitrogen fertilizer, and herbicide materials were evaluated to determine the best system for cabbage production. In each study, various cover crop practices were compared with bare soil production systems. Soil erosion was reduced by the use of rye cover crops. Cabbage was produced in the CT system, but cabbage yields were higher in bare soil plots than in the rye-covered plots. We are also in the process of developing a system of CT that involves permanent bermudagrass [Cynodon dactylon (L.) Pers.] pastures and watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. This system allows both crops to be grown simultaneously on the same land.