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  • Author or Editor: Bernd Leinauer x
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A field experiment was conducted at New Mexico State University to investigate the effect of seeding rates and ZEBA polymer [starch-g-poly (2-propenamide-co-propenoic acid) potassium salt] seed coating on the germination and establishment of warm- and cool-season grasses, and cool-season blends and mixtures. Grasses were established at recommended and reduced (50% of recommended) seeding rates with coated and uncoated seeds under two irrigation regimes (98% and 56% reference evapotranspiration). With the exception of ‘Bengal’ creeping bentgrass (Agrostis stolonifera), the polymer coating did not improve germination of the turfgrasses tested 22 days after seeding (DAS). However, at the end of the establishment period (92 DAS), plots established with ‘Bengal’, Dunes Mix [mixture of ‘Hardtop’ hard fescue (Festuca longifolia), ‘Baron’ kentucky bluegrass (Poa pratensis), ‘Barok’ sheep fescue (Festuca ovina)], ‘Panama’ bermudagrass (Cynodon dactylon), and Turf Sense™ [mixture of ‘Baronie’ kentucky bluegrass, ‘Barlennium’ perennial ryegrass (Lolium perenne), and ‘Barcampsia’ tufted hairgrass (Deschampsia cespitosa)] achieved greater coverage (based on visual estimations) when coated seed was used compared with uncoated seed. Establishment was greater for ‘Bengal’, Dunes Mix, ‘Panama’, Turf Sense™, and Turf Saver™ [blend of ‘Barlexas II’, ‘Barrington’, and ‘Labarinth’ tall fescue (Festuca arundinacea)] when normal seeding rates were applied compared with reduced seeding rates. ‘Barleria’ crested hairgrass (Koeleria macrantha) plots did not establish, regardless of the treatments applied. Results showed that seed coating has the potential to improve establishment at recommended and reduced seeding rates and can compensate for less favorable conditions such as reduced irrigation, reduced seeding rate, or for a combination of both. At the end of the establishment period, not all grasses achieved coverage greater than 50%. Further research over a longer establishment period is needed to determine if coated seed can be beneficial in achieving full coverage.

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In transitional environments, turf managers and sod producers of warm-season grasses face the issue of winter annual weeds that can dominate dormant turf stands through the winter until late spring. The use of glyphosate to control weeds in dormant bermudagrass (Cynodon dactylon) has been well documented, but information is lacking about its effect on spring green-up of other warm-season grasses. A field study was conducted on two commercial sod farms in northern Italy (Expt. 1) to evaluate the effects of glyphosate applied on two different winter dates on weed control and spring green-up of ‘Zeon’ manilagrass (Zoysia matrella). A second study was carried out at the experimental agricultural farm of Padova University (Expt. 2) to assess the effects of a winter application of glyphosate on weed control and spring green-up of ‘Yukon’ bermudagrass and ‘Companion’ zoysiagrass (Zoysia japonica). Each experiment was conducted from Jan. to June 2011, and glyphosate was applied at 1.1 kg·ha−1 on 8 and 21 Feb. in Expt. 1 and on 8 Feb. in Expt. 2. Spring recovery was evaluated by periodical visual ratings of green turf cover and by collecting normalized difference vegetation indices (NDVIs). Weed injury was visually evaluated on all plots 7 weeks after the 8 Feb. glyphosate application. The visual ratings of green cover were strongly and positively correlated with NDVI measurements. Glyphosate applied in February as a single treatment effectively controlled winter weeds in ‘Zeon’ manilagrass (Expt. 1) and ‘Yukon’ bermudagrass (Expt. 2) without negatively affecting spring green-up. In contrast, spring green-up of ‘Companion’ zoysiagrass (Expt. 2) was delayed by the application of glyphosate.

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Turfgrass water conservation has become important in many parts of the world, including the transition zones of Mediterranean Europe. Species selection is considered one of the most important factors influencing turfgrass water use, and drought-tolerant cool-season species are encouraged to be used in areas where long dormancy periods of warm-season grasses is unacceptable. A field study was conducted from Mar. 2007 to Sept. 2009 at Padova University, Italy, to evaluate establishment and performance of nine turfgrass cultivars under reduced-input maintenance. The study included hybrid bluegrass (Poa pratensis × P. arachnifera) cultivars Solar Green, Thermal Blue, and Thermal Blue Blaze; kentucky bluegrass (Poa pratensis) cultivars Cocktail, Cynthia, and Geronimo; and tall fescue (Festuca arundinacea) cultivars Apache, Murray, and Regiment. Establishment rate was assessed after two seeding dates (20 Mar. and 20 Sept.), and grasses were subsequently fertilized with 15 g·m−2 nitrogen per year and irrigated once every 2 weeks at 40% of reference evapotranspiration from June to August. Turfgrass and weed cover were estimated 60 days after seeding (DAS), and turf quality was evaluated weekly on a scale of 1 (worst) to 9 (best). Normalized difference vegetation index (NDVI) was measured weekly during 2009. Tall fescue cultivars exhibited greater quality than hybrid bluegrass or kentucky bluegrass, under both spring and autumn seeding. Hybrid bluegrass had similar quality to kentucky bluegrass cultivars, although they performed well only when sown in autumn. Our results suggest that among the tested grasses, tall fescue performed better under the reduced irrigation in a Mediterranean transition zone climate than kentucky bluegrass or hybrid bluegrass.

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Winter dormancy is the main impediment to a wide acceptance of warm-season turfgrasses in the Mediterranean countries of Europe due to a loss of color during the winter months. Scalping during late winter or early spring has been recommended anecdotally to enhance spring green-up of bermudagrass (Cynodon dactylon); however, information is lacking on the effectiveness of this practice. A study was conducted to investigate the effects of spring scalping on spring green-up of eight bermudagrass cultivars (Barbados, Contessa, La Paloma, Mohawk, NuMex Sahara, Princess-77, SR 9554, and Yukon) grown in a transition zone environment. The trial was carried out in Spring of 2009 and 2010 on plots established in July 2005 at the experimental farm of the University of Padova (northeastern Italy). Half of the plots for each cultivar were subjected to spring scalping, which was applied in both years on 13 Mar. with a rotary mower set at a height of 28 mm. Soil temperatures were recorded hourly during the research period at a depth of 2.5 cm. The percentage of green cover was estimated weekly from 0 to 98 days after spring scalping (DASS). Soil temperatures in scalped plots were greater than in unscalped plots. Among the cultivars tested, ‘Yukon’ showed earliest spring green-up, with no difference between the scalping treatments, reaching 80% green cover by the end of April. For all other cultivars, scalped plots reached 80% green cover 10 to 18 days earlier than unscalped plots. Results showed that scalping enhanced spring green-up, primarily for cultivars that recover slowly from winter dormancy.

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Warm-season grasses are not widely accepted in Mediterranean countries because they lose color during the winter months. A study was conducted at the University of Padova (Padova, Italy) to determine whether fall and spring water-soluble carbohydrate (WSC) content in stolons of seeded bermudagrass cultivars (Cynodon dactylon) influenced spring green-up in the first year of establishment. Nine bermudagrass cultivars (La Paloma, Mohawk, NuMex Sahara, Princess 77, Riviera, SR 9554, Barbados, Contessa, and Yukon) were seeded in July 2005, and dry weight and WSC content in stolons were measured in Fall 2005 and again in Spring 2006. The percentage of green cover and days needed to achieve 80% green cover (D80) were regressed against November and March values of stolon dry weight and WSC content to determine if they were good predictors of D80. ‘Yukon’ showed earliest spring green-up by end of April, and ‘Princess 77’ and ‘Riviera’ were slowest, needing 43 to 46 days more than ‘Yukon’ to reach D80. There was a significant inverse relationship between November (r2 = 0.57) and March (r2 = 0.77) WSC content in stolons and D80 for all nine bermudagrass cultivars. These results suggest that bermudagrass cultivars with high WSC in stolons recover more rapidly from dormancy during establishment than those with low WSC content.

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