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  • Author or Editor: Marco Schiavon x
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A study was conducted at New Mexico State University in Las Cruces, NM, in 2009 and 2010 to investigate the establishment of five turfgrass species {‘Barrister’ kentucky bluegrass [Poa pratensis L.], ‘Barvado’ tall fescue [Festuca arundinacea Schreb.], ‘Premier II’ perennial ryegrass [Lolium perenne L.], ‘Bargusto’ bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon. transvalensis Burtt-Davy], and ‘Sea Spray’ seashore paspalum [Paspalum vaginatum O. Swartz]} from coated and uncoated seed. The grasses were irrigated at 100% reference evapotranspiration (ET0) during fall, winter, and spring and at 120% ET0 during summer with either saline [electrical conductivity (EC) = 2.3 dS·m−1] or potable water (EC = 0.6 dS·m−1). Generally, seed coating did not affect seedling emergence negatively when irrigated with saline water. During fall, perennial ryegrass exhibited fastest emergence under both saline and potable irrigation and bermudagrass was the only grass to show greater emergence when irrigated with saline water. Perennial ryegrass and tall fescue were the fastest to emerge in spring, regardless of seed coating or water quality. Seed coating delayed early establishment (less than 50% coverage) but did not affect days to reach 95% coverage (DAS95). Bermudagrass and seashore paspalum required the most DAS95 when seeded in the fall; however, bermudagrass needed fewest DAS95 when seeded in the spring. All grasses established faster when seeded in spring compared with fall. Fall-seeded perennial ryegrass and kentucky bluegrass required similar DAS95, whereas kentucky bluegrass seeded in spring was slower to reach 95% coverage than perennial ryegrass. Saline water had no effect on establishment when grasses were sown in fall. Surprisingly, grasses established in spring and irrigated with saline water reached 95% coverage 26 days faster than plots irrigated with potable water. Moreover, the growing degree-day model used in this study did not produce similar values for the different air temperatures and irrigation water qualities.

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Germination of five turfgrass species [‘Barrister’ kentucky bluegrass (Poa pratensis L.), ‘Barvado’ tall fescue (Festuca arundinacea Schreb.), ‘Premier II’ perennial ryegrass (Lolium perenne L.), ‘Bargusto’ bermudagrass (Cynodon dactylon L. Pers.), and ‘Sea Spray’ seashore paspalum (Paspalum vaginatum O. Swartz)] from coated (ZEBA® cornstarch coating; Absorbent Technologies Inc., Beaverton, OR) and uncoated seeds was evaluated on both filter paper and agar. Final germination percentage (FGP) and germination rate (GR) were determined at salinity levels of 0.6 (tap water, control), 2.2 (saline groundwater from a local shallow aquifer), and 7.0, 12.5, and 22.5 dS·m−1 [sodium chloride and calcium chloride (1:1, w:w) dissolved in tap water]. Final germination percentage for kentucky bluegrass, perennial ryegrass, and tall fescue was greater in agar at all salinity levels but was unaffected by the medium at any of the salinities except for 7 dS·m−1 for bermudagrass and seashore paspalum. Coated seashore paspalum and coated perennial ryegrass seed exhibited greater germination than uncoated seed at four of the five salinity levels. Seed coating had no effect on FGP of bermudagrass at any salinity level and coated kentucky bluegrass seed showed reduced germination at 0.6 and 7.0 dS·m−1. Final germination percentage for seashore paspalum improved from 22% to 54% at 12.5 dS·m−1 and from 8% to 20% at 22.5 dS·m−1 when coated seed was used instead of uncoated seed. Germination rates were unaffected by salinity levels ranging from 0.6 to 12.5 dS·m−1 and were higher on agar (10%/day) than on paper (8%/day). Our study suggests that the choice of medium can influence the outcome of germination tests and that results can also vary depending on the salinity level tested and whether the seed are coated.

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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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Golf courses in coastal regions of northern California are often faced with severe injury caused by pacific shoot-gall nematodes (Anguina pacificae) on their annual bluegrass (Poa annua) host in putting greens. For years, fenamiphos was used for mitigating disease outbreaks until its registration was withdrawn in 2008. An alternative product containing azadirachtin was intended for nematode suppression. Still, it required repeated applications throughout the year with questionable efficacy, making attempts to lessen the impact of the pathogen costly. This study evaluated fluopyram as a novel nematicide for control of pacific shoot-gall disease. Various application frequencies and rates were tested at several golf courses affected by the nematode. Results revealed that fluopyram applied once at 0.22 lb/acre reduced the number of new shoot-galls and improved annual bluegrass appearance for several months. Increased rates and application frequency occasionally improved the efficacy further. Although the visual quality of turf treated with this plant protection compound was tremendously enhanced, and the number of new shoot-galls was reduced, rarely a significant effect was observed on the population density of several soil-dwelling plant-parasitic nematodes, including pacific shoot-gall nematode. It is hypothesized that fluopyram did not move significantly past the thatch layer and into the soil. However, it effectively reduced the ability of pacific shoot-gall nematode juveniles to induce new shoot galls. Due to its long half-life, it likely protected against both new nematode infections and dissemination of pacific shoot-gall nematode when the shoot-galls decomposed.

Open Access