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  • Author or Editor: J.H. Dunn x
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Abstract

Zoysia japonica ‘Meyer’, is frequently used as lawn and golf turf in the upper South because of its excellent summer qualities and superior winter hardiness compared to other warm-season grasses. Planting is mostly by vegetative methods to obtain uniform turf. Planting in existing turf slows spread of zoysiagrass because of plant competition. The objective of this study was to selectively inhibit growth, with growth retardants, of competing Kentucky bluegrass, Poa pratensis L. ‘Baron’, turf into which ‘Meyer’ zoysia had been planted. Mefluidide, at a rate of 0.028 kg/ha, enhanced the spread of zoysiagrass in bluegrass by 20% compared with untreated plots during the 1st year, without serious injury to the bluegrass turf. Fertilizing zoysiagrass plugs with UF (38N-0-0) also increased zoysiagrass cover by 10-20% during the 1st 2 years compared with control plots or those fertilized with urea after zoysiagrass had been transplanted. Irrigation location had no effect on zoysiagrass spread, possibly because of the relatively mild and wet summers of 1981-82 when minimal irrigation was needed to maintain good quality turf. Results of this study show that growth retardants in combination with certain N fertilization techniques can enhance the spread of transplanted zoysiagrass without serious injury to the existing bluegrass sward. This is attributed to selectively decreased growth of bluegrass and, therefore, partial elimination of bluegrass competition from the bluegrass or, to possible stimulation of zoysiagrass by mefluidide.

Open Access

Abstract

Carbohydrate content varied among cultivars of bermudagrass (Cynodon dactylon L.) at 3 sampling dates during dormancy and greenup. Sucrose and starch decreased in rhizomes between March and May while reducing sugars remained constant. Concentration of stored carbohydrate was correlated positively with the number of rhizomes near the soil surface during winter and early spring. Spring deadspot injury ranged from 60% of the plot area for ‘KSU, (Kansas State University) T-5, to zero for ‘Royal Cape’, ‘Mich. C-53’, ‘Midway’ and ‘KSU D-17.’ Earliest to greenup in spring was ‘KSU T-3’ while ‘KSU T-5’, ‘F-4’, ‘Md. 23’, ‘24’ and ‘U-3’ were only 13-33% green on the same date. Injury was less severe where cultivars utilized carbohydrate and greened early in the spring. Early greenup was associated with thinner layers of thatch. There was no association between thickness or number of rhizomes and spring deadspot.

Open Access

Abstract

This study was conducted to determine root distribution, soil moisture depletion, and 32P uptake, as an indicator of water absorption, by Kentucky bluegrass (Poa pratensis L. ‘Fylking’), perennial ryegrass (Lolium perenne L. ‘Manhattan’), and tall fescue (Festuca arundinacea Schreb. ‘Kentucky 31’). 32P was injected at 6, 18, 30, 42, and 54 cm from the soil surface under each turfgrass plot on 18 July 1978. Leaf blade radioactivity revealed differences in uptake among species, but was inconsistent with rooting patterns. Root mass measurements below 36 cm in late August showed tall fescue > perennial ryegrass > Kentucky bluegrass. Root mass above 12 cm showed Kentucky bluegrass > tall fescue = perennial ryegrass. Soil water content (SWC) at three depths in August reflected root distribution for the three species. SWC was lowest under Kentucky bluegrass and highest under tall fescue at 6 cm. At 54 and 78 cm, SWC was highest under Kentucky bluegrass and lowest under tall fescue. SWC was better than 32P injection for detecting species differences in water uptake.

Open Access

'Meyer' zoysiagrass (Zoysia japonica Steud.) is a popular turfgrass species for transition zone golf course fairways and tees because it is generally winter hardy while providing an excellent playing surface with minimal chemical and irrigation inputs. However, its functionality declines readily on many of the shaded areas on these courses. Reduced irradiance causes excessive shoot elongation, reduced tillering, and weak plants that are poorly suited to tolerate or recover from traffic and divoting. Trinexapac-ethyl (TE) effectively reduces gibberellic acid (GA) biosynthesis and subsequent shoot cell elongation. The objective of this study was to determine if monthly applications of TE would reduce shoot elongation of 'Meyer' zoysiagrass and improve stand persistence under two levels of shade. Shade structures were constructed in the field that continuously restricted 77% and 89% irradiance. A mature stand of 'Meyer' was treated with all combinations of three levels of shade (0%, 77%, and 89%) and three levels of monthly TE application [0, 48 g·ha-1 a.i. (0.5×), and 96 g·ha-1 a.i. (1×)] in 1998 and 1999. In full sun, the 0.5×-rate reduced clipping production by 17% to 20% over a four-week period and the 1×-rate by 30% to 37%. Monthly application of TE at the 1×-rate increased 'Meyer' tiller density in full sun and under 77% shade. Both rates of TE consistently reduced shoot growth under shade relative to the shaded control. Only the monthly applications at the 1×-rate consistently delayed loss of quality under 77% shade. The zoysiagrass persisted very poorly under 89% shade whether treated or not with TE and plots were mostly dead at the end of the experiment. Our results indicate TE can be an effective management practice to increase 'Meyer' zoysiagrass persistence in shaded environments. Chemical name used: 4-cyclopropyl-α-hydroxy-methylene-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl)

Free access

We evaluated the effect of fertilization treatments in combination with clippings disposal on perennial ryegrass (Lolium perenne L.) in two adjacent locations. Clippings left on turf during mowing decreased dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in both locations during three summers compared with clippings removed in mower baskets. However, brown patch (Rhizoctonia solani Kuhn) increased during July and Aug. 1995 when clippings were left on turf. Dollar spot was more severe with N (kg·ha–1·year–1) at 120 compared to 240; brown patch was more severe at 240. While clippings disposal had significant effects on disease incidence, implementation may not be practical because of the contrary responses of the observed diseases to this management approach.

Free access

Rhizomes of zoysiagrass (Zoysia spp.) were subjected to controlled freezing tests in Jan. and Mar. 1993 and 1994 to determine their low-temperature tolerance. In 1994, `Belair', `Korean `Common', `Meyer', and `TGS-W10' rhizomes survived temperatures as low as -18 °C, while rhizomes of `Sunburst' survived -14 °C. `Cavalier', `Crowne', `Palisades', `Emerald', and `El Toro' were killed at -10 °C or warmer temperatures. Entries surviving exposure to -14 to -18 °C in 1994 controlled freezing tests received post-winter survival ratings in the field of 6.7 to 8.7 (9 = 100% green). Entries killed at higher freezing test temperatures were slower to recover after winter in the field, with ratings of 2.0 to 3.0. Shoot number produced after freezing was a better measurement for assessing low temperature tolerance than was shoot mass. Controlled freezing tests, using regrowth as a measure of hardiness, appear to be useful for identifying low temperature tolerance of zoysiagrasses in the early years of a field study.

Free access