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  • Author or Editor: Christian M. Baldwin x
  • HortTechnology x
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With the emergence of glyphosate-tolerant cultivars, identifying management strategies not applicable with older cultivars need to be revisited. Objectives of these research trials were to quantify the growth regulation effects following a glyphosate application and to determine the safety of tank mixing glyphosate with another herbicide, various nitrogen (N) sources, and a plant growth regulator (PGR) on a glyphosate-tolerant perennial ryegrass [PRG (Lolium perenne L.)] cultivar, Replay. In the growth regulation trial, glyphosate was applied at 0 to 1.03 lb/acre, whereas PGRs flurpimidol, trinexapac-ethyl, paclobutrazol, and trinexapac-ethyl + flurpimidol were applied at 0.50, 0.18, 0.37, and 0.09 + 0.22 lb/acre, respectively, on 15 July 2010 and 2 Aug. 2012. In the tank mixing trial, dicamba (0.50 lb/acre), urea (15 lb/acre N), and ammonium sulfate [AMS (15 lb/acre N)] were applied alone or tank mixed with glyphosate at 0 to 0.52 lb/acre. Tank mixing urea with glyphosate had minimal effect on PRG color, while adding AMS consistently improved color at the highest glyphosate rate of 0.52 lb/acre. Twenty days following a glyphosate application, only rates >0.40 lb/acre resulted in significant growth regulation compared with untreated plots. This study indicates that tank mixing glyphosate with another herbicide, a PGR, and various N sources appear safe to the glyphosate-tolerant PRG cultivar. Also, the growth regulating effects of glyphosate applications would serve as an additional benefit to annual bluegrass (Poa annua L.) control reported in previous trials.

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Hollow tine cultivation is a routine practice on golf course putting greens, where the tine entry angle normally is 90°. Effects of various tine entry angles impacting putting green surfaces have not been investigated. The hypothesis was that different tine entry angles during cultivation would impact a greater area of the soil profile by enhancing water infiltration rates, reducing localized dry spots, and enhancing turf quality. Therefore, a 2-year field study in 2003 and 2004 was conducted to determine the impact of core cultivation tine entry angle on `Crenshaw' creeping bentgrass (Agrostis stoloniferous var. palustris). Treatments included three angles of hollow tine entry at 50°, 70°, and 90° and an untreated plot without cultivation. Manual cultivators consisted of four 1/4-inch- and 1/2-inch-diameter hollow tines 3 inches in length, spaced 2 inches apart. Treatment applications were in April, May, September, and October. Measurements included visual turfgrass quality (TQ), molarity ethanol droplet test (MED), and water infiltration. No treatment (control, 50°, 70°, 90°) effects in years I and II for TQ were noted. MED scores in May were 23% higher than in August and September. Tines of 1/2-inch diameter reduced soil hydrophobicity (MED) 6% compared to tines of 1/4-inch-diameter tines. Tines of 50°, 70°, and 90° had 129%, 163%, and 211% greater water infiltration than the untreated, respectively.

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Hybrid bermudagrass [Cynodon dactylon × Cynodon transvaalensis] is frequently used throughout the southern and transitional climatic zones of the United States. These grasses can only be vegetatively propagated, such as by sprigging. Turf managers will often apply high rates of sprigs and nitrogen (N) in an attempt to minimize the time to establishment. However, little is known about how planting and N rates affect establishment. The objective of this study was to determine optimum sprigging and N rates during the establishment of ‘Latitude 36’ hybrid bermudagrass to minimize time to full surface cover. The study was conducted in four locations across the southern United States during Summer 2015. Sprigging rates consisted of 200, 400, 600, and 800 U.S. bushels/acre (9.3 gal/bushel), and N rates were 0, 11, 22, and 44 lb/acre N per week. Results showed that as the N rate increased, percent cover generally increased but only slightly [7% difference between high and low rates 5 weeks after planting (WAP)]. The effect of sprig rate on percent cover indicated that as rate increased, cover also increased. Differences in establishment due to sprig rate were present until 6 WAP at which time all plots achieved 100% cover. The greatest difference between N and sprig rate was that sprig rate showed differences in percent cover immediately, whereas N rate differences were not apparent until 2 WAP. Increasing sprig rather than N rate should be considered to speed up establishment.

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