Golf Course Management

DEC 2012

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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research A. Two fungicides/two rates — one application Untreated control Bayleton 50DF (1 ounce/1,000 square feet) Bayleton 50DF (2 ounces/1,000 square feet) Tebuconazole (0.26 ounce/1,000 square feet) Tebuconazole (0.49 ounce/1,000 square feet) 400 350 300 250 200 150 100 50 0 2007 2008 2009 a A B. Soil temperature 50 F 55 F 60 F ab B B b b b B B 400 350 300 250 200 150 100 50 0 2007 2008 2009 Figure 1. A, Area under disease progress curve (AUDPC) with two fungicides (Bayleton and Tebuconazole), each applied once during the spring at two different rates over three years (2007-2009). B, AUDPC with fungicides applied at six different soil temperatures in three years. AUDPC = Area Under the Disease Progress Curve: a measure of the total fairy ring occurrence from May to September. In the same year, bars with the same letter are not significantly different from one another. Bars without letters indicate no significant differences within that year. and the high rate of Bayleton 50DF had lower dis- ease severity in 2007 and 2008 compared with the untreated control (Figure 1). The low rate of Bayleton 50DF reduced disease severity in both years but was not statistically different from the control in 2007. AUDPC values tended to be lower in plots sprayed at the 55 F and 60 F soil temperature thresholds, but were not statistically different from any other application timing. Field experiment 2: surfactant tank mix and irrigation timing Plots treated with two low-rate applications of Bayleton FLO or Triton 70WG had signifi- cantly lower AUDPC values than the untreated controls in both 2008 and 2009, and the onset of symptoms was significantly delayed in 2008. No differences were detected in the level of control afforded by either fungicide. Irrigation timing did not affect the efficacy of fungicide applications in either year (Figure 2). Although the differences were not statistically Fairy ring control on June 22, 2007, afforded by Bayleton 50DF applied at 65 F soil temperature threshold in the spring. The yellow line separates treated and untreated plots. Top: The plot to the right of the yellow line was sprayed with Bayleton at 2 ounces/1,000 square feet. Bottom: The plot to the left of the yellow line was sprayed with Bayleton at 1 ounce/1,000 square feet. significant in either year, AUDPC values were higher in plots that received a fungicide + sur- factant tank mix as opposed to fungicide alone (Figure 3). In 2009, fairy ring symptoms were observed significantly earlier in plots treated with a fungicide + surfactant tank mix than in plots that received only a fungicide. Because symptoms of localized dry spot developed in both years, plots not treated with a surfactant had signifi- cantly lower turf quality than plots that received a surfactant. 78 GCM December 2012 65 F 70 F 75 F a b b b b b AUDPC AUDPC

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