Golf Course Management

DEC 2013

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 For each run of the experiment, fungicides were applied to plots once at the rates listed in Table 1. Plots were sampled seven times at threeto four-day intervals over a three-week period (days 0, 3, 7, 10, 14, 17 and 21) by removing cup cutter plugs from each replication of each treatment plot. Bioassay experiments were run six times during the growing seasons of 2010 and 2011. Sampled plugs were inoculated with fve grains of white sorghum seed infested with a locally collected isolate of Rhizoctonia solani (the organism that causes brown patch on creeping bentgrass) and then incubated for 48 hours in a growth chamber where relative humidity exceeded 95% and temperature was maintained at 82 F (27.7 C). After the incubation period, the diameter of each 100 A. Azoxystrobin 90 Fungicides tested Fungicide product/ company Application rate (/1,000 square feet) Application rate (pounds a.i./1,000 square feet) Azoxystrobin Heritage TL, Syngenta 2.0 fluid ounces 0.013 Flutolanil ProStar 70 WP, Bayer 2.2 ounces 0.096 Tourney 50 WDG, Valent 0.37 ounce 0.012 Endorse WP, Arysta 4.0 ounces 0.006 Insignia, BASF 0.9 ounce 0.011 Fungicide active ingredient Metconazole Polyoxin D Pyraclostrobin Table 1. Fungicides used in this research included common penetrant compounds applied for brown patch control. Residual effcacy 100 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 3 7 10 14 17 100 21 C. Flutolanil 90 Residual efficacy (%) B. Flutolanil 90 0 0 3 7 10 14 100 80 70 70 60 60 50 50 40 40 30 30 20 20 10 21 D. Metconazole 90 80 17 10 0 0 3 7 10 14 17 100 21 E. Polyoxin D 90 0 0 3 7 10 14 100 80 70 70 60 60 50 50 40 40 30 30 20 20 10 21 F. Pyraclostrobin 90 80 17 10 0 0 3 7 10 14 17 21 0 0 3 7 10 14 17 Figure 1. Residual effcacy (RE) proportions for (A) azoxystrobin; (B) futolanil experiments 1, 2, 5 and 6; (C) futolanil experiments 3 and 4; (D) metconazole; (E) polyoxin D; and (F) pyraclostrobin. Data were ft to a two-parameter Weibull function to describe the decline in effcacy over time. Experiments (listed by experiment number) were initiated (1) Sept. 17, 2010; (2) Oct. 12, 2010; (3) June 8, 2011; (4) June 22, 2011; (5) July 6, 2011; and (6) Aug. 26, 2011. 21 Days after fungicide application December 2013 GCM 85

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