Golf Course Management

FEB 2017

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

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02.17 GOLF COURSE MANAGEMENT 83 Many factors influence the efficacy of turf- grass fungicides, including fungicide applica- tion rate and intervals between applications, host susceptibility, fungicide resistance, envi - ronment, nozzle type, spray volume, fungicide topical mode of action, leaf coverage, and de - pletion rate (1). Microdochium patch (Microdoc ium ni - vale) is a disease that affects turfgrass foliage. Microdochium patch is of major concern in humid, cool regions where annual bluegrass (Poa annua L.) turf is often dominant. To date, there is little published research show - ing results for the influence of nozzle types, fungicide topical mode of action, and spray volumes regarding Microdochium patch con - trol. Therefore, the main objective of this field study was to evaluate the effect on Microdo - chium patch control from the interaction of nozzle type-spray volume combinations with fungicide topical mode of action. Effects of nozzle-spray volume combinations on spray coverage A spray nozzle coverage analysis was con- ducted using a completely randomized de- sign with four replications. For this experi- ment, water was applied with four different nozzle-spray volume combinations: XR11004 (1 gallon/1,000 square feet) and XR11008 (2 gallons/1,000 square feet) (TeeJet, Glendale, Ill.) flat fans, which produce medium (226- 325 µm) and coarse (326-400 µm) droplets, respectively, and 1/4TTJ04 (1 gallon/1,000 square feet) and 1/4TTJ08 (2 gallons/1,000 square feet) (TeeJet, Glendale, Ill.), which produce extremely coarse (500-650 µm) drop - lets (TeeJet Technologies, 2008). The water was applied with a CO 2 -pressurized backpack sprayer with a three-nozzle handheld boom at 30 pounds/square inch, 20 inches off the ground. Applications took place inside to avoid the effects of wind, and treatments were repeated four times for each nozzle. Digital images were collected immediately following the spray application to water-sen - sitive paper (Spraying Systems Co., Whea- ton, Ill.), which is rigid, yellow paper that is stained blue by liquid, using a Sony DSC-H9 camera (Sony, Tokyo, Japan) mounted on an enclosed light box measuring 24 inches long by 20 inches wide by 21.5 inches tall, and then analyzed using SigmaScan Pro (v.5.0, SPSS, Chicago) to determine percent spray coverage (0%-100%) (3). The threshold settings were adjusted to a hue of 135 to 255 to select the pix - els that represented areas of the sensitive paper affected by the spray treatments (blue area); the saturation was set to a range of 0 to 100. Data were analyzed using SAS 9.3 Proc Mixed (SAS Institute, Cary, N.C.). The means were separated using Fisher's LSD (0.05). There was a large difference in spray cov - erage from the different nozzle-spray vol- ume combinations (Table 1 and Figure 1). XR11008 nozzles (2 gallons/1,000 square feet) had the greatest spray coverage (86%), followed by XR11004 nozzles (1 gallon/1,000 square feet), which provided a spray cover - age of 67%. The 1/4TTJ08 (2 gallons/1,000 square feet) provided a coverage of 56%, while the 1/4TTJ04 (1 gallon/1,000 square feet) provided the lowest coverage at 26%. Effects of nozzle-spray volume combinations and fungicides on Microdochium patch A field study was conducted at Oregon State University's Lewis-Brown Horticulture Farm in Corvallis, Ore., from Jan. 25 to April 24, 2013 and 2014, on an annual bluegrass putting green mowed weekly at 0.150 inch. The experiment used a 3-by-4 factorial, plus control, treatment structure and a random - ized complete block design structure with four replications. Factors included fungicide topi - cal mode of action, and nozzle-spray volume combinations. Three different fungicides were used: fluazinam (Secure; Syngenta, Greens - B.W. McDonald C.M. Mattox A.R. Kowalewski, Ph.D. D.K. Mosdell, Ph.D. Effects of spray nozzle and fungicide mode of action on control of Microdochium patch on an annual bluegrass putting green in western Oregon Useful conversions To convert column A to column B, multiply by Column A: Suggested unit Column B: SI unit 2.54 inch centimeter, cm 6.90 × 10 3 pound/square inch, lb/sq inch, PSI pascal, Pa 1.12 pound/acre, lb/acre kilogram/hectare, kg/ha 3.78 gallon liter, L 6.45 × 10 8 square inch square micrometer, µm 2

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