Golf Course Management

JUL 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 ences) at 0.499 pound/acre (0.56 kilogram/hectare), Ronstar (oxadiazon, Bayer Environmental Science) at 3.03 pounds/acre (3.4 kilograms/ hectare), Specticle (indazifam, Bayer Environmental Science) at 0.031 pound/acre (0.035 kilogram/hectare), and Tower (dimethenamid, BASF Corp.) at 1.49 pounds/acre (1.68 kilograms/ hectare). Pre-emergence herbicide treatment rates were chosen based on label recommendations for each herbicide. Herbicide treatments were applied with a CO2-powered backpack sprayer equipped with XR8003VS nozzle tips (TeeJet) calibrated to deliver 32.6 gallons/acre (305 liters/hectare) at 40 psi (276 kPa). Herbicide applications were made on March 15, 2011, and March 23, 2012. A nontreated check was included for comparison. Irrigation at 0.236 inch (0.6 centimeter) was applied immediately following all pre-emergence herbicide treatments to increase infltration into the soil profle and activate the chemistries. Author Leslie Beck applies pre-emergence herbicide to a bermudagrass fairway infested with spring dead spot disease. fne sandy loam (fne-loamy, carbonatic, thermic Aridic Calciustepts) soil with a pH of 8.2 and organic matter content of 1.5%. Research was located on a Tifway 419 bermudagrass [C. dactylon × C. transvaalensis (L.) Pers.] fairway with a history of spring dead spot infestation. Ophiosphaerella narmari, O. korrae and O. herpotricha were identifed from soil samples collected from this location, and no fungicides were applied to the research area the previous spring in order to encourage spring dead spot disease infestation. Plots measured 5 feet × 5 feet (1.5 meters × 1.5 meters) and were arranged in a randomized complete block design with four replications. All experimental areas were mowed 24 hours before herbicide application and twice weekly thereafter at a cutting height of 0.25 inch (0.6 centimeter). Herbicide treatments Pre-emergence herbicide treatments included Barricade (prodiamine, Syngenta) at 0.651 pound/acre (0.73 kilogram/hectare); Pendulum (pendimethalin, BASF) at 2.23 pounds/acre (2.5 kilograms/hectare), Surfan (oryzalin, United Phosphorus) at 1.49 pounds/acre (1.68 kilograms/ hectare), Dimension (dithiopyr, Dow AgroSci82 GCM July 2013 Data collection Data collected included percent bermudagrass phytotoxicity (foliar symptoms in response to herbicide application) based on visual assessments and recovery based on digital image analysis. Percent bermudagrass phytotoxicity was visually assessed one and two weeks following preemergence herbicide application on a percent scale relative to the non-treated check, where 0 equaled no bermudagrass injury and 100 equaled complete bermudagrass death. These ratings were conducted to ensure bermudagrass recovery from spring dead spot was not confounded by foliar phytotoxicity symptoms. Digital photographs were taken every two weeks following initial occurrence of spring dead spot symptoms in April until mid-June (14 weeks after treatment). Each trial was located in minimally traffcked landing zones near the beginning of the fairway, so no attempts were made to remove mechanical damage (for example, divots, scalping). Digital images were analyzed using software to quantify percent spring dead spot cover. Percent spring dead spot cover was converted to percent bermudagrass recovery (over the entire season) by comparing back to initial spring dead spot cover photographs taken in April. Initial spring dead spot cover was approximately 46% ± 5%. Bermudagrass recovery in response to pre-emergence herbicides Data for each year are presented separately

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