Golf Course Management

MAY 2019

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

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Page 70 of 141

05.19 GOLF COURSE MANAGEMENT 67 ture probes. at work conclusively shows surfactants can improve horizontal soil water distribution. Recently, much of the discussion and marketing materials have shifted to the verti - cal distribution of water and the location of enhanced water retention or drainage. Some surfactants, marketed as "retainers," are said to improve water retention and improve the vertical distribution of water in the soil. Other surfactants, marketed as "penetrants," have properties that aid infiltration and drainage and ultimately reduce water content within the soil. However, it is difficult for turfgrass scientists to measure these claims in the field. e objectives of this research are to mea - sure the vertical distribution of water in a sand-based profile treated with different types of surfactants, to relate surfactant concentra - tions in the soil to soil hydrophobicity and, ultimately, to create models to estimate soil surfactant longevity under different irriga - tion programs. is research will provide golf course superintendents greater control when designing and implementing a successful soil surfactant program. Ultimately, this will lead to higher irrigation efficiency, improved sur - face playability and enhanced turf health. Experiments is research is being conducted in 12 large lysimeters (pots) within a greenhouse at the University of Nebraska-Lincoln. e ly - simeters are 17 inches (43 centimeters) in di- ameter and built to USGA recommendations for golf putting green construction. Each ly - simeter has four 16-inch (41-centimeter) long TDR probes inserted horizontally 1, 3, 7 and 11 inches (3, 8, 18 and 28 centimeters) below the surface. We are evaluating a non-treated control and three different surfactants: Revo - lution and Dispatch from Aquatrols and an experimental product. Following application, the treatments are watered-in, and all the ly - simeters receive different levels of irrigation, depending on the run. During the first run, irrigation was withheld until widespread wilt occurred. For the current run, irrigation is being applied to replace slightly more than evapotranspiration (or ET). e next run will feature significant leaching irrigation events. ese runs will be replicated two or three more times during the next two years. In addition to taking the soil moisture measurements from the embedded TDR probes, we are removing 0.75-inch (2-centi - meter) cores weekly to measure hydrophobic- ity (from water-drop-penetration tests) and to measure the amount of surfactant in the soil. e hydrophobicity data will be correlated to soil surfactant concentrations, irrigation fre - quency, water content and soil temperature to create a crude model of surfactant degra - dation. Future research Over the past year, methodologies have been developed for extracting and modeling surfactant concentration within the soil using a mobile Fourier-transform infrared spec - troscope (FTIR). We expect to have vertical water distribution profiles and soil hydropho - bicity information from the three different ir- rigation runs by the end of 2019. is research will help the turfgrass industry understand how different surfactants impact soil water content at various depths over time on a golf course. Our ultimate goal is to create models to help schedule surfactant applications and integrate those models into our decision sup - port tool, . Michael Carlson is a research technologist and a new doc- toral student, Mark Keck is a graduate student pursuing a Master of Science degree, and Bill Kreuser (wkreuser2@ is an assistant professor and Extension turfgrass specialist in the Department of Agronomy and Horticulture at the University of Nebraska, Lincoln, Neb. To test the efficacy of surfactants in improving soil water retention and drainage, three products and an untreated control are being tested in lysimeters in a greenhouse at the University of Nebraska in Lincoln, Neb. (report) Fungicide alternatives for management of Microdochium patch Clint Mattox, M.S. Alec Kowalewski, Ph.D. Brian McDonald, M.S. Controlling Microdochium patch is a major concern for superintendents in the Pa - cific Northwest who manage annual bluegrass (Poa annua) putting greens. Restrictions in certain regions limiting pesticide use have cre - ated a quandary for superintendents attempt- ing to maintain desirable playing conditions. For several years, researchers at Oregon State University in Corvallis, Ore., have been con - ducting research to develop alternatives to traditional fungicides. is research is part of that continuing effort. Experiment 1: Civitas Turf Defense and phosphorous acid + sulfur and phosphorous acid e first trial incorporated the use of Civi - tas Turf Defense (a horticulture oil, Intelligro) and a phosphorous acid in a seasonal rotation with sulfur and a phosphorous acid. is trial also included a timing component that quan -

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