Golf Course Management

MAR 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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82 GOLF COURSE MANAGEMENT 03.19 NDVI 0.80 0.75 0.70 0.65 0.60 0.80 0.75 0.70 0.65 0.60 0.80 0.75 0.70 0.65 0.60 0.80 0.75 0.70 0.65 0.60 May 1 June 1 July 1 Aug. 1 Sept. 1 Oct. 1 June 1 July 1 Aug. 1 Sept. 1 Oct. 1 2014 2013 NDVI NDVI A B C D Revolution + 8% Revolution + 12% Revolution + 16% Control + 8% Control + 12% Control + 16% a lack of oxygen to roots, which can lead to poor nutrient uptake; stomatal closure, which reduces carbon fixation; and the accumulation of certain metabolic intermediates, which can be toxic to plant cells. Conversely, application of the soil surfactant increased SWC at the 8% SWC target when compared with turf areas at the 8% SWC target that were not treated with surfactant (Figure 1). Drought stress is an important factor even in irrigated turf. As golf course putting greens are often maintained on the dry side for playability, drought stress con - ditions can cause susceptibility to secondary stresses such as traffic and increased suscepti - bility to pathogens. us, surfactants may im- prove water availability to grasses when turf is receiving too little or too much water. Creeping bentgrass and annual bluegrass responded similarly to the water and traf - fic stress treatments with overall reductions in turf quality and NDVI resulting from the stresses. In creeping bentgrass, plots with 16% SWC had lower turf quality in 2013 com - pared with turf quality in the 8% and 12% SWC treatments (Figure 2). Application of the soil surfactant resulted in higher turf qual - ity compared with the untreated control in plots at 16% SWC in 2013. In 2014, creep - ing bentgrass at 8% SWC had lower turf qual- ity than the turf in the plots at 12% and 16% SWC. However, adding a soil surfactant in - creased turf quality in plots at 8% SWC com- pared with the turf that was not treated with a surfactant. As an example, the untreated control turf had a quality rating of 4.6, and turf treated with a surfactant had a quality rating of 6.8 at 8% SWC (Aug. 19, 2014, in creeping bentgrass). In both 2013 and 2014, a soil surfactant improved the turf quality of annual bluegrass at 8%, 12% and 16% SWC, when compared with the control. In creeping bentgrass, soil surfactant treatments affected NDVI measurements in both 2013 and 2014. Turf treated with soil surfactant had overall greater NDVI values in 2013 and 2014 when compared with the control turf at 8%, 12% and 16% SWC (Figure 3). is shows that, with the addition of a soil surfactant, less irri - gation water was required to maintain annual bluegrass NDVI when compared with plots that received more water. Traffic treatments did not affect NDVI values within creeping bentgrass in 2013 or 2014. Conclusions In conclusion, compared with the un- treated control, the surfactant treatment im- proved turf quality and NDVI in late sum- mer of both years. e surfactant increased annual bluegrass and creeping bentgrass turf quality during water deficit, excessive water, and/or foot traffic conditions. e surfactant treatment decreased moisture retention when plots were overwatered and increased moisture when plots were underwatered. Automated ir - rigation can be set to below-optimal levels to Figure 3. Normalized difference vegetation index (NDVI) under 8%, 12% and 16% target soil volumetric water content for controls or turf treated with soil surfactant within (A) creeping bentgrass, 2013; (B) creeping bentgrass, 2014; (C) annual bluegrass, 2013; and (D) annual bluegrass, 2014. Least signifi - cant difference bars are present on dates in which significant dif - ferences were detected among treatments.

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