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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03.19 GOLF COURSE MANAGEMENT 79 Kevin Laskowski Kevin W. Frank, Ph.D. Emily B. Merewitz, Ph.D. Surfactant effects on overwatering and underwatering and traffic stress of cool-season greens Surfactant treatments can improve turf quality and NDVI during water deficit, excessive water, and/or moderate to heavy foot traffic. As putting green species, creeping bent- grass (Agrostis stolonifera) and annual bluegrass (Poa annua) often endure water and traffic stresses on golf courses. Water stress includes conditions that may result in water deficit to the plant or a water surplus. Far more research has been done on water stress and/or poten - tial benefits of surfactant use for creeping bentgrass than for annual bluegrass. Growth habits and rooting characteristics, which can affect water uptake and usage and thereby af - fect irrigation rates, frequencies and timings, are different in annual bluegrass and creeping bentgrass (1, 3). Additionally, research that combines water stress with traffic stress will more accurately reflect real golf course condi - tions compared with a singular experimental stress. Most information available regarding use of surfactants on annual bluegrass also incorporates plant growth regulators or other chemical treatments with a goal of remov - ing annual bluegrass, as it is often viewed as a turfgrass weed species. For superintendents who actively culture annual bluegrass putting greens, a better understanding of the effects of surfactants on physiological responses and turfgrass performance under specific irriga - tion regimes is needed. e role of soil surfactants Soil surfactants and wetting agents are primarily used in turfgrass management to manage localized dry spot, which is often caused by hydrophobicity, or water repellency, which, in turn, is the result of organic coat - ings on sand or soil particles. Root zones of golf course greens commonly have a high sand content because the greens have been treated with sand topdressing or because they were originally constructed of sand. Organic coat - ings on sand or soil particles can lead to several problems, including lack of available water to plant roots, uneven water flow through the soil, and increased susceptibility to abiotic and biotic stresses such as wear stress (4). In addition to alleviating localized dry spot, sur - factants can also improve various other issues in water relations in sand and soils. In many cases, soil water content may not be adequate or may exceed turfgrass requirements. For in - stance, water excess or deficiencies may occur because of the amount of precipitation, breaks in irrigation equipment, poor placement or coverage of irrigation heads, and many other reasons. Even in the absence of hydrophobic sands or soils, research is needed on how sur - factants can be used in turfgrass management to optimize soil water content, particularly for high-value putting green species such as creep - ing bentgrass and annual bluegrass. Wear or traffic stress Wear or traffic stress, which occurs pri - marily on tee boxes and putting greens, is a significant problem on most golf courses and is caused by scuffing, tearing or crushing of the turfgrass plants by feet, vehicles or other mechanical objects. Over time, this damage, under either optimal conditions or periods of environmental stresses, can compromise turf - grass health and degrade playing surfaces. It can also compact soils, leading to impaired root growth and damage (1). e amount of traffic can vary widely among golf courses and within a single putting green, calling for research involving different levels of traf - fic stress. Simulating real turfgrass field con- ditions by including traffic stress as a factor has yet to be performed in research studies of water use or surfactants. e objective of this study was to determine whether a surfactant treatment would promote tolerance to over - watering, insufficient irrigation, and traffic stress for individual stands of annual bluegrass and creeping bentgrass on a sand-based green. Materials and methods Turfgrass plot maintenance In 2013, research plots received total ni - trogen (N) of 130.25 pounds/acre (146 kilo- grams/hectare), total phosphorus (P) of 14.27 pounds/acre (16.0 kilograms/hectare), and total potassium (K) of 52.28 pounds/acre (58.6 kilograms/hectare). Plots were fertilized with 21.76 pounds N/acre (24.4 kilograms/ hectare) on May 5, Aug. 2 and Oct. 1, using an 18-9-18 (N-P-K) granular fertilizer (An - dersons Golf Products). Nitrogen was applied as a foliar spray weekly from June 14 to Sept. 26, using a 28-0-0 (N-P-K) liquid fertilizer at a rate of 4.37 pounds N/acre (4.9 kilograms/ hectare). During 2014, total nitrogen applied was 117.76 pounds/acre (132 kilograms/hec - tare), and total potassium applied was 44.4 pounds/acre (49.8 kilograms/hectare). Plots This research was funded in part by GCSAA through the Environmental Institute for Golf.

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