Golf Course Management

AUG 2018

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

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70 GOLF COURSE MANAGEMENT 08.18 had more silicon in the plant tissue than un- treated grass in the control plots. In the sec- ond experiment, there was more silicon in the plant tissue that received the high silicon rate as a foliar spray (as compared to the control plots). is increase in tissue silicon did not translate to improvements in wear tolerance, however. Basically, foliar application of sili - con did not enhance wear tolerance or reduce injury of seashore paspalum. However, when potassium silicate was ap - plied as a drench at a high rate, wear tolerance was enhanced. But here's the rub — these improvements in wear tolerance and quality were a function of the potassium supplied with the silicate, and not the silicon alone. Because of the inclusion of the potassium- only check, the authors were able to state that the wear tolerance increased because of the application of either potassium alone or the combination of silicon and potassium. When only potassium was applied, wear injury was reduced from 35% to 14%, and when potas - sium + silicon was applied, wear injury was reduced from 35% to 20%, compared to plots that did not receive potassium or sili - con, or plots that received foliar applications. e authors hypothesized that potassium was working because it increased cell turgor pres - sure and cell elasticity. And a last point — only wear, injury and quality were examined, and no data were collected on disease (the ef - fects of silicon on disease have been studied elsewhere). Source: Trenholm, L.E., R.R. Duncan, R.N. Carrow and G.H. Snyder. 2001. Influence of silica on growth, quality, and wear tolerance of seashore paspalum. Journal of Plant Nutrition 24:245-259. Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn Univer - sity in Auburn, Ala., and president-elect of the Crop Sci- ence Society of America. She is a 20-year member of GCSAA. Beth Guertal, Ph.D. guertea@auburn.edu Twitter: @AUTurfFert That traffic will wear you down (verdure) Feet, carts and machinery — all conspire to inflict wear on your turfgrass, affecting both the leaf surface and the underlying soil. Silicon (Si) has long been touted as a tool for potentially increasing the rigidity of turfgrass swards, with applications of silicon possibly providing a tougher and more upright leaf that can withstand abrasive wear. To test this theory, researchers at the University of Geor - gia (L. Trenholm, Ph.D., now at the Univer- sity of Florida) examined the effects of silicon on the wear tolerance and quality of seashore paspalum. Two seashore paspalum ecotypes (an ex - perimental and SeaIsle 2000) were main- tained at a 1.25-inch (3.2-cm) mowing height. From May to July in year 1 and July to August in year 2, foliar and drench ap - plications of potassium silicate (20.8% SiO 2 and 8.3% K 2 O) were made every other week. Foliar silicon was applied at rates of 1 or 2 pounds silicon/acre (1.1 or 2.2 kilograms/ hectare), and the drench treatment was ap - plied at 20 pounds silicon/acre (22.4 kilo- grams/hectare) in a water solution of 960 gallons/acre (0.9 liter/square meter). Since the silicon source was potassium silicate, the trial was balanced to uniformity for the sup - plied potassium using potassium chloride. ere was also a potassium-only (potassium chloride) treatment, applied at 14 pounds po - tassium/acre (15.6 kilograms/hectare), which was also the rate of potassium applied with the highest potassium silicate treatment. Artificial traffic was used to simulate wear using rubber-covered rollers designed to pro - vide wear to the leaf surface with minimal pressure to the soil, reducing underlying compaction. Collected data included leaf tensile strength (the point at which leaf tis - sue broke), leaf load-bearing capacity (shoot tissue displacement when covered with a weight), shoot growth, silicon and potas - sium content in shoot tissue, NDVI spectral reflectance, and turfgrass quality, color, den - sity and injury. e low rates of silicon, applied as foliar treatments, did not improve wear tolerance or quality of the seashore paspalum. Shoot growth or leaf strength were also not im - proved. In the first experiment, seashore pas- palum sprayed with foliar potassium never The wear tolerance increased because of the application (as a high-rate drench) of either potassium alone or the combination of silicon and potassium.

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