Golf Course Management

JAN 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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108 GOLF COURSE MANAGEMENT 01.18 (FieldScout TCM 500 NDVI Turf Color Meter, Spectrum Technologies) and shear vane (rooting and soil cohesion) strength (Turf-Tec Shear Strength Tester, Turf-Tec International). NDVI is a good estimator of turf density, quality and vigor in response to traffic stress (9). When differences among seeding rate treatment levels were observed in 2013 and 2014, the mean NDVI values were not sig - nificantly different among seeding rates of 7.9 to 32.1 ounces/1,000 square feet at 44 to 51 weeks after seeding (Figure 1). A significant seeding rate × simulated traffic initiation inter - action was also observed in 2013 at 49 weeks after seeding, and demonstrated that a combi - nation of May and June traffic would decrease the NDVI values of creeping bentgrass seeded at or below 7.9 ounces/1,000 square feet when compared with the same grass seeded at 12.1 ounces/1,000 square feet that received only June traffic (Figure 2). The results were obtained under optimal growing conditions for creeping bentgrass; throughout the duration of the study, sum - mer temperatures did not exceed 90 F (32 C). Creeping bentgrass seeding rates from 12.1 to 32.1 ounces/1,000 square feet did not re - sult in different NDVI responses at 47 weeks after seeding. The data suggest that, as turf - grass plants mature (43 weeks after seeding), the NDVI value of conservatively seeded (12.1 ounces/1,000 square feet) turfgrass stands will not diminish as late-spring play begins. The conservative seeding rate will not only expe - dite putting green establishment in the first year following renovation, but it will also save money if seed prices increase or stockpiles dwindle (1). Shear vane strength and traffic Shear vane strength is a proven method of quantitatively assessing turf stability (7). Seeding rate and traffic significantly affected the shear vane strength of creeping bentgrass at 51 weeks after seeding in 2013 and 2014 (Table 1). Differences among seeding rates were observed at seeding rates of 1.9 and 3.9 ounces/1,000 square feet. In 2013, the lower seeding rates produced the lowest mean shear vane strength, whereas the highest seeding rate of 32.1 ounces/1,000 square feet pro - duced the highest mean shear vane strength. Statistically, no difference in mean shear vane strength was observed between seeding rates of 12.1 and 16.0 ounces/1,000 square feet in 2013. When differences among traffic treat - ments were observed, seeding rate treatments that received the July traffic had greater shear vane strength than those that received traffic in May and June. In 2014, no significant difference in mean shear vane strength was observed among the seeding rates of 12.1, 16.0 and 32.1 ounces/1,000 square feet. Only May and June traffic were shown to reduce shear vane strength in comparison with the control and July traffic. These results show that a sustain - able putting green surface can be achieved after renovation by seeding at the conservative rate of 12.1 ounces/1,000 square feet and then delaying play until late spring or early sum - mer. As might be expected, the deleterious ef- fects of traffic stress were not observed at the highest seeding rates. Because the intensity of the establishment cultural practices (mowing, fertility and sand topdressing) was greater than in previous studies, plant growth characteristics were af - fected before trafficking took place. Although no observable traffic stress occurred in plots that received higher seeding rates, no real advantage was gained by using those rates. Treatment Shear vane strength (Nm) † Aug. 3, 2013 Aug. 8, 2014 Seeding rate (ounces/1,000 square feet) ‡ 1.9 10.8 a § 8.5 a 3.9 12.0 b 9.9 b 7.9 13.6 c 10.6 bc 12.1 14.4 cd 11.8 cd 16.0 14.9 d 11.8 cd 32.1 15.8 e 12.0 d Traffic initiation May 12.4 a 9.7 a June 13.2 b 10.6 b July 14.0 c 11.3 c Control 14.6 d 11.4 c † Shear vane strength measured in Newton meters. ‡ V8 creeping bentgrass seeded Aug. 8, 2012, and Aug. 16, 2013. § Values within a column followed by the same letter are not significantly different (p > 0.05). Shear vane strength Table 1. Means of shear vane strength as affected by seeding rate (ounces/1,000 square feet) and traffic treatments (four passes with Jacobsen PGM 22 with 116 Black Widow Softspikes performed three times/week).

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