This recently released research study was sponsored by the USGA and conducted by the University of Florida (Williams, Kruse, Unruh & Sartain.) The USGA granted permission for us to reprint here.
Evaluating bermudagrass cultivars for traffic tolerance and recuperative ability
For more than 40 years, Tifway (419) has been the industry standard for golf course fairways in the Southeast. Over this time, Tifway has proven to provide good color, density, fine leaf texture, and growth rate. Yet in the past few years, superintendents have started turning to new bermudagrass cultivars that, along with other attributes such as increased shade tolerance, are thought to have higher wear tolerance and faster recovery. However, there is limited research comparing the performance of new bermudagrass cultivars to industry standards.
This study was set up to investigate genetic color, density, turf quality, and divot recovery of eight bermudagrass cultivars. In this study, industry standards Tifway, TifSport, Floratex, and
Riviera were compared with newer cultivars Celebration, TifGrand, T11, and Hybrid1. The objectives of this study were to characterize a typical response of these bermudagrass cultivars to varying rates of traffic, establish fertility recommendations for each of the cultivars studied under high- and low-traffic conditions, and determine the influence of fertility and traffic on the recovery rate of each cultivar.
This study was conducted at the University of Florida Plant Science Research and Education Unit located in Citra. Plots were maintained as a golf course fairway and were mowed three times per week at 0.5 fertilizer were applied (0.5, 0.75, and 1.0 lb. N/1000ft2) using a 15-5-15 turf fertilizer blend with 50% slow release nitrogen in a split application every two weeks. Half of each plot then received traffic, while the other half was left untrafficked. Divots were taken from each of the plots twice in the fall of 2009 and once to date in 2010. Visual ratings of color, quality, and density were collected, along with digital pictures.
Digital images were subjected to digital image analysis (DIA) to determine percent green cover and dark green color index (DGCI).
Traffic c was simulated during the growing season using a modified Cady traffic c simulator. Turf density was reduced by 10-20% in plots receiving traffic treatments. The data indicate a significant difference in traffic tolerance between bermudagrass cultivars. Celebration produced the darkest green color while Celebration and TifGrand maintained the highest plant density under the weekly traffic treatments. Tifway and Tifsport had the lowest density as evaluated by DIA. Tifway, Tifsport, Floratex, and Riviera consistently yielded the lightest green turf of all the cultivars. Differences in percent cover have yet to be seen in 2010, as traffic damage had not amounted to a significant level when this article was written. After a year and a half of data collection, Celebration has exhibited the best traffic tolerance of all the cultivars, keeping the highest density and darkest green color throughout the study.
No differences were observed in visual turf quality, color, or density as a result of fertility treatments. This is supported by digital image analysis, which also indicated no relationship between nitrogen rate and percent green cover or dark green color index values. This result indicates that there may have been some residual fertilizer effects from previous applications, or current nitrogen rates are too narrow in range to establish differences in growth response.
To determine the recuperative potential of each cultivar, a standardized divot was taken from each of the plots and regrowth was tracked using DIA. Divots were removed from the plots using a divot machine designed and constructed at the University of Florida. Two sets of divots were taken at different times during the fall of 2009, with additional divot recovery analysis continuing through the summer of 2010.
The driving factor in recovery speed was genetic, as certain cultivars recovered faster than others. Data have shown that under no traffic, Floratex and T11 recovered from divot damage faster than all other cultivars during the first two weeks. In plots receiving traffic, Celebration, Floratex, Hybrid1, Riviera, and T11 all performed similarly and all recovered faster than Tifway, TifSport, and TifGrand. Data from 2009 indicate that the recovery of divots under traffic was
10-20% slower than it was for divots receiving no traffic. Data from 2010 show little difference between traffic and non-trafficked plots as not enough damage has occurred to be effective.
Similar to wear tolerance data, fertility rate was not a factor in recovery speed in either 2009 or 2010. Two more sets of divots are scheduled for the 2010 growing season to collect additional information on which cultivar recovers most quickly from divot injury.
The results of this study are preliminary, as the majority of the 2010 data has yet to be collected; however, they do support the idea that there are better alternatives to Tifway for high traffic areas. Superintendents can see increased wear tolerance with Celebration and TifGrand, and faster divot recovery with T11 and Floratex. While there may not be one grass that can do it all, installing T11 on tees and Celebration in high traffic areas of the golf course can help the turf recover more quickly and provide golfers with a better all-around playing surface. Regrassing entire fairways may not be an option at every golf course, but using these grasses on small-scale projects can increase the wear tolerance of the course and provide a dark green, dense playing surface.
In the past, Tifway was the grass of choice and was installed on the majority of golf courses, but with the new cultivars available today, superintendents have options. Whether it is building a new course, renovating an old one, or just converting a tee, there are more cultivars to consider than just going with the standard.
Bradley Williams is a master’s candidate in environmental horticulture. Jason Kruse, PhD, is an assistant professor, environmental horticulture. J. Bryan Unruh, PhD, is a professor, environmental horticulture. Jerry Sartain, PhD, is a professor, Soil and Water Science.