By Kevin Morris
At any one time, the National Turfgrass Evaluation Program (NTEP) is evaluating, in nationwide tests, more than 600 cultivars and experimental selection of more than a dozen species. Data collected and summarized from these trials can be found on our website, www.ntep.org. Our data is also published on a CD, in the same format as the NTEP website, which can be purchased from NTEP.
NTEP collects data on overall turfgrass quality, appearance characteristics like color and texture, disease and cold tolerance and many other traits. In recent years, however, NTEP has focused more on testing specific performance traits, such as traffic tolerance and saline irrigation performance. This article provides insight on NTEP testing and an update on improved cultivars and new experimental selections of bermudagrass.
NTEP trials are established at university locations and evaluated for 5 years. Species such as Kentucky bluegrass, perennial ryegrass and bermudagrass have been tested by NTEP for more than 25 years. Each new trial includes recently developed cultivars, experimental entries that may become commercialized, and well-known standard cultivars. With each trial, NTEP and an industry advisory committee develops testing protocols and identifies important characteristics to be evaluated. Trials are established at locations that are important use areas for that species, or where a disease, insect or other problem is prevalent, such that NTEP can adequately evaluate the test entries for that problem. Also, NTEP establishes tests where specific stresses can be evaluated, i.e., a location that can impose simulated traffic, saline irrigation or consistent drought stress.
Evaluation procedures are developed for each of the traits; in some cases these procedures are very detailed. For instance, when testing traffic tolerance, we must consider the species being tested, its typical use patterns, the region of the country, the traffic simulation equipment available and other factors. Only then can NTEP decide how and when to impose simulated traffic and the best data collection procedures and timing for that trial.
The following is an overview of the latest traffic tolerance, cold tolerance, rate of spread and other pertinent information on the more than 60 commercially available and experimental cultivars of bermudagrass evaluated by NTEP since 2007.
Data from 2007-2012
Our recently completed bermuda trial, established in 2007, contains 25 seeded entries and six vegetative entries. Many of these entries were experimental cultivars when originally entered (http://www.ntep.org/data/bg07/bg07_13-10f/bg0713ftent.txt). However, now several of these grasses are commercially available, including the seeded entries ‘Gold Glove,’ ‘Pyramid 2,’ ‘Hollywood’ and ‘Royal Bengal.’ Commercially available seeded entries ‘Riviera,’ ‘Princess 77,’ ‘NuMex-Sahara,’ ‘Sunsport,’ ‘Yukon’ and ‘Veracruz’ were also included in this trial. Commercial vegetative entries included ‘Midlawn,’ ‘Tifway,’ ‘Premier’ (now called Premier Pro), ‘Patriot,’ ‘Latitude 36’ and ‘NorthBridge.’
NTEP evaluates warm-season grasses by comparing seeded and vegetative entries, and by separately comparing seeded vs. seeded and vegetative vs. vegetative. Therefore, you will find data collected on all submitted entries (http://www.ntep.org/reports/bg07/bg07_13-10f/bg07_13-10f.htm) broken down in different ways on our website. This section will only focus on the 16 commercially available entries from the 2007 trial.
Traffic evaluations were conducted for multiple years at the following locations: Fayetteville, AR, Gainesville, FL and Raleigh, NC. Data on traffic tolerance and recovery was collected in various seasons and in several years at these sites. Investigation of each dataset is best to identify grasses for your needs; information provided here on traffic and recovery are generalizations only.
At Fayetteville, AR, ‘Premier Pro,’ ‘NorthBridge,’ ‘Latitude 36’ (vegetative), ‘Riviera,’ ‘Hollywood’ and ‘Yukon’ (seeded) finished in the top statistical group for end of season ground cover in each year. ‘Tifway,’ ‘Pyramid 2,’ ‘Gold Glove’ and ‘Princess 77’ were in that top statistical group for 2 of the 3 years. Speed of recovery varied for the entries, depending on the time of year traffic was applied. The complete dataset can be found here: http://www.ntep.org/data/bg07/bg07_13-10f/bg0713ft21a.txt.
The Gainesville, FL location initiated seasonal traffic evaluations in fall 2008, with continuation (and breaks for recovery) in spring 2009, summer 2009, fall 2009 and fall 2011. Seeded entries ‘Veracruz’ and ‘Princess 77’ were very good for traffic tolerance in each season. Entries with good ground cover at the end of three of the four seasons include ‘Tifway’ and ‘Premier Pro.’ You can look closer at the data here http://www.ntep.org/data/bg07/bg07_13-10f/bg0713ft22a.txt.
Finally, data was collected on wear tolerance and shear strength from 2009-2012 at Raleigh, NC. The best entries for both wear tolerance and shear strength in 2009 were ‘Latitude 36,’ ‘NorthBridge’ and ‘Premier Pro.’ In 2010, ‘Latitude 36,’ ‘Pyramid 2’ and ‘Premier Pro’ had some of the highest wear tolerance ratings along with shear strength ratings over 100 newton meters. The wear tolerance ratings of ‘Tifway’ and ‘NorthBridge’ in 2010 were lower (although not statistically significant), but they still both showed shear strength ratings of 100+ newton meters. 2011 data showed ‘NorthBridge’ with the highest shear measurement, significantly greater than almost all other entries. Also in 2011, ‘Tifway,’ ‘Latitude 36,’ ‘NorthBridge’ and ‘Yukon’ had the highest wear tolerance average. ‘NorthBridge’ and ‘Tifway’ continued to deliver the highest shear strength in 2012, and along with ‘Latitude 36,’ ‘Patriot’ and ‘Princess 77’, had the best wear tolerance ratings. Curiously, ‘Midlawn’ had high wear tolerance ratings from 2009-2011 at this location; however, its shear strength ratings were significantly lower than the other top entries (http://www.ntep.org/data/bg07/bg07_13-10f/bg0713ft23a.txt).
Data was collected on several environmental stresses throughout the testing period. For example, saline irrigation was used at Las Cruces, NM with ‘Tifway,’ ‘Princess 77’ and ‘Latitude 36’ finishing the 5 years of data in the top statistical group. At Stillwater, OK and Blacksburg, VA, ‘Yukon,’ ‘Latitude 36,’ ‘NorthBridge,’ ‘Patriot,’ ‘Midlawn,’ ‘Riviera,’ ‘Hollywood,’ ‘Premier Pro’ and ‘Tifway’ showed significantly less winter damage. And at Fayetteville, AR, Raleigh, NC and Knoxville, TN, spring dead spot ([START ITAL]Ophiosphaerella sp.[END ITAL]) was noted and evaluated. Only ‘Patriot,’ ‘Latitude 36,’ ‘NorthBridge,’ ‘Pyramid 2,’ ‘Tifway,’ ‘Premier Pro’ and ‘Princess 77’ showed statistically less damage from spring dead spot at all three locations.
Data from 2013-2105
In 2013, NTEP initiated a new bermudagrass trial, containing 18 seeded entries and 17 vegetative entries (35 total entries). Twenty-one locations established the entries in spring and summer 2013, but the coldest winter in the last 30 years (2013-2014) necessitated replanting of some or all entries at seven locations. The winter of 2014-2015, although not as cold as the previous winter, was nonetheless also hard on these entries. Therefore, data collection (besides establishment and winter injury) could not commence at many locations until 2015. This report focuses on data collected through 2015, including both the 12 commercial and 23 experimental entries. Data from 2013-2015 can be found on the NTEP web site (http://www.ntep.org/reports/bg13/bg13_16-6/bg13_16-6.htm). Data from the early part of any NTEP trial needs to be used with caution, as additional years of data could affect entry performance. However, we are providing some initial data here with the caveat that these results may change over the new few years.
For 2013 and 2014, the story on these entries is primarily establishment rate and then winter injury (and recovery from injury). Bermuda establishment from seed is most often faster than from sprigs; however, not all seeded entries establish at the same rate (of course, the same is true for vegetative entries). Establishment data showed ‘JSC 2009-2-S,’ ‘JSC-2009-6-S,’ ‘Riviera’ and ‘BAR C291’ finishing in the top statistical group at each of 15 locations. ‘MBG 002,’ ‘JSC 2007-8-S’ and ‘JSC 2007-13-S’ also performed well, finishing in the top statistical group at 14 locations. These entries often bettered ‘Yukon’ for establishment, and occasionally, ‘Princess 77’ and ‘NuMex-Sahara.’
Vegetative entry establishment rate varied more than with the seeded entries, with several entries showing consistency over many locations. Several new entries established equally well, if not better than well-known commercial entries, with outstanding performance at more locations. For instance, commercial entries ‘Patriot’ and ‘Celebration’ performed very well during establishment, finishing in the top statistical group at 13 and 10 locations, respectively. Topping that however, ‘FAES 1325’ finished in the top statistical group at 14 of 15 locations; ‘OKC 1131’ (12 of 15 locations), ‘FAES 1326’ (11 of 15 locations) and ‘11-T-510’ (10 of 15 locations) also established well.
The winter of 2013-2014 brought record low winter temperatures across much of the US, and the trials showed the effects of this extreme weather in spring and summer 2014. As noted above, because of the severe damage, two locations replanted all entries in summer 2014 and five locations replanted some of their entries. Before replanting, winter damage was assessed at these and other locations. Winter injury data averaged from Lexington, KY and West Lafayette, IN showed ‘Yukon’ with the lowest injury (22.8%) among seeded types (average damage ranged from 22.8 – 98.8%. LSD Value = 12.7). Among the vegetative entries at those two locations, ‘OKC 1131’ (14.5%) and ‘Patriot’ (30.8%) had the lowest average winter injury (range is 14.5 – 98.8%, LSD Value = 23.8). Since past top performers for winter injury showed more damage, i.e., ‘Riviera’ (55.2%) and ‘Latitude 36’ (57.3%), plant breeders may have made some improvements in bermudagrass winter survival.
The third year of this trial (2015) was the first year of turfgrass quality data collected with plots being adequately established plots at all sites. As often happens, entry performance varied significantly by location. In fact, NTEP statistical analysis dictated that data from each location be published in separate tables, and not compiled by region or grouped. However, ‘JSC-2-21-18-V,’ ‘TifTuf,’ ‘OKC 1131’ and ‘Latitude 36’ were the only entries with turfgrass quality averages in the top 25% of all entries for turfgrass quality at 70+% of locations.
One trait of considerable interest to turf managers is drought tolerance. At College Station, TX drought was imposed in summer 2015, and data being collected starting during the drought (mid-August) and continuing through recovery (mid-November). Throughout this 90-day period, percent living green cover ratings varied up to 40% among entries. Turfgrass quality ratings reflected this discrepancy with ‘TifTuf’ and ‘OKC 1131’ having higher overall quality ratings than almost every other entry.
Our 2015 dataset also contains much data on traits such as color, texture and density, with initial data on traffic, drought and disease (http://www.ntep.org/reports/bg13/bg13_16-6/bg13_16-6.htm). Again, this and other data needs to be repeated in multiple years before turf managers can feel confident in these results. Watch the NTEP web site (www.ntep.org) for this trial and other specie trial updates in 2017.
Kevin Morris is Executive Director, National Turfgrass Evaluation Program, Beltsville, MD. He can be reached at firstname.lastname@example.org.