Evaluation of Bentgrass Cultivars for Putting Greens
Over the past two decades, the number of commercially available bentgrass cultivars has increased, and there are now over 40 creeping bentgrass cultivars, up to 12 colonial bentgrass cultivars, and about half a dozen velvet bentgrass cultivars on the seed market. Although the proliferation of bentgrass cultivars allows more choices, getting reliable information on cultivar performance is a challenge for golf turf managers. Seed company reps are usually a good source of information on their own cultivars, but probably not for cultivars from competing companies. You can visit golf courses that have used the cultivar(s) of interest and see the results firsthand. However, these courses may not have the same conditions and resources as yours; thus, the results at your course may be different. Also, be sure to seek opinions of United States Golf Association agronomists and/or consultants who visit numerous golf courses and see a variety of grass types and management conditions.
Another source of information includes trial data from the National Turfgrass Evaluation Program (NTEP). NTEP is an industry-sponsored organization that coordinates tests of turfgrass cultivars and experimental selections at universities across the U.S. Data generated from these tests provides turfgrass managers, seed industry representatives, and other interested persons with information about turfgrass characteristics and performance. Although this is an intermediate step in the evaluation process (the program can't simulate all the traffic and management conditions found on golf courses), the program does provide good comparative information on seedling vigor, quality, density, color, disease and insect tolerance, and other parameters.
2008-2013 Bentgrass Putting Green Test
In September 2008, nineteen bentgrass cultivars and selections were established at the Joseph Valentine Turfgrass Research Center in University Park, PA, as part of a five-year NTEP test. Entries were supplied to NTEP by private seed companies and were seeded at 1.1 lbs. seed/1000 ft2 in plots on an experimental putting green with an 80% sand:20% peat rootzone mix. Three replicate plots of each entry were used in this test and plots were randomized within each replicate. The test was mowed daily at 0.125 inch during the growing season, aerated once per year, and received between 2 to 3 lbs nitrogen/1000 ft2 per year for most of the five-year test. All assessments of turfgrass performance were made on a visual basis by the author, and are based on a scale of 1-9, with 9 indicating best performance for a particular criterion. The following performance criteria were used to assess bentgrass cultivars and selections: seedling vigor, quality (every month), color, disease incidence, and Poa annua encroachment. Quality ratings are a measure of density, texture, uniformity, and lack of disease.
Summary of Results
Data for evaluation ratings are presented in Tables 1 and 2. All cultivars listed in these tables are commercially available except AFM and SRP-1BLTR3.
Turfgrass Quality
V-8, Barracuda, Luminary, Pure Distinction, Focus, and Proclamation tended to receive the highest average quality ratings from 2009-2013 (Table 1). These cultivars generally ranked higher than other entries primarily due to their superior density, fine texture, and uniformity. Two velvet bentgrasses - Villa and SR 7200 - performed poorly over most of the five-year test period.
Bentgrass Quality Rating Averaged Over Growing Season§
| Entry | Bentgrass Species | 2009 | 2010 | 2011 | 2012 | 2013 | 5-year Avg. |
|---|---|---|---|---|---|---|---|
| V8 | Creeping | 7.5 | 8.2 | 7.8 | 7 | 7.9 | 7.7 |
| Barracuda | Creeping | 7.7 | 7.8 | 7.7 | 7 | 7.6 | 7.6 |
| Luminary | Creeping | 7.6 | 7.8 | 7.7 | 6.7 | 7.4 | 7.4 |
| Pure Distinction | Creeping | 7.4 | 7.7 | 8 | 5.5 | 7.9 | 7.3 |
| Focus | Creeping | 7.3 | 7.6 | 7.2 | 7 | 7.3 | 7.3 |
| Proclamation | Creeping | 7 | 7.4 | 7.2 | 6.7 | 6.9 | 7 |
| Pinup | Creeping | 6.5 | 7 | 6.9 | 6.6 | 7.2 | 6.8 |
| Declaration | Creeping | 7.2 | 7.2 | 6.4 | 6.7 | 6.5 | 6.8 |
| Authority | Creeping | 6.9 | 7.3 | 6.8 | 5.9 | 5.9 | 6.6 |
| T-1 | Creeping | 7.1 | 7.6 | 6.2 | 5.1 | 5.3 | 6.3 |
| AFM | Creeping | 5.6 | 6.9 | 5.9 | 6.4 | 6.3 | 6.2 |
| SRP-1BLTR3 | Creeping | 6.4 | 7 | 6.3 | 5 | 6.3 | 6.2 |
| Alpha | Creeping | 6.6 | 6.8 | 5.4 | 5.1 | 5.4 | 5.9 |
| Penn A-1 | Creeping | 6.2 | 6.4 | 5.1 | 5.2 | 5.2 | 5.6 |
| Penn A-2 | Creeping | 5.3 | 6.1 | 4.9 | 4.9 | 5.1 | 5.3 |
| L-93 | Creeping | 5.6 | 6 | 4.6 | 4.2 | 4.5 | 5 |
| Penncross | Creeping | 4.8 | 4.7 | 3.3 | 2.9 | 3.5 | 3.8 |
| Villa | Velvet | 5.7 | 4.5 | 2 | 1.3 | 1 | 2.9 |
| SR 7200 | Velvet | 4.7 | 3 | 1.1 | 0.6 | 1 | 2.1 |
| LSDǂ | 1.1 | 1 | 1.2 | 1 | 0.9 | --- |
§Quality ratings indicate the overall appearance of the turf and can incorporate several components including: density, texture, uniformity, and freedom from disease and insect damage. Quality is rated using a scale of 1 to 9, where 9 = highest quality.
ǂLSD = Least significant difference. Differences between two entries are statistically significant only if the LSD value, listed at the bottom of each column, is exceeded by the numerical difference between two entries. For example, if cultivar 'A' is 1.0 unit higher in quality than cultivar 'B', then this difference is only significant if the LSD value is 1.0 or less.
Seedling Vigor
Seedling vigor following seeding in September of 2008 was greatest with Proclamation, L-93, Penncross, and Declaration; however, ten other cultivars and selections showed seedling vigor that was very close to these four cultivars (Table 2). Cultivars that were slowest to establish were V8 and Penn A-2. By the end of the growing season, most of the plots in this test showed complete turf cover and were able to tolerate daily mowing.
Turfgrass Color
Turfgrass color ratings show that T-1 had the darkest green color, followed by Pinup (Table 2). Pure Distinction and Villa exhibited the lightest shade of green. Although genetic color of a cultivar does not influence putting performance, it can make a difference in the aesthetic appeal of the green. Whereas most people tend to favor darker green over lighter green, P. annua tends to stand out more in darker green bentgrass stands and can detract from the visual appearance of the putting surface. Color can also be an important factor when blending two or more cultivars. Bentgrasses tend to segregate over time, and a light-green cultivar blended with a dark-green cultivar may lead to a patchy appearance of the putting green.
Dollar Spot Susceptibility
Differences in dollar spot susceptibility were noticed among bentgrass entries. Both velvet bentgrasses (Villa and SR 7200) and several creeping bentgrasses showed very good tolerance to dollar spot during the test period (Table 2). Creeping bentgrass cultivars with the least amount of dollar spot included Barracuda, Declaration, Focus, V8, Luminary, Pinup, AFM, Authority, and Proclamation. According to test data, the least tolerant cultivars were SRP-1BLTR3, Pure Distinction, and Penncross. Alpha, Penn A-1, L-93, and Penn A-2 showed intermediate tolerance. In past NTEP trials, L-93 and Penn A-1 were among the top-performing creeping bentgrasses with respect to dollar spot tolerance, but data from this latest test show improved tolerance among some of the new creeping bentgrasses.
| Entry | Bentgrass Species | Seedling Vigor§ | Genetic Color§ | Dollar Spot Tolerance§ | Poa annua Encroachment§ |
|---|---|---|---|---|---|
| V8 | Creeping | 5.3 | 5.9 | 8.4 | 8 |
| Barracuda | Creeping | 6.7 | 5.1 | 8.8 | 8 |
| Luminary | Creeping | 7 | 5.8 | 8.3 | 8 |
| Pure Distinction | Creeping | 7 | 3.4 | 5.4 | 8.7 |
| Focus | Creeping | 7 | 5.7 | 8.6 | 8 |
| Proclamation | Creeping | 8 | 5.7 | 7.8 | 8.3 |
| Pin-up | Creeping | 6 | 6.9 | 8.3 | 8 |
| Declaration | Creeping | 7.3 | 5.1 | 8.8 | 8 |
| Authority | Creeping | 6.7 | 5.9 | 7.9 | 7.3 |
| T-1 | Creeping | 6.7 | 8.9 | 6.7 | 6.7 |
| AFM | Creeping | 6.7 | 4.8 | 8.2 | 7.3 |
| SRP-1BLTR3 | Creeping | 6 | 4.9 | 4.9 | 7.7 |
| Alpha | Creeping | 7.3 | 6.3 | 7.3 | 6.7 |
| Penn A-1 | Creeping | 7.1 | 6.3 | 7.3 | 5.7 |
| Penn A-2 | Creeping | 5.3 | 6.1 | 6.9 | 6.7 |
| L-93 | Creeping | 7.7 | 5.8 | 7.2 | 5.3 |
| Penncross | Creeping | 7.7 | 6 | 6.2 | 4.3 |
| Villa | Velvet | 7 | 4 | 9 | 5.3 |
| SR 7200 | Velvet | 7 | 4.6 | 9 | 2.7 |
| LSDǂ | 0.8 | 1 | 1.4 | 1.3 |
§Numerical ratings indicate seedling vigor (estimate of percent ground cover and plant height during the early stages of seedling establishment), genetic color (9 = darkest green color and 1 = yellow-green), tolerance to dollar spot (9 = no disease present and 1 = extensive disease damage), and P. annua encroachment (9 = no P. annua encroachment and 1 = extensive contamination).
ǂLSD = Least significant difference. Differences between two entries are statistically significant only if the LSD value, listed at the bottom of each column, is exceeded by the numerical difference between two entries. For example, if cultivar 'A' is 1.0 unit higher in quality than cultivar 'B', then this difference is only significant if the LSD value is 1.0 or less.
Resistance to P. annua Encroachment
One of the most important factors in selecting a bentgrass cultivar for putting greens is its ability to compete with P. annua. Poa annua began to move into the test area in 2011, and plots of certain cultivars became more heavily infested than others. Cultivars with the least amount of P. annua included Pure Distinction, Proclamation, V-8, Barracuda, Luminary, Focus, Pinup, Declaration, and SRP-1BLTR3. The greatest amount of P. annua was found in plots of velvet bentgrass (SR 7200 and Villa), L-93, and Penncross.
The results of this test reflect cultivar performance for the management regime imposed at this site and environmental conditions in central Pennsylvania. Several popular bentgrasses used on golf courses in the mid-Atlantic region (007, Penn A-4, Tyee, McKenzie, and others) were not included in this test. These cultivars were evaluated in previous NTEP tests and data from these tests can be found on the NTEP website. A new round of tests was initiated in 2014 and contains several new cultivars.
