Evaluation of Some New Bentgrasses for Putting Greens

Choosing the right bentgrass cultivar is critical for long-term performance of your putting surfaces.
Evaluation of Some New Bentgrasses for Putting Greens - Articles
Evaluation of Some New Bentgrasses for Putting Greens

Photo: P. Landschoot, Penn State

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 colonials, and about half a dozen velvets on the seed market. Having so many choices is a good thing, but now you have to do some homework on which bentgrass is right for your situation.

Getting reliable information on turfgrass 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 first-hand. Keep in mind, however, these courses may not have the same conditions and resources as yours; thus, the results at your course may be different. Be sure to talk with USGA 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 in each rep. 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.

Photo: The 2008-2013 NTEP putting green test site at Penn State. P. Landschoot, Penn State

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-1 BLTR3.

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.

Table 1. Quality ratings for the 2008-2013 National Turfgrass Evaluation Program Bentgrass Putting Green Test at Penn State. Data represent averages of monthly quality ratings for each year of the 5-year test. Quality is rated on a scale on 9 to 1, with 9 = highest quality.

Bentgrass Quality Rating Averaged Over Growing Season§

EntryBentgrass Species200920102011201220135-year Avg.
Pure DistinctionCreeping7.47.785.57.97.3
Penn A-1Creeping6.
Penn A-2Creeping5.
SR 7200Velvet4.731.10.612.1
LSDǂ1.111.210.9 ---

§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 s = 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.

Photo: Plot of V-8 creeping bentgrass showing very good density, texture, and uniformity. P. Landschoot, Penn State

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, Pin-up, 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.

Table 2. Seedling vigor, color, dollar spot, and Poa annua ratings for the 2008-2013 National Turfgrass Evaluation Program Bentgrass Putting Green Test. Ratings are based on a scale on 9 to 1, with 9 = fastest establishment, darkest green color, no dollar spot present, and no Poa annua encroachment.

EntryBentgrass SpeciesSeedling Vigor§Genetic Color§Dollar Spot Tolerance§Poa annua Encroachment§
Pure DistinctionCreeping73.45.48.7
Penn A-1Creeping7.
Penn A-2Creeping5.
SR 7200Velvet74.692.7

§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 Poa 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.

Photo: Differences in dollar spot susceptibility among bentgrass cultivars in mid-October of 2012. P. Landschoot, Penn State

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, Pin-up, 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. Time will tell if the trends for cultivar improvement continue.