‘Alpha’ and ‘T-1’ Creeping Bentgrass, New Cultivars for Golf (2024)

Keywords: turfgrass breeding; golf course; putting green; Agrostis stolonifera; Poa annua; interseeding; competition

Origin

The origins of ‘Alpha’ and ‘T-1’ trace to two sources:

1. Selections of segregated patches from old putting greens in Massachusetts, Rhode Island, Connecticut, North Carolina, and South Carolina. These golf courses were 30 to 100 years old and were likely sown to ‘South German Bentgrass’ or ‘Penncross’.

2. Selections of low growing plants from a herbicide-damaged Foundation field of ‘Putter’ creeping bentgrass (Brauen et al., 1993) in Oregon's Willamette Valley. In June 1994, a seed production field had been damaged by herbicide overapplication. For unknown reasons, the herbicide killed the taller-growing strains, leaving a population of compact, understory plants.

Clones from these two sources were grown to 3 cm in a glass house and transplanted on a grid pattern into a 1-ha mature annual bluegrass test putting green in Post Falls, ID, in 1994, mowed at 4-mm height (Fig. 1). Clones were evaluated monthly over 4 years. Those that effectively competed with annual bluegrass and grew into a sizable patch with visually attractive, dense turf and minimal thatch were selected. Selected clones were established in one of several Oregon polycross blocks based on similar phenotype; the progeny of these clones were established in a repeated clonal turf planting in 1996 and in a seeded turf trial in 1998. Breeder blocks of ‘Alpha’ and ‘T-1,’ established near Post Falls in May 1999, were comprised of top-performing lines from these two trials.

The ‘Alpha’ breeder block consisted of 2000 plants selected from the 15 top-performing entries in the 1998 seeded turf trial. Plants in this breeder block originated from seed, and as such, each was genetically unique. Approximately 8% of plants were removed before anthesis as a result of nonuniformity. Three of the 15 lines in ‘Alpha’ trace to line 98-0018 from Oregon polycross 94-8283 originating from a clone from a Massachusetts golf course. Ten pollen parents in that Oregon polycross originated from Massachusetts and South Carolina putting greens and selections from the cultivar, ‘Putter’. Three of the 15 lines in ‘Alpha’ trace to 98-0248 from Oregon polycross 94-8282 from a North Carolina golf green. Twenty-two pollen parents in that Oregon polycross originated from Connecticut, Massachusetts, North Carolina, and South Carolina golf greens and from ‘Putter’. The remaining lines trace to ‘Putter’ Foundation field selections.

The ‘T-1’ breeder block was established from 1000 plants of 11 clonal lines selected from the top competitors in the annual bluegrass putting green trial. The breeder block was planted in randomized, replicated clonal rows. One clone, 98-0172, traced to a selection from the cultivar ‘Providence’ (Skogley, 1987). One clone, 98-0167, traced to a plant selected from a South Carolina putting green, pollinated in Oregon polycross 94-8283, described previously. One clone, 98-0157, traced to a ‘Putter’ selection pollinated in Oregon polycross 94-8282. Three clones, 98-0160, 98-0163, and 98-0168, traced to Oregon polycross 94-8283 and originated from two Massachusetts golf greens. The remaining clones trace to Oregon polycross 94-8283 and ‘Putter’.

In summary, both ‘Alpha’ and ‘T-1’ were composed of ≈50% low-growing selections from ‘Putter’. The remaining background originated from selections from old New England and Carolina golf courses. ‘T-1’ also contains 10% germplasm from ‘Providence’.

Description

Plant breeding over the past 50 years has improved the performance of golf course grasses. Harivandi et al. (2005) observed differences between modern bentgrass cultivars and older types in quality, color, leaf texture, and resistance to annual bluegrass invasion.

In plots in Post Falls maintained under simulated putting green conditions (4-mm mowing height), a Noer soil profile sampler was used to quantify shoot density. ‘Alpha’ had a summer density of 25 shoots per cm², ‘T-1’ 18 shoots per cm², and ‘Penncross’ 8 shoots per cm² (a statistical analysis was not performed). These shoot counts were comparable to visual density ratings taken across nine U.S. states and one Canadian province by university researchers (Morris, 2006). ‘Alpha’ and ‘T-1’ share several characteristics in common, including a moderate to high shoot density but differ in color. ‘T-1’ is distinctly blue–green in color, darker than any other cultivar (Morris 2005, 2006). ‘Alpha’ is medium dark green in color.

In North American university trials, ‘Alpha’ and ‘T-1’ performed well across various geographies and management regimes and showed improved resistance to annual bluegrass encroachment under tee or fairway mowing heights (1 to 2 cm), particularly in Indiana and Wisconsin (Morris, 2005, 2006).

Competing against annual bluegrass is challenging for any creeping bentgrass cultivar (Harivandi et al., 2005). However, interseeding bentgrass into a mature annual bluegrass putting green is a far more difficult assignment. In interseeding, bentgrass seeds must germinate and compete against full-grown annual bluegrass plants while the putting green is under daily golf play and maintenance.

Bigelow and Chalmers (1995) studied interseeding into mature annual bluegrass using a 1980s creeping bentgrass cultivar, ‘Southshore’ (Hurley et al., 1994). They found that spring sowing resulted in the greatest increase in creeping bentgrass populations for all treatments. Henry et al. (2005) found that a combination of early summer planting and improved cultivars were the most successful for establishing bentgrass into annual bluegrass.

To demonstrate the interseeding ability of ‘Alpha’ and ‘T-1’, a trial was established 15 Apr. 2005 on the same annual bluegrass test green described. ‘Alpha’, ‘T-1’, and ‘Southshore’ were established in 3.8-m² plots at a 5, 10, or 20 g·m⁻² seeding rate in a factorial arrangement with four replications along with an unseeded control. Cultivars were seeded and topdressed with 1 mm of sand and raked to incorporate; no core aerification or vertical mowing was used. On 15 Sept. 2005, two of the four replications were seeded again to the same seeding rates and cultivars forming a set of combination spring–fall treatments with two replicates each. The plot area was mowed three times per week with clippings returned and irrigated once daily to prevent stress. The area was fertilized with 15 g·m⁻²/year nitrogen. Bentgrass surface area estimates were taken by visual estimates. All plots started the trial at 0% bentgrass. Note that a proportion of bentgrass observed in the control and probably the ‘Southshore’ plots came from ‘Alpha’ or ‘T-1’ stolons or seed migrating into the plot (Table 1).

Data analysis (analysis and least significant difference_0.05) revealed only cultivar to be the significant factor. Therefore, cultivar means were averaged across seeding date and rate treatments. Results showed that ‘Alpha’ and ‘T-1’ were able to establish by seed more readily than an earlier cultivar. By the end of 1.3 years in this trial, a majority of the surface area had transitioned from annual bluegrass to creeping bentgrass. More research is needed to verify whether results of this single-site experiment can apply to a variety of golf course conditions.

Availability

Seed of ‘Alpha’ and ‘T-1’ is produced and Breeder seed is maintained by Simplot. Seed propagation is limited to four cycles of increase Breeder, Foundation, Registered, and Certified. ‘Alpha’ and ‘T-1’ and all germplasm derived therefrom are protected under pending U.S. utility patents 10/872,695 and 10/872,697, respectively. Unauthorized breeding from the cultivars is prohibited. Seed samples are available from the author for research and testing purposes.