The search for a new and improved bermudagrass for California is over. After six years of testing over a hundred experimental lines in the Southern and Central California climate, the top candidate was identified: OKC-09.

The Turf Research Bermuda California (TRBC) project is a partnership between A-G Sod Farms, Oklahoma State University (OSU) and Sod Solutions. The research project was created with the objective of identifying a new bermudagrass variety with high agronomic performance in the southern and central parts of the state. Winter color retention and drought tolerance are the two most desirable characteristics sought after in the new grass. Additionally, dark green genetic color, less seed head production and reduced vertical growth were also important and needed to be incorporated into the final selection as well.

Initial Experimental Design

One hundred experimental bermudagrass selections developed by OSU were established in a randomized complete block design in three replications. The trial was planted at A-G Sod Farm in Nuevo, CA on May 17, 2016. After three years of testing, 11 experimental lines were selected and moved to the second phase. The selection was based on the traits mentioned above.

The top 11 entries selected were:

OKC-09                          OKC-26                       OKC-42

OKC-10                          OKC-35                        OKC-44

OKC-15                          OKC-37                         OKC-55

OKC-22                                                                  OKC-91

Second Phase

The objective of the second phase was to test sod strength, drought tolerance and cold tolerance at two locations: Nuevo and Fresno.

The experimental layout was 5-by-20-foot plots with two replications. Each plot was planted with plugs produced in a greenhouse in Nebraska during the early spring of 2019. Plug trays were planted using sprigs collected in Nuevo at the original plots.

The test plot area was planted in April 2019 (Nuevo) and in May 2019 (Fresno). After several evaluations during the summer of 2019 including a dry-down period, four final candidates were selected to advance to a third and final rounds of testing.

OKC-09        OKC-10        OKC-44       OCS-243

Third Phase

The third phase was planted in June 2021. All final four selections were planted in Nuevo and Selma, CA. This time plot areas were much larger (20-by-25 feet) in order to allow harvesting to test tensile strength and also provide more plant stock material for expansion of the final selection. Besides evaluating the performance of the grasses during the summer, winter color was rated during the winter of that year and all four experimental lines went into a dry-down period during August 2022.

The experimental line OKC-09 had the best summer performance as well as the best look during and after the dry-down period. OKC-09 also had the best tensile strength of the final four selected lines. Results were the same in Nuevo and Selma, which confirms the ability of OKC-09 to perform well in both locations.

OKC- 09 will be expanded in 2023 into a Breeder Block area, between half an acre to one acre in size. The location is still to be determined but it will probably be in Central California at one of the sod farms that A-G Sod has there. It will be the starting point and the source of plant stock material for future expansions. OKC-09 will receive a commercial trademarked name in 2023.

Summary: (Make the Summary a chart design element on the page.)

• 2016 – Planting of 100 entries in Nuevo, CA

• 2017 – Evaluations and ratings collected.

• 2018 – Evaluations and ratings collected.

• 2019 – Selection of the 11 best entries. Planting of the second phase.

• 2020 – Evaluations and ratings collected. First dry-down test.

• 2021 – Selection of the best 4 entries. Planting of the third phase.

• 2022 – Evaluations and second dry-down test.

• 2022 – Final selection: OKC-09