New OSU Orange Blossom CL+ wheat variety brings a strong resistance package to Oklahoma fields

Monday, April 28, 2025

Media Contact: Alisa Gore | Office of Communications & Marketing, OSU Agriculture | 405-744-7115 | alisa.gore@okstate.edu

Oklahoma wheat fields are overdue for another groundbreaking wheat comparable to the Doublestop CL Plus variety with strong disease resistance and good protein content.

Oklahoma State University Agriculture will launch a new Clearfield wheat variety this summer with all the strong qualities the wheat industry needs, such as high yield potential, strong tolerance to leaf rust, stripe rust and spring freezes, and good milling quality.

High yield potential means a more profitable crop for producers. The greatest virtue of the Orange Blossom variety is its ability to fight off stripe rust infection in multiple environments, beginning with stem extension. This protects the high yield potential that comes from Clearfield genetics. Stripe rust, which has become a problem in Oklahoma, can cause low yields for farmers, reducing the amount of wheat available in the food industry for bread and other grain products.

OSU has not released a Clearfield variety in several years, with Doublestop CL Plus released in 2013 and Strad CL Plus in 2017. Clearfield Plus varieties have strong resistance to the annual grass control herbicide called Beyond due to two gene mutations within the Clearfield genetic line.

“The time was ripe for an upgrade. Given the popularity of Doublestop CL Plus with Oklahoma and south-central Kansas wheat producers, it made sense that upgrade would come from Doublestop CL Plus genetics,” said Dr. Brett Carver, wheat genetics chair and regents professor in the OSU Department of Plant and Soil Sciences. “I wanted the new variety name to connect to its direct parent, Doublestop CL Plus, in a musical way and to OSU (with orange as the school color) as the variety developer. The name Orange Blossom CL+ was one way to cover both.”

Orange Blossom Special is a famous, fast-paced musical piece created by Ervin T. Rouse in the 1930s, primarily played with a fiddle. The song also uses double stops, a musical technique of simultaneously playing two notes simultaneously on a stringed instrument.

After six years of field trials across the state, OSU Wheat Improvement Team members are confident that this variety, with about 66% Doublestop CL Plus lineage, is well adapted to Oklahoma's various climate conditions and pest pressures.

The following are the variety’s characteristics:

• Strong yield potential in the absence of a fungicide – Orange Blossom CL+ exceeded Doublestop CL Plus in yield by nearly 15%, while its test weight was equal to or slightly better than Doublestop.

“This is an extremely rare trait combination inside or outside the Clearfield genetic pipeline,” Carver said. “Surpassing the yield of Doublestop CL Plus alone is not so extraordinary, but to couple this yield advantage with a comparable or slightly higher test weight would be difficult to repeat.”

• Orange Blossom CL+ has a high tolerance to leaf rust, stripe rust and spring freezes. It offers significant improvement over Doublestop CL Plus, and possibly Strad CL Plus, for protection against leaf rust. In Oklahoma and Washington, where stripe rust infections can be catastrophic, the variety displayed developmentally earlier and stronger resistance than almost 95% of the elite germplasm in the OSU wheat variety development program.

“Growers should be aware of a change in the leaf rust pathogen population observed late in the 2023-24 crop season,” Carver warned. “New races exist that could compromise the leaf rust resistance of Orange Blossom CL+ and many other varieties.”

• Orange Blossom CL+ has dual-purpose potential with good forage production and grazing recovery and an extended grazing period similar to the Doublestop CL Plus variety. Orange Blossom CL+ can be planted deeper than most varieties due to a longer-than-average stem-like structure. Dual-purpose means cattle can graze the wheat during its vegetative state before it grows grain. This reduces feed costs for cattle producers.
• The new variety has a high wheat protein concentration that is only slightly below Doublestop CL Plus.
• The milling quality of Orange Blossom CL+ is exceptional, but the baking quality is only average due to an estimated 30% reduction in mixing tolerance compared to Doublestop CL Plus. The protein concentration and water absorption of its flour are above average for hard red winter wheat. This means it will fit well into the grain commodity system, where grains are blended to make bread products.
• Potential weaknesses of the new variety include a variable reaction to barley yellow dwarf, which was moderately susceptible at worst, and a susceptible reaction to wheat soilborne mosaic.

“We have a good combination of yield, protein and test weight, and we have the testing rigor to back it up,’ Carver said. “Wheat Improvement Team scientists hesitate to classify the stripe rust resistance in Orange Blossom CL+ as all-season resistance because seedling assays of the Orange Blossom revealed susceptibility. Nevertheless, this stripe rust resistance package – which only OK Corral can come close to – is robust and currently highly reliable and far superior to that of Showdown, High Cotton and Doublestop CL Plus.”

Carver leads the Wheat Improvement Team, a multi-disciplinary group of scientists committed to strengthening the Oklahoma wheat industry by developing highly adapted winter wheat cultivars with marketable grain quality.

OSU Agriculture recently launched an Agronomy Discovery Center fundraising initiative to upgrade the existing Agronomy Research Station at OSU, which is home to the Wheat Improvement Team. Plans for the Agronomy Discovery Center include the construction of a new headhouse, 12 research greenhouses and a dynamic and multipurpose Research and Education Center. The new center will also house laboratory spaces for the Wheat Quality Laboratory; Soil, Water and Forage Analytical Laboratory; and the Plant Disease and Insect Diagnostic Laboratory.

“We are doing state-of-the-art research, but we are doing it in antiquated facilities,” said Jayson Lusk, vice president and dean of OSU Agriculture. “The Agronomy Discovery Center will provide the infrastructure we need to compete in the modern era, continue to produce new wheat varieties and achieve our mission of feeding and nourishing the world.”

A limited quantity of seeds for Orange Blossom CL+ will be commercially available to producers at the OSU Foundation Seed Stocks this summer for fall planting.