b'According to Carver, Orange Blossom CL+ is likely one of the last Clearfield vari-eties developed at OSU using a closed-loop breeding system, where all parents carried two-gene CL Plus herbicide tolerance.This allowed me to ratchet up selec-tion pressure for grain yield with the assurance we would not sacrifice past gains in key traits like herbicide tolerance, he says.Early Stripe Rust Resistance Expands Protection WindowThe stripe rust resistance package is a notable feature, with protection appear-ing earlier than in most wheat varieties grown in the region.Stripe rust resistance in Southern and Central Plains wheat varieties is largely of the adult-plant kind, which does not usu-ally kick in until after anthesis or flower-ing, Carver says. In some years, thats enoughbut in years like 2024 and 2021, we needed protection earlier in crop development to have a better chance of realizing yield potential.This earlier resistance could offer an advantage for growers in seasons with high early disease pressure, particularlyGreenhouse-grown Orange Blossom CL+ wheat showing uniform growth and head when fungicide use is limited. development during late-stage trials at Oklahoma State University.PHOTO: BRETT CARVER/OSUEvolving Leaf Rust PathogensDeeper Planting Flexibility Prompt New Breeding Strategies Emerges After ReleaseData from the 20232024 growingCarver says the variety also showed season also highlighted new challenges.deeper planting ability, which may be Carver and his team observed reactionsuseful in drier planting windows. This to leaf rust in Orange Blossom CL+ thattrait, identified after the initial release, is suggest emerging pathogen races arelinked to a longer coleoptile.shifting the resistance landscape. The deeper planting ability of We already knew this, but the leafOrange Blossom CL Plus stems from its rust reaction we saw on Orange Blossomlonger coleoptile, which can be an asset CL+ late in the 20232024 season pro- in either [grain-only or dual-purpose] vided a stark reminder of the importancesystem, Carver says. We did not know of deepening and broadening our leafthis important fitness characteristic rust packages moving forward, Carveruntil after its release, and we credit our says. For leaf rust, we have to add moreOSU wheat genetics chair and regentswheat extension specialist Amanda Silva stuff to the stew by combining differentprofessor Brett Carver. for discovering it.kinds of resistance into each variety, suchCarver emphasizes that planting as all-season resistance and adult-plantOrange Blossom CL+ does not carry anyflexibility could benefit producers work-resistance. of the known leaf rust resistance genesing in dual-purpose grazing and grain That ongoing effort is led by OSUcommonly deployed in hard winter wheatsystems by increasing access to soil wheat pathologist Meriem Aoun.grown in the US Great Plains, she says.moisture during fall droughts.Orange Blossom CL+ is resistant toWe are quickly working to identify andBroader fitness allows wheat pro-prevalent leaf rust pathogen races incharacterize the novel leaf rust and stripeducers greater freedom to operate, he Oklahoma. Based on molecular markers,rust resistance genes in this cultivar. adds.66/ SEEDWORLD.COMDECEMBER 2025'