New Pima cotton variety shows gains in yield and disease tolerance
PhytoGen cottonseed, a Corteva brand, has announced a new Pima cotton variety for the 2026 growing season designed to improve yield potential and tolerance to Fusarium Race 4, a persistent disease affecting Pima cotton production in the Southwest.
The new variety, PHY 859 RF, was advanced following breeder and university trials that showed consistent yield performance and fiber quality. Company officials said the variety builds on earlier Pima releases while addressing disease pressures identified in California and Arizona.
Joel Faircloth, portfolio leader for cotton at Corteva, said the variety has been tested for several years and has performed at or above the level of PHY 861 RF, a widely planted Pima variety. He noted that increased tolerance to Fusarium Race 4 and a slightly higher micronaire were key traits identified by growers.
In company breeding trials, PHY 859 RF averaged 1,751 pounds per acre with a micronaire of 4.3. That represents a 13-pound-per-acre advantage over PHY 861 RF and a 0.1 increase in micronaire, according to Corteva data.
Fusarium Race 4 remains a primary production concern for Pima growers, particularly in California. Dan Gorman, global cotton breeding lead for Corteva, said multiple strains of the pathogen have been identified in the region, prompting the company to incorporate those strains into its breeding program.
Gorman said breeders use both field evaluations and laboratory screenings to assess tolerance, allowing multiple evaluations per year and helping identify genetic lines with improved resistance.
The variety also performed well in university testing. PHY 859 RF was the top entry in the University of Arizona’s 2025 Pima Cotton Variety Trial at Thatcher, yielding 1,403 pounds per acre, 137 pounds above the trial average. It also recorded the highest fiber length at a 52 staple and a 4.2 micronaire.
Kristen Nelson, a PhytoGen product agronomist for California and Arizona, said the variety has been evaluated across multiple growing environments and is intended to help growers balance yield, fiber quality and disease management.
Company officials said the development reflects ongoing investment in Pima breeding and research infrastructure, including operations in Corcoran, California.
For more information, see a representative or visit PhytoGen.com.
