The Fight Against FOV4 Continues In Texas

Christi Short
Rochester, Texas

In 2019, I wrote an article on the Cotton Research and Promotion Program’s work in California to identify and stop the spread of Fusarium wilt race 4 (FOV4) in Pima and Upland cotton. Substantial progress had been made in Pima cotton as FOV4-resistant varieties were widely available for a decade as a result of previous research investments in the Far West. However, similar resistance had not been identified in Upland cotton.

The battle against FOV4 is now intensely focused on Texas, as damage from this pathogen has been observed in the state. Several areas around El Paso have served as “ground zero” for the disease because fields have been observed as heavily infested with FOV4. In 2018, Dr. Don Jones, Agricultural and Environmental Research Director at Cotton Incorporated, approached Dr. Jim Olvey, a private cotton breeder with O&A Enterprises, to begin field screening Upland germplasm on a massive scale at a site with high FOV4 spore count. At the same time, Dr. Christopher Saski, a Clemson University scientist, joined the collaboration by directing the molecular aspects of the project. Their objectives were to identify and publicly release highly FOV4-resistant germplasm and identify the causative genes for the resistance.

“This public-private sector collaboration is a model seldom funded by Cotton Incorporated,” said Dr. Jones. “Dr. Olvey and his small team at O&A Enterprises had two decades of proven field screening techniques that had resulted in highly FOV4-resistant Pima varieties, and he agreed to share his knowledge with the entire Upland cotton community by managing the field screening operation.”

Field Screening Success

In 2018, dozens of scientists from across the Cotton Belt sent in lines for FOV4 field screening. Dr. Saski and his doctoral student, Stephen Parris, established a new laboratory screening protocol, applied a novel statistical technique to analyze field results and identified the resistance genes and associated molecular markers. Dr. Jones credits the collaboration of a field-focused breeding team with a couple of gifted molecular biologists to the success of identifying resistant germplasm and understanding which specific genes provided resistance.

As a result of this extensive project, four Upland cotton germ-plasm lines, U1 (2021), U2 (2022), U3 (2022) and U4 (2022), are publicly available. Each is highly resistant to FOV4 and is a germplasm source available to seed providers as they work to incorporate these into future varieties from their companies. In addition, two causative resistance genes were identified. The first is on the D03 chromosome and the second on the A02 chromosome. Both genes are needed for high FOV4 resistance.

El Paso’s Role

In addition to this massive breeding and genomic project, Dr. Libo Shan, a plant pathologist with the University of Michigan, formerly at Texas A&M University, has been very involved in the effort against FOV4. Since 2016, Dr. Shan has collaborated with Cotton Incorporated and research plant breeders to monitor field symptoms and outbreaks of FOV4 that have been seen across Texas. Specifically, El Paso has provided researchers with the unique opportunity to observe the evolution of FOV4 year after year.

Aerial view of large-scale field screens for FOV4-resistant germplasms in El Paso, Texas.

“The field data and pathology work we did in El Paso hot spots has allowed us not only to monitor symptoms in the field, but also compare lab data, and ultimately discover pathogenic mechanisms. The reason this particular FOV4 outbreak has been so aggressive is because it has, and will continue to evolve,” said Dr. Shan. “It’s impossible to get rid of FOV4, but with the partnership and work of pathologists, plant breeders and geneticists, we can predict the evolutionary trends of this disease and have a strategy to minimize damage and devastation to the lowest level.”

Investment in establishing groundwork on the FOV4 disease, resistant varieties and future implications of FOV4 are top priorities for the agricultural research team at Cotton Incorporated. Not only will these collaborations continue to combat FOV4 in the years to come, but they will also allow research models to be used for outbreaks of different diseases in the future. With the support of Cotton Incorporated, these Upland cotton lines are publicly available, and work has been done to move the needle on molecular genetic techniques, diagnostic processes and observation of the evolutionary trajectory of cotton diseases.

For questions on FOV4, reach out to Dr. Don Jones at Cotton Incorporated at 

Christi Short is The Cotton Board’s regional communications manager for the Southwest. Email her at

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