The Search for Improved Pythium Tolerance in Spinach
May 1, 2026 
Photo: Cultiva
Researchers at the University of Arkansas Division of Agriculture are aiming to improve spinach tolerance to Pythium, a common, fungus-like pathogen that causes root rot, thrives in moist conditions, and is especially prevalent in controlled environments, including greenhouses, hydroponics, and indoor farming operations.
Funding for the project to identify spinach cultivars tolerant of multiple Pythium variants has come from a U.S. Department of Agriculture’s National Institute of Food and Agriculture (USDA-NIFA) three-year grant of $615,000, awarded to vegetable breeder Ainong Shi and his team at the Arkansas Agricultural Experiment Station. This single grant is part of a larger $10.2 million in funding toward 18 projects to support public breeding efforts “aimed at improving crop productivity, efficiency, and performance.”
Why Spinach Is Particularly Vulnerable to Pythium
Shi notes that, compared to other crops of note, most spinach cultivars were developed for open fields, making them unprepared for indoor controlled-environment conditions. Additionally, while a few varieties have been identified for partial tolerance, “There are currently no highly resistant cultivars of spinach.”
To speed up the selection process of different spinach varieties, Shi and his team use a data-driven approach to estimate Pythium tolerance by evaluating 480 diverse spinach genotypes, with sources including:
- 400 from the USDA Agricultural Research Service’s Germplasm Resources Information Network
- 50 commercial cultivars and hybrids
- 30 Arkansas breeding lines.
The goal for the project, titled “Development of Genomic Resources for Pythium Tolerance in Spinach,” is to “identify more than 30 Pythium-tolerant spinach lines and validate genomic prediction models.”
For additional information on the details of the USDA-NIFA grant and collaborators involved in the project, please read the full article here.