Database Research Summaries
Developing Tools to Protect Soybean Stand from Seedling Disease caused by Pythium Species

calendar_today Year of Research: 2018
update Posted On: 05/23/2019
group Alison Robertson (Principal Investigator, Iowa State University)
bookmark Iowa Soybean Association

Research Focus

The focus of this project is to increase soybean farmer competitiveness through the development of improved tools that will improve productivity and profitability while improving environmental stewardship. Specifically, this project will improve our understanding of the soybean-Pythium interaction.


  • Determine how timing of cold stress affects susceptibility to Pythium.
  • Identify when during germination and emergence are soybeans most susceptible to Pythium.
  • Determine if cold tolerance and susceptibility to Pythium is correlated.
  • Develop a seedling disease risk assessment model that growers could use to schedule planting.


  1. We determined that cold (<50F) stress periods (2 to 4 days long) that occur 1 to 4 days after planting increase susceptibility to Pythium and consequently reduce emergence and stand count.
  2. Susceptibility of soybean to infection by Pythium depended on the species and temperature at planting. In general, soybean was very susceptible during the early stages of germination (inbibition, radicle emergence, hypocotyl elongation) and susceptibility declines as the soybeans emerge.
  3. We screened the SoyNAM parents, and varieties that vary in resistance to cold tolerance, for susceptibility to Pythium. Data were confounded by seed quality, and further studies were not pursued.
  4. Data from Objective 1 and 2 were used to start developing a seedling disease risk model. Additional experiments to provide data on the effect of planting depth, soil temperature and moisture are currently in progress. These data are needed for improved model development. The model will be validated using data from seed treatment trials that has been captured


  • This data will be used to develop a seedling disease risk tool that soybean farmers could use to schedule planting and make seed treatment decisions to ensure successful stand establishment.

For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.