Several fungi can cause seedling diseases. Pythium and Phytophthora are closely related fungi and most chemicals have the same efficacy for the two fungi. In a wet season in early planted fields, Pythium should be the major targeted fungus. Phytophthora likes warmer soil and, therefore, causes stand problems in late-planted soybeans. If you do not know what type of fungi may be causing stand reduction in your fields, target Rhizoctonia, Pythium , and Phytophthora because these three fungi account for 90 percent of seedling disease problems in Iowa.
Some products contain several different compounds effective to control all three fungi.
Pathologists in different states, including Iowa, have conducted seed treatment experiments for many years. I have found the performance trials of tested chemicals to be generally consistent among states. Although the information is from Ohio, recommendations apply to seedling diseases that occur in Iowa. Methods of treatment. Many chemicals can be used for this purpose, but check with your chemical dealer for products based on the compounds listed in the table.