Soybean planted in cold, wet soil is most subject to infection by Pythium. If disease occurs in warm conditions, it is more likely caused by Phytophthora. Rhizoctonia and Fusarium also can cause seedling diseases. Seedling diseases by these fungi are different from those caused by Pythium and Phytophthora. Seedling blight by Rhizoctonia normally appears as the weather becomes warm.
Infected stems remain firm and dry.
The reddish brown color is a good symptom to aid in diagnosing the disease. Compared with other fungi, Fusarium is a minor pathogen in Iowa, causing about 10 percent of the seedling disease problems each year. This information subject to a usage policy .