Extension plant pathologist, Marty Draper says two diseases you may have in fields that have been heavily saturated with rain are pythium and phytophthora. Draper says if not treated the diseases can cause your plants to die. After a soybean plant has grown you will not have to worry about pythium killing the plant. Pythium is restricted by the age of the plant it really is not going to be a problem after the plant is six inches tall. There's enough secondary thickening in the stem hypocotyl that you're not going to see the plant dying.
Pythium favors cool soil conditions and usually affects early seeded beans.
Really we see most of our problem with phytophthora by mid season that's going to be a little worse. Draper says you should use a metalalxyl seed treatment fungicide. Well, at this point, if we're in a situation where there's been such an extreme losses that we have areas in the field that may need to be reseeded. I'd really recommend people using a seed treatment as they go back in there. To determine if conditions are favorable in your soybean field for pythium or phytophthora you can ask yourself these questions.