Early Season Soybean Diseases

Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison

As the soybean season is progressing slowly, questions have come in about seedling diseases and early season disease of soybean.  With the cool wet weather, we have seen some fields with emergence issues this season.  On May 16 I wrote a WCM article on planting into cool, wet soil and disease implications.  The article can be found at this link https://ipcm.webhosting.cals.wisc.edu/blog/2013/05/soybean-planting-into-cool-wet-soil/.  We have seen quite a bit of Pythium already this season.  Remember, there really is nothing that can be done at the seedling stage to manage seedling blights.  Most management strategies must be implemented before the seed is planted (e.g. seed treatment use, deploying Rps genes for Phytophthora resistance, tillage, etc.).

While symptoms are not readily seen yet this early in the season, the sudden death syndrome-fungus, Fusarium virguliforme, takes advantage of these wet spring conditions to infect plants during the seedling and early vegetative phases of soybean growth.  A fact sheet has been developed to address sudden death syndrome of soybean in Wisconsin and can be downloaded as a PDF by clicking on this link:  http://fyi.uwex.edu/fieldcroppathology/files/2013/04/Sudden-Death-Syndrome-of-Soybean.pdf.  Again, remember any decision to manage sudden death syndrome has to be made pre-plant.  There are no mid-season management strategies that can be implemented.