With additional reports of sudden death syndrome (SDS) in soybean fields including areas of the state we have not previously detected SDS, we are receiving increased numbers of questions if we have detected brown stem rot (BSR) as well in these fields. First off, not every field will have SDS as we have seen several other diseases in 2010 that might have similar looking symptoms to SDS or BSR. One of the general things we are noting, however, is the following sort of statement: “we are seeing yellow patches in some of the fields.” Given our own observations from research trials both on our UW research farms as well as our on-farm locations, when you see the yellow patch, stop and take a closer look at the symptoms.
In regards to the question about BSR, to date, the samples we have received into the Field Crops Plant Pathology lab and tested have had only SDS. We use a molecular approach to our diagnostics to differentiate SDS from BSR and the results have been very clear when examining these samples. As an additional piece of information, we are also working to isolate the respective pathogen(s). We will continue to monitor the situation for both diseases as the season progresses. Lastly, we want to emphasize that if you have a positive field for SDS take a soil sample to look for the presence of Soybean cyst nematode.