May 22, 2020, 9:00 AM
Many soybean growers in the Upper Midwest face annual challenges to soybean production. Brown Stem Rot (BSR) is an economically important disease and is the result of the soil-borne fungus Phialophora gregata  that affects the inner stem of soybean plants. It may not be visible without splitting stems open on the infected plants . BSR can cause significant yield loss and can also cause premature senescence of the infected plants , leading the soybeans to mature faster than what the relative maturity indicates. This disease is often misidentified as Sudden Death Syndrome (SDS), as the leaf symptoms in the reproduction phase can be similar.
|Picture 1 
Photo credit: University of Minnesota Extension
|Picture 2 
Photo credit: University of Nebraska-Lincoln
Picture #1 is of two split soybean stems, the one on the left has BSR noted by the dark discoloration of the pith and the one on the right is infected with SDS and has white/clear pith. Picture #2 shows BSR leaf symptomology:
Since there are no chemical controls for Brown Stem Rot, here are a few management practices that can be used to minimize the potential of infection:
Brown Stem Rot is a disease in soybeans that can cause yield loss without many visual symptoms. Often mistaken with SDS, BSR is best identified by splitting stems open to look for a browning in the stem pith. BSR can cause significant yield losses up to 30%. Even plants that show no leaf symptoms can have yields reduced by 5-15% . Although not as widespread as SDS across the Midwest, BSR can be a silent yield robber for soybean producers across the Upper Midwest given the right conditions. Keeping good field history notes and choosing resistant varieties for known infected fields is the best management practice at this time.