These strains produce toxins that lead to interveinal necrosis in which tissue between the veins turns brown and dries rapidly, while tissue adjacent to the veins remains green a few days longer. Foliar symptoms of BSR can be misidentified as sudden death syndrome. Stem symptoms of brown stem rot. Don't be surprised if you find BSR because this fungus is present in at least 95 percent of Iowa soybean fields. The importance is the severity of the disease.
Severe disease causes premature yellowing of leaves, sometimes followed by lodging and defoliation.
Leaf symptoms of brown stem rot. Recent studies at ISU and other universities show that incidence of BSR normally is higher in reduced tillage fields than in conventional tillage fields. This is because the BSR fungus survives in soybean residues, and the risk of disease increases as the amount of infected residue increases. Therefore, no-till fields should receive more attention in scouting. Management of this disease is relative easy because of the availability of resistant varieties.