Caused by Phialophora gregata, a fungus that survives in soybean residue. The pathogen infects soybean roots early in the season, but plants remain asymptomatic until pods begin to fill. Usually, vascular browning occurs along with leaf necrosis and chlorosis. In some cases, only internal vascular browning occurs.
The pathogen of brown stem rot survives in soybean residue that was previously colonized during the pathogen's parasitic phase. The severity of the disease depends on the ambience, soil environments, and crop management systems. Stem and foliar symptoms are most severe when air temperatures range between 60 and 80 F.
Maintain a soil pH of 7 to reduce the risk of brown stem rot.
Foliar fungicides have no effect on brown stem rot. Furthermore, seed treatment fungicides will also have no effect as just protecting the seedling won't be sufficient to inhibit infection after the materials have dissipated.