Brown stem rot has increased in incidence and severity in Ohio in the past few years. This disease occurs most commonly in fields that have been in continuous soy, short rotations, reduced tillage or no-till. Environments that favour high yield potential also favor brown stem rot development.
Under high disease severity, yield reductions from 10-38 percent have been reported. This soy disease is caused by a residue-borne fungal pathogen, Phialophora gregata.
The most common symptom of brown stem rot is the brown to reddish-brown discoloration of the soybean stem pith. This internal stem browning is the diagnostic character of this disease, but the discoloration may only occur in sections of the stem. When disease is severe, the discoloration is continuous throughout the stem from the base of the plant upwards, and the outside base of the stems have a "greasy" appearance.
Foliar symptoms may be absent, but when present consist of wilting, chlorosis and browning of the tissue between the veins. These foliar symptoms are very similar to another soy disease, sudden-death syndrome. With brown stem rot, the leaves will wilt and eventually die.
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Article made possible through the contribution of Ohio State University Extension.