Brown stem rot
Area of impact: Stem
Description: In stems, browning of the vascular system will occur. Infected tissue will be dark brown. In leaves, look for browning and yellowing between leaf veins. Leaves may also dry and remain attached to stem.
Pathogen involved: Phialophora gregata (a fungus)
Timing/Conditions: Occurs early in the season but symptoms won’t be visible until 10 to 30 days before harvest. Cool wet weather during pod fill followed by hot dry weather are ideal conditions.
Contributing factors: Overwinters in soybean stem residue and soil. The fungus infects plants through the roots and stem.
Management practices: Plant resistant varieties and rotate with non-host crops.