Area of impact: Stem and roots
Description: The pathogen can rot seeds and seedlings anytime. In young plants, stems look bruised, soft leaves are yellowed and secondary roots are rotted. Plants usually die. In older plants, dark brown lesions form on the roots followed by rotting. Stems will be distinctly brown, and leaves will yellow and wilt. Leaves will stay attached after plant dies.
Pathogen involved: Phytophthora sojae (a fungal-like pathogen)
Timing/Conditions: Can occur all season long but usually after wet weather and in poorly drained areas especially on clay soils.
Contributing factors: Soybeans are the only known host for this disease. The disease can survive in soil for up to 10 years in the presence of decomposed soybean tissue.
Management practices: Plant varieties with race-specific resistance. Use fungicidal seed treatments, improve soil drainage and rotate crops.