Damping-off diseases and Anthracnose (Colletotrichum truncatum and Glomerella glycines)
They are caused by an array of fungi including Colletotrichum truncatum and Glomerella glycines (cause of anthracnose). The diseases cause rotting of seeds before emergence from the soil or death of seedlings after emergence.
The two species of fungi produce similar symptoms on the petioles, stems and pods particularly when plants are nearing maturity. Diseased areas have dark sunken lesions. Under moist weather the lesions become covered with a pink spore mass. The disease is seed-borne. When infected soybean seeds are planted, many of the seeds rot in the soil. Those that emerge from the soil often have brown, sunken cankers on the cotyledons (seedling leaves). The fungi may grow from them into the young stems. The damping-off seedling losses are probably more serious phases of soybean anthracnose than symptoms on older plants. The disease is favoured by cool wet weather.
- Use certified disease-free seeds.
- Plant resistant varieties, if available.
- Practise crop rotation with non-legumes.
- Practise proper water management.