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Rhizoctonia Damping-off and Root Rot of Soybean
Causal Agent:
Rhizoctonia solani
Symptoms and Signs:
- Reddish-brown, sunken lesions on hypocotyls of young seedlings
- Damping-off, pre- and post-emergence
- Stunted growth and chlorosis of older plants
- Persistant sunken, reddish-brown canker on plants that survived seedling infection
Disease Cycle:
- Survives in field as mycelium (filamentous fungal body) or sclerotia (mycelial ball in a melanized rind) in the soil.
- In warm and wet conditions, sclerotia can germinate and mycelium will infect the host. No spores are produced.
- Symptoms such as damping-off will occur early in the season, while surviving plants will be stunted, chlorotic and may senesce early.
- Mycelium and sclerotia are produced in plant tissues and can survive in the soil for subsequent growing seasons.
Disease Management:
- Use high quality seed
- Use fungicide treatments with efficacy for true fungi
- Plant varieties with partial resistance to R. solani
- Rotate to non-hosts such as corn or wheat
- Improve soil drainage
- Test soil for proper pH and fertility, as over fertilization can encourage R. solani growth