Rhizoctonia solani (fungus)
FIGURE 1 – Rusty-brown lesions on soybean stems
FIGURE 2 – Soybean seedlings with girdled stems
FIGURE 3 – Seedlings dying in a row
AUTHORS: Dean Malvick and Sam Markell
SYMPTOMS
• Rusty-brown, dry, sunken lesions on lower parts of stems
• Dark brown lesions than girdle the stems near the soil
• Plants stunted, yellow, and wilting
FACTORS FAVORING DEVELOPMENT
• Warm and moist soil while plants are in early vegetative stages
• Delayed planting in spring due to rain
• High soil organic matter
• Plant stress due to physical or chemical/herbicide injury
IMPORTANT FACTS
• Dry edible beans, corn, sugar beet and pulse crops can be hosts
• Causes most damage to plants in early vegetative growth stages
• Rhizoctonia is dispersed with soil (on equipment, in water, by wind, etc.)
• Management: some seed treatments, crop rotation, tillage, early planting
• Soybean varieties vary in susceptibility to Rhizoctonia
• Commonly confused with other roots rots