Rhizoctonia root rot
Rhizoctonia root rot was once considered one of the most common soilborne diseases of soybean worldwide, but is of low economic importance in NY thanks to the widespread deployment of seed treatments.
The fungus is long-lived and ubiquitous in most field soils and can cause seed rot, damping-off, root rot and stem rot. Emerged infected seedlings will have distinctive red lesions near the soil line that often girdle the stems and kill the seedlings. Infected seedlings that survive may have sunken, reddish-brown lesions on the lower stems, and may be stunted and chlorotic.
Use of fungicide seed treatments is the best management practice, but rotation with small grains and corn may reduce pathogen populations in a highly infested field.