By Dean Malvick, University of Minnesota
Red crown rot of soybean has been found for the first time in Minnesota. It was detected and confirmed in one field in southwestern Minnesota. This disease can cause significant yield loss in soybean depending on severity, weather, and timing of disease development.
Red crown rot is caused by a soilborne fungal pathogen (Calonectria ilicicola) that infects the roots and lower parts of stems of soybean plants. Symptoms on leaves include yellow and brown patches between veins that are like symptoms of sudden death syndrome (SDS) and brown stem rot (BSR). Red coloration (similar to Rhizoctonia stem rot) and reddish dots develop on roots and lower stems, and roots are often rotted. The disease in Minnesota was confirmed to be red crown rot based on signs and symptoms of the disease as well as by isolation and identification of the pathogen via DNA sequencing.
Red crown rot can be a challenging disease to manage. Most or all soybean varieties adapted to the Midwest that have been evaluated appear to be susceptible to this disease, although differences in disease susceptibility have been reported. The red crown rot pathogen is thought to survive for multiple years in soil, thus minimizing the usefulness of crop rotation. Some seed treatment fungicides have been reported to reduce red crown rot. More needs to be learned about the efficacy of these and other potential disease management options as well as the distribution of red crown rot in Minnesota.
Known distribution of red crown rot in the U.S.: https://cropprotectionnetwork.org/maps/red-crown-rot-map
Red crown rot of soybean has been found for the first time in Minnesota. It was detected and confirmed in one field in southwestern Minnesota. This disease can cause significant yield loss in soybean depending on severity, weather, and timing of disease development.
Red crown rot is caused by a soilborne fungal pathogen (Calonectria ilicicola) that infects the roots and lower parts of stems of soybean plants. Symptoms on leaves include yellow and brown patches between veins that are like symptoms of sudden death syndrome (SDS) and brown stem rot (BSR). Red coloration (similar to Rhizoctonia stem rot) and reddish dots develop on roots and lower stems, and roots are often rotted. The disease in Minnesota was confirmed to be red crown rot based on signs and symptoms of the disease as well as by isolation and identification of the pathogen via DNA sequencing.
 |
Red crown rot symptoms
on roots and leaves of soybean (Photos courtesy of N. Kleczewski, S.
Geisler, and D. Telenko and the Crop Protection Network). |
Red crown rot was first found in Midwestern soybean fields in Illinois in 2018 and had spread to multiple fields in Illinois as well as fields in Missouri, Indiana, Ohio, and Michigan prior to its detection in Minnesota. When the disease was found in Minnesota (Rock County) in August 2025, the nearest known location with red crown rot was over 400 miles away in NW Illinois. Red crown rot has also recently been confirmed in south central Wisconsin. The modes by which red crown rot is spreading in the Midwest are unknown. In the 1990s, red crown rot of soybean was a problem in the southern U.S. in Louisiana and Mississippi, but it appears to have since become uncommon in those areas. Although red crown rot is known to occur in only one field in Minnesota, it can be difficult to diagnose and could have escaped detection in other fields.
Red crown rot can be a challenging disease to manage. Most or all soybean varieties adapted to the Midwest that have been evaluated appear to be susceptible to this disease, although differences in disease susceptibility have been reported. The red crown rot pathogen is thought to survive for multiple years in soil, thus minimizing the usefulness of crop rotation. Some seed treatment fungicides have been reported to reduce red crown rot. More needs to be learned about the efficacy of these and other potential disease management options as well as the distribution of red crown rot in Minnesota.
Additional information about red crown rot of soybean:
Background information on diagnosis of red crown rot and more photos of symptoms: https://cropprotectionnetwork.org/encyclopedia/red-crown-rot-of-soybeanKnown distribution of red crown rot in the U.S.: https://cropprotectionnetwork.org/maps/red-crown-rot-map
Comments
Post a Comment