Red crown rot of soybean, caused by Calonectria Ilicicola, continues to be a concern in Indiana. We have identified our first symptoms in 2026 in a field that has had a previous history with soybeans at beginning pod (R3) growth stage. There weren’t any foliar symptoms, but when we pulled back the canopy we could see the red discoloration at the crown/soil line (Figure 1 B).
Figure 1. A: Foliar symptoms of red crown rot (chlorosis, interveinal necrosis and chlorosis), B. red discoloration at the crown of the soybean plants in the field; C: red, spherical perithecia forming on crown and stem. Photo credits: Darcy Telenko
Figure 2 show the map of Indiana counties where red crown rot has been confirmed in previous years. As we move through the rest of the growing season, we are actively surveying fields to better understand the distribution and prevalence of red crown rot across Indiana. Grower participation is critical to this effort, and we encourage anyone who suspects red crown rot to report affected fields and submit samples to help document its occurrence.
What to look for: Red crown rot often occurs in patches within a field and can resemble other soilborne diseases such as sudden death syndrome (SDS) and brown stem rot. Early foliar symptoms include interveinal chlorosis (yellowing) and necrosis (browning) of leaf tissue, making diagnosis based on foliage alone difficult (Figure 1A). If these symptoms are observed, collect several affected plants and examine the lower stem and roots. Plants affected by red crown rot typically exhibit a reddish discoloration at the stem base near the soil line, often accompanied by small, red, spherical perithecia on the stem surface (Figures 1 and 2). When stems are split open, the pith may appear gray to dark gray, roots are often rotted, and plants can be pulled easily from the soil due to root deterioration.
Figure 2. Map of confirmed counties with red crown rot in Indiana. Discolored patch of soybean plants infected by red crow rot, red discoloration at the soil-line and red, spherical perithecia forming on outer surface of soybean crown. Photo credit: Darcy Telenko
We are working with colleagues across the mid-west to track this disease. Samples of soybean infected with red crown rot will greatly assist us in determining the distribution of red crown rot and guide future research.
We greatly appreciate the samples that we have received previously and want to encourage you to get out and look at these suspect areas in your fields.
If you have (or think you have) red crown rot in your field, please collect several plants showing the symptoms and send them to the Purdue Plant Pest Diagnostic Laboratory (PPDL). Please ship early in the week. If you are sending samples from multiple locations, please label them and provide the date collected, variety, field zip code or county, and previous crop.
Mail to: Plant and Pest Diagnostic Laboratory
LSPS-Room 116, Purdue University
915 W. State Street
West Lafayette, Indiana 47907-2054
Checkoff funding from the United Soybean Board and Indiana Soybean Alliance are supporting this initiative and sample processing, therefore there will be no charge for soybean samples submitted to the clinic.
Questions: please contact Darcy Telenko (dtelenko@purdue.edu/764-496-5168) or PPDL (ppdl-samples@purdue.edu/765-494-7071)
