By Blake Jackson
Red crown rot is a serious disease that affects soybean crops, and once it spreads, it cannot be reversed. According to Mandy Bish, a state plant pathologist at the University of Missouri Extension, there is no cure for red crown rot. The disease can lead to yield losses of up to 80% in severe cases. While seed treatments may reduce symptoms and infections, they cannot eliminate the fungus, which remains in the soil.
The first confirmed cases of red crown rot in Missouri were reported in the summer of 2024 in Marion and Audrain counties. This disease, originally identified in the southern U.S. in the 1960s, was first confirmed in Illinois in 2018. Though the exact cause of its spread to the north-central U.S. is unknown, experts believe that the movement of contaminated farming equipment has played a role in its rapid spread.
Red crown rot is often confused with sudden death syndrome (SDS), as both diseases cause yellowing and browning of the soybean leaves. However, the key distinguishing feature of red crown rot is the reddish discoloration at the base of the stem and root near the soil line. The fungus survives in plant debris over winter and prefers wet conditions, often infecting seedlings but showing symptoms later in the growing season, particularly during the reproductive stage.
Management of red crown rot is challenging. The most effective approach is containment, which requires careful planning and actions like thoroughly cleaning equipment when moving between fields and rotating crops. Since the fungus thrives in soil temperatures between 77 and 86°F, planting times and soil temperature can affect the severity of the disease. It is also advisable to rotate with non-host crops like corn and improve field drainage.
Red crown rot has now been confirmed in 11 soybean-producing states, including Missouri. For diagnosis and further assistance, farmers can contact the MU Plant Diagnostic Clinic or visit the Crop Protection Network for updates on managing plant diseases.
Photo Credit: istock-oticki
Categories: Missouri, Crops, Soybeans