Soybean stem canker
scouted Sept. 15, 2025
- Scientific Name
- Diaporthe sp.
- Background
- Double-cropped soybeans in Hyde County were being scouted, and it was observed that the field was affected by black spots on pods and stems. It was also observed that there were some signs of Diaporthe/Phomopsis. A sample was submitted to the PDIC for diagnosis. This particular site received heavy rain around Aug 11-15, and the ground remained saturated for two weeks.
- Conclusion
- The issue was identified as soybean stem canker, caused by fungus of the genus Diaporthe. The first symptoms are often dead plants with dried leaves that remain attached to the petioles late in the season. The diseased plants usually occur in patches within the field. Lesions start out as small reddish-brown spots at the base of a branch and then expand to form sunken cankers. In some cases, it can cause top dieback by forming a dark brown canker on the upper internodes, which kills only the top of the plant. Unfortunately, there are limited management practices to implement, as it is best managed with resistant varieties and crop rotation to non-host crops such as corn or wheat, as the pathogen survives in soybean residue. There is no data currently on fungicide efficacy for management.
- Resources
