Soybean stem canker
scouted June 24, 2026
- Scientific Name
- Diaporthe sp.
- Background
- A soybean field, variety AG54XFO, was being scouted, and it was observed that 50% of the field was affected by blight, canker, defoliation, and dieback. A sample was submitted to the PDIC for diagnosis.
- Conclusion
- The cause 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 ocurr in patches within 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