Soybean stem canker
scouted Sept. 10, 2024
- Scientific Name
- Diaporthe sp.
- Background
- Soybeans in Caswell County were scouted and it was observed that about 15% of the field was affected by defoliation and dieback. Patches of the field showed blackened and yellowing leaf spots. The field was dry. The affected areas appeared to be randomly distributed. Samples were collected from the field edge, semi-affected areas, and the middle of the impacted zone.
- Conclusion
- The cause was identified as soybean stem canker, caused by the 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
