Soybean stem canker
scouted Sept. 5, 2024
- Scientific Name
- Diaporthe sp.
- Background
- Soybeans in Catawba County, variety AG56XF0, were scouted, and it was observed that 15% of the field was affected by general yellowing, root rot, stem rot, stunting, and wilting in spots. The spots are about 20' wide all around the field that have pale, stunted plants. Root systems in these spots have a sort of a knot in them and are very small and weak. Grower reports that a hot period wilted the plants in poor spots. The agent was also able to rub off some of the root surface with a finger. Low area and wet site. This is in a newly acquired river bottom. The soil is river loam and has some very sandy spots on the surface. Field and crop conditions are highly variable and have been in soybean rotation 3+ years. A sample was submitted to the PDIC for diagnosis.
- 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
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- No resources have been added.
