Soybean stem canker

scouted Aug. 24, 2026

Scientific Name
Diaporthe sp.
Background
A soybean field in Franklin County was being scouted, and it was observed that 10% of the field was affected by browning and yellowing in random areas of the field. There is suspicion of guava root-knot nematode. A sample was submitted to the PDIC for diagnosis.
Conclusion
This issue was identified as soybean stem canker. Symptoms associated with soybean stem canker can include reddish-brown lesions on the main stem at the base of a lower stem, small black spots that appear on dead tissue, and dead leaves that remain attached to the stem. There are no options to remedy this issue in this season; however, you can best manage this disease with resistant varieties and crop rotation to non-host crops such as corn or wheat.

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