Downy Mildew
scouted Sept. 15, 2025
- Scientific Name
- Peronospora manshurica
- 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 cause of the problem was identified to be soybean downy mildew, caused by Peronospora manshurica. It's a common disease that causes light green to yellow spots. It mostly affects younger leaves, which means it's usually found in the upper canopy, and it only seldomly causes yield loss. There are many sources of resistance.
- Resources
