As the growing season starts to wind down, corn fields should be continued to be monitored and scouted for stalk integrity or standability concerns before harvest. Checking fields to help prioritize those with significant stalk rot for earlier harvest can reduce harvest losses, reduce the stress of slow harvest, and reduce future issues with volunteer corn.
A couple methods exist for monitoring fields for stalk rots: the “pinch test” and the “push test.”
“Pinch test”
- Check stalk firmness by pinching the lower internodes near the ground between your thumb and forefinger
- Be concerned when: stalks crush easily
“Push test”
- Push the plant at shoulder height approximately 30 degrees from vertical
- Be concerned when: plants pinch over, plants fail to snap back to vertical
Regardless of method chosen, check a minimum of 100 plants per field, preferably by evaluating at least 20 plants in 5 different areas. If more than 10% of plants in a field crush easily or lodge this indicates stalk rot may be an issue, and that field should be prioritized for harvest. Each year may present special challenges in doing these checks. In years where downed corn is prevalent due to wind or root worm damage, Farmers may need to use multiple field entrances to check different areas whenever possible.
Several stalk rots might be present in crop fields. Use the resources below to learn more about the different types of stalk rots we can see in fields. For more information or in-field assistance, please reach out to your local ISU Extension and Outreach field agronomist.
More resources:
- Professor of Plant Pathology and Microbiology
- Extension Field Crops Pathologist
- Field Agronomist in Central Iowa