September 20, 2023
By Gentry Sorenson, Iowa State University
After walking several fields last week before harvest got into full force, I noted fields where stalk integrity was a concern. If you have not done so already, I would encourage walking fields before harvest to understand how your crop will stand through the harvest season. A pre-harvest walk will help to prioritize harvest of fields and will help reduce harvest loss of compromised corn.
Corn has experienced stress this year from drought, areas of hail, crown and stalk rots, as well as premature death. A recent ICM blog touches on some standability concerns. Doing the push test is an easy way to recognize plant weakness. When I check fields to prioritize harvest, I check several rows across several areas of the field to understand field variability. If there are different hybrids in a field, be sure to check each hybrid.
Push test: Push 20 plants approximately 30 degrees, if 10% of the stalks kink or break that field should be prioritized for harvest.
Pinch test: The pinch test applies pressure to the stalk in areas to check for any stalk integrity issues. Like the push test, if 10% of the stalks fail the pinch test, then that field should be prioritized for harvest. The pinch test does a nice job of showing which part of the stalk is weak.
Also check the soundness of the ear shank as stresses through the growing season may lead to a weak shank and ultimately ear droppage. Corn rootworm populations in fields may have weakened root systems leading to lodged corn after wind events. Review your scouting notes from the season to understand what and where stressors were present and evaluate those areas for harvest.
Evaluation of corn before harvest can also assist with combine setup. It is also important to verify combine adjustments during harvest periodically. Check for losses from the combine head as well as form the rotors/cylinder and sieves. Taking the time during harvest to understand if and where losses are occurring and making needed combine adjustments will help to minimize harvest loss.
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