The last couple heat waves combined with continued drought stress has brought on premature corn death. What should be expected as corn grain harvest gets underway? First and foremost expect VARIABILITY of both grain moisture and yield within and between fields. Next plan for variable and possibly low test weight corn. This is especially important in a drought year where a hybrid may have died prematurely.
While we often talk about test weight as a grain quality indicator, we don’t always remember that test weight and grain moisture are inversely related. Checking fields early at a high grain moisture may give a false ‘low test weight’ indication. As grain dries, test weights increase because kernels shrink and become more slight; this allows for more kernels to fit into a bushel.
We can expect lighter corn test weight because grain fill in late August and early September was impacted by high temperatures and extreme drought conditions. Sure there will be areas of Iowa where timely rains may have saved the corn crop but there is a large portion of Iowa impacted by severe to extreme drought. In addition to lower test weights, expect grain yield decreases more the earlier premature death occurs (ranges from 5-10% in late dent up to 20-40% at beginning dent stage).
Tips for harvesting corn that has prematurely died:
- Set the combine for variable crop conditions.
- Calibrate yield monitors frequently (at least daily or when you change from one hybrid to the next).
- Make drying and storage a priority.