Late planting and replanting corn
If planting at the middle planting date, June 11, the two earliest-season hybrids yield the best at the two northern locations; of course frost risk is higher with the 93 day hybrid than the 83 day hybrid at those locations when planted on June 11. For the Central location planted on June 11, the three earliest hybrids outperform the latest hybrid (112d) with the least frost risk (33 percent, with the earliest hybrid (93d)). At the SE location, all four hybrids had similar simulated yields when planted on June 11; of course higher frost risks are associated with the later-maturing hybrids. With the last planting date, June 25, the earliest hybrid had the highest simulated yield at all locations. However, at the northern locations, frost risk was at or near 100 percent even with the earliest-season hybrid (83d).
Summary of Modeling Approach
- Full-season hybrids planted in June will encounter high probabilities of frost damage before maturity.
- Earlier hybrids perform as well or better than full-season hybrids when planted late at all locations.
- Late-planting of full-season hybrids carries more risk and lower yield potentials than earlier-season hybrids especially at the northern locations.
Decisions to plant corn late or replant are never easy. A checklist for replanting is included on the ISU agronomy corn production website. As mentioned above, Part 2 in this series will look at the same question using actual field data. In that article, we will also compare and contrast the two approaches. The crop-model simulation discussed in this article summarizes average simulated hybrid responses with a weather data base going back to the mid to late 1980’s. Certainly the data are most useful in estimating maturity dates and frost potentials on those dates.