As of May 9th, corn producers were reported to be about 75% planted which is actually on track with Tennessee’s 5-year average for corn planting progress. With some producers indicating only a few fields to go, and some replants, we are still within the full coverage crop insurance window for corn. For west TN counties the full coverage window runs to May 20th. For TN river counties and all counties eastward, the full coverage window runs to May 25th. Both options have a 15-day late plant window.
Although it is best to plant dryland corn in April or early May (May 10th to May 15th seems to be preferred cutoff on upland ground), the strong corn price is incentive to continue to plant later corn in bottom fields that should supply adequate water, or under irrigation. It isn’t necessary to switch to an earlier maturity hybrid when planting in May. Regardless of the maturity planted by May 20th, corn will black layer in September when we typically generate decent heat units for drydown. For example, with a May 19th planting date in Gibson county, black layer should occur between Sept 1-10th for 110 RM; Sept 6-16th for 115 RM; and Sep 10-20th for 119 RM hybrid (based on estimates generated in https://mrcc.illinois.edu/U2U/gdd/). Planting into June is more likely to delay maturity and drydown because black layer is pushed into October, where often we cannot generate the same number of heat units that we do if black layer occurs in August and September.
Some potential issues with later planted corn:
- delayed harvest that conflicts with other crops
- delayed drydown (planting at very end of May or June); some hybrids may perform better than others based on drydown scores; having access to on-farm dryers means you can offset delayed harvest and weather effects on grain quality
- potential to have more insect pests or foliar diseases or require treatment for Southern rust; planting Bt hybrids with a solid disease resistance portfolio is key to managing diseases; Southern rust is ‘hit or miss’ on whether fields need treatment in Tennessee, but may be more likely in later planted corn.