Corn Hybrid Maturities and Late Planting

Corn Hybrid Maturities and Late Planting June 13, 2019

It’s not news to any of us that delayed crop planting affects productivity. As of Sunday, June 9, USDA-NASS reported 6% of Nebraska’s corn acres remained unplanted. High water tables in some areas and portions of fields that remain fully saturated or have standing water may make it impossible to plant soon, if at all. In addition, tough planting conditions have led to poor stands on some fields. Certainly, if farmers intend to plant corn yet this year, hybrid changes are in order. In addition, having an idea of the chances of hybrids with different relative maturities actually maturing before typical frost dates is of interest.

The U2U GDD tool  provides an excellent way to address this. It allows us to compare scenarios of hybrids and planting dates at locations across the Corn Belt and compares the current year to a 30-year normal for each location.

Table 1 displays some scenarios for two locations, the South Central Ag Lab near Clay Center in south central Nebraska and the Haskell Ag Lab near Concord in northeast Nebraska. For example, a 110-day RM hybrid planted on June 14 at SCAL would not mature before the average 28oF frost date of October 19. In order for corn to mature by that frost date, hybrids with RMs less than 100 days would need to be planted.

For HAL, if planting could occur on June 14, we’d need to plant hybrids with RMs of 95 days or less. The average 28°F frost date for HAL is Oct. 11. Yields with late-planting dates and with short RMs like these will very likely be reduced from those of similar RM or longer-season hybrids planted earlier. (See Windows of Opportunity for Corn Planting: Data from Across the Corn Belt.)

Remember, Table 1 is based on the average 28o frost date. The U2U GDD tool provides a graphic view not only of the range of possible frost dates but also the variation in GDD accumulation over the 30 years of weather data for each location.

Here are some other brief ideas and a bit of a summary:

  • Hybrids do adapt for later planting by shortening their life cycle. (See this CW story.) Fall frost represents a dead-end for crop growth and development.
  • As the previous CW story on corn with flooded soils reported, corn growing in saturated or flooded soils, will perform poorly, likewise, “mudded-in” corn — corn planted in very wet soils — likely will not perform well.
  • To minimize the risk of a premature fall frost, use earlier maturing corn hybrids.
  • Earlier-season hybrids are probably not well adapted to our production systems/ environment and thus may not perform on par with what they do in their zones of adaptation — but we know there are exceptions to this with specific hybrids.
  • Earlier-season hybrids in general will yield less (as mentioned above).
  • Later R6 dates mean wetter grain and the likelihood of increased drying costs.
  • Explore options for corn silage or high moisture corn for late-planted fields.
  • Killing frosts before crop maturity will reduce yields through reduced kernel weights and test weights.
Table 1. How planting date and relative maturity affect risk of corn hybrids maturing with a 28°F  freeze threshold at two locations — south central and northeast Nebraska. (Generated via the U2U Corn GDD tool)

Clay Center/ SCAL

Avg 32o Frost 10 Oct
Avg 28o Frost 19 Oct

Relative Maturity 80 85 90 95 100 105 110
Hybrid GDD to R6 1917 2038 2159 2280 2401 2521 2642
Planting Date Estimated R6 Date
1-Jun 25-Aug 30-Aug 5-Sep 12-Sep 20-Sep 29-Sep 10-Oct
14-Jun 7-Sep 14-Sep 22-Sep 2-Oct 14-Oct 1-Nov ***
28-Jun 28-Sep 8-Oct 23-Oct 21-Nov *** *** ***
Dates in red print are beyond average date of a 28oF frost event.
*** The crop won't mature.
Data from U2U decision Support Tools, HPRCC: https://hprcc.unl.edu/gdd.php 
Concord/ HALAvg 28o Frost
11 Oct
Avg 32o Frost
3 Oct
Relative Maturity 80 85 90 95 100 105 110
Hybrid GDD to R6 1917 2038 2159 2280 2401 2521 2642
Planting Date Estimated R6 Date
1-Jun 30-Aug 6-Sep 13-Sep 22-Sep 3-Oct 18-Oct 18-Nov
14-Jun 15-Sep 24-Sep 5-Oct 22-Oct *** *** ***
28-Jun 11-Oct 31-Oct *** *** *** *** ***
Dates in red print are beyond average date of a 28oF frost event.
*** The crop won't mature.
Data from U2U decision Support Tools, HPRCC: https://hprcc.unl.edu/gdd.php