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Should I Change to an Earlier Maturity Corn Hybrid?

Categories: PLANTING, CORN
  • On average, hybrids will only lose 1 bushel for every 10 days of planting delay prior to May 10

  • Planting dates after May 10 can experience up to 1 bu/day of delay yield loss.

  • Yield benefits of full-season hybrids offset potential grain drying cost enough to discourage switching relative maturity (RM) prior to last week of May.

  • Corn hybrids mature with fewer accumulated heat units when planting is delayed, minimizing the risk of fall frost injury.

Historical Golden Harvest® Agronomy in Action research and numerous university trials have shown that there is minimal yield loss (0.11 bu/day) from delayed planting up until May 10. After May 10 there is a much bigger penalty (1 bu/day) for delayed planting (Graph 1). The thought of switching to an earlier maturity hybrid as result of planting delay happens frequently. Thoughts of an early fall frost start to make the decision even more emotional. Before making big shifts to an earlier maturity hybrid, it is important to understand what we have learned from previous research to make the most profitable decision. This article is meant to review key considerations regarding delayed planting.

Scatter plot graph showing the effect of planting date on corn yield potential.
Graph 1. Effect of planting date on corn yield potential.

A slight delay in planting does not always translate into the need to switch to a shorter relative maturity (RM) hybrid to avoid wet corn or frost injury. It is well understood that corn hybrids mature with fewer accumulated heat units when planting is delayed.1,2 This allows the same RM hybrid to reach physiological maturity in fewer days than earlier planting dates, reducing the risk of delayed maturity and potential frost injury. There still may be a need to switch to an earlier RM hybrid at some point in time, however a 1-day delay in planting does not mean a day delay in harvest.

Line graph comparing effect of corn hybrid planting date on gross return in dollars by corn relative maturity group.
Graph 2. Effect of planting date on gross return by corn relative maturity group

Golden Harvest Agronomy in Action research has conducted multi-year studies to better understand the financial impact associated with switching to an earlier RM hybrid too soon. Looking at Graph 2, assumptions of $7.00 per bushel grain price and 10¢ per point moisture removed (down to 15.5%) per bushel drying costs along with yield and moisture data from planting date trials were used to calculate $/A return for full (green line), mid (orange line) and short (blue line) season hybrids adapted for the area. Full-season hybrids were defined as the maximum acceptable RM for the trial area. Mid-season hybrids were 4-7 RM earlier than the full-season hybrids, and short-season hybrids were 8-11 RM earlier than full-season hybrids. In over 41 trials, the yield benefits of planting a full-season hybrid outweighed the drying costs at harvest for planting dates up to May 18. After May 23, switching from full- to mid-RM hybrids (4-7 RM earlier than maximum RM for area) may start to provide slight return advantages. Aggressive changes of 8 or more RM earlier than the maximum RM for your area may result in drier grain. However, less yield potential of earlier RM hybrids will result in lower profit than drying a fuller season hybrid. University recommendations for most Midwestern corn producing states such as Michigan State University, University of Minnesota, Iowa State University and University of Wisconsin support waiting until May 20-May 30 before switching to earlier RM hybrids.

There are many other reasons to consider switching to an earlier RM hybrid that also need to be considered. Lack of access to grain drying capabilities (bu/hour), grain contract delivery dates and harvest capacity (A/day) are just a few reasons to consider switching earlier. If these factors are not a concern, you may have an opportunity to maximize your profit potential by sticking to your original hybrid selection. For more agronomic insights or for assistance on making this decision contact your local Golden Harvest Seed Advisor or agronomist.

1Brown, Greg A. 1999. Influence of Delayed Planting on Growing Degree Day Requirements of Corn (Zea mays L.) Hybrids DuringGrain Fill and Maturation. M.S. Thesis, Purdue University.
2Nielsen et al. 2002. Delayed Planting Effects on Flowering and Grain Maturation of Dent Corn.
3Purdue University; Corny News Network

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