- 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 costs, enough to discourage switching relative maturity (RM) prior to the last week of May.
- Corn hybrids mature with fewer accumulated heat units when planting is delayed, minimizing the risk of fall frost injury.
When is the best time to plant corn?
Historical Golden Harvest® Agronomy in Action research, as well as numerous university trials, have shown that there is minimal yield loss (0.11 bu/day) from delayed planting before May 10 or thereabouts. After May 10, the penalty (1 bu/day) for delayed planting is much bigger. Frequently, farmers consider switching to an earlier-maturity hybrid as a result of delayed planting and concerns around an early fall frost. Before considering an earlier-maturity hybrid, it is important to understand the research in order to make the most profitable decision.
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.
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 per bushel (down to 15.5%), 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.
- 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.
Some earlier hybrids are available and are actually top-performing choices when placed on the right soil types. For example, in Michigan, Golden Harvest® hybrids G95D32-3110 and G90Y04A-3110A have shown top yields and won plots when placed against fuller season hybrids multiple years in a row. As you can see from the combined 2016 and 2017 data, these 2 hybrids have considerable yield potential. In more than 2,500 trials across the U.S., these hybrids have averaged nearly 200 bu/A.
Planting hybrids such as these allows you to take full advantage of what is left of the growing season while limiting your risk of yield loss due to a shorter growing season.
Switching to Soybeans
Once June 10 passes, changing corn acres to soybean acres becomes a more serious conversation. Evaluate a couple of goals as you consider the switch:
- Do you need corn to feed livestock? What are your options for silage vs. high-moisture corn?
- How important is it to keep a good crop rotation? Sometimes it comes down to planting or not getting a crop in the ground.
If you do switch to soybeans, remember that later-planted soybeans also have a few more management considerations to ensure success. Michigan State University offers several agronomic insights on maximizing yield in delayed planting situations.
For more agronomic insights or for assistance to make 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 During Grain 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.
Product performance assumes disease presence.
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