Published on Friday, May 03, 2019
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In delayed planting situations, there are some key concepts to consider when deciding to whether or not to continue as planned with corn, move to an earlier maturity hybrid, or switch to soybeans altogether.
Heat Unit Accumulation Corn development is largely based on the accumulation of heat units or Growing Degree Days (GDDs). A given hybrid requires a set number of GDDs to reach pollination and maturity. As corn relative maturity (RM) increases, more GDDs are necessary to reach black layer or physiological maturity. Below is a tool that uses planting date and corn RM to determine the probability of reaching black layer before frost. This tool uses historical weather data at a local level to help you make decisions on maturity selection to determine the likelihood of success in real time.
Disclaimer: This tool does not account for the reduction in necessary GDDs after May 1 and needs to be manually adjusted within the tool to compensate.
Click here to create a Growing Degree Day graph for your area.
When to Switch to An Earlier Maturity
As planting is further delayed, the question arises, “Do I need to switch to an earlier maturity?” Often the short answer is “Not just yet,” and here is why:
The warmer environment with later planting dates speeds up corn development through the vegetative growth stages. This translates into only about four additional days to reach maturity with approximately 78 fewer heat units when compared to planting dates from early May to mid-June. This is approximately the average difference between a 101 RM hybrid and a 105 RM hybrid if they are planted at the same time. For more information, click here.
Know Before You Switch Maturity Quick Facts
As a general rule, farmers will see the highest rate of success if they stick with their original planting plan with their original hybrids into the later parts of May, even though yields may fall slightly towards the tail end of the month. The yield benefit of later RM hybrids usually outpaces the results of switching to an earlier RM hybrid despite drying costs.
Additional Considerations Before You Switch
When Should I Switch to Soybeans?
Generally, once June 1 hits, farmers may want to consider switching to soybeans. Here are some important reminders:
Author: Eric Wilson
Categories: Agronomy, Agronomy Talk