With all the rain we have had in our area and more in the forecast, I have received several questions about whether or not there is a need to switch to planting an earlier maturity corn hybrid. Eric Wilson, Beck’s field agronomist in northern Iowa, and I have put together the following information to help you decide if you need to make a change.

Planting Later Affects the Maturity Rate of Corn Hybrids

Hybrids mature faster, requiring fewer growing degree units (GDU), when planted after May 1^st.

• Research from Purdue University and The Ohio State University has shown that, on average, a hybrid requires 6.8 GDU’s less per day to reach black layer (R6) when planted after May 1.
• For example, a hybrid planted on April 30 may require 2,500 GDU’s to reach R6, but that same hybrid planted on May 31 would only require 2,289 GDU’s to reach R6.
• Based on GDU’s required to reach R6 for some Beck’s products, this is approximately equal to the same difference when switching from XL® 5140™* (105 RM) to BECK 4323 (93 RM)
• How is this possible?
  • When hybrids are planted later, they adapt by shortening their vegetative growth stages. This is the period of time from planting to tasseling (VT).
  • The time it takes the hybrid to progress through reproductive stages (R1 to R6) remains largely unchanged.

What are the Risks of Keeping My Current Hybrids?

The main concern about planting full-season hybrids later is the grain moisture at harvest:

• Grain moisture at the end of the season is subject to many factors such as crop management, hybrid characteristics, and weather patterns.
• In general, earlier maturity hybrids will be drier in comparison to later maturity hybrids.
• Later planting does tend to result in less difference in grain moisture across hybrid maturities.
• Since grain moisture is so dependent on the environment, there is no guarantee that an earlier maturity hybrid will be drier in comparison to a later maturity hybrid.

Another major concern, especially in the north, is the risk of a killing frost before the corn reaches full maturity at black layer.

The best tool I have found for assessing this risk is from the University of Illinois. This tool analyzes 30 years of weather data from your county to chart expected GDU accumulation and potential frost dates. You can enter hybrid maturities to see when a hybrid is expected to reach black layer at different planting dates. The only downside is that this tool does not automatically account for the late planting reduction of 6.8 GDU’s per day after May 1^st, but you can adjust for that manually.

Click here to access the tool now.

Eric Wilson made a video demonstrating how to use this tool that you can watch by clicking below.

What are the Risks of Changing Hybrids?

• In general, the benefits of planting adapted hybrids for the area more than offset the consequences if planting up to June 1. The hybrid you planned to plant was chosen for that field for a reason. If you switch to an earlier maturing hybrid that is unfit for the field, the lost yield potential could outweigh the savings on drying costs.
• If planting after the end of May, drying costs could overshadow the yield benefit from adapted hybrids and it may be best to switch to earlier maturities.
• You will give up some yield potential as later maturity hybrids will almost always have more yield potential than earlier maturity hybrids.
• Later planting effectively shortens vegetative growth stages regardless of maturity. While this works in our favor to help corn mature in a timely fashion, it also reduces overall yield potential. This is the same reason we have seen a yield advantage to planting early in PFR testing.
• The hybrid you switch to may require different management than the one you had originally planned on planting. For example, some hybrids respond to higher populations, fungicide, or additional nitrogen. Make sure to account for these changes if you do decide to switch.

If you have any remaining questions, please reach out to your team of Beck’s representatives who are happy to work with you make the best decision for your operation.