Stay the Course

ReachOut: Stay the Course from Central Valley Ag on Vimeo.

by Mike Zwingman

by Mike Zwingman

Friends, this has been a planting season like few I can remember; in parts of the CVA territory it has been smooth sailing start to finish thanks to few rainy days. In others, well, there has been more mud than most years and things are dragging along. This tale of disparity is going to be a topic of a future article, but for today we are going to talk about the latter.

Somewhere along the way last week I started to hear rumblings about some growers wanting to switch to a shorter maturity hybrid because it was getting late.  If you are having that conversation with yourself or at the coffee pot please let me interject for just a minute. Today and through the next few weeks there is no need to shorten the maturity of your corn hybrids or soybean varieties. This may sound like I am trying to help out in the “not having to swap hybrids around” process, but there is a sound science behind all of this.
Today’s hybrids are more

Today’s hybrids are more adaptable to a compressed growing season than previous hybrids that have been available to us. They keep us from paying the shorter growing season penalty twice. In the past, we have paid for the planting date and a second time in the difference in yield potential between a full season and short-season hybrid. The new hybrids actually shorten about 6.8 GDU’s per day when planted after May 5th or so. Shortening a hybrids GDU needs by about 9 days over the course of a 2700 GDU growing season. The fuller the season hybrid the more consistent the GDU requirements are between silking and black layer. The most acceleration will come between corn emergence and silking. We also accumulate growing degrees faster because of the warmer May temps vs cooler April temps. I’m not trying to make a case for later planted corn in general, but I am making the case for some peace of mind if you haven’t finished yet.


If you are ever wondering how many GDU’s you have accumulated and how it compares to normal, or how GDU’s are going to affect when your corn silks and when it will reach black layer, there are some great tools out there for you.  The one I use most is called Useful to Usable.  It has great weather data and solid information. Just for fun, I did a comparison for corn planted on April 25th near Columbus, NE and planting the same hybrid on May 15th using the same weather model. On the early planting date, using the average growing season model, the corn planted there should silk around July 16th; give or take a few days and will probably reach black layer on roughly September 16th. If you go to the same hybrid planted 20 days later, it will silk around July 20th and reach black layer around September 22nd.  Either way, we are ahead of the 50% probability of a killing frost and should not see a tremendous amount of yield difference.


More important than the science of hybrid adaptability, is the fact that the hybrid you planned was selected for a reason. That hybrid was selected because agronomically, it was the best fit for those acres and has the greatest chance of success.  The chances of us finding the same agronomic fit in a greatly shortened hybrid is low, and the risk is greater.  If you want to talk about how to manage a new set of yield and profitability expectations that would be great!  I know where the perfect place to do that is. Come out to one of the RD Summer Series events.  We can talk through how to reevaluate your yield potential and how to manage profitability for you!