Corn Hybrid Switching 2017 – Too Early to Panic

  • May 03
    Greg Stewart
    Corn Hybrid Switching 2017 – Too Early to Panic By Greg Stewart on May 3, 2017
    Categories: Corn Hybrid Selection, Planting

    Although we are in just the first few days of May, persistent rainfall is delaying corn planting across Ontario and the questions are already coming about switching to less than full season hybrids.  The main message is that it is certainly too early to panic.  Most data sources suggest that the appropriate switch date from full season to shorter season hybrids is in the May 21 to May 27 window.

    The most recent planting date work done in Ontario (U. of Guelph and OMAFRA) demonstrates that May 25 essentially indicates about a 5% yield loss compared to those same adapted hybrids planted before May 10.  Although this represents an unwanted loss, it does mark a threshold where switching to shorter season hybrids before that date will, in most years, cause you to give up more than 5% yield.

    Joe Lauer, a Wisconsin based agronomist has also done some analysis of planting date studies and found that drying cost was an important factor in determining switch dates between full-season and shorter-season hybrids.  If your corn drying costs are relatively expensive, then switch dates should move to the earlier part of the window.

    Corn Plays Catch Up

    Corn Belt research has indicated that later planted hybrids actually require fewer CHUs to reach maturity than those same hybrids planted earlier in May.  The numbers essentially suggest that a 3000 CHU hybrid planted on May 5 would require, no kidding, 3000 CHU to reach black layer.  That same hybrid planted on May 25 (20 days later) reaches black layer in about 2875 CHUs. Most of the CHUs that you give up because of a May 25 planting date are made up by the later planted corn developing with relatively fewer CHUs.


    In shorter season (< 2850 CHU), snow friendly areas, it may be prudent to not push adapted hybrids past the holiday Monday, May 22.  As you move south towards 3200 CHU areas and beyond, there is another week to stick to adapted full season hybrids.

    Other Notes

    The thoughts on this page are sound as long as you have not already picked hybrids that are 150 CHU longer than your normal full season options.  Although this is a nice strategy to push yields, you may have to forego it in 2017.  Similarly, growers who have already selected a nice range in hybrid maturities are under less pressure to switch hybrids compared to those who are already weighted heavily to full season selections.

    When planting opportunities arrive, make planting the priority; there are 45 days and about 45 ways to get nitrogen applied after planting, so leave it until then.

    If you can’t fight Mother Nature and need to switch to shorter season hybrids, be sure to discuss the possibilities with your Maizex representative.  There will be some great hybrid options to make work on your farm.