A question we’re hearing from growers across the Corn Belt as of late is, “should I switch from my full-season hybrid to an earlier maturing hybrid?” This question is complex because not every situation is the same, but the short answer is “not yet.”
Frequent spring rains are keeping some growers out of the field in parts of Missouri, Kansas, Illinois, Kentucky and Ohio, while other areas in South Dakota, Minnesota and northern Iowa are still dealing with the aftermath of heavy snow in April. For some growers, it may be a week or more before they even think about turning a wheel. What’s important for growers in times like these is to not let your anxiety get the best of you; stick to your planting plan as long as you possibly can. Here’s why.
Historically, full-season hybrids yield higher than early-season hybrids. Studies show that even if you lose some bushels planting full-season hybrids in mid-May, the yield loss is more significant when switching to earlier maturities. According to Penn State Extension and the Penn State Agronomy Guide, “in most areas, switching to a shorter than adapted hybrid maturity should not be considered until at least the last week of May.” In areas that plant longer-season maturities, corn may not even need to be in the ground until mid-May, so there’s no need to rush if the ground is still wet. This applies to states such as Wisconsin, Minnesota, Iowa, Nebraska and Illinois — areas still well within the optimal corn planting dates for their maturities.
Another thing to consider is growing degree days. According to Penn State Extension, if you are questioning a switch, you should consider the approximate number of growing degree days left in the season before a fall killing frost could strike. Remember, heat units drive maturity. If your corn has more time to mature, the more bushels you’ll add. Switching to an early-season hybrid may rush the process.
Stine Technical Corn Agronomist Tony Lenz recommends holding off on adjusting hybrid maturities until mid- to late-May, and even then, he only recommends switching to a five to seven day earlier maturity than your full-season hybrid. He notes, "these recommended dates can vary from region to region because of factors such as grain prices, drying costs and whether your crop is used for grain or for livestock feeding."
If field conditions have prevented you from getting into the field, don’t act prematurely. Stick with your planting plan. If it gets closer to late-May and things still haven’t progressed, contact your local extension office or Stine agronomist to discuss your options before switching to a different hybrid.