As corn planting gets off to a slow start in many areas one concern is whether we should think about switching hybrids. In general, the answer is no, not until later in May.
Adapted hybrids can be planted until about May 20–25 without a need to switch to earlier maturities. Sometimes switching now will get you earlier hybrids that are not that well adapted or top performers, and may not yield that well.
A couple of other factors can be considered as well. One is that many folks have shortened up on corn maturity already and these earlier hybrids have lower GDD requirements than some of the full season materials that were popular in the past. Second, corn hybrids have the ability to shorten up their growing degree day requirements a bit (150 GDDs or so) and can adapt to shorter growing season lengths caused by cool weather or late planting.
The main concern on hybrid maturity is where some pretty full season hybrids are being planted that may not mature unless planted early in a normal season. Planting these hybrids in mid-May can increase the risk of frost before maturity and some of the long, slow dry down problems that we have experienced in this region in the past.
In this situation, consider planting these hybrids first or perhaps switching to an earlier hybrid if silage or high-moisture corn is not an option and planting gets delayed until mid-May. It’s difficult to give an exact recommendation based on our geography and hybrids, but most experienced corn growers have an idea of the maturities that fall in this category on their farm.