In many areas of the Eastern Corn belt planting has been delayed due to wet spring weather. While some growers have been fortunate enough to plant most of their corn, others have not been able to get started or are considering the need to replant. With the continued planting delays some growers may begin to wonder if they should switch to earlier maturing hybrids.
When considering late-planted corn, it is important to keep in mind that hybrids can adjust the amount of Growing Degree Days required to reach maturity. In this C.O.R.N Newsletter Article, Ohio State’s Peter Thomison states: “In Ohio and Indiana, we’ve observed decreases in required heat units from planting to kernel black layer which average about 6.8 growing degree days (GDDs) per day of delayed planting. Therefore a hybrid rated at 2800 GDDs with normal planting dates (i.e. late April or early May) may require slightly less than 2600 GDDs when planted in late May or early June, i.e. a 30 day delay in planting may result in a hybrid maturing in 204 fewer GDDs (30 days multiplied by 6.8 GDDs per day).” Because hybrids can adjust their required GDDs, late-planted hybrids can still reach physiological maturity before first killing frost in the fall.
In his article, “Update: ‘Safe’ Hybrid Maturities for Delayed Corn Planting in Indiana”, Bob Nielsen includes two useful charts that list “safe” maturities for late planting dates. Based on the data in the charts, Purdue experts do not recommend switching to earlier maturing hybrids until the second week of June.
It looks like the weather will allow for more corn planting progress this week, however, if delays continue it is important to keep in mind that growers can plant typical hybrid maturities adapted to their areas late into May and even early June.