Considering the historically early planted crop last year, many farmers were anxious this spring’s oft-delayed planting season due to cooler temperatures and abundant rainfall throughout April and May in much of the Midwest. But will that late-planted crop lead to a late harvest? Not necessarily, explains Burrus Hybrids agronomist Matt Montgomery.
"Can we really say that late planting equals a late harvest – is there a relationship?" Montgomery wondered. So he and the Burrus agronomy team reviewed 17 years of planting, harvest and growing degree data from the USDA and the Midwestern Regional Climate Center. They found no significant relationship with the percent of corn planted by late May corresponding with a harvest being classified as early, average or late.
"Seventy percent of corn has typically gone through the combine by mid to late October regardless of the pace of planting," Montgomery says. "In a couple of cases, a faster planting pace even matched up with later harvest dates. We just cannot state that late planting absolutely will mean a late harvest."
Too many other factors are at play, Montgomery says – planting date just tells a small part of the story. Growing degree day accumulation is probably a better predictor of harvest date, he says.
"The relationship between accumulated growing degree days and harvest date is significant," he says. "The degree days accumulated by mid-July and early August make a tremendous difference in when combines roll through the field."
Many areas did indeed catch up this summer, but Climate Corp reported that the corn crop in the Dakotas, Wisconsin and Iowa would require a stretch of unusually warm weather to help it catch up so it can reach maturity before fall’s first killing freeze.
Your corn needs a variable amount of GDU accumulation, depending on the maturity of your hybrids—the typical requirement ranges from 2,400 to 2,800 units. Bottom line—an average harvest pace is still a very real possibility. Calculate how many GDUs your fields have accumulated and know how many GDUs your hybrids still need before hitting the panic button.
So don’t fret just yet, Montgomery says – an average harvest pace is still a very real possibility, even for those who planted late.