With some of the Illinois corn crop still unplanted and other fields struggling due to heavy rainfall, growers must decide whether or not it makes sense to plant this late in the season, says University of Illinois Crop Sciences Professor Emerson Nafziger. “It’s very late to plant corn, so we need to decide first whether it makes sense to plant corn this late, and if not, whether the best option is prevented planting insurance or replacement with soybeans, as crop insurance provisions allow,” Nafziger says.

Most corn-planting date studies include planting only through the end of May. “Going beyond that is a little shaky,” he says. “However, we have projected that corn reaches the point where we can expect 50% of maximum yield if it is planted sometime between June 15 and June 20.”

Based on this, June 15-20 might be considered the last practical dates to plant corn in order to produce grain, Nafziger adds.

“We know that corn planted during or after the middle of June will produce fair to good yields in some years and very little yield in other years, depending on unpredictable weather that follows,” he says.

If corn is planted in mid- to late June, planting a very early hybrid, having the option of harvesting the crop as silage if grain production looks unlikely and getting good rainfall throughout the rest of the season will all improve the probability of a profitable crop, Nafziger says.


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 “The chances of having enough frost-free days to grow a crop are higher in central and southern Illinois than farther north, but higher water-loss rates and lower water-holding capacity of soils in the southern half of the state can cancel this advantage,” he says. “It may also be difficult to get seed of very early hybrids, and because early hybrids are not developed for the central and southern Corn Belt, there is no guarantee that they will do well under late planting.”