Is there a date at which growers should simply abandon the idea of planting for this year?

"That answer depends on what insurance we have taken out," Nafziger says. "Between June 1 and June 15-20, we can expect to lose another 25% of potential yield, bringing yields down to about half their full potential. Variability of realized yields following such late planting actually decreases some, but only because low yields become more likely and good yields become rare indeed."

The "glide path" for soybean yields as planting is delayed into June is less steep than for corn, but the "half-yield" date for soybean may be only a week or so later than for corn, perhaps two weeks later in southern Illinois, Nafziger says. At current prices – with corn price per bushel only about half the price of soybean – soybean has a smaller margin to work with compared to corn. This means that the planting date at which returns are equal is later than when the price ratio is less favorable to corn.

"With some very heavy rain coupled with high temperatures following soybean planting this past week, we can expect some substantial stand loss, especially in the places where water stood for a day or two," he says. "There's little guesswork here – soybean seed will barely last a day submerged at 85° or 90° F, especially if the germination process has started. Stand loss for both soybean and corn will be common in low areas where water stood this past week, and replanting these low areas should be considered if it can be done within the next week or two."

For more information, read The Bulletin.