Temperature extremes could chill corn yields
The concern is on high temperature during pollination. Over this week and next, it’s estimated that 85 percent of the U.S. corn crop will be pollinating. Thanks to advances in crop genetics, pollen supply and shedding is not as much of a worry today.
While a full out crop failure is not likely, weather stress during this time could produce short, ears that are less filled out, which would reduce yield.
Excessive heat also increases leaf roll, which can interrupt pollination. “By rule-of-thumb, corn yield can be cut by 1 percent for every 12 hours of leaf-roll,” Elmore and Taylor note. During silking, that shifts to a 1 percent drop for every 4 hours of leaf roll.
If soil moisture dries up, the concern sets in by the fourth consecutive day of +90 F temperatures, when a 1 percent yield decline starts to build. On the fifth day, a 2 percent yield reduction becomes a reality, increasing to 4 percent on day six. At that point, trend-line yields become a past goal.
For this year, that could present a serious challenge as the carryover is short and demand, worldwide, by many sectors is high. Users are counting on trend-line yields or better to cover new-crop demand.