Based on current and upcoming weather conditions, there is risk that the average yield will fall below 150 bushels per acre, according to an analysis this week by Darrel Good and Scott Irwin at the University of Illinois.  A corn yield below 150 bushels per acre will require higher prices to ration the crop, the analysts added.  USDA forecast a record average corn yield of 166 bushels per acre for this year.

Good and Irwin noted that an above-trend corn yield, which 166 bushels per acre is, requires timely planting and very favorable weather conditions over a very wide area throughout the entire growing season.  Most important are weather conditions during the reproductive and grain filling stages of the growing season, about late June through August in much of the Corn Belt this year.  Above average precipitation and below average temperatures during that period are most conducive for high yields.  Most recently, these type of conditions prevailed in 2004 and 2009.  Based on weather and crop conditions to date and the hot, dry near term forecast, an above trend yield is “clearly not in the cards this year.”

In a related report, Pat Guinan, a University of Missouri agricultural extension program director, said this year “it is a unique growing season.”  High heat and lack of rain indicate possible prolonged drought, he added.  “It’s beginning to look a lot like 1988,” Bill Wiebold, University of Missouri, reported.  Guinan believes 1988 was one of the three worst droughts of the last century, including the mid-1950s and the dust bowl days of the 1930s.

“We’re not there yet,” Guinan said  “But you do have to go back to 1988 to find a drier May and June than we’ve had this year.  Hot, dry weather in the spring isn’t a good start.”  The most critical time of the growing season for corn yield potential is underway, Wiebold noted.  Pollen release from tassels at the top of the stalk and silk emergence from ears at mid-stalk must coincide.  Pollen from the tassels must connect with freshly emerged silks from the ear.  Hot weather dries silks before pollination can occurr. Each silk must receive one pollen grain to set one kernel of corn on the cob.  The kernel must receive moisture to grow and fill the ear during the remaining growing season.  Kernels per cob contribute to the size of the corn harvest, the agronomist explained.