Chicago Board of Trade corn futures fell on Friday as traders locked in profits from the market's rally earlier this week to its highest since August 12.
Traders were anxiously awaiting the US Agriculture Department's harvest forecast due next week.
The Trump administration on Friday unveiled a plan to boost US biofuels consumption. The plan would require an unspecified increase in the amount of ethanol that oil refiners must add to their fuel in 2020, and would also aim to remove further barriers to the sale of higher ethanol blends of gasoline like E15.
Private analytics firm IEG Vantage lowered its forecast of the average US 2019 corn yield to 167.5 bushels per acre from 169.6 a month ago and its production forecast to 13.695 billion bushels from 13.906 billion bushels.