A sign advertising E15, a gasoline with 15 percent of ethanol, is seen at a gas station in Clive, Iowa, United States, May 17, 2015.
The government and labor unions reached a deal last Thursday that averted a railway shutdown, possibly supporting a rebound in ethanol output for the current week.
But a near-term recovery may be capped by sagging U.S. gasoline demand and poor corn crop prospects.
Some analysts have questioned these figures, based on recent traffic trends that might suggest better fuel demand, though high prices have pained consumers for much of this year.
A subpar U.S. corn crop could also disrupt the ethanol industry, especially if harvest results are worse than expected.