Ethanol tumbled, widening the discount to gasoline, as cheaper corn enabled distillers to boost production of the biofuel.

The spread widened 7.38 cents to 79.99 cents a gallon, the biggest one-day expansion since Oct. 4. Pratt Energy said Oct. 24 that it restarted operations at a plant that was idle for more than five years.

“There’s been news of plants coming back online,” said Will Babler, a broker at Atten Babler Risk Management in Galena, Illinois. “It seems like production is trending higher.”

Denatured ethanol for November delivery fell 3 cents, or 1.6 percent, to $1.831 a gallon on the Chicago Board of Trade. Futures are down 16 percent this year.

Gasoline for November delivery rose 4.38 cents, or 1.7 percent, to $2.6309 a gallon on the New York Mercantile Exchange. The contract covers reformulated gasoline, made to be blended with ethanol before delivery to filling stations.

Ethanol is made primarily from corn in the U.S. About 59 percent of the crop was harvested as of yesterday, up from 39 percent the previous week, the Agriculture Department said today.

Farmers planted a record number of acres as they sought to recover from last summer’s drought that destroyed yields and raised prices for the grain.

Corn for December delivery dropped 9.25 cents, or 2.1 percent, to $4.3075 a bushel in Chicago. The December corn crush spread of corn to ethanol was 11 cents, up from 10 cents Oct. 25, data compiled by Bloomberg show.

Production Rising

Production jumped 3.2 percent to 897,000 barrels a day in the week ended Oct. 18, the highest since June 2012, Energy Information Administration data show. Stockpiles climbed 0.5 percent to 15.5 million barrels, according to the Energy Department’s statistical arm.

Inventories are below average for this time of year. Babler said more production is needed to replenish supply.

The EPA tracks compliance with the federal ethanol-use mandate with Renewable Identification Numbers, or RINs, tradable certificates that are attached to each gallon of biofuel.

Corn-based RINs fell 1.5 cents to 21 cents, the lowest since Jan. 24. Advanced RINs, which cover biodiesel and Brazilian sugarcane-based ethanol, decreased 5 cents to 28 cents, data compiled by Bloomberg show.

The U.S. hasn’t made any foreign purchases of the biofuel since Sept. 27, according to EIA data.

In cash market trading, ethanol in New York rose 3 cents to $2.155 a gallon; on the West Coast prices gained 2.5 cents to $2.185; in Chicago the additive lost 2.5 cents to $2.035; and in the U.S. Gulf the biofuel dropped 1.5 cents to $2.125 a gallon, data compiled by Bloomberg show.

The West Coast’s premium to Gulf Coast expanded 4 cents to 6 cents, while Chicago’s discount to New York widened 5.5 cents to 12 cents.