CHICAGO: Corn and soyabean futures tumbled on Friday after a US Supreme Court ruling bolstered a bid by small oil refineries seeking exemptions from laws requiring them to blend ethanol or other biofuels into their products, traders said.

“Each time the markets start to stabilize, having priced in the latest round of bearish news, another shot of news knocks the markets off their feet again,” said Arlan Suderman, chief commodities economist at StoneX. “Today’s news was a Supreme Court decision.”

The closely watched case, reflecting a long-running dispute between the oil and corn industries, was seen as a major setback for biofuel producers.

Winter wheat futures also fell, with the most-active Chicago Board of Trade soft red winter wheat contract hitting its lowest since mid-April, as the ongoing harvest in the northern hemisphere boosted supplies.

Corn and soyabeans also faced pressure from rains across large swaths of key US growing areas.

“The heart of the Corn Belt is getting a good shot of rain at a very timely moment,” said Greg Grow, director of agribusiness at Archer Financial Services.

CBOT December corn futures settled down 16-3/4 cents at $5.19-1/4 a bushel and CBOT November soyabeans were 22 cents lower at $12.69-3/4.

“The long-awaited rains in the Iowa region are particularly welcome,” consultancy Agritel said in a note, referring to the largest US corn-producing state.

Market participants are turning their attention toward the US Department of Agriculture’s June 30 acreage report. Analysts expected an increase in corn and soya area estimates compared with USDA’s March projections.

CBOT September soft red winter wheat futures were down 11-1/4 cents at $6.40-3/4 a bushel.

But MGEX spring wheat futures for September delivery were up 2-3/4 cents at $8.08 a bushel as the crop in the northern US Plains and Black Sea has been stressed by drought.