Wheat jumped the most since 2010 in Chicago, capping the biggest monthly gain in six years as Russia’s invasion of Ukraine chokes supplies from a major breadbasket and sends shock waves through crop markets.

Activity at Ukrainian ports has been halted since Russia invaded its neighbor last week, and grains trade from Russia is also effectively on pause. Sanctions have been ratcheted up to further isolate commodity-rich Russia from global finance by sanctioning its central bank and cutting off various leaders from the critical SWIFT financial messaging system.

Restricting grain supplies from the Black Sea region threatens to further boost global food prices that are near a record high, at a time when supplies are already strained with adverse weather in many growing regions. Wheat futures soared as much as 8.7% on Monday—rising by the exchange limit—while other crops from corn to palm oil also rallied.

Most-active wheat futures advanced 8.6% to settle at $9.34 a bushel in Chicago. Prices soared about 23% in February, the biggest monthly gain since 2015.

“I’m not going to put a lid on what might happen,” said Arlan Suderman, chief commodities economist at StoneX. “We could easily be looking at record prices.”

Corn futures in Chicago also rose by the exchange limit, while soybeans climbed as much as 4.4%.