Wheat in Chicago surged as U.S. drought and trade route obstacles in Ukraine threaten to tighten global grain supplies.

Only 30% of America’s winter-wheat crop is in good or excellent condition, the Department of Agriculture said Monday in its first national ratings of the year. That’s the lowest score for this point in the season in data spanning three decades. Parts of Europe are also facing spring frosts or snow, according to Paris-based adviser Agritel.

Farmers in big wheat-growing states like Kansas are facing severe drought. While there’s still a few months left for rain to improve conditions, producers are worried about harvest size. Adding to concern are record-high fertilizer prices that could lead some growers to skip applying the chemicals, potentially hurting grain quality. Meanwhile, the ongoing dryness prompted wildfire warnings on Tuesday.

“The Western Plains are under increased fire risk today, with strong winds and dry conditions, not ideal for the wheat crop,” CHS Hedging commodity broker Jim Warren said in an online post.

Grain supplies are already constrained by Russia’s war in Ukraine. Some Ukrainian crops are being shipped out by rail and road, but flows are much smaller than traditional export routes by sea, UkrAgroConsult said.

“A full recovery of exports will only take place after the Black Sea ports are unblocked,” the Kyiv-based analyst said. “The grain export potential under the current conditions is limited to 1 million tons per month,” fivefold lower than normal.

Wheat futures for May rose 3.5% to $10.4525 a bushel in Chicago after climbing as much as 6.3%. Corn gained 1.2% to $7.5975, buoyed by a U.S. export sale to China of more than 1 million tons, while soybeans added 1.8%.

In softs commodities, raw sugar and arabica coffee edged higher while cocoa slid.

Moscow’s efforts to avoid sovereign default took a blow after the U.S. halted dollar debt payments from the country’s accounts at U.S. banks. The European Union is proposing to ban coal imports from Russia.

Agricultural products haven’t been directly targeted by sanctions. Russia is one of the world’s biggest wheat suppliers and managed to ship a significant amount abroad in March. Still, its grain-export union has cited restrictions with logistics, insurance and payment for Russian supply.