The price of wheat is rising, pushed higher by demand from China and worries over the weather.
Wheat for December delivery is up 3.5 per cent for the day. Prices for corn and soybeans are also up.
Prices for all three have spiked since June because of a drought that has hurt crop yields.
But many investors have already accounted for the drought in their trading, and Wednesday's rise seemed to be driven by other factors.
China is buying both wheat and soybeans, pushing up prices. And Hurricane Isaac will cut into harvesting time for crops in the United States Southeast.
Major metals like gold, silver and copper are all slightly down. The price of oil is also down.