Corn futures plunged by the exchange limit, heading for their worst day in at least six years, after the U.S. Department of Agriculture reported more of the grain was planted than analysts had estimated.

With or without retaliatory tariffs, Chinese companies probably will show little interest in buying U.S. corn because the jump in Chicago benchmark futures since May has wiped out the price advantage over domestic supplies, according to Yigu Info Consulting Ltd.

After a cold, soggy start to the season, it’s finally feeling like summer in the Midwest, and corn fields are recovering. A turn toward warmer weather should be beneficial for the battered crop, and government data signal that conditions are starting to bottom out.