GRAINS-Chicago corn hits 18-month high as crop tour heightens yield concerns

The most-active corn contract Cv1 on the Chicago Board of Trade (CBOT) was up 1.2% at $5.04 a bushel by 1220 GMT. It earlier reached its highest since February 2025 at $5.04-1/2 as it breached the psychological $5 threshold.

CBOT soybeans Sv1 added 0.4% to $12.42 a bushel.

CBOT wheat Wv1 was up 1.0% at $7.04-3/4, after hitting its highest in almost four weeks at $7.06-1/2.

Traders are closely watching reports from the Pro Farmer field tour after the U.S. Department of Agriculture cut its corn and soybean yield forecasts last week.

Corn yield potential and soybean pod counts across western Iowa are down from last year but remain near or above three-year averages, Pro Farmer scouts said on Wednesday.

On the third day of a four-day, seven-state event, Pro Farmer scouts projected the average corn yield for Illinois, the No. 2 U.S. corn state, at below the 2025 crop tour average and the tour's three-year average.

"After weaker results in Ohio, South Dakota, Indiana and Nebraska, the pattern is becoming increasingly difficult to dismiss," commodity data firm CM Navigator said in a note.

There was growing market chatter about importers considering alternatives to Russian and Ukrainian supplies, as attacks on Black Sea grain infrastructure disrupt shipments.

A slide in the dollar index =USD, which hit a three-month low on Thursday, also supported Chicago prices by making them more attractive for overseas buyers.