BEIJING, Aug 19 (Reuters) - Chicago wheat futures fell for a second session on Tuesday, pressured by an upward revision to Russia's wheat crop forecast and recent talks to end the war in Ukraine, which raised expectations of ample global grain supplies.
The most-active wheat contract on the Chicago Board of Trade (CBOT) Wv1 was down 0.43% at $5.23 per bushel, as of 0249 GMT.
On Monday, Russia's IKAR consultancy raised its 2025 wheat crop forecast to 85.5 million metric tons from 84.5 million tons.
"Grain prices have continued their retreat on the back of bearish news, including an increased Russian wheat crop," said Andrew Whitelaw of agricultural consultants Episode 3.
Hopes of progress in ending the war in Ukraine also weighed on sentiment, he said.
On Monday, U.S. President Donald Trump told Ukraine President Volodymyr Zelenskiy that Washington would help guarantee Ukraine's security in any deal to end Russia's war there, though the extent of any assistance was not immediately clear. Zelenskiy hailed the promise as "a major step forward".
Both Russia and Ukraine are major grain exporters.
The U.S. Department of Agriculture's weekly report on Monday showed half of the U.S. spring wheat crop was rated to be in "good to excellent" condition, up one percentage point from a week earlier and above expectations.
Corn conditions dipped slightly over the past week but remained at their strongest since 2016, while soybean ratings were steady.
Corn Cv1 slipped 0.49% to $4.05 a bushel, while soybeans Sv1 edged up 0.34% to $10.45 a bushel.
Traders are also awaiting results from the Pro Farmer Midwest crop tour, which is surveying corn and soybean fields across the U.S. this week.
Ohio and South Dakota's corn yield prospects and soybean pod counts are higher than both last year and the three-year average, according to scouts on an annual tour of top U.S. production states on Monday.
Farmers are expected to harvest a bumper soybean crop and a record corn crop after favourable weather across much of the Midwest this summer.