As of 12:56 p.m. CDT (1756 GMT), Chicago Board of Trade December corn was down 1-1/2 cents at $3.59-1/2 per bushel after dipping to a contract low at $3.56-1/2. CBOT December wheat was up 10 cents at $4.63-1/2 a bushel and November soyabeans were up 7 cents at $8.75-1/2 a bushel.
Corn extended its slide after the US Department of Agriculture late Tuesday rated 58% of the US corn crop in good-to-excellent condition, up from 57% the previous week, in line with trade expectations.
The crop's development is behind normal following widespread spring planting delays, but forecasts call for seasonal temperatures throughout September that should prolong the Midwest growing season, raising the odds that crops will have time to mature.
Front-month K.C. hard red winter wheat rallied from a 14-year low set Tuesday while Minneapolis Grain Exchange spring wheat futures bounced from a 10-year low. Plentiful global supplies have pressured wheat prices globally as suppliers vie for export business in a crowded market.
Paris wheat futures have slipped to their lowest levels in over a year. Soyabean futures drew support from USDA's confirmation that private exporters sold 451,766 tonnes of US soyabeans to Mexico.
Soyabeans also edged up as the drop in the dollar and gains across commodity and equity markets lent support.
Soyabean investors continued to seek fresh indications on US-Chinese discussions to resolve a trade dispute that has stalled US soyabean exports.