US corn and soybeans slid around half a percent, with traders expecting prices to rebound on expectations of crop losses in drought-hit South America. Chicago Board of Trade March wheat rose 0.1 percent to $6.48 a bushel by 0353 GMT, after finishing 6-1/4 cents lower at $6.47-1/4 cents per bushel on Friday. March soy fell 0.6 percent to $12.11-1/2 a bushel and corn for March delivery also lost 0.6 percent to $6.38 a bushel. "Yes, there has been some speculation about Russia applying brakes on wheat exports, but the market will have to wait for some clear signal," said Lynette Tan, analyst with Phillip Futures in Singapore. Last week, US wheat posted its largest weekly bounce in more than a month on growing export demand and worries over production. The US Department of Agriculture on Friday said exporters sold 133,200 tonnes of US wheat to an unknown destination as well as 170,200 tonnes of US corn to Mexico. Traders expect Russia, which has dominated global wheat export trade this year, to soon curb exports as it nears a self-imposed quota of 25 million tonnes. "The pace of wheat exports has been brisk and from now on all eyes will be on Russia," Tan said. A fierce cold snap engulfed Russia's southern wheat growing regions, where hard winter frosts are unusual, the Hydrometeorological Service, Russia's state forecaster, said on its website on Thursday. Analyst ProAgro said on Thursday the grain harvest of major exporter Ukraine was likely to come in at about 40 million tonnes in 2012, about 29 percent down from a record of 56.7 million in 2011, due to a fall in acreage because of bad weather when winter crops were being sown. Tan said corn prices are expected to be more volatile from next month, affected by dry weather conditions in Argentina. "I see some softening in corn. After all, it was overbought, and I also expect corn to be volatile in the days to come," she said. The dryness that blighted Argentine farm areas in December and early January will cut yields of early-planted corn while later-seeded fields have been revived by recent rains, the government said on Friday. Argentina's 2011/12 soy and corn harvests will be smaller than in the previous crop year, the Buenos Aires Grains Exchange said, underlining concerns that the drought might crimp world food supplies at a time of growing demand.