* Corn ticks down on strong planting progress and crop ratings
* Soy edges down on spillover weakness from corn
* Wheat stumbles as U.S. harvest speeds along
CHICAGO, June 4 (Reuters) - Chicago Board of Trade corn and soy dipped in choppy trade on Tuesday as traders weighed U.S. planting progress and strong corn ratings with adverse weather in importer Mexico and downgrades to soybean harvest forecasts in major exporter Brazil.
The most-active corn contract on the Chicago Board of Trade (CBOT) was down 1/4 cent at $4.43-1/4 a bushel as of 1610 GMT. CBOT soybeans inched down 1/2 cent to $11.84 a bushel
"The market is starting to look at the international arena of weather," Dan Basse, president of AgResource, said.
A drought and intense heat in Mexico could damage the country's crop and stimulate demand for U.S. corn, traders said.
Soybean losses related to recent floods in Brazil's southernmost state of Rio Grande do Sul were estimated at 2.71 million metric tons, crop agency Emater said on Tuesday, in line with private forecasts ranging from 2.8 million to 3 million tons.
Monday's U.S. Department of Agriculture crop progress report underscored a favourable start to the U.S. growing season and strong conditions for U.S. corn, but traders said the positive news had mostly been factored into the market.
"People had expected a good rating and good crop, so it's not much of a surprise," Austin Schroeder, analyst at Brugler Marketing, said.
Wheat futures slipped on strong ratings of U.S. winter wheat as the harvest advances, traders said. Concerns over frost and drought damage to the Russian wheat crop are fading, analysts said.
"You're running out of steam with the Russian story, Schroeder said. "It's still supportive long term, but you're losing momentum with that."
CBOT wheat slipped by 12-3/4 cents to $6.60-1/2 a bushel.
(Reporting by Heather Schlitz in Chicago. Additional reporting by Gus Trompiz in Paris and Bernadette Christina in Jakarta; Editing by Subhranshu Sahu, Varun H K and David Evans)
