* Grain, soybeans slip back after rising on Tuesday
* Traders awaiting monthly USDA data due on Thursday
* China exempts some goods from tariffs, not soybeans orcorn(Adds closing prices)
By Karl Plume
CHICAGO, Sept 11 (Reuters) - U.S. soybean futures retreatedon Wednesday ahead of an eagerly awaited U.S. government cropreport, pressured by forecasts for favorable Midwest cropweather and disappointment that China did not include theoilseed on a list of U.S. imports exempted from tariffs.
Corn also weakened as late-planted U.S. crops were seenbenefiting from a late-summer heat wave, although positioningahead of the U.S. Department of Agriculture's (USDA) monthlysupply-and-demand report due on Thursday limited declines.
Wheat eased in tandem with corn and soy, pulling back fromone-month highs in the prior session.
Much of the market's focus was on the upcoming USDA report,which is expected to show smaller U.S. corn and soybean cropsafter the agency sprung a surprise last month with ahigher-than-anticipated forecast.
Now, warmer-than-normal weather across much of the Midwestfarm belt was expected to accelerate the maturity oflate-planted crops, reducing the risk that frost would damageyields.
"The weather forecast continues to show above-normaltemperatures weather in the 8-14 day forecast. The beans wouldbe the most susceptible to any frost in that time frame," saidTed Seifried, chief market strategist with the Zaner Group.
Chicago Board of Trade November soybeans fell 5-1/2cents to $8.66-1/2 a bushel. CBOT December corn shed 1-1/2cents to $3.60 a bushel, while December wheat fell 4-3/4cents to $4.77-1/2 a bushel.
The losses partly erased a rally on Tuesday, when hopes forrenewed Chinese purchases of U.S. agricultural products liftedthe market ahead of high-level trade talks next month aimed atending a year-long trade war.
Steep tariffs imposed last year have slashed Chinese importsof U.S. goods. China announced a short list of tariff exemptionson Wednesday, but key farm products were not included.
"We had the optimism yesterday that China's going to sweetenthe deal by buying more agricultural products. But when they putout their tariff exemptions, beans, corn, ethanol and wheat werenot on there," Seifreid said.
Senior White House adviser Peter Navarro tamped downexpectations on Tuesday for an early-round breakthrough in talksand urged investors, businesses and the public to be patient. OnWednesday, U.S. President Donald Trump called the China's tariffexemptions a "good gesture."(Reporting by Karl Plume in ChicagoAdditional reporting by Nigel Hunt in London and Naveen Thukralin SingaporeEditing by Lisa Shumaker and Matthew Lewis)