GRAINS-US soybeans down nearly 3 pct as Brazilian currency dives

* Weaker currency seen boosting Brazilian soy sales, exports

* Corn follows soy down, despite worrisome U.S. weather

* Wheat lower but export demand lends support

(New throughout; updates prices, adds quotes, changes byline, changes dateline from previous PARIS/SINGAPORE) CHICAGO, May 18 (Reuters) - U.S. soybean futures fell nearly 3 percent on Thursday as a plunge in the value of Brazil's currency threatened U.S. soy exports and encouraged Brazilian farmers to step up sales from their record-large harvest, analysts said. Corn and wheat followed soybeans lower. As of 11:34 a.m. CDT (1634 GMT), Chicago Board of Trade July soybean futures were down 27-3/4 cents at $9.48 per bushel after dipping to $9.46, the contract's lowest since April 11. CBOT July corn was down 5-3/4 cents at $3.65-3/4 a bushel, and July wheat fell 1-1/2 cents at $4.25-1/2 a bushel. Soybeans sank as the Brazilian real tumbled more than 7 percent following corruption allegations against Brazilian President Michel Temer. Soybeans are priced in dollars, and because Brazilian farmers are paid in the domestic currency, a weaker real means farmers earn more money for their crop. Brazil just completed the harvest of its largest-ever soy harvest, estimated by the U.S. Department of Agriculture at 111.6 million tonnes. But farmers had sold only about half of it

"The big story in Brazil was, when would they sell? Now, with this much of a drop, this will incentivize Brazilian farmers to sell soybeans," said consultant Michael Cordonnier, president of Soybean and Corn Advisor. The currency move also makes Brazilian soy more attractive on the world market, inhibiting export demand for U.S. supplies. "The decline of the real is weighing on the soy complex, getting Brazilian origins more competitive," consultancy Agritel said in a note. The slide in CBOT soybeans pressured corn futures. But concerns about excessive moisture in portions of the U.S. Corn Belt lent underlying support. "The corn market has a little bit of its own story with weather forecasts suggesting excessive water in recently planted fields. Will they have to plant again? Will it be too late, and will they have to shift to beans?," asked Tom Fritz, a partner with EFG Group, a brokerage in Chicago. Tempering wheat futures' fall was support from larger-than-expected weekly U.S. export sales and news from Wednesday that Egypt's state grain buyer purchased two cargoes of U.S. wheat at its latest tender. The USDA reported export sales of U.S. wheat in the latest reporting week at 640,600 tonnes (old and new marketing years combined), topping a range of trade expectations.

CBOT prices at 11:32 a.m. CDT (1632 GMT):

Net Pct Volume

Last change change

CBOT wheat Wc1 425.50 -1.50 -0.4 44365 CBOT corn Cc1 366.25 -5.25 -1.4 141546 CBOT soybeans Sc1 948.50 -27.25 -2.8 188720 CBOT soymeal SMc1 308.60 -6.70 -2.1 75266 CBOT soyoil BOc1 32.48 -0.67 -2.0 69196

NOTE: CBOT wheat, corn and soybeans shown in cents per bushel, soymeal in dollars per short ton and soyoil in cents per lb.

(Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; editing by Tom Hogue, Ed Osmond and W Simon)