* Corn rises on extended planting delays
* CBOT wheat falls on profit-taking after 2-month top
* Soybeans drop after three days of gains
* More rain in Midwest forecast, Plains seen dry
* Coming up: Traders monitoring U.S. Fed meeting
(Rewrites, adds new analyst quote, details, updates prices)
By Mark Weinraub
CHICAGO, April 26 (Reuters) - U.S. corn futures rose to a two-week high on Tuesday as forecasts for rains in the U.S. Midwest threatened to further delay spring planting, raising the value of extremely low old-crop stocks.
Wheat futures dropped on a profit-taking setback despite a supportive fundamental picture.
Soybean futures also were weaker after a three-day winning streak on concerns that farmers may switch some of their intended corn acreage to soy if planting delays continue.
Traders were wary of taking on big positions as the U.S. Federal Reserve's policymaking committee began a two-day meeting on Tuesday. The meeting was not expected to lead to a rate cut or a change to its $600 billion bond buying program, but a groundbreaking news conference by Chairman Ben Bernanke was expected to set a tone for the markets.
Chicago Board of Trade May corn was up 4-1/4 cents at $7.66-3/4 a bushel at 11:09 a.m. CDT (1609 GMT).
The CME Group, which owns the Chicago Board of Trade, is considering widening the daily trading limit in corn to 50 cents per bushel, from the current 30 cents, a spokesman for the exchange said Tuesday.
CBOT May wheat was down 6-3/4 cents at $8.19-1/4 a bushel and CBOT May soybeans were down 10-1/4 cents at $13.79-1/4.
Damp soil in the Midwest has virtually stalled corn seeding in some key states with the window for optimum yields narrowing at a time when the United States needs a bumper crop to replenish extremely low supplies.
The U.S. Agriculture Department said on Monday afternoon that just 9 percent of intended corn acreage had been seeded as of April 24. A year ago, corn planting was 46 percent complete and the five-year average for late April is 23 percent.
"You are going to see little if any fieldwork getting done here," said Mike Palmerino, forecaster at Telvent DTN. "There is just so much (corn) acreage this year that you just wonder if it is all going to get planted."
The slow start to planting dashes hopes that an early harvest would provide some relief to the tight old-crop supply situation. Robust demand for U.S. corn has left domestic stocks at their tightest level since the 1930s.
"The fact that the crop is going to be late has pushed more emphasis back into the old-crop market," said Greg Grow, director of agribusiness at Archer Financial Services. "In a crop that is planted early, sometimes you will get early corn available in late August or early September. That is going to be tough this year.
BUMPER S. AMERICAN HARVEST PRESSURES SOY
Additional pressure on soybeans came as overseas buyers look to South America to fill their soybean needs amid the harvest of a bumper crop from Argentina and Brazil.
"You are facing a little bit of headwind too from the fact that you have had some lousy (export) inspections here," said Dewey Strickler, president of Ag Watch Market Advisors. "We had been expecting a slowdown (in exports) and we are seeing it."
Farmers in the U.S. Plains were facing the opposite problem of their Midwest counterparts as dry weather stresses the developing hard red winter wheat crop. Little relief was forecast during the next 10 days, Palmerino said.
"It looks like that the areas that are the driest ... those areas are going to continue to struggle here," Palmerino said. "That is going to continue to likely allow for further deterioration in crop conditions."
The market had already factored in severe losses in southern reaches of the Plains but the crop in Kansas, the top wheat-producing state, was starting to deteriorate as well, Palmerino said. (Reporting by Mark Weinraub; Editing by Lisa Shumaker)