* USDA says U.S. corn 12 pct seeded, slowest since 1984
* U.S. soybeans 2 percent planted
* Winter wheat ratings drop, 32 pct rated good/excellent
By Julie Ingwersen
CHICAGO, May 6 (Reuters) - Stalled by rain and late-season snow in the last week, U.S. farmers have planted just 12 percent of their intended corn acres, the slowest pace since 1984, the U.S. Department of Agriculture said in a weekly report on Monday.
Soybean planting was 2 percent complete by Sunday, tied with 1983 and 1993 for the second-slowest place by early May, following the 1984 record of 1 percent.
The five-year average for planting progress at this time of year is 47 percent for corn and 12 percent for soybeans.
Producers working fields in the heart of the U.S. Corn Belt were interrupted by storms at mid-week.
"Temperatures dropped low enough for snowfall to be seen across much of Iowa. Records for both May snowfall and coldest daily high temperature were set in some areas," the Iowa field office of USDA's National Agricultural Statistics Service said in its weekly report.
Corn is the biggest U.S. crop and Iowa is the top producer. Corn planting progress in Iowa stood at 8 percent by Sunday, up from 2 percent a week earlier but still the slowest since 1995.
Flooding was noted in parts of Illinois, the No. 2 U.S. corn producer, while snow fell from Minnesota southward into Missouri, Kansas and even Oklahoma. Western and north-central Missouri received 1 to 5 inches (2 to 12 cm) of snow from May 2 to May 4.
Seeding progress fell short of trade expectations, including a Reuters poll of 14 analysts ahead of USDA's report that pegged corn planting at 15 percent complete.
Nonetheless, corn, soybean and wheat futures on the Chicago Board of Trade fell Monday as forecasts called for warmer and drier weather next week that should help U.S. farmers catch up.
"It's a backward-looking report," Terry Linn, analyst with the Linn Group, a Chicago brokerage, said of the USDA's crop progress report. "The more important thing is looking out over the rest of the first half of May, and things are much better than it appeared they were going to be," Linn said.
WINTER WHEAT RATINGS DECLINE
USDA said 32 percent of the U.S. winter wheat crop was rated in good to excellent condition, down from 33 percent a week earlier and the lowest since 1996. The poorest ratings remained in the Plains states, which have struggled with drought as well as spring freeze damage.
In Kansas, the top U.S. producer of hard red winter wheat, used for bread, 27 percent of the crop was rated good to excellent, unchanged from a week earlier, while 40 percent was rated poor to very poor, up 1 percentage point.
In Texas, another major HRW wheat grower, nearly three-quarters of the crop, 74 percent, was rated poor to very poor, up 6 points for the week.
"While producers still expect to harvest some of their wheat for grain, many fields were being baled for hay," USDA's Texas field office wrote.
Wheat ratings were mixed in the Midwest, which produces soft red winter wheat used in cookies and snack foods. Crops improved in Ohio and Indiana, but ratings fell sharply Illinois and Missouri.
Seedings of spring wheat, most of which is high-quality milling wheat produced in the northern Plains, continued to lag due to cold and wet conditions.
In North Dakota, the top U.S. spring wheat state, spring wheat planting was 7 percent complete, up from 2 percent a week earlier but far behind the five-year average of 40 percent. (Reporting by Julie Ingwersen; Editing by Carol Bishopric)