UPDATE 1 — US corn rating seen steady, harvest 13% done; soy rating likely down

(Updates with USDA data) By Karl Plume CHICAGO, Sept 21 (Reuters) — U.S. corn and soybean condition ratings held steady at three-year lows over the past week, as harvesting of both crops advanced modestly despite widespread rains in parts of the Midwest, according to a weekly U.S. Department of Agriculture report released on Monday. The USDA said 57% of the nation's corn crop and 58% of soybeans were in good-to-excellent condition as of Sunday, unchanged from a week earlier. The ratings for both crops were be the lowest for this time of year since 2023, according to USDA data. Analysts polled ahead of the report expected the corn rating to hold steady and the soybean rating to dip by one point. Corn and soybean harvesting was slowed in some areas of the Midwest last week by excessive rains, analysts said. Soggy field conditions and more showers this week are likely to continue restricting harvest progress, they said. The USDA said 13% of the U.S. corn crop was harvested as of Sunday, up from 8% a week earlier. Soybeans were 12% harvested, up from 6% a week earlier. Both figures were in line with trade estimates. Spring wheat harvesting was winding down. The USDA said.