KANSAS CITY — Corn and soybean crop condition ratings continued to tumble in key states as indicated by the U.S. Department of Agriculture’s latest Crop Progress report issued on July 9.

Corn condition ratings dropped in each of the three leading corn states of Iowa, Illinois and Nebraska. Condition ratings for soybeans planted in top-producers Illinois and Iowa also decreased noticeably in the past week, although Michigan, the state with the third-largest area planted to soybeans this year, saw its soybean crop condition rating hold mostly steady from the previous week.

In the past few weeks, row crops have struggled amid triple-digit temperatures and expanding drought conditions. Futures prices for corn and soybeans have been soaring, reflecting the difficult growing conditions, particularly in the Midwest.

The U.S.D.A.’s most recent Crop Progress report indicated corn crop condition in Iowa, which was projected to harvest 13,600,000 acres of corn this year, was 46% good to excellent on July 8, marking a steep decline from the 62% good-to-excellent rating of a week earlier. The U.S.D.A. said only 19% of Illinois’ corn was in good-to-excellent condition compared with 26% the week before.

Nebraska, the state with the third-largest number of corn acres forecast to be harvested in 2012, also saw its corn good-to-excellent ratings slashed. The U.S.D.A. said 47% of the state’s crop was good to excellent, down sharply from 65% on July 1.

Soybean crop condition ratings in two of the three top-producing states, Iowa and Illinois, also declined. In Michigan, the soybean crop condition rating was even with the previous week’s report.

Iowa was forecast to harvest 9,440,000 acres of soybeans in 2012. The U.S.D.A. reported 48% of the state’s crop was in good-to-excellent condition on July 8, down from 59% a week earlier. Illinois, which was forecast to harvest 8,570,000 acres of soybeans this year, had 20% of its crop rated good to excellent, down from 28% in the week ended July 1.

Michigan, with a 2012 harvest forecast at 6,920,000 acres, saw its corn crop condition hold steady at 34% good to excellent.