WASHINGTON — The percentage of the corn crop rated good to excellent as of July 27 in the 18 major states was 75%  compared with 76% the previous week and 63% in the same week a year ago. Six per cent of the crop was rated very poor to poor compared with 5% the previous week, the U.S. Department of Agriculture said in its Monday Crop Progress report.  In top-producing Iowa, 78% of the crop was rated good to excellent in the latest week.

Conditions of the soybean crop in the 18  major states also weakened, with 71% rated good to excellent as of July 27 compared with 73% the previous week and 63% in the same week a year ago. Six per cent of the crop was rated very poor to poor compared with 5% the previous week, the U.S.D.A. said.  In top-producing Iowa, 74% of the crop was rated good to excellent in the latest week.

The U.S.D.A. said conditions of the spring wheat crop in the six major states held firm at 70% rated good to excellent as of July 27.  Ninety-three per cent of the crop was headed in the latest week compared with 93% as the five-year average.

The U.S.D.A. said 78% of the corn crop had reached the silking stage in the latest week compared with the 75% five-year average. Silking is a part of the key pollination process, when kernel development is established. Seventeen per cent of the crop in the 18 major states was in the dough stage compared to 16% as the five-year average.

The U.S.D.A. said 76% of the soybean crop in the 18 major states was blooming as of July 27 compared with the five-year average of 72%. In addition, 38% of the crop was setting pods in the latest week compared with a 31% average.

Eighty-three per cent of winter wheat in the 18 major states was harvested as of July 27, the U.S.D.A. said, compared with an 80% five-year average. Most hard red winter wheat states were about finished with harvest, such as Kansas (97% complete), Texas (100%) and Oklahoma (100%), while several states were progressing toward completion, such as Colorado (87%), Nebraska (79%) and South Dakota (27%).

Major soft red winter wheat states were also mostly finished with their harvests, such as Ohio (97% complete), Illinois (100%), Indiana (98%) and Missouri (100%). Michigan lagged at 72% complete in the latest week, the U.S.D.A. said.

The U.S.D.A. said 44% of the oats crop was harvested in the nine major states compared with 35% as the five-year average. Conditions of the crop were steady at 64% rated good to excellent.