KANSAS CITY — Modest but continuing deterioration in the corn and soybean crops was reported in the latest Crop Progress data from the U.S. Department of Agriculture for the week ended July 29. Spring wheat crop conditions improved slightly during the period, the U.S.D.A. said.

Drought conditions continued without significant improvement in much of the Midwest in the latest week. Weather conditions in spring wheat areas were somewhat milder, allowing for slight improvement where the crop was not yet fully mature. The harvest continued to make progress well ahead of average.

In the 18 major corn-growing states, only 24% of the corn crop was rated good to excellent, down from 26% the previous week, the U.S.D.A. said. A total of 48% of the crop was in very poor to poor condition as of July 29, up from 45% a week earlier. A year ago in the same week, 62% of the crop was rated good to excellent and only 14% was very poor to poor.

As of July 29, a total of 29% of the soybean crop was rated good to excellent in the 18 major soybean-growing states, down from 31% the previous week, the U.S.D.A. said. A total of 37% of the crop was in very poor to poor condition during the latest week, up from 35% very poor to poor in the previous week. In the same week a year ago, 60% of the soybean crop was rated good to excellent and only 12% was very poor to poor.

In contrast to corn and soybeans, the condition of the spring wheat crop remained strong. The U.S.D.A. said 63% was in good to excellent condition in the six major spring wheat states, up from 60% in the previous week but below 70% in the same period a year ago. A total of 11% of the crop was in very poor to poor condition as of July 29, the same as in the previous week and up from 7% the same week a year ago, the U.S.D.A. said.

Almost all of the 2012 corn crop had gone through the silking stage as of July 29, well ahead of average. A total of 94% of the crop silked in the latest week, up from 78% in the same week a year ago. The crop continued to dough and dent well ahead of average as well. A total of 37% had reached the dough stage in the latest week, up from 17% as the 2007-11 average for the date. The crop was 13% dented in the 18 states, up from 3% as the five-year average, the U.S.D.A. said.

Soybeans also were progressing ahead of average. In the 18 major soybean states, a total of 88% of the crop had bloomed as of July 29, up from 72% in the same week a year ago and above the 2007-11 average of 75%. Some 55% of the crop was setting pods, up sharply from 29% in the same week a year ago and 35% as the 2007-11 average.

The spring wheat harvest was 28% completed as of July 29, well ahead of 1% at the same time last year and 3% as the 2007-11 average for the date.