WASHINGTON — The silking process in the 2013 corn crop advanced rapidly last week and is now only four percentage points behind the 75% five-year average, the U.S. Department of Agriculture said in its latest Crop Progress report.

In the 18 main corn-growing states, silking as of July 28 stood at 71%, up sharply from 43% the previous week.  Silking indicates the key pollination process that determines the number of kernels per ear is under way and is sensitive to extreme heat and dryness. Weather in the Corn Belt recently has been relatively cool and wet, which agronomists view as favorable for the pollination process.

A total of 8% of the crop was in the dough stage as of July 28, the U.S.D.A. said, down from a five-year average of 17%. Because of persistent rainfall and cool spring temperatures, the crop experienced planting delays, which consequently pushed development behind average.

But mostly favorable weather since planting has maintained mostly good to excellent crop condition ratings. The U.S.D.A. said 63% of the crop in the 18 states was rated good to excellent as of July 28 and 11% was very poor to poor, the same as the previous week and far better than a year earlier when only 24% of the crop was rated good to excellent while 48% was rated poor to very poor.

A total of 65% of the soybean crop in the 18 main soybean-growing states was blooming in the latest week, up from 46% blooming the previous week but behind 74% as the five-year average, the U.S.D.A. said. Twenty per cent of the crop was setting pods as of July 28, down from 34% as the five-year average but up from 8% as of July 21, the U.S.D.A. reported.

The soybean crop’s condition ratings deteriorated slightly with 63% rated good to excellent, down one percentage point from a week earlier, and 9% was rated very poor to poor, up a percentage point from the previous week, the U.S.D.A. said. As with corn, the soybean crop fared far better than a year ago when 29% was rated good to excellent and 37% was rated poor to very poor.

The winter wheat crop was 81% harvested in the 18 main growing states, nearly even with the 82% five-year average. Harvest was completed in the hard winter states of Kansas, Texas and Oklahoma and in the soft wheat states of Arkansas, Indiana, Ohio, Missouri and North Carolina.

The spring wheat crop in the six main states was 94% headed as of July 28, nearly even with the 95% five-year average, the U.S.D.A. said.  A total of 68% of the crop was rated good to excellent in the latest week, the same as the previous week, and 6% was rated very poor to poor, up slightly from 5% a week earlier.

A total of 27% of the oats crop was harvested in the nine main oats-growing states, down from a 36% five-year average, the U.S.D.A. said. The condition of the crop was unchanged from the previous week at 56% good to excellent and 14% very poor to poor.

The rice crop in the six main rice-growing states was 36% headed, down from 43% as the five-year average. The crop was rated 69% good to excellent, down from 72% a week earlier and just below 70% a year ago, the U.S.D.A. said.