After a few weeks when it seemed the harvest in the United States was careening toward disaster, some glimmers of good news emerged on Monday.

The government said recent floods were likely to damage the corn and soybean harvest less than feared, and it also reported that farmers had planted more corn than previously expected, which should bolster output.

“This will allow a little breathing room  assuming we don’t have inclement weather during the rest of the growing season,” said Daniel W. Basse, president of AgResource, a consulting firm in Chicago.

Corn prices, which have repeatedly hit new highs this year, fell sharply Monday to $7.25 a bushel after the report from the Agriculture Department. Wheat, which had been moving up in the general enthusiasm for commodities, also tumbled. Soybean prices fluctuated but moved above $16 a bushel to a new high on supply worries.