CHICAGO: Chicago Board of Trade corn futures declined on Wednesday for a fourth straight session as favorable weather in the Midwest and improving US crop ratings supported expectations for a big harvest.

CBOT September corn settled down 4-1/2 cents at $3.15-1/2 per bushel and most-active December corn fell 3-3/4 cents to settle at $3.26-1/4 after hitting $3.26, the contract's lowest since June 29.

Stress from dryness will be limited to only about 15% of the US Corn Belt over the next two weeks, the Commodity Weather Group said in a client note.

The US Energy Information Administration said weekly production of corn-based ethanol rose in the latest week to 958,000 barrels per day, while stockpiles rose to 20.272 million barrels.

Ahead of Thursday's weekly US Department of Agriculture export sales report, traders expected the government to report US corn sales in the week ended July 23 at 600,000 to 1.550 million tonnes (old and new crop years combined).