CHICAGO: Chicago Board of Trade (CBOT) corn futures firmed on Thursday on worries that dry conditions would drag down crop yields in parts of the US Midwest, traders said.

* CBOT September corn fell 3/4 cent to $4.10-1/4 per bushel and new-crop December corn closed down 1/2 cents at $4.17-3/4 a bushel.

* For the week, December futures gained 2% in the first weekly gain in four weeks.

* Traders squared positions ahead of next week's US Department of Agriculture (USDA) supply-and-demand report, which is expected to show a smaller crop and fewer planted acres.

* Dry weather in parts of the central and eastern US Midwest has elevated concerns about lower yields. Forecasters expect drier than normal conditions to persist in the 6- to 15-day outlook.