Chicago Board of Trade corn futures rose on Friday on technical buying and concerns that unfavorably hot weather will threaten the developing US crop, traders said. CBOT September corn ended up 5-1/4 cents at $3.59-1/2 a bushel, while new-crop December corn ended up 5-1/4 cents at $3.71-1/4. Heat is increasing in the US corn belt, particularly along and west of the Mississippi River, according to a meteorologist for the US Department of Agriculture. Drier-than-normal weather is also expected in the region.