By Ian Berry
    Of DOW JONES NEWSWIRES
 
 
   CHICAGO (Dow Jones)--Chicago Board of Trade corn futures ended lower Tuesday,
 failing to recover after being "ambushed" by plunging crude-oil prices.
 
   September corn ended down 15 1/2 cents to $6.48 1/4, December corn ended down
 15 1/2 cents to $6.66 3/4 and March 2009 corn ended down 15 cents to $6.85 1/4.
 
   Prices in corn, along with other commodities, fell early in trading after
 crude oil plummeted more than $9, analysts said. Crude settled more than $6
 lower, its largest dollar drop since 1991.
 
   "Crude oil took in a huge gulp of air and choked everything else down," Jerry
 Gidel, analyst for North America Risk Management Services.
 
   The market continued to erase gains from its June rally on historic flooding,
 as the December contract closed below the 50-day moving average for a second
 straight day. Prior to Monday it had not closed below that average since March,
 and then only for one day.
 
   "Technically, we're still a mess," a trader said. "The only thing we've got
 going for it is that it's potentially oversold."
 
   On July 2, prices closed higher by almost 30 cents, the daily trading limit,
 on concerns about a potential heat wave in the long-range forecast. Since that
 July 2 close at $7.80 1/2 for December corn, prices have ended higher seven of
 eight days.
 
   Traders are very sensitive to the weather now but are finding little bullish
 news in forecasts. A rally is unlikely until and unless a hot, dry weather
 pattern emerges that could place the crop in danger, traders and analysts said.
 
   Analysts had expected a technical rebound today on oversold conditions and
 overnight gains, but the drop in energy prices halted any upside momentum.
 
   One trader said that the broader economy is starting to pressure commodities.
 A developing deflationary environment could damp demand, he said.
 
   CBOT oats futures ended lower on fund selling and pressure from other
 markets, a trader said. September oats were down 7 1/2 cents to $4.32 per
 bushel, December oats were down 8 1/2 cents to $4.49 and March oats were down 7
 1/2 cents to $4.67. The trader said commercial buyers gave underlying support
 to the December and March contracts.
 
   Ethanol ended lower. September ethanol fell $0.101 to $2.585 per gallon, and
 December ethanol was flat at $2.675.