Keith Jackson, the folksy voice of college football who for decades weaved backwoods wit through Saturday afternoon ABC broadcasts, died Friday night. He was 89.In a 52-year broadcasting career, Mr. Jackson covered a wide variety of sports for radio and TV, including a rowing competition in the former Soviet Union, but he was best known as ABC’s voice of NCAA football and for his homespun phrases.To Mr. Jackson, linemen were "the big uglies." Running backs didn’t drop the ball, there was a "fuumm-bull!" Of an undersize player, he might say, "He’s a little-bitty thing, a bantam rooster. But he’s young. If he keeps eatin’ his cornbread, he’ll be man-sized some day."And, of course, there was "Whoa, Nellie!," his signature phrase. Or was it?Strangers in restaurants, airports, stadium parking lots and downtown streets would sidle up to Mr. Jackson and bellow, "Whoa, Nellie!" Mr. Jackson, however, always maintained that he might have — might have, mind you — used the phrase a time or two early in his career but that mostly impersonators, primarily Roy Firestone, were responsible for the spread of the phrase."This ‘Whoa, Nellie!’ thing is overrated," he said frequently. "There were all kinds of stories going around. People said I had a mule in Georgia named Nellie. Well, we had a mule in Georgia, but her name was Pearl."ABC wouldn’t let Mr. Jackson retire the first time he tried. He announced before the 1998 season that it would be his last, that, at 70, he was tired of getting on airplanes. But he was back in the booth in the fall of 1999, the network having lured him with a promise of keeping him close to his Los Angeles Oaks home by restricting his assignments to the Pacific time zone. He finally called it a career after describing the Texas win over Southern California in the national championship game at the Rose Bowl after the 2005 season."Keith Jackson and college football. You can’t say one without the other," Penn State coach Joe Paterno once said. "You always know it’s a big game when Keith is there.’’Mr. Jackson was born Oct. 18, 1928, in Carrollton, Ga., about 50 miles west of Atlanta. He practiced broadcasting as a youngster growing up on a farm, recalling someone saying: "The kid’s walking crazy around the cornfield, talking to himself.’’By the early 1950s. Mr. Jackson had served a four-year overseas stint in the Marine Corps and was attending Washington State University, studying criminology and political science. As Mr. Jackson listened to a student broadcast of a football game, he thought, "I can do better than that."The professor in charge of the broadcasting program gave him a tape recorder and told to go cover something. He chose a basketball game at Pullman High as his first assignment. "They turned the lights out at halftime," he said. "I didn’t have the foggiest idea what to do, so I just told stories."Mr. Jackson’s broadcasting philosophy: "Amplify, clarify and punctuate, and let the viewer draw his or her own conclusion.""If I’ve helped people enjoy the telecast, that’s fine," he said. "That’s my purpose."