Wayne DeFrancesco, playing with the confidence of a professional, ended an impressive amateur career yesterday by winning his second District Amateur golf championship.

DeFrancesco, 23, defeated Dave King of Bethesda, 5 and 4, in the scheduled 36-hole title match at Washington Country Club's National Course. King, 40, has played the tournament the last 16 years and reached the final in 1977.

DeFrancesco, who will play in a professional minitour in Florida next month, won the title in 1978. He is the first to win the tournament twice since Dave Oakley (1966 and 1970) and Bobby Brownell, who won 10 times in the 1940s and '50s.

The tournament was marred by an accident. Bob Benson, a District Golf Association official, was pinned among four golf carts Saturday and suffered broken ribs.

DeFrancesco, who plays out of Cedar Crest, attended Langley High School and was first-team all-America while at Louisiana State. During his best year, in 1979, he finished third in the NCAA tournament.

He gave up competitive golf last year. After he changed his mind, back injuries sidelined him until only nine weeks ago.

In the first round of the Belle Haven Four-Ball, DeFrancesco and Perky Cullinane defeated King and Dave Pelz with a birdie 3 on the seventh extra hole.

Yesterday's match wasn't as tight.

King was tired. He had played six rounds since he was the No. 5 qualifier with two-over-par 72 Thursday. Yesterday, he had trouble, driving into the rough and water.

King, who won the first two holes, got no closer than 1 down after the 18-hole morning round. In the afternoon, they halved the first two holes before DeFrancesco won four straight to go 5 up.

The two halved the 25th through 28th holes. King came back on the 29th with a birdie 2, halved No. 30, but drove into the water twice on the next hole for double bogey.

A half on No. 32 decided the match.

DeFrancesco, who played in the U.S. Open earlier this month, will move to Florida next month and try to earn his PGA card.

"I came out of the Open thinking that I'm up with any tour players," he said. "I am 100 percent sure I can make it."