James Farrah continued an impressive summer when he won the 16- to 18-year-old division of the 17th annual Dewey Ricketts Memorial Junior Cup yesterday at Norbeck Country Club in Rockville. The Georgetown Prep senior defeated high school teammate Kevin O'Connell in a playoff, claiming his third Washington Metropolitan Golf Association junior tournament championship of the season.

Farrah won with a par on the first playoff hole after tying O'Connell at 5-over-par 221 over 54 holes.

Although two junior tournaments still remain--the Bubby Worsham Memorial and the WMGA's Junior Open--the WMGA named Farrah its junior golfer of the year following his win yesterday because he has been so dominant this summer.

Farrah also won the WMGA's Frank Emmett Schoolboy and Bobby Gorin Memorial. He reached the quarterfinals of the Bobby Bowers.

"I started hitting the ball well before the Emmett," Farrah said. "After I started hitting it well, I went into that tournament with some confidence. Then I played well through that tournament. . . . Each tournament has given me more confidence."

Farrah started the final round with a two-stroke advantage over O'Connell, who has chased Farrah all summer. O'Connell finished second to Farrah at the Emmett and reached the semifinals of the Gorin.

After Farrah bogeyed the third hole, O'Connell birdied No. 5 to tie for first. They both bogeyed three of their remaining 13 holes to force the playoff.

Farrah was able to get up and down for par on the extra hole, while O'Connell three-putted to finish in second place.

Brian Fairbank, a 14-year-old who will be a freshman at the Potomac School in the fall, shot a 223 to win the 14- to 15-year-old division by six strokes.