Jim Estes of Rockville and Bethesda Country Club is set to defend his Maryland Amateur golf championship in somewhat unfamiliar territory, at Baltimore's Elkridge club starting today and running through Sunday. Estes is exempt from today's qualifying.

"I played it Elkridge when I was 13," said Estes, now 21. "It's a short golf course, conducive to a straight hitter, That's the reason why I think it will be good for me," said Estes. He won last year at Congressional's Gold Course, which is longer than Elkridge.

Estes transferred from the University of Tennessee to the University of Maryland last autumn, and will be able to use his final year of varsity eligibility to play golf for Maryland Coach Fred Funk this fall.

Funk, who won the Maryland Open in 1983, is having another good year. He has won four Middle Atlantic PGA pro-ams, and last week played in his second straight U.S. Open, at Shinnecock Hills on Long Island. He shot 84-77-161 and missed the cut.

In last year's Open at Oakland Hills near Detroit, Funk tied for 23rd and missed finishing in the top 16 by one stroke, which would have landed him in April's Masters.

Funk predicted this could be the "best year yet" for his Maryland varsity with Estes joining Mike Kavka, Rusty Mason and Errki Valimma.

Fred Widicus of Jefferson High and Army Navy Country Club will defend his title in the 53rd Frank Emmet Schoolboy, starting Monday at Manor. Jason Raivel, Tom Iredell and Hap Peden are also in the tournament, which runs through Thursday . . . A full field of more than 400 golfers, plus tennis players, are expected Monday for the Lombardi Memorial outing at Indian Spring, which raises money for cancer research at Georgetown University.

The 36-hole, $7,000 Capital City Open is set Saturday and Sunday at Langston in Washington. Among the pros expected to compete for the $1,800 first prize are Tony DeLuca, Chuck Thorpe, Al Green, Al Morton, Mel Rifman, Willie Jefferson, Bill Bishop and Bobby Mayes.

Kenwood will host the Women's District Golf Association Championships, Monday through Friday of next week. Curtis Cup player Kim Williams of Bethesda will not play, as she will be competing in the women's Western Amateur near Chicago. Williams is an automatic qualifier for the Women's U.S. Amateur (Aug. 11-16 in Santa Cruz, Calif.) and the Women's U.S. Open (July 10-13 in Kettering, Ohio). She will also play in the Maryland Women's Amateur (July 15-18) at Chevy Chase.

Hobbit's Glen will host the inaugural Kenny Horton Memorial Junior Masters, Monday, July 21. It is a stroke play event for boys and girls. Advertisements to be displayed at each hole are being sold to sponsors in an effort to raise $5,000 for junior golf.

Members of the Washington Redskins "Over the Hill Gang" team will play in a cystic fibrosis benefit, Monday, Aug. 4, at Lakewood in Rockville. Roy Jefferson, celebrity chairman, said Billy Kilmer, Ron McDole, Diron Talbert, Ted Vactor, Terry Hermeling, Bobby Mitchell and former Washington Senators baseball player Chuck Hinton are among the golfers committed so far. Persons interested in contributing $175 and playing with a celebrity should contract the Cystic Fibrosis Foundation at 459-8444.

A celebrity tournament to benefit the Shock Trauma Unit of the Prince George's County Hospital will be held Monday, July 28 at Lake Arbor (formerly Newbridge). The day includes lunch, golf and a cocktail party. For more information, contact Regina Schewe at 556-0844.