Tight end Rich Caster, still recuperating from a 1981 knee injury, has been placed on the unable-to-perform list by the Washington Redskins.

Caster now will have most of training camp to finish rehabilitating the knee, which is about 87 percent healed, according to Coach Joe Gibbs.

"When he feels he is ready to practice, he will let us know," Gibbs said. "We want him to feel comfortable with it and right now he doesn't. If he isn't able to come back, we'll put him on waivers."

Caster, the former New York Jets star, would give the Redskins a pass-catching tight end. However, the team would be more inclined to go with younger players, if they perform up to expectations in camp. If they don't, the coaches would like to have Caster available.

The Redskins made their first two cuts, dropping tight end Vince Rogusky and linebacker George Lewis . . . Wide receiver Alvin Garrett, the only unsigned Redskin entering camp, has agreed to a new contract. Garrett has made some fine catches the first two days of practice, as has Charlie Brown . . . Tackle Don Laster, a 12th-round pick from Tennessee State, spent Thursday night in Carlisle Hospital because of dehydration, but worked out today.

Scout Charley Casserly now is training camp director, replacing Dick Myers, the new general manager of Washington's United States Football League team . . . Public practices here will end Aug. 4 . . . The heaviest Redskins among this first group of players are Laster (286 pounds), defensive end Ed Jackson (280) and guard Gary Sayre (275) . . . Gibbs said he was pleased with the first three workouts of camp. This afternoon's session was especially crisp for an early practice. Rookie cornerback Vernon Dean turned one tipped ball into a would-be touchdown . . . Fullback Wilbur Jackson, who spent most of last season on injured reserve, is working himself into shape before other veterans report. He has yet to participate in contact drills . . .This is the 20th straight year the Redskins have trained at Dickinson College.