Rose was co-leader with Immelman after round one
England's Justin Rose crashed out of Masters contention with a triple-bogey eight to trail halfway leader Trevor Immelman by 10 shots at Augusta.
Rose, 27, led with Immelman after round one, but found water at the par-five 15th after laying up in two on his way to a 78 for two over par.
"The 15th was a 20-second lapse in concentration," said Rose.
"In hindsight, I probably should have gone for the green. It was right on the limit, just one of those things."
Rose, the world number nine, played his third shot into the water guarding the front of the green, took a penalty drop and then raced his fifth shot through the green.
He chipped back almost into the water again before getting up and down in two for an eight. Rose then bogeyed the par-three 16th.
"I laid up way too close to the green and the way they grow the grain into you, I had a bit of a tricky lie and no yardage," said Rose, who played in the day's final group.
"That was hard but that just proved the struggle. I struggled all day with my concentration. It was such a long round and coming in last was tough. There was a lot of noise and I felt I was struggling.
"Yet it could have turned around nicely for me. I had a birdie chance on the 13th and 14th with the par-five 15th to play. I felt good about playing my way back into the tournament.
"Obviously there is plenty to play for but it's not the exciting weekend I was looking forward to."
Rose has twice before led the Masters after the first round but finished 22nd in 2004 after a third-round 81 and a year ago he came fifth after double-bogeying the 17th when one behind winner Zach Johnson.