PORT ST. LUCIE, Fla. — Moises Alou will have surgery for a hernia and miss the start of the season, the most serious in a string of recent setbacks for the depleted Mets.

After reporting discomfort in his right groin, the oft-injured Alou left spring training camp yesterday and was sent back to New York for tests. He is scheduled to undergo surgery today.

The 41-year-old left fielder is expected to resume baseball activities in four to six weeks, making it likely he’ll be sidelined for at least most of April.

Alou batted .341 with 13 home runs and 49 RBIs in 328 at-bats last season, when he was limited to 87 games because of a quadriceps injury. Now, six of New York’s eight regulars are sidelined, plus one member of the rotation — and it’s still early in spring training.

Remember all that excitement and bravado after Johan Santana was acquired from Minnesota last month? With the best pitcher in baseball suddenly on their side, the star-studded Mets were supposed to be NL favorites.

But age is becoming a major question mark for this team, which might be too injury-prone to win.

“I myself have never seen so many injuries at one time,” general manager Omar Minaya said. “The good thing is it’s early in camp.”