Even if his nickname were changed to “Grandpa Smurf,” the feds say a reputed Genovese wise guy still belongs behind bars.

Prosecutors have asked Manhattan federal Judge Kevin Castel not to be swayed by the age card being played by mobbed-up garbage carter Carmine “Papa Smurf” Franco, 78, insisting he get just less than three years in prison for being the ringleader of a multifamily organized-crime effort to control New York and North Jersey’s waste-hauling industry.

As The Post reported last week, the geriatric goodfella is hoping his “advanced age,” laundry list of health ailments and need to care for his ill wife will convince the judge to let him do community service at a New Jersey church as a substitute for the prison time he agreed to when pleading guilty to racketeering and other criminal charges last November.

But Assistant US Attorney Brian Blais said in the government’s sentencing request Friday that “Franco, through his conduct, has shown that advanced age, of itself, has not prevented him from engaging in criminal conduct.”