Hurricane Irma plundered Florida’s orange belt, leaving a trail of uprooted trees, downed fruit and flooded groves worse than anything growers say they have seen in more than 20 years. It could even be the knock-out blow for a product — orange juice — that has been slipping in popularity among Americans, although the beverage still ranks as the country’s favorite fruit. The most recent estimates of the widespread damage to Florida’s orange trees put the statewide losses as high as 70 percent.