Berries are commonly sold in pints and occasionally quarts here in NE USA so they may be sold in gallons as well. Recipes sometimes uses these 'liquid' measure as well. 3 gal x 3/4 = 9 pints or 2 gals, 1 pint---assuming direct comparison.
In my part of North Shore Long Island, mulberry trees grew occasionally curbside and when people parked their cars under them their only recourse, when it was time to pick up their commuter husbands at the rail station, was to drive, semi-blindly, to Stan Buckowski's Mobil station, where I, teenage pump jockey, had to laboriously scrub dozens of windshields--"Right now or I'll be late!"--lickety-split or jiggety-jig. They almost never tipped. God, I hated mulberry trees.