WELLINGTON, New Zealand (AP) — When is a potato not a potato?

When it's a tuber of a gourd, according to Guinness World Records.

A New Zealand couple who believed they had dug up the world's largest potato in the garden of their small farm near Hamilton have had their dreams turned to mash after Guinness wrote to say that scientific testing had found it wasn't, in fact, a potato after all.

Colin Craig-Brown, who first hit the tuber with a hoe last August when gardening with his wife Donna, said it sure looked and tasted like a potato. Mind you, he added, he's never tasted a gourd tuber.

"What...