Applebloom is harvesting zap apples with Applejack and Big Mac, when Applejack mentions their parents.

Applebloom then asks why she never met her parents, where are they, and what happened.

The three siblings go to Granny Smith, and she tells them about the Fate of their parents.

It was about 5 or 6 years ago, when Appebloom was just a filly. Big Mac smelled zap apple season coming, but from the beginning, he knew something was wrong.