D&C 24
To the early saints, the Lord instructed -
"For thou art called to prune my vineyard with a mighty pruning, yea, even for the last time; yea, and also all those whom thou hast ordained, and they shall do even according to this pattern..." (Doctrine and Covenants 24:19)
In my mind, the pruning of the vineyard as described in Jacob 5 is cutting off branches that produce bad fruit, or teach false doctrine and untruths.