Q.Half My Lemon Tree Is Unproductive. Should I Prune The Barren Branches?
It seems a fruit-bearing tree was grafted onto stock that is completely barren of blossoms or fruit. The unproductive branches, however, are producing most of the growth and height gains. If I cut them back, will the tree devote more energy to fruit? Will the barren growth ever yield fruit?

Certified GKH Gardening Expert
If the barren branches are dead, you need to prune them off. You can tell by scratching off the top layer of bark. If it is green underneath it is still alive. If it is white or gray, you can cut them off at the branch collar.
If the branches are coming from the rootstock (below where the graft is), they need to be removed. They may have taken over your tree which is not good. Whenever you see a branch growing from below the graft, it needs to be removed as soon as possible.
https://www.gardeningknowhow.com/edible/fruits/lemons/suckers-on-lemon-trees.htm
https://www.gardeningknowhow.com/edible/fruits/lemons/how-to-grow-a-lemon-tree.htm
https://www.gardeningknowhow.com/edible/fruits/lemons/lemon-tree-not-fruiting.htm