Weed tree, trash tree, table-eating tree, time to step back!
Cutting back the invading box elder from the work table, using antique garden shears, the best tool I have at hand, seems kind of brutal, but this is tiny farming. The whole idea is to direct some space, some land, to your liking. It is kind of militaristic in nature, there’s no getting away from that! Take over, suppress what you don’t want, install what you do, and hunker down to maintain position. I’m kidding, of course, actually thinking about farming and gardening in those stark terms is stressful, not useful or fun. IMHO, you layer on your story to suit the situation, and do what you have to do.
The garden shears only work well on the pencil-thick still-green upper stems, but that’ll do for now. Loppers—lopping shears, with long leveraging handles—would be perfect here, the tool for the job, though at the base this tree is probably a little past even them. So then, a pruning saw. I have neither, so a real saw, a sharp pocket knife, and some bending and twisting may be involved for a decent cutback. Or, much as I don’t want to invest in a box elder battle, I’ll get ahold of a pruning saw. I wonder how much the roots can expand, year after year, without any leaves to feed them…