so @Jenna1 , below is a jujube lateral segment. The segment below spanning X to X.
jujubes are the easiest species to espalier as the stems are initially bendy and can grow up to 4 feet long, and they are typically borne perpendicular to the main trunk. They literally espalier on their own as uprights develop from the laterals and capable of developing at the most distal nodes. On photo below, the upright stem labeled as B is more proximal to the main trunk, so it obviously gets the lions share of sap. Generally speaking, if there are several uprights borne on a lateral, the upright most proximal to the trunk will be the most robust, and in this photo, it has practically taken over as shown by the girth of the segment from base of B towards the trunk is quite thick, whereas the lateral segment distal to base B(depicted by yellow arrow) has lagged in bulking up and quite spindly. If i wanted to impart ‘physiologic relevance’ to the lagging segment(the distal segment), all i really need to do is decapitate B and radically prune or de-node the rest of the tree and just let the nodes on upright A to grow. Ultimately the distal segment would get thicker as the upright stem finally gets the lion’s share of sap. This is what i meant by “leaf out or die”, because the tree will be obliged to grow more leaves and stems where there are viable nodes, and if the only viable nodes are at the tips of the laterals, the tree will have to develop . Jujubes are fairly related to apples, but even if they are not, if you look at the shoots growing along the lengths of OP’s laterals, the most robust ones are closest to the main trunk. By pruning those proximal shoots radically, the tree will be obliged to develop new growth at the distal segments of the laterals, which would then further thicken the entire lateral and impart the seasoned, muscular appearance
and below is another example of a jujube tree espaliering on its own. It is not too visible because there are so many other branches of neighboring trees, but the lateral segment spanned from X to X is 3.5 feet long and is borne at a right angle to the trunk. Can make it longer by decapitating the sole upright on it to let the distal segment develop, or simply cut the distal segment and just bend that upright down and splint it with the lateral, to make the lateral even longer and in a straight line. Anyway, below photo again exemplifies the need to keep an eye on active shoots(on laterals) growing close to the trunk. If we leave them to their own devices, the lateral segment distal to the bases of said shoots will regress(segment of lateral depicted by yellow arrow)
