Crotch angles. Yup, that’s a phrase fruit tree growers use, and i certainly giggle when i say it…it refers to the angle of the main branching relative to the central trunk. I’m shaping me trees to have an open center, where the central trunk stops 3 feet up and there are 4 main branches radiating from the top of that. This allows more light and air to get to the center of the tree, yielding more fruit and less disease (molds).
The risk of having “steep” crotch angles, or more vertical branching, is that, the branch can split from the main trunk when loaded with fruit. Especially when the tree is larger and heavily baring, there can be tens of pounds of apples. Apply that force at 4 or 5 feet from the trunk, and you have the potential to literally split the trunk in 4! The branch peels down, taking a strip bark with it, and you could loose the whole tree.
One of the simplest ways to deal with this is establishing good tree structure early on, using clothes pins. Talk about old school! Simply put a fews clothespin at the end of the branch, and the weight will pull them down to a “wide” crotch angle. Leave them on for a month or two, and the sapwood will stiffen into that position. This is what my new apple tree looks like now (i’ll be pruning the lowest branches off this winter, as they will touch the ground when fruiting):
Make sure that the pins are not pinching the branch, as you will damage the bark and stunt it’s growth. The pins are great because it allows the tree to sway- versus staking the branches to guy lines in the ground- potentially damaging the tree should heavy winds come along. If the branches are more established, guy lines will be in order, which i’ll have to do with my 3 year old tree. Keep those crotch angles wide!