encouraging growth in specific areas

[Shills]

Hi there,

I wanted to pick your brains on best ways for encouraging growth in spots we want it.

I haven’t got a lot of experience in this area as I’ve only recently started working on shaping my tree, other than just growing it and trunk chopping it.

I have made a poor illustration of what I mean. The red part is the smaller trunk/branch we might want to encourage because it is too small

For a forked trunk/branch, if one of the trunks/branch needs to be grown much more because it is not a leader as such, I can:
• prune back the dominant one and leave alone the smaller one until it becomes the leader
• shade the dominant one so that the smaller one gets more light, or similarly give the small one more light so it grows more.
• Defoliate the dominant one so the smaller one is more productive and would then become the leader.

Are these ideas likely methods? Are there other better ways to encourage growth in certain areas? Is it even possible to make a plant switch leaders that easily?

Hoped that made sense and I appreciate any advice. Thanks.

[Ryceman3]

I’ll ask the obvious question... what kind of tree are you referring to?
Looking at your profile, I’ll bet a maple - but just for clarity!
The process will change depending. Developing conifers for example will require different thinking than deciduous.

[Shills]

sorry. yes it is a trident maple.

[shibui]

It does not really matter what sort of tree you are growing. Most trees are similar in growth. Areas with more resources grow faster and stronger than parts with fewer.
The more leaves a section has the more it will grow Fewer leaves means less growth. Less light means less growth.
Trees also put in more effort in some areas - usually upper and outer areas so top branches almost always grow faster than lower ones.

The strategies you have outlined would all work. In practice it is hard to shade one section so I have always used pruning and defoliation to encourage growth in slower branches.
Repeatedly trim the strong section. That will help reduce the auxins produced by apical buds and the tree will throw more resources to the other branch as it grows. Let the weaker one grow untrimmed for a season or until it looks like it has reached the desired thickness. Allowing free growth is where you may need to differ in trees that don't bud on bare wood - pines, etc. You may also need to monitor changes in deciduous like maples. If really long internodes develop in new growth you will need to remove them at some stage.

Defoliating the strong section can also help but defoliation too often can weaken the tree so use some discretion. We don't need to do complete defoliation to achieve a result. Removing say half the leaves on the stronger area will make a difference. We do similar on pines when we needle pluck in autumn, leaving a few more needles on the weakest shoots and less on stronger ones.

I do not know anything that will make an instant difference in relative size of the branches. You may need to keep repeating the treatments for several years. It won't happen overnight but it will happen.