The secondary is the branching that is inbetween the primary branch and the tertiary branches.
The Primary Branches are the structure of the tree. These are the largest branches that emerge from the trunk. They will set the overall mood of the tree and support all that is above.
The Secondary Branches are the branches that emerge from the primaries. These branches define the shape of the tree. They may be longer on one side and shorter on the other. They may be used as counterbalances and will offer support for the canopy.
The Tertiary Branches are those that emerge from the secondaries. These are also called the ramification of the tree.
I wish to talk about the secondaries because I feel this is the most important, and most often over looked part of the tree building process. It is also the most misunderstood. It is misunderstood because people do not take the necessary time to actualy build the proper secondaries. Building this part of the tree requires time and patience to build proper secondaries. It take as much or possibly more chops to make a good branch. It requires growing and chopping but also need timing to include important buds back close to each chop to help ramify the branch later. Allowing the branch to grow unhindered will increase girth of the branch, but internodes will be long and taper will be little.
In this photo, the primaries are in red, the secondaries in blue and the teriary in orange.
A proper secondary will also look natural and will be achieved thru proper use of directional pruning. Wireing on trident maples will give it an unnatural look and should only be used to force primary branches to a proper place while allowing directional pruning to achieve branch directions in the secondaries. Wire is sometimes used to help coax a secodary into a position to help fill a void in the canopy.
Secondaries are built up over seasons. Typically it takes about three seasons to get a trident to the point of beginning to put on the final ramification. This may be thought of stage one, stage two and stage three.
It is important that when building the secondaries to pinch out the first buds in spring to capture a second budding very close to the base of the previous years growth. This insures that future chopbacks will always have viable buds with which to cut back to. This small branch sticking above is a sacrifice to keep the branch growiung strong. It will be cut off later. Notice how the buds are close to the base of the branch so that later when that first section reaches the correct size, I can cut back to that point, make a directional change, retain a side branch and grow the branch on with the other bud.
here is an example of wiring a branch and introducing unatural beands to capture movement. It does not ammter right now since all of this will be cut off later and only the basel extension will be retained.
Another case of retaining a branch to use as a sacrifice.
This branch is ready to be cut back. It has extended and the branch has reached the proper size. The wire is there to keep the branches from crossing. They were all over the place prior to the wire. No movement has been put in, just keeping them in the proper place. the next season will incur directional pruning.