The things that stand out in winter...!
1) A tree trimming crew is coming to prune the fir in my back yard, which lost its top to borers. I'm giving the crew pictures from your Trees magazine, about how to establish a new leader, to give the tree a new pointy tip rather than a flat top. We did that at your workshop but I have to give the crew the picture because I can't go up on the ladder to show them how, or I don't think they will let me anyway.
2) Well, the top is off my spruce, and wow, can you see the holes made by the borer! It ended up with one side shoot that might become the new leader. The tree company wanted to trim it off with the pole pruner but I said NO.
Will that branch take over eventually? It looks funny at this time, but so what. - M.M. -
Great photos, M.M. -- they really tell the tale. (All photographs on this page ©2012 M.M. c/o this website)
We think that tip will turn up and turn into a good new leader. It could have been started on its way with some temporary support to train it upright but we think you'll see it turn vertical so quickly in spring it'll make your eyes pop.
Firs and spruces are pretty good at recovering from borer damage. Check out a demonstration of their recovery power, in the 45 mph department.
The highest point on a tree begins growing first in spring and is able to regulate growth in cells below so that none match its speed or overall extension. This is called apical dominance and it's at work in any plant but particularly strong in fir and spruce. It's the force that keeps those pyramidal evergreens in shape. It will be in effect on this tree in spring.
A gardener can encourage and direct this natural re-shaping by giving an advantage to a particular branch.
Consider M.M.'s fir top at left as in the diagram on the page Train a new leader. You could strap a cane to the trunk to extend it vertically. Tie the chosen limb to that cane to keep the growing tip in a higher plane than any others. Tie loosely and use cotton cord as you strap the cane and train the branch, so that year's growth won't be girdled and ties will rot away before causing trouble.
In addition, shorten competing or potentially competing leaders. If a tip of a side branch is in or very near the plane of the selected tip, it can become a co-dominant leader. Multiple tops will develop. Those tops will have a higher risk of splitting away from each other as weight builds above their points of attachment to the trunk. They are also likely to deform the tree's shape.
All the side branches on this fir look to be well below the new tip's level. Good! But keep an eye on them and have a pole pruner ready to reach up and nip off any that turn up to give your chosen tip a run for its money.