It takes a little practice to start recognising these points, but once you get the put up of it, you will never do a bad pruning job again. You will also notice that the final pruning cut looks right and the job is finished. Another thing you will start noticing is all the bad pruning jobs around. You will be amazed and surprised at how forgiving trees are. There is another cause to follow these two procedures, and that is, if you do, you will release the natural chemicals in the tree (that I call antiseptics) that seals the wound and deal with off bacteria, fungi and attacking insects. Just behind the collar is where all these chemicals are stored, and they are released as soon as the wound is made. That is why flush cuts are so bad, because they cut off the collar, removing the antiseptic agents.
Pruning trees is an ability and a necessary one to learn because if you do it incorrectly, you can severely limit the life of the tree. Trees are magnificent and a little understanding their biology will help you manage them properly. Trees can not heal themselves as we do when we cut our skin. When a tree is wounded, the tissue does not repair itself, it does not heal, and instead, the trees reaction is to seal the wound. Two things happen, the damaged area is compartmentalised, and a barrier zone is created around the wound. Trees do not heal from the inside, rather callus tissue forms on the outside at the sides of the wound, and the new wood eventually grows over, sealing it off from pathogens. This method has only been famous in different countries for about the last 20 years, but it is a giant leap in the understanding of how trees react to being wounded. All pruning creates a wound, and the idea is to create the smallest one possible. Previously, we did not understand this and consequently many trees died unnecessarily early from poor pruning techniques, the flush cut being the main culprit. It creates a huge wound, and many of Melbourne’s street trees were flush cut in the early days, and consequently, these huge wounds came to be contaminated with fungi, bacteria, and insects. They had no natural defences, as they had been removed in the flush cut.
If you are willing to prune a branch off a tree, the 1st thing you do is try and locate the tree pruning saw. It is a swelling near the base of the branch near where the branch joins the trunk. Sometimes they are subtle and really difficult to find. It is the focal point where trees will inherently shed a limb from. If you find it, use it as an overview to prune off the branch. Instead, you use it as a guide. With your pruning saw you remove the branch following the line of the collar about 5 – 10cm (1/2 an inch) out from it. Don’t worry if you can’t find it because you can use the BBR method to remove the limb. The BBR is the tissue, which separates the branch from the main stem and it forms what I call wrinkles between the branch and the trunk. All trees have a collar, but with some species like Magnolia grandiflora, the BBR is easy to find, whereas others like Eucalypts sp. are really hard to find. When you find the BBR, operate out a 45 degree away from the BBR, and that is the spot where you start cutting. Pruning trees are risky especially if you are pruning high up. Realistically, tree pruning is for the qualified arborists who are trained people who manage and understand how to prune trees correctly. They know how to handle their equipment properly and how to climb trees safely. For any pruning jobs above your head, I suggest you hire an arborist. If you do it yourself create sure your ladder is firmly affixed to the ground and you do not take risks. Qualified arborists should only use chainsaws. They are very dangerous in the hands of amateurs. There are many cowboys out there, so beware of people claiming to be tree surgeons. When you are engaging an arborist to ask to see their qualifications if they have personal and property insurance and whether they understand the Branch Bark Ridge (BBR) technique. If they appear at you blankly on the third question, It is the correct technique used today for pruning divisions off trees.