A Few Important Hints It goes without saying that to prune the proper way requires a basic knowledge of the anatomy, biology and, yes, mechanics of that living being - the tree. Otherwise you will have weakened, diseased and, later on, hazardous, pest infected trees.
TIPPING, means removing the tips all the way around the tree; remember that this also implies removing proteins or the precursors.
TOPPING, as it often is practiced is really mutilation. We starve the roots when we remove the tops which supply their FOOD. This may later lead to root rot.
POLLARDING, mean establishing the framework i.e. the size and shape of a tree. This has to be begun when the tree is young and repeated yearly by removing the sprouts without injuring the swollen areas and without leaving a stub. It is not only tree care, it is an art and avoids later improper tipping or topping. Appropriate SHAPING involves removal of crossing branches within the crown and the pruning of V-crotches i.e. removal of the lesser limb of the V and preservation of the dominant one. This avoids later "including of the bark", a site for wound infection.
This leads us to the concepts of DOSE, TIMING and NATURAL TARGETS. Just as you can only add an appropriate amount of water and elements, there is also an appropriate amount , a dose, of tree which you can remove at a given time. A young tree with its very thin periderm and cortex can be pruned a hundred percent i.e. close to the ground, as is done in nurseries. A sprout from a new site will then grow from the stump. There is no dead wood shedding in a young tree but as the tree matures only the dead wood should be removed. Natural targets such as the branch collars should be left in place without leaving a stub.
The fact that there are three crowns to a tree adjusts it to the weather. The innermost crown functions when it is hot, and the outermost when it is cool. And then there is an intermediate zone. Thus one should be aware of the possibility of overpruning, the real reason for what is often called sun scold, frost cracks, pests and lightening.
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