HISTORY OF TREE PRUNING PROBLEMS
Pruning of trees is one of the oldest plant treatments. Man pruned trees to regulate size and shape and to improve the quantity and quality of flowers, fruit, and timber and to provide shade and windbreaks. These treatments were for the benefit of man.
Hundreds of books and scientific papers have been written on pruning. If so much information exist, why then do we see so much improper pruning? Here are some possible reasons.
Tree pruning developed as four independent practices, for gardens, orchards, forests, and bonsai.
Garden trees were pruned to regulate size and shape, and to increase flower quantity and beauty. Garden pruning gave us topiary, espalier, pleaching, and pollarding. These pruning practices took a great deal of time and skill, and they had to be repeated frequently.
Orchard pruning was done to increase the quantity and quality of fruit and to facilitate harvesting.
Forest tree pruning was done to improve the quality of wood for products. (Note: flush cuts were made at this time thus reducing the quality of the products desired.) Forest tree pruning was also done to maintain the quality of fast-growing trees that were planted far apart. When trees are planted far apart, they grow faster, but lower branches stay alive longer. The large lower branches had to be pruned. They thought making flush cuts would provide all good product. When decay was the result, rather than making adjustments to the pruning targets the race for the best wound dressing began to stop the decay.
Bonsai was done to regulate size and shape to an extreme. Now, when a house developer carves homesites into a forest, the homeowner wants trees in the garden, fruit trees behind the house, a bonsai on the patio, a windbreak of forest trees, and fast growing trees near the house and power lines.
THE CONFUSION STARTS
The homeowner remembers seeing pollarding and topiary in pruning books. Why not do the same to the forest trees and the fruit trees? If small trees can be topped why not big trees? Then the big trees get mutilated. But the mutilation is called pollarding. The fruit trees and flowering trees get sheared and "rounded over" by pruning them as if they were shrubs or rose bushes.
The point. There have been very few, if any, tree pruning books that discuss pruning from the view of tree health first. People have seen too many books where trees are discussed along with shrubs, roses, and raspberries.
Another reason. For centuries people were told how to take branches off trees. It was not until 1985 that a scientific paper was published by Dr. Alex L. Shigo that explained how branches were attached to trees. As a result of this research, we now have a better understanding of the anatomy of branch attachment, and of the natural defense system in the base of the branch.
The point. Once you understand branch anatomy, you will know how to remove a branch properly.
Next reason. People knew that pruning caused wounds. And, wounds should "heal". "Callus"-woundwood-was considered a sign of wound "healing". The larger the pruning wound, the larger the "callus". The larger the wound, the larger the column of rot in the tree. But, now that they knew how to "heal" wounds, it was the responsibility of others to find a wound dressing to stop the rot. That dressing has not yet come.
And last. People think that because trees are so big and tough you can do anything to them and they will stay alive. There is still great confusion over what a tree will tolerate and what is beneficial for the tree. Some trees such as London plane, linden or lime, and willows will tolerate mutilation. This does not mean it is good for them.
The point. It is time to focus on tree health first. A healthy tree will provide much, for many, for a long time. (Source SHIGO CD's)
Suggested book on "Pruning".
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