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When pruning thicker material with a chainsaw it is the accepted practice to make a cut sloping up to the branch bark ridge if one exists. | |
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It may be necessary in some instances to form a single stem from a forked union. | |
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This would involve a large wound which would attract fungal attack and possibly destroy the tree. The implications of such risks in common species may not be too critical. However, it may be a rare exotic which must be preserved at all costs: what then? |
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The method to employ here is to reduce the leaf area over several years on the part to be removed. This will limit the photosynthetic process in that branch or stem, and therefore avoid large wounds near the union. |
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It may take several years for the other stem to become dominant, but as the crown develops it will shade out
the inferior stem to the extent that it serves no further use for the plant's survival. The Sun's rays cannot reach the chlorophyll in the leaves to convert the carbon dioxide and water into carbohydrates. During the process of storing the Sun's energy in the form of carbohydrates, transpiration takes place releasing oxygen into the atmosphere. Once the desired stem has taken over the role of storing energy for survival, the stem which has no further function has been busy building up a barrier zone at the union and forming a pronounced collar which is compartmentalised, ready for total removal with minimal risks. Illustrated at left, the former dominant shoot on the right of the Azara microphylla was reversed by using this method. |
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When a union is seen to have a crease instead of a branch bark ridge, it is an indication that there is included bark. Included bark unions usually separate as the stem or limb gets heavier, therefore early formative pruning is preferred. |