“Pruning properly done is one of the most difficult tree treatments. Every branch will be different…Rules are too absolute for Mother Nature.” (Dr. Alex Shigo, A New Tree Biology). It’s possible to rely too much on the “1/3 Rule” as a criterion for deciding how far back to reduce a branch or stem. Some call this Natural Target Pruning, and criticize any cut to a smaller lateral as a topping cut. It is time for this anti-topping passion to cool, and look at the 1/3 guideline in the larger context. Laterals are also selected for vitality, health, exposure, and angle of attachment. A larger lateral may not be a good choice if it is weak, diseased, shaded, or growing in the wrong direction.
Nodes are Natural Targets
In A New Tree Biology Dictionary Dr. Shigo tells us, “Pruning cuts that are made at nodes cause less injury than cuts made at internodes…A node is the position on a stem or trunk that was occupied by the terminal bud and its associated buds.” “Topping is done internodal; proper crown reduction is done at nodes, or at crotches. So the first separation must be nodes—good, internodes—bad.” (A New Tree Biology, p. 458) Dormant buds in these nodes were formed long before, and have a vascular connection to the cambium. The adventitious growth from these preformed buds can result in strong new branches, unlike the adventitious growth that originates from newly formed, adventitious buds.
Pic #1 is of a dormant bud visible on the outside of a red oak tem. Pic #2 is an inside shot of the same spot, showing a pith trail embraced by compacted xylem. Tropical and semi-tropical species do not have such well-defined nodes, perhaps because their growing seasons are not as well-defined. On any tree, laterals are of course preferred pruning targets. Leaving stubs is an option when branches are broken and there are no laterals left.
If you see dormant buds at nodes in your area's trees, please slice them at that point to expose pith trails and post the pictures. If they are used in the ongoing research project, you will get attribution. Below pictures taken by Jim Scarlata, Manistee MI.
Nodes are Natural Targets
In A New Tree Biology Dictionary Dr. Shigo tells us, “Pruning cuts that are made at nodes cause less injury than cuts made at internodes…A node is the position on a stem or trunk that was occupied by the terminal bud and its associated buds.” “Topping is done internodal; proper crown reduction is done at nodes, or at crotches. So the first separation must be nodes—good, internodes—bad.” (A New Tree Biology, p. 458) Dormant buds in these nodes were formed long before, and have a vascular connection to the cambium. The adventitious growth from these preformed buds can result in strong new branches, unlike the adventitious growth that originates from newly formed, adventitious buds.
Pic #1 is of a dormant bud visible on the outside of a red oak tem. Pic #2 is an inside shot of the same spot, showing a pith trail embraced by compacted xylem. Tropical and semi-tropical species do not have such well-defined nodes, perhaps because their growing seasons are not as well-defined. On any tree, laterals are of course preferred pruning targets. Leaving stubs is an option when branches are broken and there are no laterals left.
If you see dormant buds at nodes in your area's trees, please slice them at that point to expose pith trails and post the pictures. If they are used in the ongoing research project, you will get attribution. Below pictures taken by Jim Scarlata, Manistee MI.
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