|
|
|
Where to prune: natural target pruning
Cuts that are flush with the trunk open the sapwood to invasive
pathogens and reduce the ability of the tree to compartmentalise
decay. Based on his experience and model of decay, Alex Shigo
promoted an approach called Natural Target Pruning (NTP) which
is done in steps (refer to photos below).
1. Locate the branch bark ridge (BBR)
2. Find target A—outside BBR
3. Find target B—where branch meets collar
4. If B cannot be found, drop an imaginary line at AX. Angle
XAC equals XAB.
5. Cut along line AB
.jpg)
Natural target pruning of Pinus radiata
(top),
Casuarina cunninghamiana and Eucalyttus nitens using loppers.
Large branches should first be cut well
out from the stem to reduce their weight. If using a saw,
first undercut the branch to eliminate the risk of bark stripping.
Branches less than about 2.5 centimetres in diameter can be
cut in a single action with loppers. Even slight damage to
the branch collar of Eucalyptus.
nitens at the time of pruning slows
recovery and increases the possibility of decay.
Queensland kauri pine (Agathis
robusta) is one species in which
quite large live branch stubs are eventually ejected cleanly
from the stem. Unless diameter growth is very rapid, the stubs
will be ejected cleanly. This suggests that pruning might
only require cutting the branches back to 10 or 20 centimetres.
Large branches should be cut as normal.
If the collar is not damaged the wound will heal quickly and
evenly with the callus forming a doughnut shape as it grows
over the stub.
.jpg)
The healing process following natural target
pruning of black walnut showing the formation of the doughnut
indicating there was no damage to the collar.
Back to top
|
