CLASS II Pruning (aka Standard Pruning)
Posted In: Grounds Maintenance, How To
Pruning Standard for Class II Pruning
This standard, revised in 1989, is provided by the National Arborist Association to assist tree service companies, utilities, municipalities, etc. in writing contract specifications for tree pruning. It is not intended to be a “how-to” guide, but to define the limits and criteria for arboricultural work, recognizing that regional practices may dictate variations in this standard. It was prepared by the Standard Practices Committee of the National Arborist Association, Inc., a professional trade association founded in 1938
Standard pruning is recommended where aesthetic considerations are secondary to structural integrity and tree health concerns. Standard pruning shall consist of the removal of dead, dying, diseased, decaying, interfering, objectionable, obstructing and weak branches, as well as selective thinning to lessen wind resistance. The removal of such described branches is to include those on the main trunk, as well as those inside the leaf area. An occasional branch, up to one inch in diameter may remain within the main leaf area where it is not practical to remove it.
All cuts shall be made as close as possible to the trunk or parent limb, without cutting into the branch collar or leaving a protruding stub. Bark at the edge of all pruning cuts should remain firmly attached.
All branches to large to support with one hand shall be pre-cut to avoid splitting or tearing near the bark. Where necessary, ropes or other equipment should be used to lower large branches or stubs to the ground
Treatment of cuts and wounds with wound dressing or paints has not been shown to be effective in preventing or reducing decay, and it is not generally recommended for that reason. Wound dressing over infected wood may actually stimulate the decay process. If wounds are painted for cosmetic or other reasons, then materials non-toxic to the cambium layer of meristematic tissue must be used. Care must be taken to apply a thin coating of the material only to the exposed wood.
Old injuries are to be inspected. Those not closing properly and where callus growth is not already completely established should be bark traced if the bark appears loose or damaged. Such tracing shall not penetrate the xylem (sapwood), and margins shall be kept rounded.
Equipment that shall damage the bark and cambium layer should not be used on or in a tree, (spurs, hooks, irons). Sharp tools shall be used so that clean cuts will be made at all times.
All cut limbs shall be removed from the crown upon completion of the pruning.
Trees susceptible to serious infectious diseases should not be pruned at the time of year during which the pathogens causing the diseases or the insect vectors are most active. Similarly, if pruning wounds may attract harmful insects, pruning should be timed so as to avoid insect infestation.
The presence of any disease condition, fungus fruit bodies, decayed trunk or branches, split crotches or branches, cracks or other structural weakness should be addressed and corrective measures recommended to the owner.
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