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Reduction Cuts

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A reduction cut reduces the length of a stem or branch by removing the terminal portion back to a living lateral branch of equal or smaller diameter. The cut should be made just beyond a lateral branch that is large enough to prevent excessive death of sapwood, decay, or visible bark death. This size varies with species, but should be no less than one-third the diameter of the cut stem; the preferred minimum is one-half the diameter.

Traditionally the cut was executed by bissecting the angle between the branch bark ridge and an imaginary line perpendicular to the stem to be removed. However, recent research found decay was less when wound diameter was small (Dujesiefken 2002; Gilman and Grabosky 2007), suggesting a cut that makes a smaller wound.

Do not cut parallel to the branch bark ridge because this exposes too much wood surface area, results in more decay, and can create a weak point. The objective is to find a cut angle and position that minimizes surface area of the cut as well as bark and cambium dieback behind or under the pruning cut. This can depend on species, time of year, and factors we do not fully understand such as temperature and presence of decay-causing fungi. The arborist has just made a reduction cut on the elm shown to the right. More

Making a reduction cut
A reduction cut was made on the left stem Sprouts emerging behind a reduction cut

Removing the larger of two stems is a reduction cut.

Sprouts that emerge from behind a reduction cut are of no concern. Sprouts are a normal reaction and will help close the wound.

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