docs\lectsupl\Pruning\pruning

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PRUNING TERMINOLOGY AND OBJECTIVES

TERMINOLOGY
pruning- removal of plant parts, branches, shoot tips, buds, roots, etc.
dehorning - heavy drastic pruning of large limbs; should be avoided at all times;
                    also called pollarding.
thinning out - removal of branches back to their point of origin.
    Used to:
    1) decrease density of the canopy
    2) encourage other branches to grow and rejuvenate plant
    3) redirect growth
heading back - removal of the terminal portions of a branch.
    Used to:
    1) increase density of the canopy
    2) encourage branching
pinching - removal of the young, succulent tips of shoots.
hedging - removal of growth flushes on hedges or shrubs to shape canopy and induce
                dense growth.
disbudding - removal of excessive flower buds on flowering pot plants.
root pruning - pruning of roots, usually with a shovel, to prepare plants for transplanting.

OBJECTIVES OF PRUNING
1) Health and safety
2) Maintain desired form
3) Dwarfing
4) Invigoration
5) Increase productivity
6) Equalize root/shoot ratio
7) Develop strong branch framework

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PRUNING METHODS

SPECIALTY, NOVELTY OR ORNAMENTAL PRUNING
topiary - pruning to produce a 3-dimensional design or form.
espalier - pruning to produce a 2-dimensional design or form.

WIDE (Y) VERSUS NARROW (V) CROTCH ANGLES

Wide (Y) Crotch Angle
very strong, select for when pruning

Narrow (V) Crotch Angle
very weak, selectively prune-out
see example

CORRECT METHOD TO PRUNE A BRANCH
Called Target Pruning (click for more detail)

incorrect method

correct method for
wide crotch angle
(click on image for animated version)

correct method for
narrow crotch angle

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FACTORS TO CONSIDER ON WHEN TO PRUNE

1) Growth State: best when inactive or dormant

2) Susceptibility to winter injury: for plants easily damaged by winter freezes

prune after cold of winter.
remove all winter killed tissue.

you may need to allow some spring growth to tell if tissue is dead or not.

3) Time of flower bud formation on flowering plants:

a) spring flowering plants:

flower on last years growth (2 year old wood); i.e. flower buds present since last summer or fall.
therefore, prune right after flowering in spring and before new buds form.

b) summer or fall flowering plants:

flower on current years growth (1 year old wood); i.e. flower buds form on new growth of current year.
therefore, prune fall, winter or early spring, but best to prune after cold of winter and before new growth starts in spring.

4) Transplanting: pruning should be to equalize root/shoot ratio, thus, decrease transplanting shock.

To equalize root/shoot ratio:

a) thin-out immediately after or at the time of transplanting

b) root prune before transplanting (months to years).

CHEMICAL PINCHING AGENTS
Chemicals that selectively kill or disrupt shoot tips to remove apical dominance.
1) Atrinal
2) Off-Shoot-0
3) Maleic hydrazide
4) Emgard 2007