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Horticulture Principles and Practices

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Rejuvenation<br />

Pruning<br />

Cut canes to<br />

about 6 inches<br />

above ground<br />

FIGURE 19–9 Renewal pruning<br />

<strong>and</strong> rejuvenation.<br />

Renewal<br />

pruning<br />

Before<br />

Remove 1/3 of<br />

shrub canes<br />

FIGURE 19–10 Renewal pruning<br />

of an old tree removes old<br />

<strong>and</strong> unproductive or damaged<br />

branches <strong>and</strong> heads back limbs to<br />

encourage new growth.<br />

Cut away<br />

in the process. Homeowners who request or undertake this procedure themselves feel their<br />

trees are overgrown <strong>and</strong> pose a hazard. Because of the severe reduction in the canopy, the<br />

tree is deprived of most of its photosynthetic surface, leading to stress from inadequate<br />

food supply. The tree trunk is weakened <strong>and</strong> predisposed to disease <strong>and</strong> insect attack, as<br />

well as bark splitting from sunburn. The stubs are prone to decay <strong>and</strong> also produce many<br />

rapidly growing weak new shoots. Topping reduces the life of the tree <strong>and</strong> is expensive,<br />

since a weakened tree is prone to weather-related damage <strong>and</strong> often needs pruning after<br />

a few years.<br />

19.8 PRUNING ROOTS<br />

Unlike the pruning of aboveground plant parts done as part of the plant management<br />

operation, roots are pruned once during the plant establishment process. Roots of large<br />

plants are pruned immediately or shortly before transplanting (Figure 19–11). If pruned<br />

long before transplanting, the roots have the opportunity to develop a new mass of<br />

secondary roots for better establishment when transplanted. Sometimes pruning is<br />

necessary to reduce the root size in order to fit the hole for transplanting. Tractormounted<br />

mechanical root pruners are used by large commercial nurseries that produce<br />

<strong>and</strong> sell large plants.<br />

19.8 Pruning Roots 579

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