09.04.2018 Views

Horticulture Principles and Practices

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

(a)<br />

Cut<br />

Prune<br />

(b)<br />

FIGURE 19–16<br />

Steps in the development of artificial multistem tree form.<br />

FIGURE 19–17 Developing heading<br />

height of trees. (a) Low heading<br />

height <strong>and</strong> (b) high heading height.<br />

19.11 MAINTENANCE OF ESTABLISHED TREES<br />

Once established, ornamental trees need occasional pruning to remove unwanted<br />

growth, correct growth, or repair damage. Specific pruning activities include those<br />

described in the following sections.<br />

19.11.1 REMOVING SHOOTS<br />

A tree has dormant buds under its bark that may be stimulated to produce shoots on the stem.<br />

These shoots are called epicormic shoots (or water sprouts or water shoots). They are undesirable<br />

because they deplete plants of food <strong>and</strong> also distract from the tree’s form <strong>and</strong> general<br />

attractiveness. Sometimes shoots arise from the roots of adult trees such as aspen<br />

(Populus tremula) as part of their natural development. Suckers may arise when certain<br />

plants such as black poplar (Poplar nigra) are wounded. These shoots should be removed.<br />

19.11.2 REPAIRING DAMAGE<br />

Trees in the l<strong>and</strong>scape may suffer damage from a variety of sources. Lightning, strong<br />

winds, hail, ice, <strong>and</strong> other weather-related damage may occur. Humans may v<strong>and</strong>alize <strong>and</strong><br />

l<strong>and</strong>scape maintenance equipment physically damage trees. Animals in the l<strong>and</strong>scape may<br />

also cause injury. Broken branches <strong>and</strong> torn barks need to be repaired by cutting them away.<br />

Epicormic Shoots<br />

Shoots that develop from<br />

previously dormant buds<br />

under tree bark after being<br />

stimulated by external<br />

factors such as wounding.<br />

19.11.3 REMOVING DISEASED BRANCHES<br />

Deadwood provides a hiding place for insects <strong>and</strong> tissue for disease organisms including<br />

fungi. Any diseased branches should be removed.<br />

19.11.4 PROVIDING PHYSICAL SUPPORT<br />

Sometimes tree branches become excessively inclined <strong>and</strong> need to be physically propped<br />

up to avoid snapping (Figure 19–18). Propping with a forked branch may help to enhance<br />

the appearance of a tree by improving its form.<br />

19.11 Maintenance of Established Trees 583

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!